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Sample records for 140-ghz long-pulsed gyrotron

  1. Experimental results of the 140 GHz, 1 MW long-pulse gyrotron for W7-X

    Science.gov (United States)

    Koppenburg, K.; Arnold, A.; Borie, E.; Dammertz, G.; Giguet, E.; Heidinger, R.; Illy, S.; Kuntze, M.; Le Cloarec, G.; Legrand, F.; Leonhardt, W.; Lievin, C.; Neffe, G.; Piosczyk, B.; Schmid, M.; Thumm, M.

    2003-02-01

    Gyrotrons at high frequency with high output power are mainly developed for microwave heating and current drive in plasmas for thermonuclear fusion. For the stellarator Wendelstein 7-X now under construction at IPP Greifswald, Germany, a 10 MW ECRH system is foreseen. A 1 MW, 140 GHz long-pulse gyrotron has been designed and a pre-prototype (Maquette) has been constructed and tested in an European collaboration between FZK Karlsruhe, CRPP Lausanne, IPF Suttgart, IPP Greifswald, CEA Cadarache and TED Vélizy [1]. The cylindrical cavity is designed for operating in the TE28,8 mode. It is a standard tapered cavity with linear input downtaper and a non-linear uptaper. The diameter of the cylindrical part is 40.96 mm. The transitions between tapers and straight section are smoothly rounded to avoid mode conversion. The TE28,8-cavity mode is transformed to a Gaussian TEM0,0 output mode by a mode converter consisting of a rippled-wall waveguide launcher followed by a three mirror system. The output window uses a single, edge cooled CVD-diamond disk with an outer diameter of 106 mm, a window aperture of 88 mm and a thickness of 1.8 mm corresponding to four half wavelengths. The collector is at ground potential, and a depression voltage for energy recovery can be applied to the cavity and to the first two mirrors. Additional normal-conducting coils are employed to the collector in order to produce an axial magnetic field for sweeping the electron beam with a frequency of 7 Hz. A temperature limited magnetron injection gun without intermediate anode ( diode type ) is used. In short pulse operation at the design current of 40 A an output power of 1 MW could be achieved for an accelerating voltage of 82 kV without depression voltage and with a depression voltage of 25 kV an output power of 1.15 MW at an accelerating voltage of 84 kV has been measured. For these values an efficiency of 49% was obtained. At constant accelerating voltages, the output power did not change up to

  2. Velocity diagnostics of electron beams within a 140 GHz gyrotron

    International Nuclear Information System (INIS)

    Experimental measurements of the average axial velocity vparallel of the electron beam within the M.I.T. 140 GHz MW gyrotron have been performed. The method involves the simultaneous measurement of the radial electrostatic potential of the electron beam Vp and the beam current Ib. Vp is measured through the use of a capacitive probe installed near or within the gyrotron cavity, while Ib is measured with a previously installed Rogowski coil. Three capacitive probes have been designed and built, and two have operated within the gyrotron. The probe results are repeatable and consistent with theory. The measurements of vparallel and calculations of the corresponding transverse to longitudinal beam velocity ratio α = vperpendicular/vparallel at the cavity have been made at various gyrotron operation parameters. These measurements will provide insight into the causes of discrepancies between theoretical rf interaction efficiencies and experimental efficiencies obtained in experiments with the M.I.T. 140 GHz MW gyrotron. The expected values of vparallel and α are determined through the use of a computer code entitled EGUN. EGUN is used to model the cathode and anode regions of the gyrotron and it computes the trajectories and velocities of the electrons within the gyrotron. There is good correlation between the expected and measured values of α at low α, with the expected values from EGUN often falling within the standard errors of the measured values. 10 refs., 29 figs., 2 tabs

  3. Experimental results of the 1 MW, 140 GHz, CW gyrotron for W7-X

    International Nuclear Information System (INIS)

    A 10 MW ECRH system will be provided by FZK in collaboration with several European associations for the stellarator W7-X. The RF power will be delivered by 10 gyrotrons operating at 140 GHz in CW with 1 MW each. The development of this gyrotron has been performed within a European collaboration in an industrial frame. Two R and D tubes have been built, up to know one serial tube has been passed the acceptance tests. The design of the gyrotron will be described and short pulse and long pulse results of the first serial gyrotron will be discussed. This gyrotron has been successfully operated at more then 900 kW with a pulse length of 30 min. (author)

  4. Operational Characteristics of a 14-W 140-GHz Gyrotron for Dynamic Nuclear Polarization

    OpenAIRE

    Joye, Colin D.; Griffin, Robert G.; Hornstein, Melissa K.; Hu, Kan-Nian; Kreischer, Kenneth E.; Rosay, Melanie; Shapiro, Michael A; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Woskov, Paul P.

    2006-01-01

    The operating characteristics of a 140-GHz 14-W long pulse gyrotron are presented. The device is being used in dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) spectroscopy experiments. The gyrotron yields 14 W peak power at 139.65 GHz from the TE(0,3) operating mode using a 12.3-kV 25-mA electron beam. Additionally, up to 12 W peak has been observed in the TE(2,3) mode at 136.90 GHz. A series of mode converters transform the TE(0,3) operating mode to the TE(1,1) mod...

  5. Start current analysis of a 140 GHz CPI gyrotron

    Science.gov (United States)

    Yeddulla, M.; Nusinovich, G. S.; Antonsen, T. M.

    2003-12-01

    In a gyrotron, it is difficult to accurately predict in advance where the resonant interaction between the electrons and outgoing radiation stops. For accurately calculating the start currents for the interacting modes, the exit coordinate has to be fixed where the resonant interaction stops. This paper discusses the difficulty in fixing the exit coordinates for studying start currents in an overmoded gyrotron. Start currents are studied for the operating and the most dangerous parasitic mode of a 140 GHz gyrotron being developed by Communication and Power Industries (CPI). Calculations show that the start currents vary over considerably large values with varying exit coordinates that can cause difficulties in predicting which mode dominates the mode competition.

  6. 140 GHz gyrotron development program. Quarterly report No. 4, January-March 1985

    International Nuclear Information System (INIS)

    The objective of this program is to develop a gyrotron oscillator capable of producing 100 kW CW at 140 GHz. Further analysis of the electron guns, interaction cavity, and beam tunnel designs for the first two experimental tubes, Experimental Tube 1 and preprototype Tube 1, is presented. A window deflection tester has been built and initial deflection test results are given. The first 140 GHz gyrotron magnet has successfully passed the major points in the acceptance test. The detailed results of the magnet acceptance test are discussed. Progress concerning the fabrication of 149 GHz gyrotron components, diagnostics, and protective devices, as well as the status of Experimental Tube 1, are summarized

  7. Development and Preliminary Commissioning Results of a Long Pulse 140 GHz ECRH System on EAST Tokamak (Invited)

    Science.gov (United States)

    Xu, Handong; Wang, Xiaojie; Liu, Fukun; Zhang, Jian; Huang, Yiyun; Shan, Jiafang; Wu, Dajun; Hu, Huaichuan; Li, Bo; Li, Miaohui; Yang, Yong; Feng, Jianqiang; Xu, Weiye; Tang, Yunying; Wei, Wei; Xu, Liqing; Liu, Yong; Zhao, Hailin; Lohr, J.; A. Gorelov, Y.; P. Anderson, J.; Ma, Wendong; Wu, Zege; Wang, Jian; Zhang, Liyuan; Guo, Fei; Sun, Haozhang; Yan, Xinsheng; East Team

    2016-04-01

    A long pulse electron cyclotron resonance heating (ECRH) system has been developed to meet the requirements of steady-state operation for the EAST superconducting tokamak, and the first EC wave was successfully injected into plasma during the 2015 spring campaign. The system is mainly composed of four 140 GHz gyrotron systems, 4 ITER-Like transmission lines, 4 independent channel launchers and corresponding power supplies, a water cooling, control & inter-lock system etc. Each gyrotron is expected to deliver a maximum power of 1 MW and be operated at 100-1000 s pulse lengths. The No.1 and No.2 gyrotron systems have been installed. In the initial commissioning, a series of parameters of 1 MW 1 s, 900 kW 10 s, 800 kW 95 s and 650 kW 753 s have been demonstrated successfully on the No.1 gyrotron system based on calorimetric dummy load measurements. Significant plasma heating and MHD instability suppression effects were observed in EAST experiments. In addition, high confinement (H-mode) discharges triggered by ECRH were obtained. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2011GB102000, 2012GB103000 and 2015GB103000)

  8. Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW

    Energy Technology Data Exchange (ETDEWEB)

    Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.

    1986-12-01

    Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized.

  9. Recent operating experience with Varian 70 GHz and 140 GHz gyrotrons

    International Nuclear Information System (INIS)

    The design features and initial test results of Varian 70 GHz and 140 GHz CW gyrotrons are presented. The first experimental 140 GHz tube has achieved an output power of 102 kW at 24% efficiency under pulsed conditions in the desired TE0310 cavity mode. Further tests aimed at achieving the design goal of 100 kW CW are currently underway. The 70 GHz tube has achieved an output power of 200 kW under pulsed conditions and possesses a wide dynamic range for output power variations. 6 refs., 8 figs

  10. Installation and operation of the 400 kW 140 GHZ gyrotron on the MTX experiment

    International Nuclear Information System (INIS)

    This paper describes the installation and operation of the 400 kW 140 GHz gyrotron used for plasma heating on the Microwave Tokamak Experiment (MTX) at Lawrence Livermore National Laboratory (LLNL). The Varian VGT-8140 gyrotron has operated at a power level of 400 kW for 100 ms in conjunction with MTX plasma shots. The gyrotron system is comprised of a high voltage (- 80 kV) modulated power supply, a multistation CAMAC computer control, a 5-tesla superconducting magnet, a series of conventional copper magnets, a circulating fluorinert (FC75) window cooling system, a circulating oil cooling system, a water cooling system, and microwave frequency and power diagnostics. Additionally, a Vlasov launcher is used to convert the gyrotron TE 15,2 mode to a Gaussian beam. Two versions of the Vlasov launcher have been used on the gyrotron, one version designed by LLNL and one version designed by the Japan Atomic Energy Research Institute (JAERI). The Varian VGT-8140 gyrotron has been installed on the MTX tokamak experiment to provide electron cyclotron resonant heating (ECRH) of the tokamak plasma. The gyrotron has been operated with the tokamak for periods as long as 100 ms at power levels of 400 kW. he gyrotron will also be used as the RF driver for the intense microwave prototype (IMP) wiggler associated with the electron test accelerator (ETA). In this configuration, the IMP wiggler will produce multigigawatt, 140 GHz, 50-ns pulses at a 5-kHz repetition rate. The plasma heating efficiency of the long RF pulse from the gyrotron can then be compared with the higher power but shorter RF pulses from the wiggler. The M2 mirror can be reversed to determine whether the gyrotron microwave beam or the IMP wiggler microwave beam is directed into the MTX tokamak. When the IMP wiggler is in operation, the gyrotron will be used as the master oscillator to drive the wiggler

  11. 140 GHz high-power gyrotron development for the stellarator W7-X

    International Nuclear Information System (INIS)

    Electron cyclotron resonance heating (ECRH) has proven to be one of the most attractive heating schemes for stellarators. Therefore, ECRH was chosen to be the main heating method for the Wendelstein 7-X stellarator (W7-X) now under construction at IPP Greifswald, Germany. A 10 MW ECRH system with continuous wave (CW) possibilities, operating at 140 GHz will be built up to meet the scientific goals of the stellarator. Two prototype gyrotrons with an output power of 1 MW were developed in collaboration between European research laboratories and European industry (Thales Electron Devices, France). The gyrotrons are equipped with a single-stage depressed collector, an optimised quasi-optical mode converter and a CVD-diamond window. The prototypes have been successfully tested at FZK. With the second one, an output power of 0.89 MW at a pulse duration of 3 min and an output power of 0.54 MW for about 15 min have been obtained

  12. Installation and operation of the 400 kW 140 GHz gyrotron on the MTX experiment

    International Nuclear Information System (INIS)

    This paper describes the installation and operation of the 400 kW 140 GHz gyrotron used for plasma heating on the Microwave Tokamak Experiment (MTX) at Lawrence Livermore National Laboratory (LLNL). The Varian VGT-8140 gyrotron has operated at a power level of 400 kW for 100 ms in conjunction with MTX plasma shots. The gyrotron system is comprised of a high voltage (-80 kV) modulated power supply, a multistation CAMAC computer control, a 5-tesla superconducting magnet, a series of conventional copper magnets, a circulating fluorinert (FC75) window cooling system, a circulating oil cooling system, a water cooling system, and microwave frequency and power diagnostics. Additionally, a Vlasov launcher is used to convert the gyrotron TE 15,2 mode to a Gaussian beam. Two versions of the Vlasov launcher have been used on the gyrotron, one version designed by LLNL and one version designed by the Japan Atomic Energy Research Institute (JAERI). The Gaussian beam from the Vlasov launcher is transported to the MTX tokamak by a series of 5 mirrors in a 35-meter-long, high-efficiency, quasioptical beam transport system. A twist polarizer is built into one of the mirrors to adjust for horizontal polarization in the tokamak. No windows are used between the Vlasov reflector and the MTX tokamak. A laser alignment system is used to perform the initial system alignment. A summary of the design and operating characteristics of each of these systems is included. Also included is a summary of the system operation and performance

  13. Experimental results of the 1 MW, 140 GHz, CW gyrotron for W7-X

    International Nuclear Information System (INIS)

    For the stellarator Wendelstein 7-X now under construction at IPP Greifswald, Germany, a 10 MW ECRH system is foreseen. A European collaboration has been established between Forschungszentrum Karlsruhe (FZK), IPP Garching/Greifswald, IPF Stuttgart, CRPP Lausanne, CEA Cadarache and TED Velizy, to develop and build the 10 gyrotrons each with an output power of 1 MW for continuous wave (CW) operation. The dependence of the output power and efficiency of the first series tube versus the beam current will be shown in short pulse operation (without depressed collector) and in CW operation (up to 30 minutes, depressed collector operation). RF-field measurements have been performed in order to characterise the output field of the gyrotron and to minimise losses during the transmission to the W7-X device. Several parameters have been optimised (e.g. beam radii, magnetic field) to maximise output power and efficiency of the tube. At FZK site, long pulse tests up to 180 s have been performed (limited by the available power supply), at IPP site the pulse length could be extended to 30 min, both at a power level of 1 MW and high efficiency. (author)

  14. Development of high power long pulse gyrotron for ITER

    International Nuclear Information System (INIS)

    A development of 170GHz gyrotron has been carried out as a task of ITER/EDA, and remarkable progress was obtained. Critical issues on the gyrotron development; low efficiency, high heat load at the resonator, window problem, have been solved by breakthroughs; a depressed collector, 1MW single mode oscillation with a high order mode TE31,8, and development of the diamond window gyrotron, respectively. The prototype ITER gyrotron which integrated these technologies were fabricated and tested. Up to now, the power output of 0.45MW, 8sec has been obtained with a diamond window gyrotron. These results give a clear prospect of the 1MW/CW 170GHz gyrotron. (author)

  15. Progress on the Development of High Power Long Pulse Gyrotron and Related Technologies

    International Nuclear Information System (INIS)

    Full text: In the development of a higher power dual-frequency gyrotron, a high order mode gyrotron, which permits to select the oscillation at 170 GHz or 137 GHz, has been fabricated and tested. Short pulse experiments (0.5 ms) were performed with 1.3 MW power output at more than 30% of the oscillation efficiency for both frequencies. In long pulse experiments, 760 kW/46%/60 s at 170 GHz and 540 kW/42%/20 s at 137 GHz are achieved. It is the first time long pulse experiments with the dual-frequency gyrotron/triode electron gun. Since the RF beam direction from the output window is designed to be almost the same for both frequencies, good power couplings to the transmission line, which are 96% for 170 GHz and 94% for 137 GHz, are obtained by using a pair of identical phase correcting mirrors. Pulse extension is underway aiming for > 1 MW at CW operation. A 5 kHz full power modulation experiment was performed using the 170 GHz gyrotron of TE31,8 mode oscillation. The 5 kHz full power modulation was achieved with the full beam modulation by employing a fast voltage switching between the anode and cathode of the triode type electron gun. This satisfies the requirement of ITER. For further improvement, an advanced anode power supply system is proposed to reduce the oscillation period of adjacent mode at the start-up phase of each pulse. (author)

  16. Status of the 140 GHz, 10 MW CW transmission system for ECRH on the stellarator W7-X

    International Nuclear Information System (INIS)

    The stellarator W7-X, which is currently under construction at IPP Greifswald, Germany, will be equipped with a 10 MW ECRH system working at 140 GHz in CW regime. The microwave power will be generated by 10 gyrotrons delivering 1 MW each and will be transmitted from the gyrotron hall to the W7-X stellarator ports via a fully optical system. The status of the construction of the transmission lines and the design of the launchers is reported. Low-power tests of a prototype system at IPF Stuttgart are reviewed. Now, the first two gyrotrons are operating at IPP Greifswald, and high-power long-pulse tests have started. Measurements on transmission performance, behaviour of the water-cooled mirrors under thermal and microwave loads as well as alignment issues, characteristics of directional couplers, calorimetric loads, and other diagnostics are discussed

  17. Development in Russia of high power gyrotrons for fusion

    International Nuclear Information System (INIS)

    Full text: Electron cyclotron systems of fusion installations are based on powerful millimetre wave sources - gyrotrons, which are capable to produce now microwave power up to 1 MW in very long (hundreds of seconds) pulses. The paper presents the latest achievements in development at IAP/GYCOM of MW power level gyrotrons for fusion installations. Among them are a new versions of 170 GHz gyrotron for ITER and multi-frequency (105-140 GHz) gyrotron for Asdex-Up. The gyrotrons are equipped with diamond CVD windows and depressed collectors. The most efforts were spent for development of ITER gyrotron. The tests are carried out at specially prepared test stand in Kurchatov Institute. The following gyrotron output parameters were demonstrated so far in many pulses: 1MW/30 sec and 0.64 MW/300 sec. Also a gyrotron with a higher power -1.5 MW was designed and tested in short pulses. The tests continue. In two tested long-pulse dual-frequency gyrotrons, power in the output Gaussian beam exceeding 0.9MW at 140GHz and 0.7MW at 105GHz was attained at specified 10-s pulse duration. The multi-frequency gyrotron should operate at least at four frequencies in the frequency range 105GHz-140 GHz. Two window concepts for the gyrotron are considered: Brewster window and two-disc adjustable window. Last years significant efforts were done by IAP/GYCOM in order to solve the whole scope of problems associated with the use of CVD diamond windows in gyrotrons: growing of discs, their cutting and polishing, and then high-temperature brazing and mounting to a tube. Two setups for growing diamond discs have been put into operation. The first discs grown at IAP have acceptable mechanical and electrical parameters. The IAP/GYCOM discs have been successfully brazed at near 800 deg. C temperature to metal constructions and tested with high-power gyrotrons. (author)

  18. HIGH POWER LONG PULSE PERFORMANCE OF THE DIII-D GYROTRON INSTALLATION

    Energy Technology Data Exchange (ETDEWEB)

    J. LOHR; Y.A. GORELOV; R.W. CALLIS; H.J. GRUNLOH; J.J. PEAVY; R.I. PINSKER; D. PONCE; R. PRATER; R.A. ELLIS,III

    2002-05-01

    At DIII-D, five 110 GHz gyrotrons are operating routinely for 2.0 s pulses at generated power levels {ge}750 kW per gyrotron. A sixth gyrotron is being installed, which should bring the generated power level to >4 MW and the injected power to about 3.0 MW. The output power now can be modulated by the plasma control system to fix T{sub e} at a desired value. The system is being used as a tool for control of current diffusion, for current profile control and other experiments leading to advanced tokamak operation.

  19. Start currents in an overmoded gyrotron

    Science.gov (United States)

    Yeddulla, M.; Nusinovich, G. S.; Antonsen, T. M.

    2003-11-01

    High-power long-pulse millimeter-wave gyrotrons operate in high-order modes. The spectral density of these modes is very high. Therefore, self-excitation conditions can be fulfilled for several modes simultaneously. Correspondingly, in order to determine which mode will be excited first in such a device, the starting currents of competing modes should be calculated much more accurately than in gyrotrons with a rarer spectrum. In the present paper, an existing linear theory is generalized to take into account effects of magnetic field tapering, cavity profile, finite beam thickness, velocity spread and axially dependent beam coupling to the fields of competing modes. Starting currents are calculated for the operating and the most dangerous competing mode in a 140 GHz gyrotron, which is under development at Communication and Power Industries. Calculations show that the radial position of the electron beam plays a critical role in deciding which mode dominates the mode competition.

  20. 1 MW and long pulse operation of Gaussian beam output gyrotron with CVD diamond window for fusion devices

    International Nuclear Information System (INIS)

    A 110 GHz-Gaussian beam output gyrotron with chemical vapor deposition (CVD) diamond window was developed for electron cyclotron heating and current drive on JT-60U. A stable Gaussian output beam power of 1.0 MW for 2 s was obtained with depressed collector operation. The temperature at the center of the diamond window was stabilized at the ΔT∼25 K. Gaussian beam output from the gyrotron remarkably improved the coupling efficiency to the HE11 mode in the transmission waveguide. 94% of the gyrotron output power was coupled to the corrugated waveguide of 31.75 mm in diameter, via a matching optics unit with two mirrors. A combination of the Gaussian output and the diamond window are indispensable for high power gyrotron operation at more than 1 MW and efficient coupling to the transmission line

  1. Millimeter-wave, megawatt gyrotron development for ECR (electron cyclotron resonance) heating applications

    Energy Technology Data Exchange (ETDEWEB)

    Jory, H.; Felch, K.; Hess, C.; Huey, H.; Jongewaard, E.; Neilson, J.; Pendleton, R.; Tsirulnikov, M. (Varian Associates, Inc., Palo Alto, CA (USA))

    1990-09-17

    To address the electron cyclotron heating requirements of planned fusion experiments such as the International Thermonuclear Experimental Reactor (ITER) and the Compact Ignition Tokamak (CIT), Varian is developing gyrotrons at frequencies ranging from 100--300 GHz with output power capabilities up to 1 MW CW. Experimental gyrotrons have been built at frequencies between 100--140 GHz, and a study program has addressed the critical elements of designing 280--300 GHz gyrotrons capable of generating CW power levels up to 1 MW. Initial test vehicles at 140 GHz have utilized TE{sub 15,2,1} interaction cavities, and have been designed to generate short-pulse (up to 20 ms) power levels of 1 MW and up to 400 kW CW. Recently, short-pulse power levels of 1040 kW at 38% efficiency have been obtained and average powers of 200 kW have been achieved. Long-pulse operation has been extended to pulse durations of 0.5 seconds at power levels of 400 kW. Gyrotron oscillators capable of generating output powers of 500 kW CW at a frequency of 110 GHz have recently been designed and a prototype is currently being tested. Design work for a 1 MW CW gyrotron at 110 GHz, is in progress. The 1 MW CW tube will employ an output coupling approach where the microwave output is separated from the microwave output. 15 refs., 10 figs., 3 tabs.

  2. Gyrotrons

    International Nuclear Information System (INIS)

    The purpose of this study is to bring together some relevant ideas and developments in the field of gyrotrons. The development of the electron cyclotron resonance maser (ECRM or Gyrotron) was an important break through in microwave electronics in the 1970s. As we look to the 1980's, we find scientists channelling their collective efforts to shorten the wavelength and increase output power and efficiency, thereby yielding an important device for generating high power microwave radiation. 24 refs

  3. Experimental results of series gyrotrons for the stellarator W7-X

    International Nuclear Information System (INIS)

    A powerful ECRH system with 10 MW RF power at 140 GHz and CW operation is foreseen for the stellarator W7-X, being under construction at IPP Greifswald. The RF power will be delivered by 10 gyrotrons, each capable of 1 MW, CW. Nine gyrotrons are being manufactured by Thales Electron Devices (TED), Velizy, France, one gyrotron was produced by CPI, Palo Alto, CA. Testing of the TED gyrotrons is performed at the test stand at FZK (pulse duration 3 min) and the final tests are performed at IPP (pulse length 30 min). Both, the first TED series gyrotron and the CPI gyrotron have passed the acceptance tests successfully. The acceptance tests of the TED series gyrotrons are ongoing. The RF output beam quality of all tubes tested so far is at a constant high level of about 97% in the Gaussian beam. In short pulse operation the gyrotrons have achieved the specified parameters. However, for long pulse operation the performance decreases due to the occurrence of parasitic oscillations which are assumed to be excited by the electron beam in the beam tunnel close to the cavity. Experimental results of this effect and possible modifications of the beam tunnel geometry will be discussed. (author)

  4. Research on long pulse ECRH system of EAST in support of ITER

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojie, E-mail: xjiew@ipp.ac.cn; Liu, Fukun; Shan, Jiafang; Xu, Handong; Wu, Dajun; Li, Bo; Tang, Yunying; Zhang, Liyuan; Xu, Weiye; Hu, Huaichuan; Wang, Jiang; Yang, Yong; Xu, Li; Ma, Wendong; Feng, Jianqiang [Institute of Plasma Physics Chinese Academy of Sciences, Shushan lake road 350, 230031, Hefei (China); Wei, Wei [Institute of Plasma Physics Chinese Academy of Sciences, Shushan lake road 350, 230031, Hefei (China); Hefei University of Technology, 230009, Hefei (China)

    2015-12-10

    Experimental Advanced Superconducting Tokamak (EAST), as a fully superconducting tokamak in China, aims to achieve high performance plasma under steady-state operation. To fulfill the physical objectives of EAST, a program of 4-MW long pulse electron cyclotron resonance heating and current drive (EC H&CD) system, which would offer greater flexibility for plasma shape and plasma stabilization has been launched on EAST since 2011. The system, composed of 4 gyrotrons with nominal 1MW output power and 1000s pulse length each, is designed with the feature of steerable power handling capabilities at 140 GHz, using second harmonic of the extraordinary mode(X2). The missions of the ECRH system are to provide plasma heating, current drive, plasma profile tailoring and control of magneto-hydrodynamic (MHD) instabilities. Presently, the first two 140-GHz 1-MW gyrotrons, provided by GYCOM and CPI, respectively, have been tested at long pulse operation. The tubes, the associated power supplies, cooling system, cryogenic plant, 2 transmission lines and an equatorial launcher are now installed at EAST. The power generated from each tube will be transmitted by an evacuated corrugated waveguide transmission line and injected into plasma from the low field side (radial port) through a front steering equatorial launcher. Considering the diverse applications of the EC system, the beam’s launch angles can be continuously varied with the optimized scanning range of over 30° in poloidal direction and ±25° in toroidal, as well as the polarization could be adjusted during the discharge by the orientations of a pair of polarizers in the transmission line to maintain the highest absorption for different operational scenarios. The commissioning of the first 2MW ECRH plant for EAST is under way. The design, R&D activities and recent progress of the long pulse 140-GHz ECRH system are presented in this paper. As the technological requirements for EAST ECRH have many similarities with ITER

  5. Results of 170 GHz gyrotron tests

    International Nuclear Information System (INIS)

    During the last few years the development of 170 GHz gyrotron for ITER have been under way. Sketchy description of experiment and test results of an improved design gyrotron with a depressed collector, are reported. The analysis of the phenomena causing the destruction of the output window is submitted. The projects for the following experiments are presented. The new 170 GHz/1 MW/50%/CW gyrotron with depressed collector and CVD diamond window was developed by GYCOM. This gyrotron was tested with BN window and then with diamond window. The gyrotron testing showed that practically all ITER requirements are satisfied except of pulse duration limited to that time by brick load arcing. Imperfection of arc protection system gave the possibility for arc-plasma to come to the window and destroy it. New loads have been created and tested at 140 GHz, with output gyrotron power Phf = 820 kW and the pulse duration T = 3.5 s. A new version of protection system has been developed and tested in experiment. The next gyrotron with modified electron gun has been manufactured. After first stage test, BN window will be replaced with new CVD diamond unit, which is assembling now. Testing of this gyrotron is planned to carry out in May 2002. (authors)

  6. A 140 GHz pulsed EPR/212 MHz NMR spectrometer for DNP studies

    Science.gov (United States)

    Smith, Albert A.; Corzilius, Björn; Bryant, Jeffrey A.; DeRocher, Ronald; Woskov, Paul P.; Temkin, Richard J.; Griffin, Robert G.

    2012-10-01

    We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz (1H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE011 resonator acts as both an NMR coil and microwave resonator, and a double balanced (1H, 13C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S = 1/2 electron spins, 100 kHz on 1H, and 50 kHz on 13C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (⩾3 T).

  7. Demonstration of a 140-GHz 1-kW Confocal Gyro-Traveling-Wave Amplifier

    OpenAIRE

    Joye, Colin D.; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.

    2009-01-01

    The theory, design, and experimental results of a wideband 140-GHz 1-kW pulsed gyro-traveling-wave amplifier (gyro-TWA) are presented. The gyro-TWA operates in the HE06 mode of an overmoded quasi-optical waveguide using a gyrating electron beam. The electromagnetic theory, interaction theory, design processes, and experimental procedures are described in detail. At 37.7 kV and a 2.7-A beam current, the experiment has produced over 820 W of peak power with a –3-dB bandwidth of 0.8 GHz and a li...

  8. Theory and Modeling of High-Power Gyrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Nusinovich, Gregory Semeon [Univ. of Maryland, College Park, MD (United States)

    2016-04-29

    This report summarized results of the work performed at the Institute for Research in Electronics and Applied Physics of the University of Maryland (College Park, MD) in the framework of the DOE Grant “Theory and Modeling of High-Power Gyrotrons”. The report covers the work performed in 2011-2014. The research work was performed in three directions: - possibilities of stable gyrotron operation in very high-order modes offering the output power exceeding 1 MW level in long-pulse/continuous-wave regimes, - effect of small imperfections in gyrotron fabrication and alignment on the gyrotron efficiency and operation, - some issues in physics of beam-wave interaction in gyrotrons.

  9. Recent result of gyrotron operation in NIFS

    Directory of Open Access Journals (Sweden)

    Ito Satoshi

    2015-01-01

    Full Text Available In the last Large Helical Device (LHD experimental campaign, a 154GHz gyrotron which had been conditioned to generate 1 MW/2 s, 0.5 MW/CW was installed for LHD experiments. Four high power gyrotrons (three-77 GHz/1~1.5 MW and one-154 GHz/1 MW and a CW gyrotron (84 GHz/0.2 MW are ready. Our experiment requires high energy and various injection patterns for Electron Cyclotron Resonance Heating (ECRH. Higher individual injection power and various injection patterns, we developed a power enhancement method by stepped anode acceleration voltage control and operated the gyrotron in the hard excitation region. These operations were realized by a remote controlled waveform generator. However the oscillation map of high power or long pulse operation in the hard excitation region were limited because in order to achieve the hard excitation region by the anode voltage control one must pass through the high anode current phase within a time short enough that the anode or the anode power supply is not overloaded. This limitation becomes more critical when the gyrotron beam current is increased in order to increase the output power. In the long pulse operation it was impossible to reach the hard excitation region in a low beam current (<10A.

  10. Gyrotron Development in the EU for Present Fusion Experiments and for ITER

    International Nuclear Information System (INIS)

    The long term strategy of the EU in the field of gyrotrons in fusion plasma applications is based on two approaches: R and D in laboratories to develop advanced concepts and industrial development of state-of-the-art tubes for use in present experiments like TCV, Tore Supra (118 GHz, 0.5 MW, CW) and W7-X (140 GHz, 1 MW, CW). The results from these two approaches are then applied to the development of a coaxial cavity gyrotron operating at 170 GHz and delivering 2 MW-CW for the electron cyclotron wave system of ITER. This paper will recall the main achievements of this program and will outline the present status of the 170 GHz coaxial cavity gyrotron development

  11. THE CONTRIBUTION OF RADIO GALAXY CONTAMINATION TO MEASUREMENTS OF THE SUNYAEV-ZEL'DOVICH DECREMENT IN MASSIVE GALAXY CLUSTERS AT 140 GHz WITH BOLOCAM

    Energy Technology Data Exchange (ETDEWEB)

    Sayers, J.; Mroczkowski, T.; Czakon, N. G.; Golwala, S. R.; Downes, T. P.; Muchovej, S. J. C.; Siegel, S. [Division of Physics, Math, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Mantz, A. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ameglio, S.; Pierpaoli, E.; Shitanishi, J. A. [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089 (United States); Koch, P. M.; Lin, K.-Y.; Umetsu, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Molnar, S. M. [LeCosPA Center, National Taiwan University, Taipei 10617, Taiwan (China); Moustakas, L., E-mail: jack@caltech.edu [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)

    2013-02-20

    We describe in detail our characterization of the compact radio source population in 140 GHz Bolocam observations of a set of 45 massive galaxy clusters. We use a combination of 1.4 and 30 GHz data to select a total of 28 probable cluster-member radio galaxies and also to predict their 140 GHz flux densities. All of these galaxies are steep-spectrum radio sources and they are found preferentially in the cool-core clusters within our sample. In particular, 11 of the 12 brightest cluster-member radio sources are associated with cool-core systems. Although none of the individual galaxies are robustly detected in the Bolocam data, the ensemble-average flux density at 140 GHz is consistent with, but slightly lower than, the extrapolation from lower frequencies assuming a constant spectral index. In addition, our data indicate an intrinsic scatter of {approx_equal} 30% around the power-law extrapolated flux densities at 140 GHz, although our data do not tightly constrain this scatter. For our cluster sample, which is composed of high-mass and moderate-redshift systems, we find that the maximum fractional change in the Sunyaev-Zel'dovich signal integrated over any single cluster due to the presence of these radio sources is {approx_equal} 20%, and only {approx_equal} 1/4 of the clusters show a fractional change of more than 1%. The amount of contamination is strongly dependent on cluster morphology, and nearly all of the clusters with {>=}1% contamination are cool-core systems. This result indicates that radio contamination is not significant compared with current noise levels in 140 GHz images of massive clusters and is in good agreement with the level of radio contamination found in previous results based on lower frequency data or simulations.

  12. Development of 100 GHz band high power gyrotron for fusion experimental reactor

    International Nuclear Information System (INIS)

    In JAERI, 1MW gyrotrons of 170GHz and 110GHz are under development for ITER (International Thermonuclear Experimental Reactor) and JT-60U, respectively. Both gyrotrons have a depressed collector for an efficiency improvement and a low loss synthetic diamond window that enables Gaussian beam output over 1MW. Three 110GHz gyrotrons are used on an electron cyclotron heating and current drive(ECH/ECCD) system on JT-60U, in which the output power of ∼0.8MW/3sec was generated from each gyrotron. As for 170GHz, output power of 1.2MW with electron beam of 85kV/49A was obtained on a short pulse gyrotron. The efficiency of ∼57% was attained at 1.1MW with the depressed collector. Based on these results, the 1MW 170GHz gyrotron for long pulse operation was fabricated. (author)

  13. Optimization of oversized corrugated waveguide bends for higher-order TE0n-modes at 140 GHz

    International Nuclear Information System (INIS)

    Oversized corrugated 900 waveguide bends with a waveguide diameter of 27.79 mm were optimized for TE0n (n = 3...6) transmission lines to transmit power of about 200 kW for Electron-Cyclotron-Resonance-Heating of plasmas in thermonuclear fusion research at a frequency of 140 GHz. The corrugation removes the degeneracy of the mode pairs TE0n/TM1n. The bends were optimized by numerical integration of the coupled-mode differential equations for six coupled modes: TE0n, HE1n, EH1n, EH1,n+1, HE2n and EH2n. During the optimization procedure three parameters were varied: curvature distribution, corrugation depth and arc length. Following curvature distributions were studied: sine-sine-squared, triangular and specific Fourier series. The last one was found to be the best. The optimum corrugation depth increases with increasing mode number n, whereas the arc length decreases. It was found, that a small elliptical deformation of less than 0.04 mm has a negligible influence on TE03- and TE04-bends. In the case of TE05- and TE06-bends the arc length must be increased in order to maintain a pure output mode. (orig.)

  14. Design considerations in achieving 1 MW CW operation with a whispering-gallery-mode gyrotron

    International Nuclear Information System (INIS)

    Varian is developing high-power, CW gyrotrons at frequencies in the range 100 GHz to 150 GHz, for use in electron cyclotron heating applications. Early test vehicles have utilized a TE15,2,1 interaction cavity, have achieved short-pulse power levels of 820 kW and average power levels of 80 kW at 140 GHz. Present tests are aimed at reaching 400 kW under CW operating conditions and up to 1 MW for short pulse durations. Work is also underway on modifications to the present design that will enable power levels of up to 1 MW CW to be achieved. 7 refs., 2 figs

  15. Investigation of a 140 GHz gryo-backward wave oscillator and a 95 GHz gyro-traveling wave

    International Nuclear Information System (INIS)

    There is current interest in developing a high-power source of continuously tunable millimeter wave radiation as a RF driver for high-power gyrotron, CARM, or FEL amplifiers. The gyrotron backward wave oscillator is a voltage-tunable fast-wave device that can satisfy these requirements. This thesis reports on the design and experimental investigation of a 130--145 GHz gyrotron backward wave oscillator Novel operating features of this design include the use of a 80-kV, 6.2-A Pierce-wiggler electron beam source, a broadband motheye window and an overmoded TE1,2 cylindrical interaction waveguide. Although this device has demonstrated voltage-tunable operation over the design range in the TE1,2 mode, the frequency tuning is not continuous, output powers were low and full-beam transmission through the interaction region was not possible. Simulations indicate that the beam has very high velocity spread induced by space charge forces in the compression region. After increasing the diameter of the beam tunnel to achieve full transmission, the TE1,2 was not found. It is felt that the scraping off of the beam edge in the initial experiments allowed a better quality beam to enter the interaction region and inhibited coupling into competing forward wave modes. The need for radar systems with greater resolution has led to renewed interest in the development of efficient high-power amplifiers at 95 GHz. Current sources are limited to 6--8 kW of output power due to ohmic loading on the slow-wave circuit. A gyrotron traveling wave tube amplifier is capable of efficient operation over a wide bandwidth with the added attraction of low ohmic loading on the smooth fast-wave circuit. This thesis reports of the design a 95-GHz gyrotron traveling wave tube amplifier that is capable of high power (125 kW), high gain (38 dB), large bandwidth > 5 GHz and high efficiencies (> 30%)

  16. Active heater control and regulation for the Varian VGT-8011 gyrotron

    International Nuclear Information System (INIS)

    The Varian VGT-8011 gyrotron is currently being used in the new 110 GHz 2 MW ECH system installed on D3-D. This new ECH system augments the 60 GHz system which uses Varian VA-8060 gyrotrons. The new 110 GHz system will be used for ECH experiments on D3-D with a pulse width capability of 10 sec. In order to maintain a constant RF outpower level during long pulse operation, active filament-heater control and regulation is required to maintain a constant cathode current. On past D3-D experiments involving the use of Varian VA-8060 gyrotrons for ECH power, significant gyrotron heater-emission depletion was experienced for pulse widths > 300 msec. This decline in heater-emission directly results in gyrotron-cathode current droop. Since RF power from gyrotrons decreases as cathode current decreases, it is necessary to maintain a constant cathode current level during gyrotron pulses for efficient gyrotron operation. Therefore, it was determined that a filament-heater control system should be developed for the Varian VGT-8011 gyrotron which will include cathode-current feed-back. This paper discusses the mechanisms used to regulate gyrotron filament-heater voltage by using cathode-current feed-back. 1 fig

  17. Technical developments at the KIT gyrotron test facility

    International Nuclear Information System (INIS)

    Parasitic beam tunnel oscillations have been discovered on some of the series production gyrotrons for W7-X and also on the coaxial pre-prototype gyrotron for ITER. Solutions to remedy these problems have resulted in a modified beam tunnel design, technologically close to the existing beam tunnel. The new design has successfully been tested on both the coaxial and also the f-step-tunable gyrotrons and has subsequently been implemented on one of the W7-X series-production-tubes presently undergoing factory acceptance tests in Karlsruhe. The ECRH test loads at KIT are operated under normal atmospheric conditions. Several loads have eventually failed in 1 MW long pulse experiments and KIT has therefore started to design its own loads. The first KIT-load is based on a fixed conical mirror and an aluminum cylinder coated with a lossy material for increased absorption. The new load has so far successfully been used during the acceptance tests of two 1-MW CW gyrotrons. Nevertheless a new load based on pure (uncoated) stainless steel absorbers is being developed as a backup solution for the ongoing high priority gyrotron testing. A superconducting magnet capable of rapid field changes between 4.15 and 5.67 T for frequency step-tunable gyrotrons has been procured, has demonstrated a (static) field of 7.2 T and its capability of rapid field-changes.

  18. Development of dual frequency gyrotron and high power test of EC components

    Directory of Open Access Journals (Sweden)

    Sakamoto K.

    2012-09-01

    Full Text Available In JAEA, development of high-power long-pulse gyrotrons is underway. The output power of the gyrotron was applied for high-power long-pulse tests of the transmission line (TL and the equatorial launcher (EL mock up for ITER. The feature of design in the dual frequency gyrotron is the simultaneously satisfying the matching of both frequencies at a window and the same radiation angle at an internal mode convertor for both frequencies. The dual frequency gyrotron was developed and high power operations at 170 GHz and 137 GHz were carried out. The 170 GHz high power experiment of 40 m length ITER relevant TL was carried out and transmission efficiency and mode purity change caused by long pulse operation were measured. The mock-up model of EL was also tested using 170 GHz gyrotron. The power transmission through the quasi-optical beam line in EL was demonstrated using the full scale mock up model. Furthermore, the high power test results of the transmission components will be summarized.

  19. Long pulse operation on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Monier-Garbet, P

    2004-07-01

    This document gathers a series of transparencies dedicated to the long pulse operation on Tore-Supra. The structure of the document is described as follows: the first part is an introduction recalling fusion basis and presenting the different physical and technological phenomenon time scales. The second part is dedicated to the production of long pulses through non-inductive drive and some experimental scenarios illustrate it. The final part is devoted to physics issues like particle retention.

  20. Long pulse operation on Tore Supra

    International Nuclear Information System (INIS)

    This document gathers a series of transparencies dedicated to the long pulse operation on Tore-Supra. The structure of the document is described as follows: the first part is an introduction recalling fusion basis and presenting the different physical and technological phenomenon time scales. The second part is dedicated to the production of long pulses through non-inductive drive and some experimental scenarios illustrate it. The final part is devoted to physics issues like particle retention

  1. High-harmonic gyrotrons

    Science.gov (United States)

    McDermott, D. B.; Luhmann, N. C., Jr.

    1984-08-01

    There is currently much interest in the development of moderate to high power (1 kW - 1 MW) millimeter wave sources. Considered applications are mainly related to radar and communication systems. There are, however, also applications in plasma diagnostics, heating, and the nondestructive testing of dielectrics. The dominant source of high-power, high-frequency radiation has become the gyrotron. Jory et al. (1983) have reported operation of a 60 GHz, CW gyrotron, producing output powers in excess of 200 kW. High power, compact submillimeter-wave sources have become possible by making use of the concept of a high-harmonic gyrotron, in which the magnetic field can be reduced by an order of magnitude. Attention is given to synchronism, negative-mass instability, energy requirements, oscillators, efficiency, high power, dielectric loading, the peniotron, and amplifiers.

  2. From reactors to long pulse sources

    International Nuclear Information System (INIS)

    We will show, that by using an adapted instrumentation concept, the performance of a continuous source can be emulated by one switch on in long pulses for only about 10% of the total time. This 10 fold gain in neutron economy opens up the way for building reactor like sources with an order of magnitude higher flux than the present technological limits. Linac accelerator driven spallation lends itself favorably for the realization of this kind of long pulse sources, which will be complementary to short pulse spallation sources, the same way continuous reactor sources are

  3. An integrated gyrotron controller

    Energy Technology Data Exchange (ETDEWEB)

    Michel, Georg, E-mail: michel@ipp.mpg.de; Sachtleben, Juergen

    2011-10-15

    The ECRH system of W7-X is composed of 10 independent gyrotron modules. Each module consists of one gyrotron and its peripherals such as power supplies, cooling plants and distributed PLC systems. The fast real-time control functions such as the timing of the two high voltage supplies, trigger pulses, protection, modulation and communication with the central control of W7-X, is implemented in an integrated controller which is described in this paper. As long-term maintainability and sustainability are important for nuclear fusion experiments, the choice fell on an FPGA-based design which is exclusively based on free (as in 'freedom') software and configuration code. The core of the controller consists of a real-time Java virtual machine (JVM) that provides the TCP-IP connectivity as well as more complicated control functions, and which interacts with the gyrotron-specific hardware. Both the gyrotron-specific hardware and the JVM are implemented on the same FPGA, which is the main component of the controller. All 10 controllers are currently completed and operational. All parameters and functions are accessible via Ethernet. Due to the open, FPGA-based design, most hardware modifications can be made via the network as well. This paper discusses the capabilities of the controllers and their integration into the central W7-X control.

  4. State-of-the-art and recent developments of high-power gyrotron oscillators

    Science.gov (United States)

    Thumm, Manfred

    1999-05-01

    Gyrotron oscillators (gyromonotrons) are mainly used as high-power millimeter wave sources for electron cyclotron resonance heating (ECRH) and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. High unit power and high efficiency single-mode CW gyrotrons with conventional cylindrical (1 MW) and advanced coaxial (2 MW) cavities are worldwide under development. 118 GHz, 140 GHz and 170 GHz conventional cavity gyrotrons with output power Pout≈0.5 MW, pulse length τ≈5.0 s and efficiency η≈35% are commercially available. Advanced internal quasi-optical mode converters generate linearly polarized output wave beams from the high-order cavity modes (e.g., TE22,6) with efficiencies of 90-95% and separate the millimeter-wave beam from the electron beam, thus allowing the use of large CW-relevant depressed collectors for energy recovery. Overall efficiencies between 50 and 60% have been already achieved at JAERI, FZK, and GYCOM employing single-stage depressed collectors (SDC). First successful experiments at FZK employing a broadband Brewster window gave up to 1.5 MW output power at around 50% efficiency (SDC) for all operating mode series in the frequency range from 114 to 166 GHz (frequency tuning in 3.7 GHz steps by variation of the magnetic field strength in the cavity). Gyrotrons with advanced coaxial cavities designed for operation in the TE28,16 and TE31,17 modes at 140 and 165 GHz, respectively, are under development and test at IAP Nizhny Novgorod and FZK Karlsruhe. A maximum output power of 1.7 MW has been measured at 165 GHz with an efficiency of 35.2% (SDC, FZK). Cryogenically edge-cooled single-disk sapphire (T=77 K) and Au-doped silicon (T=230 K) windows as well as CVD-diamond windows with water edge-cooling at room temperature are under investigation in order to solve the window problem. Commercial CVD-diamond disks will easily allow the transmission of 2 MW power level at 170 GHz, CW. Bonding and

  5. State-of-the-art and recent developments of high-power gyrotron oscillators

    International Nuclear Information System (INIS)

    Gyrotron oscillators (gyromonotrons) are mainly used as high-power millimeter wave sources for electron cyclotron resonance heating (ECRH) and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. High unit power and high efficiency single-mode CW gyrotrons with conventional cylindrical (1 MW) and advanced coaxial (2 MW) cavities are worldwide under development. 118 GHz, 140 GHz and 170 GHz conventional cavity gyrotrons with output power Pout≅0.5 MW, pulse length τ≅5.0 s and efficiency η≅35% are commercially available. Advanced internal quasi-optical mode converters generate linearly polarized output wave beams from the high-order cavity modes (e.g., TE22,6) with efficiencies of 90-95% and separate the millimeter-wave beam from the electron beam, thus allowing the use of large CW-relevant depressed collectors for energy recovery. Overall efficiencies between 50 and 60% have been already achieved at JAERI, FZK, and GYCOM employing single-stage depressed collectors (SDC). First successful experiments at FZK employing a broadband Brewster window gave up to 1.5 MW output power at around 50% efficiency (SDC) for all operating mode series in the frequency range from 114 to 166 GHz (frequency tuning in 3.7 GHz steps by variation of the magnetic field strength in the cavity). Gyrotrons with advanced coaxial cavities designed for operation in the TE28,16 and TE31,17 modes at 140 and 165 GHz, respectively, are under development and test at IAP Nizhny Novgorod and FZK Karlsruhe. A maximum output power of 1.7 MW has been measured at 165 GHz with an efficiency of 35.2% (SDC, FZK). Cryogenically edge-cooled single-disk sapphire (T=77 K) and Au-doped silicon (T=230 K) windows as well as CVD-diamond windows with water edge-cooling at room temperature are under investigation in order to solve the window problem. Commercial CVD-diamond disks will easily allow the transmission of 2 MW power level at 170 GHz, CW. Bonding and

  6. Feasibility of ion temperature measurement with a gyrotron scattering alpha particle diagnostic

    International Nuclear Information System (INIS)

    Collective Thomson scattering can be used to diagnose localized ion temperature as well as alpha particle velocity distribution and density in a D-T burning tokamak. With one diagnostic beam a simultaneous, but independent, measure of the bulk ion temperature and alpha particle parameters can be made. Use of a long pulse, millimeter-wave gyrotron offers a significant margin in signal to noise ratio capability (√Δftau > 1000) not previously possible with lasers. 9 refs., 2 figs

  7. Long pulse operation with actively cooled limiters

    International Nuclear Information System (INIS)

    We present here the major results obtained with actively cooled plasma facing components during long pulse operation (plasma duration >3 x surface temperature time constant=steady-state). Shots up to 120 s have been achieved in Tore Supra when the plasma was leaning on the large inner toroidal actively cooled limiter with a moderate deposited power density heat flux (up to 0.3 MW/m2). For larger power density heat flux up to 4.5 MW/m2 (design value), modular limiters have been used. A prerequisite for any actively cooled limiter is the absence of any cooling defect (crack parallel to the surface in the tile or non-correct bonding). If a defect is present it leads to a super-brilliance event (with its corresponding local power heat flux increase) which propagates. This deleterious effect is unfortunately a runaway effect. (orig.)

  8. Gyrotron oscillators for fusion heating

    International Nuclear Information System (INIS)

    Recent experiments have been performed to determine the ultimate power capability of a 28 GHz 200 kW CW gyrotron design. A power output of 342 kW CW was measured in these tests with an efficiency of 37%. Progress in the development of 60 GHz 200 kW pulsed and CW gyrotrons is discussed. An output of 200 kW with 100 msec pulse length has been achieved with the pulsed design

  9. Development of high power gyrotron and transmission line for ECH/ECCD system

    International Nuclear Information System (INIS)

    170 GHz, high power and long pulse gyrotron with CVD diamond output window (tanδ ≤ 1.4 x 10-4, σ = 1800 W/m/K) has successfully been developed. The operation of 0.45 MW-8.0 sec and of 0.52 MW-6.2 sec were performed. Temperature increase of the window center was 150 deg. C at the operation of 0.52 MW-6.2 sec, moreover, the increment saturated, which well agreed with the simulation result. No damage on the gyrotron window and the gyrotron itself was observed through the experiment. We have constructed the 40 m run transmission line to demonstrate the efficient transmission of high power and long pulse millimeter wave. The total transmission loss has been estimated as less than 18%, which includes the loss in mirror optical unit, assumed as 10%. The transmission efficiency, the mode purity and the polarization are mainly investigated in the high power transmission experiment. The diamond window assembly as tritium or vacuum barrier in a transmission line was fabricated for high pressure test. The disk was failed at pressure of 0.465 MPa, which is consistent with the material strength. (author)

  10. Design of an ultra-broadband single-disk output window for a frequency step-tunable 1 MW gyrotron

    International Nuclear Information System (INIS)

    Output window design is one of the key issues to realize broadband output of a multi-frequency gyrotron. Corresponding to the recent development of a frequency step-tunable 1 MW gyrotron at Forschungszentrum Karlsruhe (FZK), this paper reports about a newly designed ultra-broadband CVD-diamond disk Brewster window. The thickness of the disk and the geometry of the window unit have been optimized to get low power reflection over a broadband incident angle range around the Brewster angle at different operating frequencies. Detailed calculations of mm-wave transmission characteristics for this Brewster window have been performed for all the considered operation modes from TE17,6 at 105 GHz up to TE23,8 at 143 GHz, and for thickness of the disk from 1.5 to 2.0 mm. Calculations show if one prefers to place the low reflection area in the middle of the discussed frequency range (120-130 GHz), the thickness of 1.6 mm is near optimum and its -20 dB bandwidth angle is more than 30o. For operation near 105 and 140 GHz, a 1.9 mm disk is preferable and its -20 dB bandwidth angle is around 30o

  11. Advances in high power calorimetric matched loads for short pulses and CW gyrotrons

    International Nuclear Information System (INIS)

    ) and the CW version at 2 MW, 170 GHz, are described in the paper. High power tests on short-pulse loads have been done using a double frequency gyrotron, 105 GHz/600 kW for 0.5 s and 140 GHz/800 kW for 1 s. Also a method for emulating 2 MW conditions while using 1 MW gyrotron has been applied to test the load to be used for the European 2 MW coaxial cavity gyrotron development programme

  12. Development and Applications of High—Frequency Gyrotrons in FIR FU Covering the sub-THz to THz Range

    Science.gov (United States)

    Idehara, Toshitaka; Sabchevski, Svilen Petrov

    2012-07-01

    Powerful sources of coherent radiation in the sub-terahertz and in the terahertz frequency range of the electromagnetic spectrum are necessary for a great and continuously expanding number of applications in the physical research and in various advanced technological processes as well as in radars, communication systems, for remote sensing and inspection etc.. In recent years, a spectacular progress in the development of various gyro-devices and in particular of the powerful high frequency (sub-terahertz and terahertz) gyrotron oscillators has demonstrated a remarkable potential for bridging the so-called terahertz power gap and stimulated many novel and prospective applications. In this review paper we outline two series of such devices, namely the Gyrotron FU Series which includes pulsed gyrotrons and Gyrotron FU CW Series which consist of tubes operated in a CW (continuous wave) or long pulse mode, both developed at the FIR FU Center. We present the most remarkable achievements of these devices and illustrate their applications by some characteristic examples. An outlook for the further extension of the Gyrotron FU CW Series is also provided.

  13. Systematic Observation of Time-Dependent Phenomena in the RF Output Spectrum of High Power Gyrotrons

    Directory of Open Access Journals (Sweden)

    Kern Stefan

    2012-09-01

    Full Text Available At IHM/KIT, high power gyrotrons with conventional cavity (e.g. 1 MW CW at 140 GHz for the stellarator Wendelstein 7-X and coaxial cavity (2 MW shortpulse at 170 GHz for ITER for fusion applications are being developed and verified experimentally. Especially with respect to the problem of parasitic RF oscillations in the beam tunnel of some W7-X tubes, investigations of the gyrotron RF output spectrum have proved to be a valuable source of diagnostic information. Signs of transient effects in millisecond pulses, like frequency switching or intermittent low-frequency modulation, have indicated that truly time-dependent measurements with high frequency resolution and dynamic range could give deeper insight into these phenomena. In this paper, an improved measurement system is presented, which employs a fast oscilloscope as receiver. Shorttime Fourier transform (STFT is applied to the time-domain signal, yielding time-variant spectra with frequency resolutions only limited by acquisition length and STFT segmentation choice. Typical reasonable resolutions are in the range of 100 kHz to 10 MHz with a currently memory-limited maximum acquisition length of 4 ms. A key feature of the system consists in the unambiguity of frequency measurement: The system receives through two parallel channels, each using a harmonic mixer (h = 9 – 12 to convert the signal from RF millimeter wave frequencies (full D-Band, 110 – 170 GHz to IF (0 – 3 GHz. For each IF output signal of each individual mixer, injection side and receiving harmonic are initially not known. Using accordingly determined LO frequencies, this information is retrieved from the redundancy of the channels, yielding unambiguously reconstructed RF spectra with a total span of twice the usable receiver IF bandwidth, up to ≈ 6 GHz in our case. Using the system, which is still being improved continuously, various transient effects like cavity mode switching, parasitic oscillation frequency variation

  14. Systematic Observation of Time-Dependent Phenomena in the RF Output Spectrum of High Power Gyrotrons

    Science.gov (United States)

    Schlaich, Andreas; Gantenbein, Gerd; Kern, Stefan; Thumm, Manfred

    2012-09-01

    At IHM/KIT, high power gyrotrons with conventional cavity (e.g. 1 MW CW at 140 GHz for the stellarator Wendelstein 7-X) and coaxial cavity (2 MW shortpulse at 170 GHz for ITER) for fusion applications are being developed and verified experimentally. Especially with respect to the problem of parasitic RF oscillations in the beam tunnel of some W7-X tubes, investigations of the gyrotron RF output spectrum have proved to be a valuable source of diagnostic information. Signs of transient effects in millisecond pulses, like frequency switching or intermittent low-frequency modulation, have indicated that truly time-dependent measurements with high frequency resolution and dynamic range could give deeper insight into these phenomena. In this paper, an improved measurement system is presented, which employs a fast oscilloscope as receiver. Shorttime Fourier transform (STFT) is applied to the time-domain signal, yielding time-variant spectra with frequency resolutions only limited by acquisition length and STFT segmentation choice. Typical reasonable resolutions are in the range of 100 kHz to 10 MHz with a currently memory-limited maximum acquisition length of 4 ms. A key feature of the system consists in the unambiguity of frequency measurement: The system receives through two parallel channels, each using a harmonic mixer (h = 9 - 12) to convert the signal from RF millimeter wave frequencies (full D-Band, 110 - 170 GHz) to IF (0 - 3 GHz). For each IF output signal of each individual mixer, injection side and receiving harmonic are initially not known. Using accordingly determined LO frequencies, this information is retrieved from the redundancy of the channels, yielding unambiguously reconstructed RF spectra with a total span of twice the usable receiver IF bandwidth, up to ≈ 6 GHz in our case. Using the system, which is still being improved continuously, various transient effects like cavity mode switching, parasitic oscillation frequency variation, and lowfrequency

  15. Long-pulse-width narrow-bandwidth solid state laser

    Science.gov (United States)

    Dane, C.B.; Hackel, L.A.

    1997-11-18

    A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications. 5 figs.

  16. Long-pulse-width narrow-bandwidth solid state laser

    Science.gov (United States)

    Dane, C. Brent; Hackel, Lloyd A.

    1997-01-01

    A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications.

  17. The Los Alamos Long-Pulse-Spallation-Source driver

    International Nuclear Information System (INIS)

    A Los Alamos study has investigated the possibility of adapting the LANSCE facility to a 1-MW Long-Pulse Spallation Source (LPSS) delivering H+ beam to a new spallation target in 1-ms long pulses at a repetition rate of 60 Hz, while maintaining the present short-pulse capabilities. The study noted limitations of the LANSCE linac and has specified a scheme for high-reliability operation with low beam loss. Such an upgrade would provide a very inexpensive spallation source equivalent to a large reactor. Novel aspects of the scheme are stressed. (author) 5 figs

  18. Free-electron masers vs. gyrotrons prospects for high-power sources at millimeter and submillimeter wavelengths

    CERN Document Server

    Thumm, M K

    2002-01-01

    The possible applications of high-power millimeter (mm) and sub-mm waves from free-electron masers (FEMs) and gyro-devices span a wide range of technologies. The plasma physics community has already taken advantage of recent advances in applying high-power mm waves generated by long pulse or continuous wave (CW) gyrotron oscillators and short pulse very high-power FEMs in the areas of RF-plasma production, heating, non-inductive current drive, plasma stabilization and active plasma diagnostics for magnetic confinement thermonuclear fusion research, such as electron cyclotron resonance heating (28-170 GHz), electron cyclotron current drive , collective Thomson scattering , microwave transmission and heat-wave propagation experiments. Continuously frequency tunable FEMs could widen these fields of applications. Another important application of CW gyrotrons is industrial materials processing, e.g. sintering of high-performance functional and structural nanostructured ceramics. Sub-mm wave sources are employed in...

  19. Narrow band tuning with small long pulse excimer lasers

    Energy Technology Data Exchange (ETDEWEB)

    Sze, R.C.; Kurnit, N.; Watkins, D.; Bigio, I.

    1985-12-01

    We discuss frequency narrowing and tuning with simple dispersion elements with small long-pulse excimer lasers. The improved performance over short-pulse lasers is discussed and attributed to the increased number of round trips. A physical model of the dynamics of line narrowing is presented.

  20. Long-pulse operation of an intense negative ion source

    Energy Technology Data Exchange (ETDEWEB)

    Takeiri, Yasuhiko; Osakabe, Masaki; Tsumori, Katsuyoshi; Kaneko, Osamu; Oka, Yoshihide; Asano, Eiji; Kawamoto, Toshikazu; Akiyama, Ryuichi; Kuroda, Tsutomu [National Inst. for Fusion Science, Nagoya (Japan)

    1997-02-01

    In the National Institute for Fusion Science, as the heating system for the Large Helical Device (LHD), the negative ion NBI system of 20 MW incident power has been planned, and the development of a large current, large size negative ion source has been advanced. Based on the results obtained so far, the design of the LHD-NBI system was reconsidered, and the specification of the actual negative ion source was decided as 180 KeV-40A. This time, the grounding electrode with heightened heat removal capacity was made, and the long pulse operation was attempted, therefore, its results are reported. The structure of the external magnetic filter type large negative ion source used for the long pulse experiment is explained. In order to form the negative ion beam of long pulses, it is necessary to form stable are discharge plasma for long time, and variable resistors were attached to the output side of arc power sources of respective filament systems. By adjusting the resistors, uniform are discharge was able to be caused for longer than 10 s stably. The results of the long pulse experiment are reported. The dependence of the characteristics of negative ion beam on plasma electrode temperature was small, and the change of the characteristics of negative ion beam due to beam pulse width was not observed. (K.I.)

  1. Analytic theory of the gyrotron

    International Nuclear Information System (INIS)

    An analytic theory is derived for a gyrotron operating in the linear gain regime. The gyrotron is a coherent source of microwave and millimeter wave radiation based on an electron beam emitting at cyclotron resonance Ω in a strong, uniform magnetic field. Relativistic equations of motion and first order perturbation theory are used. Results are obtained in both laboratory and normalized variables. An expression for cavity threshold gain is derived in the linear regime. An analytic expression for the electron phase angle in momentum space shows that the effect of the RF field is to form bunches that are equal to the unperturbed transit phase plus a correction term which varies as the sine of the input phase angle. The expression for the phase angle is plotted and bunching effects in and out of phase (0 and -π) with respect to the RF field are evident for detunings leading to gain and absorption, respectively. For exact resonance, field frequency ω = Ω, a bunch also forms at a phase of -π/2. This beam yields the same energy exchange with the RF field as an unbunched, (nonrelativistic) beam. 6 refs., 10 figs

  2. State-of-the-art of high power gyro-devices and free electron masers 1994

    International Nuclear Information System (INIS)

    At present, gyrotron oscillators are mainly used as high power millimeter wave sources for electron cyclotron resonance heating (ECRH) and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. 140 GHz gyrotrons with output power Pout=0.54 MW, pulse length τ=3.0 s and efficiency η=42% are commercially available. Total efficiencies around 50% have been achieved using single-stage depressed collectors. Diagnostic gyrotrons deliver Pout=40 kW with τ=40 μs at frequencies up to 650 GHz (η≥4%). Recently, gyrotron oscillators have also been successfully used in material processing and plasma chemistry. Such technological applications require gyrotrons with the following parameters: f≥24 GHz, Pout=10-50 kW, CW, η≥30%. This paper reports on achievements and problems related to the development of very high power mm-wave gyrotrons for long pulse or CW operation and describes the microwave technological pecularities of the different development steps. In addition, this work gives a short overview of the present development of gyrotrons for technological applications, relativistic gyrotrons, quasi-optical gyrotrons, cyclotron autoresonance masers (CARMs), gyro klystrons, gyro-TWT amplifiers, gyrotwystron amplifiers, gyro-BWO's, peniotrons and free electron masers (FEMs). The most impressive FEM output parameters are: Pout=2 GW, τ=20 ns, η=13% at 140 GHz (LLNL) and Pout=15 kW, τ=20 μs, η=5% in the range from 120 to 900 GHz (UCSB). (orig.)

  3. 372-mJ long pulse pyrotechnically pumped laser

    Institute of Scientific and Technical Information of China (English)

    Nan Xiao; Zongfu Jiang; Weihong Hua; Shengfu Yuan

    2008-01-01

    A pyrotechnically pumped Nd glass laser is demonstrated by the use of pyrotechnic flashlamps composed of several chemical materials arranged in a stable plane concave resonator cavity. The flashlamp was made of chemical mixture with oxidant, fuel, and binder. The emission spectrum of pyrotechnic flame covered most of the absorption bands of Nd3+ in phosphate glass. Under 4.56-g chemical mixture pumping, long pulse output power of about 5.5 W was achieved.

  4. Long-pulse induction acceleration of heavy ions

    International Nuclear Information System (INIS)

    A long-pulse induction acceleration unit has been installed in the high-current Cs+ beam line at LBL and has accelerated heavy ions. A maximum energy gain of 250 keV for 1.5 μs is possible. The unit comprises 12 independent modules which may be used to synthesize a variety of waveforms by varying the triggering times of the low voltage trigger generators

  5. Linear and nonlinear analysis of a gyro-peniotron oscillator and study of start-up scenario in a high order mode gyrotron

    Science.gov (United States)

    Yeddulla, Muralidhar

    linear theory of gyrotrons is extended to include effects of magnetic field tapering, cavity wall profile, finite beam thickness, velocity spread and axially dependent beam coupling to the fields of competing modes. Starting currents are calculated for the operating and the most dangerous competing mode in a 140 GHz gyrotron, which was developed at Communications and Power Industries (CPI). Start-up scenario of this device is also studied using the non-stationary code MAGY, which is a tool for modeling slow and fast microwave sources.

  6. Commissioning a Megawatt-class Gyrotron with Collector Potential Depression

    Science.gov (United States)

    Lohr, J.; Cengher, M.; Gorelov, Y. A.; Ponce, D.; Prater, R.

    2013-10-01

    A 110 GHz depressed collector gyrotron has been installed on the DIII-D tokamak. The commissioning process rapidly achieved operation at full parameters, 45 A and 94 kV total voltage, with 29 kV depression. Although short pulse, 2 ms, factory testing demonstrated 1.2 MW at 41% electrical efficiency, long pulse testing at DIII-D achieved only 33% efficiency at full power parameters, for pulse lengths up to 10 s. Maximum generated power was ~950 kW, considerably below the 1.2 MW target. During attempts to increase the power at 5 s pulse length, it was noted that the collector cooling water was boiling. This led to the discovery that 14 of the 160 cooling channels in the collector had been blocked by braze material during manufacture of the tube. The locations of blocked channels were identified using infrared imaging of the outside of the collector during rapid changes in the cooling water temperature. Despite these difficulties, the rf beam itself was of very high quality and the stray rf found calorimetrically in the Matching Optics Unit, which couples the Gaussian rf beam to the waveguide, was only 2% of the generated power, about half that of our previous best quality high power beam. Details of the power measurements and collector observations will be presented. Work supported by the US DOE under DE-FC02-04ER54698.

  7. A digital long pulse integrator for EAST Tokamak

    International Nuclear Information System (INIS)

    Highlights: • This digital integrator is done in real time integration and data transmission. • Chopper technology and linear compensation is used for drift correction. • This integrator has achieved results of 411 s long pulse plasma discharge in 2012 EAST campaign. - Abstract: A digital integrator has been developed to be compatible with the long pulse plasma discharges on the Experimental Advanced Superconductor Tokamak (EAST), in which the induced signal is modulated by a chopper, and a field programmable gate array (FPGA) in the 16-bit digitizer is used to realize the digital integration in real time. After rectification and integration, the drift is almost linear and stable in controlled temperature, so a period of 50 s is used to determine the linear drift rate for drift compensation. The integration data can be directly transferred to the reflective memory (RFM) card, which is installed in the same PCI eXtensions for Instrumentation (PXI) chassis, so the data transmission can be also done in real time. The test results show that the real time data transmission rate is up to 10 kHz, the integration drift is typically less than 0.4 uVs/s and drift performance is a little worse in real long pulse discharge, which can be reduced further by using more precise data acquisition

  8. Beta limits in long-pulse tokamak discharges

    Energy Technology Data Exchange (ETDEWEB)

    Sauter, O.; La Haye, R.J.; Chang, Z.; Gates, D.A.; Kamada, Y.; Zohm, H.; Bondeson, A.; Boucher, D.; Callen, J.D.; Chu, M.S.; Gianakon, T.A.; Gruber, O.; Harvey, R.W.; Hegna, C.C.; Lao, L.L.; Monticello, D.A.; Perkins, F.; Pletzer, A.; Reiman, A.H.; Rosenbluth, M.; Strait, E.J.; Taylor, T.S.; Turnbull, A.D.; Waelbroeck, F.; Wesley, J.C.; Wilson, H.R.; Yoshino, R. [CRPP, Assoc. Euratom-Switzerland, PPB-Ecublens, 1015 Lausanne (Switzerland)]|[ITER-JCT, 11025 N Torrey Pines Rd., La Jolla, California 92037 (United States)]|[General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)]|[Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States)]|[UKAEA Fusion, Culham, Abingdon, Oxfordshire, OX14 3DB (United Kingdom)]|[JAERI, Naka-machi, Naka-gun, Ibaraki-ken, 311-01 (Japan)]|[MIP fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany)]|[Chalmers University of Technology, Goeteborg (Sweden)]|[University of Wisconsin, Madison, Wisconsin 53706-16787 (United States)]|[CompX, 12839 Via Grimaldi, Del Mar, California 92014 (United States)]|[IFS, University of Texas, Austin, Texas 78712 (United States)

    1997-05-01

    The maximum normalized beta achieved in long-pulse tokamak discharges at low collisionality falls significantly below both that observed in short pulse discharges and that predicted by the ideal MHD theory. Recent long-pulse experiments, in particular those simulating the International Thermonuclear Experimental Reactor (ITER) [M. Rosenbluth {ital et al.}, {ital Plasma Physics and Controlled Nuclear Fusion} (International Atomic Energy Agency, Vienna, 1995), Vol. 2, p. 517] scenarios with low collisionality {nu}{sub e{sup {asterisk}}}, are often limited by low-m/n nonideal magnetohydrodynamic (MHD) modes. The effect of saturated MHD modes is a reduction of the confinement time by 10{percent}{endash}20{percent}, depending on the island size and location, and can lead to a disruption. Recent theories on neoclassical destabilization of tearing modes, including the effects of a perturbed helical bootstrap current, are successful in explaining the qualitative behavior of the resistive modes and recent results are consistent with the size of the saturated islands. Also, a strong correlation is observed between the onset of these low-m/n modes with sawteeth, edge localized modes (ELM), or fishbone events, consistent with the seed island required by the theory. We will focus on a quantitative comparison between both the conventional resistive and neoclassical theories, and the experimental results of several machines, which have all observed these low-m/n nonideal modes. This enables us to single out the key issues in projecting the long-pulse beta limits of ITER-size tokamaks and also to discuss possible plasma control methods that can increase the soft {beta} limit, decrease the seed perturbations, and/or diminish the effects on confinement. {copyright} {ital 1997 American Institute of Physics.}

  9. Long pulse and steady state operation activities at KSTAR

    Science.gov (United States)

    Bae, Young-Soon; KSTAR Team; KAERI Collaboration; JAEA Collaboration; PPPL Collaboration; SNU Collaboration

    2014-10-01

    The mission of Korea Superconducting Tokamak Advanced Research (KSTAR) is to develop a steady state capable advanced tokamak (AT) operation. The original AT operation mode at KSTAR is a reversed shear scenario with the plasma current of 2 MA, the toroidal magnetic field of 3.5 T, βN of 5, safety factor q95 of 3.7. Recently, the stationary long pulse H-mode discharge is sustained for maximum pulse duration of 20 s using heating of 2.5-MW NBI and 0.7-MW, X3 170 GHz ECH with low density level ~ 0.3 × 1020/m3. The main activities of long pulse and steady state operation in KSTAR are the density feedback control, optimization of plasma shape and vertical control, real-time β control, and steady state capable heating upgrade. For the longer pulse H-mode discharge at the increased plasma current upcoming KSTAR campaign, there have been improvements in plasma control system and upgraded heating systems. Meanwhile, steady state operation scenario in KSTAR next 4-year is being investigated using time-dependent integrated transport simulation code with possible heating upgrade-schemes. The promising steady state scenario near future is a reversed shear using a new 4 MW off-axis neutral beam injector for broad pressure profile peaked at off-axis, and using ECH for local current profile control aiming at βN > 3 with Ip ~ 1 MA. This paper present activities and plan for steady state operation in KSTAR as well as the long pulse H-mode discharge results in the recent KSTAR campaign.

  10. High-resolution processing of long-pulse-lidar data

    Science.gov (United States)

    Gurdev, L. L.; Dreischuh, T. N.; Stoyanov, D. V.

    1992-01-01

    The purpose of this work is to demonstrate the performance of the Fourier-deconvolution technique developed to improve the resolution of the long-pulse coherent lidar power profile, and to take into account the multiplicative fluctuations. The behavior of the error due to the power fluctuations and a method to reduce it are analyzed theoretically and simulated numerically. A processing of real data obtained from the National Oceanic and Atmospheric Administration (NOAA) ground-based Doppler lidar is also presented. Similar problems were investigated using a different approach based on introducing a correction function to the lidar equation.

  11. Long-pulse microwave radiation from large plane diode victor

    International Nuclear Information System (INIS)

    The structure and the measuring arrangements of vircator with a large plane velvet cathode diode to induce long pulsed microwave radiation are given. The cathode-anode plasma closed velocity, the maximum pulse width of the microwave radiation, the microwave peak power and frequency are measured. It is shown that there exists physically restriction in this kind of flat diode vircator between radiation pulse width, radiation frequency and radiation power. It is pointed out that coaxial vircator will be a new way to get rid of such a restriction

  12. State-of-the-art of high power gyro-devices and free electron masers

    International Nuclear Information System (INIS)

    At present, gyrotron oscillators are mainly used as high power millimeter wave sources for electron cyclotron resonance heating (ECRH) and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. 140 GHz gyrotrons with output power Pout = 0.58 MW, pulse length τ = 2.0 s and efficiency η = 34% are commercially available. Diagnostic gyrotrons deliver Pout = 40 kW with τ = 40 μs at frequencies up to 650 GHz (η ≥ 4%). Recently, gyrotron oscillators have also been successfully used in material processing and plasma chemistry. Such technological applications require gyrotrons with the following parameters: f ≥ 28 GHz, Pout = 10-30 kW, CW, η ≥ 30%. This paper reports on achievements and problems related to the development of very high power mm-wave gyrotrons for long pulse or CW operation and describes the microwave technological pecularities of the different development steps. In addition, this work gives a short overview of the present development of gyrotrons for technological applications, quasi-optical gyrotrons, cyclotron autoresonance masers (CARMs), gyro-klystrons, gyro-TWT amplifiers, gyro-BWO's and free electron masers (FEMs). The most impressive FEM output parameters are: Pout = 2 GW, τ = 20 ns, η = 13% at 140 GHz (LLNL) and Pout = 15 kW, τ = 20 μs, η = 5% in the range from 120 to 900 GHz (UCSB). (orig.)

  13. The 110 GHz Gyrotron System on DIII-D: Gyrotron Tests and Physics Results

    International Nuclear Information System (INIS)

    The DIII-D tokamak has installed a system with three gyrotrons at the 1 MW level operating at 110 GHz. Physics experiments on electron cyclotron current drive, heating, and transport have been performed. Good efficiency has been achieved both for on-axis and off-axis current drive with relevance for control of the current density profile leading to advanced regimes of tokamak operation, although there is a difference between off-axis ECCD efficiency inside and outside the magnetic axis. Heating efficiency is excellent and electron temperatures up to 10 keV have been achieved. The gyrotron system is versatile, with poloidal scan and control of the polarization of the injected rf beam. Phase correcting mirrors form a Gaussian beam and focus it into the waveguide. Both perpendicular and oblique launch into the tokamak have been used. Three different gyrotron designs are installed and therefore unique problems specific to each have been encountered, including parasitic oscillations, mode hops during modulation and polarization control problems. Two of the gyrotrons suffered damage during operations, one due to filament failure and one due to a vacuum leak. The repairs and subsequent testing will be described. The transmission system uses evacuated, windowless waveguide and the three gyrotrons have output windows of three different materials. One gyrotron uses a diamond window and generates a Gaussian beam directly. The development of the system and specific tests and results from each of the gyrotrons will be presented. The DIII-D project has committed to an upgrade of the system, which will add three gyrotrons in the 1 MW class, all using diamond output windows, to permit operation at up to ten seconds per pulse at one megawatt output for each gyrotron

  14. Effect of ion compensation of the beam space charge on gyrotron operation

    Energy Technology Data Exchange (ETDEWEB)

    Fokin, A. P.; Glyavin, M. Yu. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Nusinovich, G. S. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742-3511 (United States)

    2015-04-15

    In gyrotrons, the coherent radiation of electromagnetic waves takes place when the cyclotron resonance condition between the wave frequency and the electron cyclotron frequency or its harmonic holds. The voltage depression caused by the beam space charge field changes the relativistic cyclotron frequency and, hence, can play an important role in the beam-wave interaction process. In long pulse and continuous-wave regimes, the beam space charge field can be partially compensated by the ions, which appear due to the beam impact ionization of neutral molecules of residual gases in the interaction space. In the present paper, the role of this ion compensation of the beam space charge on the interaction efficiency is analyzed. We also analyze the effect of the electron velocity spread on the limiting currents and discuss some effects restricting the ion-to-beam electron density ratio in the saturation stage. It is shown that the effect of the ion compensation on the voltage depression caused by the beam space charge field can cause significant changes in the efficiency of gyrotron operation and, in some cases, even result in the break of oscillations.

  15. Upgrade Of The TH1506B 118 GHz Gyrotron Using Modeing Tools

    International Nuclear Information System (INIS)

    The first TH1506B prototype showing problems of overheating and spurious oscillations, a new modified gyrotron was built. During the tests, the extwo peaks, which was never predicted by simulations. Various low evel tests were performed on the mode converter with different shapes for the launcher but without real improvement. Besides measurements, the use of a new software Surf3D[l] showed that the problem mainly comes from the 3rd mirror whose curvature is too high and not well taken nto account by the calculation. This analysis software is based on ntegral equations and the complete 3D modelling alowed to determine a new profile for the 3rd mirror. An aluminium model of a new mirror was manufactured and thorough low level tests made at FZK showed that there was no double peak.The next step would consist in building a gyrotron based on this new design, to confirm the simulation and to valdate it for long pulses

  16. Calorimetric Power Measurements of the DIII-D Gyrotron System

    Science.gov (United States)

    Gorelov, I.; Lohr, J.; Callis, R. W.; Cary, W. P.; Ponce, D.; Pinsker, R. I.; Chiu, H.; Baity, F. W.

    2001-10-01

    Gyrotron power measurements are an integral part of rf experiments on DIII-D. The ECH complex at General Atomics is built up from four 110 GHz, 1 MW gyrotrons, one from Communication and Power Industry (CPI) and three from Russia's Gyrotron Company (Gycom). Power measurements are made calorimetrically using the temperature and flow measurements of the gyrotron cooling circuits. Three such circuits are measured on the Gycom gyrotrons: window, MOU and dummy load. Interior cooling circuits are additionally measured on the CPI gyrotron that are very useful when tuning for maximum power and efficiency. Calorimetric signals from each cooling circuit are acquired by computer, where the dissipated energy is calculated with a LabView program. From these calculations, total rf power and efficiency were determined. Thus, calorimetry measurements were effectuated during gyrotron operations to provide the average power of each pulse.

  17. Treatment of rosacea with long-pulsed Nd: YAG laser

    Directory of Open Access Journals (Sweden)

    Ekin Meşe Say

    2013-03-01

    Full Text Available Background and Design: Rosacea is a chronic inflammatory disorder of the face. There is no curative treatment for the disease. Facial flushing and vascular lesions due to rosacea may significantly affect a patient’s quality of life. Topical and oral antibiotics are not effective for treating rosacea. Currently, laser treatment of vascular lesions has been reported in the literature. We aimed to investigate the efficacy of long-pulse 1064-nm neodymium: YAG (Nd: YAG laser in the treatment of vascular lesions (erythema and telangiectasia in rosacea patients. Materials and Methods: Thirty-nine patients (29 women, 10 men with erythematotelangiectatic rosacea (ETR were recruited into the study. Severity of the disease (ETR-score: 0-3 was assessed for all patients. We used long-pulsed Nd: YAG laser for vascular lesions at 3-4 weeks intervals. The face was divided into seven anatomic regions for evaluation. Assessment was made by comparing pretreatment and posttreatment photographs by using ETR-scores. For evaluating patient satisfaction, a scale of 0 to 3 was used. Results: The patients were divided into three groups according to the ETR scores [ETR-1 (n=12, ETR-2 (n=9, ETR-3 (n=18]. Following an average of 3.95 (2-8 sessions laser treatments, the clinical improvement was statistically significant in all groups (p<0.05. The mean reduction of ETR-score was 91.70% in patients with ETR-1 and. the clinical improvement was to be decreased in severe forms of ETR. The most common sites for the lesions were the malar region, ala nasi and the nasal dorsum, respectively. The lesions on the ala nasi were more recalcitrant to the treatment than those on the other areas. Regarding to physician assessment of treatment’s success, 97% of the patients was associated with moderate and excellent improvement. According to physicians’ assessment, excellent improvement was noticed in 43.58% and, 61.5% of patients reported a high degree of satisfaction with this

  18. Options for neutron scattering instruments on long pulse neutron sources

    International Nuclear Information System (INIS)

    Instrumenttion on long pulse sources can be approached either by instruments from short pulse sources and hence using mainly inverted time of flight techniques or by adopting reactor type instruments and making use of the time dependence of the source flux to enhance their performance substantially. While the first approach requires more or less single use of a beam line by one instrument, the second one allows multiple use of neutron guides, as customary on reactors and hence can make much better use of the source with gains up to 100 for time of flight spectrometers. To a certain extent, the design parameters of the source depend on which of the two approaches is chosen. (author) 8 figs., 1 tab., 16 refs

  19. Long-pulse magnetic field facility at Zaragoza

    Science.gov (United States)

    Algarabel, P. A.; del Moral, A.; Martín, C.; Serrate, D.; Tokarz, W.

    2006-11-01

    The long-pulse magnetic field facility of the Laboratorio de Magnetismo - Instituto de Ciencia de Materiales de Aragón (Universidad de Zaragoza-CSIC) produces magnetic fields up to 31, with a pulse duration of 2.2s. Experimental set-ups for measurements of magnetization, magnetostriction and magnetoresistance are available. The temperature can be controlled between 1.4 and 335 K, being the inner bore of the He cryostat of 22.5 mm. Magnetization is measured using the mutual induction technique, the magnetostriction is determined with the strain-gage and the capacitive cantilever methods, and the magnetoresistance is measured by means of the aclock-in technique in the 4-probes geometry. An overview of the facility will be presented and the presently available experimental techniques will be discussed.

  20. Aspects of long pulse commercial tokamak reactor design

    International Nuclear Information System (INIS)

    Illustrative design parameters have been developed for an Ultra-Long Pulse Tokamak Reactor (ULTR) with a pulse length of 24 hours. The principles developed for the 24 hour pulse length ULTR design have also been used in a scoping study for machines with shorter pulses. Parameters for a machine with a 4 hour pulse length are given. The ULTR design has an ohmic transformer which is optimized to satisfy the conflicting requirements of maximized OH drive and for reaction of the inward forces of the TF coil. The toroidal field magnet is completely modularized, with each coil in its own cryostat and shearing panels at room temperature. Analysis of effects of thermal fatigue on a representative first wall design has been performed. Windows of allowed operation have been found, limited by primary stress, swelling and fatigue. The analysis has been carried out for first walls made of stainless steel or vanadium

  1. Web Based System Architecture for Long Pulse Remote Experimentation

    Energy Technology Data Exchange (ETDEWEB)

    De Las Heras, E.; Lastra, D. [INDRA Sistemas, S.A., Unidad de Sistemas de Control, Madrid (Spain); Vega, J.; Castro, R. [Association Euratom CIEMAT for Fusion, Madrid (Spain); Ruiz, M.; Barrera, E. [Universidad Politecnica de Madrid (Spain)

    2009-07-01

    INDRA is the first Information Technology company in Spain and it presents here, through a series of transparencies, its own approach for the remote experimentation architecture for long pulses (REAL). All the architecture is based on Java-2 platform standards and REAL is a totally open architecture. By itself REAL offers significant advantages: -) access authentication and authorization under multiple security implementations, -) local or remote network access: LAN, WAN, VPN..., -) on-line access to acquisition systems for monitoring and configuration, -) scalability, flexibility, robustness, platform independence,.... The BeansNet implementation of REAL gives additional good things such as: -) easy implementation, -) graphical tool for service composition and configuration, -) availability and hot-swap (no need of stopping or restarting services after update or remodeling, and -) INDRA support. The implementation of BeansNet at the TJ-2 stellarator at Ciemat is presented. This document is made of the presentation transparencies. (A.C.)

  2. Instrumentation system for long-pulse MFTF neutral beams

    International Nuclear Information System (INIS)

    The instrumentation system for long pulse neutral beams for MFTFS consists of monitoring and protective circuitry. Global synchronization of high speed monitoring data across twenty-four neutral beams is achieved via an experiment wide fiber optic timing system. Fiber optics are also used as a means of isolating signals at elevated voltages. An excess current monitor, interrupt monitor, sparkdown detector, spot detector and gradient grid ratio detector form the primary protection for the neutral beam source. A unique hierarchical interlocking scheme allows other protective devices to be factored into the shutdown circuitry of the power supply so that the initiating cause of a shutdown can be isolated and even allows some non-critical devices to be safely ignored for a period of time

  3. Recent achievements on tests of series gyrotrons for W7-X and planned extension at the KIT gyrotron test facility

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, M., E-mail: martin.schmid@kit.edu [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute for Pulsed Power and Microwave Technology (IHM) (Germany); Choudhury, A. Roy; Dammertz, G. [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute for Pulsed Power and Microwave Technology (IHM) (Germany); Erckmann, V. [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Max-Planck-Institute for Plasmaphysics, Association EURATOM-IPP, Greifswald (Germany); Gantenbein, G.; Illy, S. [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute for Pulsed Power and Microwave Technology (IHM) (Germany); Jelonnek, J. [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute for Pulsed Power and Microwave Technology (IHM) (Germany); Institute of High Frequency Techniques and Electronics (IHE) (Germany); Kern, S. [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute for Pulsed Power and Microwave Technology (IHM) (Germany); Legrand, F. [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Thales Electron Devices, Vélicy (France); Rzesnicki, T.; Samartsev, A. [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute for Pulsed Power and Microwave Technology (IHM) (Germany); Schlaich, A.; Thumm, M. [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute for Pulsed Power and Microwave Technology (IHM) (Germany); Institute of High Frequency Techniques and Electronics (IHE) (Germany)

    2013-10-15

    Highlights: ► Solution found to suppress parasitic beam tunnel oscillations on high power gyrotrons. ► Electron beam sweeping technique to avoid plastic deformation on collector of high power gyrotrons. ► Ongoing investigations on limitations of gyrotron efficiency. ► Upgrade of 10 MW CW modulator for gyrotrons with multistage depressed collectors. -- Abstract: Parasitic beam tunnel oscillations have been hampering the series production of gyrotrons for W7-X. This problem has now been overcome thanks to the introduction of a specially corrugated beam tunnel. Two gyrotrons equipped with the new beam tunnel have fully passed the acceptance tests. Despite excellent power capability, the expected efficiency has not yet been achieved, possibly due to the presence of parasitic oscillations suspected to be dynamic after-cavity-oscillations (ACI's) or due to insufficient electron beam quality. Both theoretical and experimental investigations on these topics are ongoing. On previous W7-X gyrotrons collector fatigue has been observed, not (yet) leading to any failures so far. The plastic deformation occurring on the collector has now been eliminated due to the strict use (on all gyrotrons) of a sweeping method which combines the conventional 7 Hz solenoid sweeping technique with a 50 Hz transverse-field sweep system. Starting in 2013, the gyrotron test facility at KIT will be enhanced, chiefly with a new 10 MW DC modulator, capable of testing gyrotrons up to 4 MW CW output power with multi-stage-depressed collectors.

  4. Recent achievements on tests of series gyrotrons for W7-X and planned extension at the KIT gyrotron test facility

    International Nuclear Information System (INIS)

    Highlights: ► Solution found to suppress parasitic beam tunnel oscillations on high power gyrotrons. ► Electron beam sweeping technique to avoid plastic deformation on collector of high power gyrotrons. ► Ongoing investigations on limitations of gyrotron efficiency. ► Upgrade of 10 MW CW modulator for gyrotrons with multistage depressed collectors. -- Abstract: Parasitic beam tunnel oscillations have been hampering the series production of gyrotrons for W7-X. This problem has now been overcome thanks to the introduction of a specially corrugated beam tunnel. Two gyrotrons equipped with the new beam tunnel have fully passed the acceptance tests. Despite excellent power capability, the expected efficiency has not yet been achieved, possibly due to the presence of parasitic oscillations suspected to be dynamic after-cavity-oscillations (ACI's) or due to insufficient electron beam quality. Both theoretical and experimental investigations on these topics are ongoing. On previous W7-X gyrotrons collector fatigue has been observed, not (yet) leading to any failures so far. The plastic deformation occurring on the collector has now been eliminated due to the strict use (on all gyrotrons) of a sweeping method which combines the conventional 7 Hz solenoid sweeping technique with a 50 Hz transverse-field sweep system. Starting in 2013, the gyrotron test facility at KIT will be enhanced, chiefly with a new 10 MW DC modulator, capable of testing gyrotrons up to 4 MW CW output power with multi-stage-depressed collectors

  5. 100 GHz, 1 MW, CW gyrotron study program. Final report

    International Nuclear Information System (INIS)

    The results of a study program to investigate the feasibility of various approaches in designing a 100 GHz, 1 MW CW gyrotron are presented. A summary is given of the possible configurations for a high average power, high frequency gyrotron, including an historical survey of experimental results which are relevant to the various approaches. A set of basic scaling considerations which enable qualitative comparisons between particular gyrotron interaction circuits is presented. These calculations are important in understanding the role of various electron beam and circuit parameters in achieving a viable gyrotron design. Following these scaling exercises, a series of design calculations is presented for a possible approach in achieving 100 GHz, 1 MW CW. These calculations include analyses of the electron gun and interaction circuit parts of the gyrotron, and a general analysis of other aspects of a high average power, high frequency gyrotron. Scalability of important aspects of the design to other frequencies is also discussed, as well as key technology issues

  6. Gyrotron electromagnetic wiggler for a compact free electron laser

    International Nuclear Information System (INIS)

    We have demonstrated a novel, high power (≥1 MW), short wavelength (2 mm) gyrotron electromagnetic (GEM) wiggler for use in a compact free electron laser (FEL). The gyrotron consisted of an electron gun and resonator section followed by a special high Q cavity for storing the power created in the gyrotron resonator. The electromagnetic field stored in the high Q cavity would then be appropriate for use as a wiggler field in an infrared or visible FEL with a moderate energy (4 to 10 MeV) electron beam. The gyrotron experiment tested the practical limits due to ohmic loss, mode conversion, etc. on the strength of such a stored field. It also tested the effect of strong feedback from the high Q cavity back onto the gyrotron resonator. The proposed research utilized the technology of high power, high frequency gyrotrons developed at M.I.T. as part of the Department of Energy program on development of sources for plasma heating

  7. Complementarity of long pulse and short pulse spallation sources

    International Nuclear Information System (INIS)

    The complementarity of short pulse spallation sources (SPSS) and steady state (CW) reactors is a widely accepted concept. SPSS and long pulse spallation sources (LPSS) are complementary in two ways: a) in their performance in neutron scattering experiments LPSS closely emulate CW reactors. In this respect two facets of the time-of-flight (TOF) monochromator method adequate for LPSS will be discussed: the superiority of the TOF approach to the crystal monochromator method in high resolution powder diffraction, and the novel technique of repetition rate multiplication in TOF spectroscopy, b) LPSS combined with adequate chopper systems can also emulate SPSS in a number of applications. It will be shown that the LPSS method of producing short neutron pulses is more efficient for cold and thermal neutrons (below an energy of about 100 MeV), while SPSS is the more favourable approach for hot, epithermal neutrons, i.e. in the slowing down regime in contrast to the moderated regime. These two aspects of complementarity of LPSS and SPSS lead to the conclusions that for about 75% of the spectrum of neutron scattering experiments as known of today the LPSS approach is the most advantageous one with a feasible neutron intensity exceeding that available at ILL by a factor of about 30, while for the remaining 25% of applications the SPSS technique is superior with a well-known potential of a similar gain over present day performances. (author) 7 figs., 6 refs

  8. Web based system architecture for long pulse remote experimentation

    International Nuclear Information System (INIS)

    Remote experimentation (RE) methods will be essential in next generation fusion devices. Requirements for long pulse RE will be: on-line data visualization, on-line data acquisition processes monitoring and on-line data acquisition systems interactions (start, stop or set-up modifications). Note that these methods are not oriented to real-time control of fusion plant devices. INDRA Sistemas S.A., CIEMAT (Centro de Investigaciones Energeticas Medioambientales y Tecnologicas) and UPM (Universidad Politecnica de Madrid) have designed a specific software architecture for these purposes. The architecture can be supported on the BeansNet platform, whose integration with an application server provides an adequate solution to the requirements. BeansNet is a JINI based framework developed by INDRA, which makes easy the implementation of a remote experimentation model based on a Service Oriented Architecture. The new software architecture has been designed on the basis of the experience acquired in the development of an upgrade of the TJ-II remote experimentation system.

  9. Web Based System Architecture for Long Pulse Remote Experimentation

    International Nuclear Information System (INIS)

    Remote experimentation methods will be essential in next generation fusion devices. Requirements for long pulse operation will be the real-time visualization of data, the real-time monitoring of data acquisition processes and the real-time interaction with data acquisition systems (start, stop or set-up modifications). INDRA Sistemas S.A., CIEMAT and UPM (polytechnic university of Madrid) have designed a specific software architecture for these purposes. The architecture is based on the BeansNet platform, whose integration with an application server provides a proper solution to the requirements. BeansNet is a JINI based framework developed by INDRA, which makes easy the implementation of a remote participation model based on a Service Oriented Architecture. BeansNet and its interaction with the Messaging Services provides the users with the information acquired by real time acquisition systems, with no further delay than the derived from the information transmission over the network, depending on its bandwidth. The new software architecture has been designed based on the existing experience with the TJ-II remote experimentation system. In that case, different aspects of remote participation in experiments from distributed environments were addressed, as remote configuration of data acquisition systems or user authentication. The new design allows the required real-time interactions within a secure environment and with an easy system administration. (authors)

  10. Cryogenic pellet production developments for long-pulse plasma operation

    Energy Technology Data Exchange (ETDEWEB)

    Meitner, S. J.; Baylor, L. R.; Combs, S. K.; Fehling, D. T.; McGill, J. M.; Duckworth, R. C.; McGinnis, W. D.; Rasmussen, D. A. [Oak Ridge National Laboratory, 1Bethel Valley Rd Oak Ridge, TN 37831 (United States)

    2014-01-29

    Long pulse plasma operation on large magnetic fusion devices require multiple forms of cryogenically formed pellets for plasma fueling, on-demand edge localized mode (ELM) triggering, radiative cooling of the divertor, and impurity transport studies. The solid deuterium fueling and ELM triggering pellets can be formed by extrusions created by helium cooled, twin-screw extruder based injection system that freezes deuterium in the screw section. A solenoid actuated cutter mechanism is activated to cut the pellets from the extrusion, inserting them into the barrel, and then fired by the pneumatic valve pulse of high pressure gas. Fuel pellets are injected at a rate up to 10 Hz, and ELM triggering pellets are injected at rates up to 20 Hz. The radiative cooling and impurity transport study pellets are produced by introducing impurity gas into a helium cooled section of a pipe gun where it deposits in-situ. A pneumatic valve is opened and propellant gas is released downstream where it encounters a passive punch which initially accelerates the pellet before the gas flow around the finishes the pellet acceleration. This paper discusses the various cryogenic pellet production techniques based on the twin-screw extruder, pipe gun, and pellet punch designs.

  11. 1 GJ long pulse control on Tore Supra

    International Nuclear Information System (INIS)

    Full text: With the goal of addressing the critical issue of long pulse steady-state operation of next fusion devices, the experimental programme of the Tore Supra has been devoted in 2003 to study simultaneously current profile control, heat removal capability and particle exhaust. This required both advanced technology integration and steady-state real time plasma control, obtained on Tore Supra with a complete set of measurements and actuators built around a shared memory network. Plasma position control was improved within a few millimetres range, taking in account small changes in the pick up coils temperature. Fully non inductive current drive, in a MHD stable regime, was maintained during more than 6 minutes, with the capability to recover from transient failures of the RF power (arcs in the wave-guides). Infrared imaging of the first wall, analysed in real time, shows a stable surface temperature, as more than 98% of the injected power was recovered in the cooling water loop. A world record of injected-extracted energy, exceeding 1 GJ, was obtained in this new powerful regime. (author)

  12. Long-pulse, high-power vircator experiments

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, P.D.; Aurand, J.F.

    1988-01-01

    An experiment designed to achieve long pulse virtual cathode oscillator (VCO) operation at approx. 700 MHz is described. Low frequency operation allowed operating at large A-K gaps and low current densities which facilitated the 800 ns pulsewidth operation. The VCO was configured in a 91 cm diameter drift tube and consisted of a 76 cm diameter planar cathode separated from an anode screen by an A-K gap that was varied from 5 to 10 cm. The diode was directly driven by a Marx generator with a resultant A-K voltage of 350 kV. Power was extracted axially from the cylindrical waveguide through a Lexan window. Application of a transverse magnetic field downstream of the virtual cathode swept the beam into the wall. This method of dumping the beam avoided plasma formation at the window and a resultant shortening of the radiated pulse. The frequency was observed to chirp from 600 to 800 MHz. The radiation pattern was measured by a seven element B-dot array located 2.4 m from the exit window. Comparison of these patterns to computer code predictions indicated a mix of TM/sub 0/exclamation and TM/sub 02/ modes.

  13. High harmonic terahertz confocal gyrotron with nonuniform electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Wenjie; Guan, Xiaotong; Yan, Yang [THz Research Center, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2016-01-15

    The harmonic confocal gyrotron with nonuniform electron beam is proposed in this paper in order to develop compact and high power terahertz radiation source. A 0.56 THz third harmonic confocal gyrotron with a dual arc section nonuniform electron beam has been designed and investigated. The studies show that confocal cavity has extremely low mode density, and has great advantage to operate at high harmonic. Nonuniform electron beam is an approach to improve output power and interaction efficiency of confocal gyrotron. A dual arc beam magnetron injection gun for designed confocal gyrotron has been developed and presented in this paper.

  14. 28 GHz Gyrotron ECRH Upgrade for LDX

    Science.gov (United States)

    Michael, P. C.; Woskov, P. P.; Ellsworth, J. L.; Kesner, J.; Garnier, D. T.; Mauel, M. E.; Ellis, R. F.

    2009-11-01

    A 10 kW, CW, 28 GHz gyrotron is being implemented on LDX to increase the plasma density and to more fully explore the potential of high beta plasma stability in a dipole magnetic configuration. Higher density increases the heating of ions by thermal equilibration and allows for improved wave propagation in planned ICRF experiments. This represents over a 50% increase in the 17 kW ECRH from sources at 2.45, 6.4, and 10.5 GHz. The higher frequency will also make possible access to plasma densities of up to 10^13 cm-3. The 1 Tesla resonances are located above and below the floating coil near the dipole axial region. The gyrotron beam will be transmitted in TE01 mode in 32.5 mm diameter guide using one 90 bend and a short Tesla resonance region. A layout of the planned system will be presented.

  15. Improved Collectors for High Power Gyrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Ives, R. Lawrence; Singh, Amarjit; Read, Michael; Borchard, Phillipp; Neilson, Jeff

    2009-05-20

    High power gyrotrons are used for electron cyclotron heating, current drive and parasitic mode suppression in tokamaks for fusion energy research. These devices are crucial for successful operation of many research programs around the world, including the ITER program currently being constructed in France. Recent gyrotron failures resulted from cyclic fatigue of the copper material used to fabricated the collectors. The techniques used to collect the spent beam power is common in many gyrotrons produced around the world. There is serious concern that these tubes may also be at risk from cyclic fatigue. This program addresses the cause of the collector failure. The Phase I program successfully demonstrated feasibility of a mode of operation that eliminates the cyclic operation that caused the failure. It also demonstrated that new material can provide increased lifetime under cyclic operation that could increase the lifetime by more than on order of magnitude. The Phase II program will complete that research and develop a collector that eliminates the fatigue failures. Such a design would find application around the world.

  16. Design of Single disc RF window for High Power Gyrotron

    International Nuclear Information System (INIS)

    In this paper investigates the design of water edge cooled single-disc CVD-diamond window for 120 GHz, 1MW gyrotron. The design of RF window for 120 GHz, 1MW gyrotron has been carried out using the CST microwave studio. In 120 GHz gyrotron single disc of diameter 90 mm and thickness 2.0 mm CVD diamond window has been used in the simulation. The return loss (S11) and transmission loss (S21) of the 120 GHz gyrotron window have been found - 40.0 dB and -0.02 dB respectively. Thermal analysis of single disc rf window has also been carried out using ANSYS software for high power 120 GHz gyrotron. The temperature range on the disc surface has been found to be 100 °C - 300 ° C.

  17. Free-electron masers vs. gyrotrons: prospects for high-power sources at millimeter and submillimeter wavelengths

    Science.gov (United States)

    Thumm, Manfred

    2002-05-01

    The possible applications of high-power millimeter (mm) and sub-mm waves from free-electron masers (FEMs) and gyro-devices span a wide range of technologies. The plasma physics community has already taken advantage of recent advances in applying high-power mm waves generated by long pulse or continuous wave (CW) gyrotron oscillators and short pulse very high-power FEMs in the areas of RF-plasma production, heating, non-inductive current drive, plasma stabilization and active plasma diagnostics for magnetic confinement thermonuclear fusion research, such as electron cyclotron resonance heating (28-170 GHz), electron cyclotron current drive , collective Thomson scattering , microwave transmission and heat-wave propagation experiments. Continuously frequency tunable FEMs could widen these fields of applications. Another important application of CW gyrotrons is industrial materials processing, e.g. sintering of high-performance functional and structural nanostructured ceramics. Sub-mm wave sources are employed in high-frequency broadband electron paramagnetic resonance and other types of spectroscopy. Future applications which await the development of novel high-power FEM amplifiers and gyro-amplifiers include high-resolution radar ranging and imaging in atmospheric and planetary science as well as deep-space and specialized satellite communications and RF drivers for next-generation high-gradient linear accelerators (supercolliders). The present paper reviews the state-of-the-art and future prospects of these recent applications of gyro-devices and FEMs and compares their specific advantages.

  18. Reliability of High Power Laser Diode Arrays Operating in Long Pulse Mode

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

    2006-01-01

    Reliability and lifetime of quasi-CW laser diode arrays are greatly influenced by their thermal characteristics. This paper examines the thermal properties of laser diode arrays operating in long pulse duration regime.

  19. Investigation of long pulse laser induced flame on Al in air using optical interferometry

    Science.gov (United States)

    Zhang, Hongchao; Lu, Jian; Shen, Zhonghua; Ni, Xiaowu

    2013-05-01

    The process of long pulse laser(1ms) interaction with the aluminum plate was analyzed using Mach-Zehnder interferometer in this paper. A continuous semiconductor laser with about 50mW power and 532nm wavelength was used to detect the flame which induced by long pulse laser interaction with the aluminum plate. A high speed camera was used to capture the interferograms. The exposure time of the high speed camera is about 2 microseconds. And the frame rate is 2130fps. The high-speed camera and the long pulse laser pulse was synchronously controlled by the four-channel digital delay (Stanford Research Systems DG535).The FFT(Fast Fourier transform ) analysis is applied to extract the phase of the interferograms. The results provide an understanding of the process of long pulse laser drilling of the Al target.

  20. Simulation calculation of 24kV long pulse TESLA modulator

    Institute of Scientific and Technical Information of China (English)

    TAO Xiao-Ping; Stefan CHOROBA

    2004-01-01

    A 24 kV long pulse modulator is designed for DESY's TESLA Test Facility (TIF). This modulator,with a 120 kV, 1.7 ms width pulse output, is used to drive a Thomson TH1801 multibeam klystron. In order to make waveform flatness of the klystron voltage less than ±0.5%, it is necessary to use a bouncer circuit. This paper gives the Pspice simulation results of the 24 kV long pulse TESLA modulator.

  1. Long-pulsed dye laser versus long-pulsed dye laser-assisted photodynamic therapy for acne vulgaris: A randomized controlled trial

    DEFF Research Database (Denmark)

    Haedersdal, M.; Togsverd, K.; Wiegell, S.R.;

    2008-01-01

    Background: Long-pulsed dye laser (LPDL)-assisted photodynamic therapy has been suggested to be superior to laser alone for acne vulgaris but no evidence is available. Objective: To evaluate the efficacy and safety of LPDL alone versus LPDL in photodynamic therapy with methylaminolevulinic acid...

  2. A high-order particle-in-cell method for low density plasma flow and the simulation of gyrotron resonator devices

    Energy Technology Data Exchange (ETDEWEB)

    Stock, Andreas

    2013-04-26

    of its huge computational demand and the thereby resulting long calculation time. Using the presented high-order discontinuous Galerkin Particle-in-Cell scheme on high-performance-computers, this thesis demonstrates for the first time that full-wave and transient research- and design-simulations of gyrotron resonators with high mode-indices can be efficiently performed. For benchmark issues the developed discontinuous Galerkin Particle-in-Cell scheme is verified with a 30 GHz resonant cavity and the results are compared to the SELFT code, which is a state-of-the-art design code for resonators. The discontinuous Galerkin Particle-in-Cell scheme is used to simulate the resonator of the 1 MW, 140 GHz, TE(28,8)-mode gyrotron, used for plasma heating of the Wendelstein 7-X fusion-reactor. Due to the huge number of degrees of freedom and particles, this type of simulation can only be performed on high-performance-computers with enough memory and computational power. Hence, the discontinuous Galerkin Particle-in-Cell code is improved by a new parallelization approach for the high-order shape-function deposition method on unstructured grids, allowing for a high-order coupling between the particles and the electromagnetic field. To further improve the discontinuous Galerkin Particle-in-Cell code, a multi-rate time-stepping method, based on an Adams-Bashforth approach, for the hyperbolic divergence cleaning is developed and verified. This new approach considers the different time scales occurring in the hyperbolic divergence cleaning allowing for a more efficient time-stepping-algorithm then standard time-stepping-schemes. A rule for the construction of arbitrary-order multi-rate time-stepping methods has been derived. The presented simulations provide new physical insights to the complex particle-field-interaction appearing in gyrotrons. The discontinuous Galerkin Particle-in-Cell scheme can be used to analyse transient phenomena, such as beam-miss-alignment, mode competition

  3. 110 GHz, 1 MW Gyrotron Design Upgrades

    Science.gov (United States)

    Cauffman, Steve; Felch, Kevin; Borchard, Philipp; Cahalan, Pat; Chu, Sam; Dubrule, Craig

    1999-11-01

    Communications and Power Industries has incorporated a number of design changes into its most recent series of 110 GHz 1 MW gyrotrons, for use in ECH and ECCD experiments on the DIII-D tokamak. Two development gyrotrons previously installed at DIII-D used a modulating-anode electron gun design and output windows consisting of double-disk face-cooled sapphire on one system and an edge-cooled CVD diamond disk on the other. Three new systems presently in fabrication and test employ (a) a single-anode electron gun to avoid excitation of spurious modes during turn-on and turn-off and to simplify power supply requirements, (b) a modified TE_22,6 cavity to reduce competition from neighboring modes, (c) a two inch aperture edge-cooled CVD diamond window to allow transmission of a 1 MW Gaussian output beam, (d) a superconducting magnet system with a cryo-cooler to reduce liquid helium consumption, and (e) a number of internal and external plumbing simplifications to make cooling system connections more straightforward. Initial test results, if available, will be presented.

  4. 28 GHz Gyrotron ECRH on LDX

    Science.gov (United States)

    Woskov, P. P.; Kesner, J.; Michael, P. C.; Garnier, D. T.; Mauel, M. E.

    2010-12-01

    A 10 kW, CW, 28 GHz gyrotron has been implemented on LDX to increase the plasma density and to more fully explore the potential of high beta plasma stability in a dipole magnetic configuration. This added power represents about a 60% increase in ECRH to a new total of 26.9 kW with sources at 2.45, 6.4, and 10.5 GHz. The 1 Tesla resonances in LDX form small rings encompassing the entire plasma cross-section above and below the floating coil (F-coil) near the dipole axial region. A 32.5 mm diameter TE01 waveguide with a partial Vlasov step cut launches a diverging beam from above the F-coil that depends on internal wall reflections for plasma coupling. Initial gyrotron only plasmas exhibit steep natural profiles with fewer hot electrons than with the other sources. The background scattered radiation suggests that only about half the power is being absorbed with the present launcher.

  5. High power millimeter and submillimeter wave lasers and gyrotrons

    Science.gov (United States)

    Temkin, R. J.; Cohn, D. R.; Danly, B. G.; Kreischer, K. E.; Woskoboinikow, P.

    1985-10-01

    High power sources of coherent radiation in the millimeter and submillimeter wavelength range are useful in a number of applications, including plasma heating, plasma diagnostics, radar and communications. Two of the most important sources in this wavelength range are the optically pumped laser and the gyrotron. Major recent advances in both laser and gyrotron research are described. Possible techniques for improving the efficiency and operating characteristics of these devices are also reviewed.

  6. A simple quantum-electronic approach to the Gyrotron and its application to the solid-state gyrotron

    Science.gov (United States)

    Ho, P.-T.; Granatstein, V. L.

    1986-01-01

    A simple, unifying theory of the gyrotron is presented. It is of the Lamb type. Within its framework, important results from different approaches can be easily obtained. As an application, gyrotron action in InSb is reexamined, and coherent emission at 10 to the 12th Hz appears possible with an output power of about 0.5 mW/sq mm of the device.

  7. Gyrotrons for magnetic fusion applications at 110 GHz and 170 GHz

    Directory of Open Access Journals (Sweden)

    Cahalan P.

    2012-09-01

    Full Text Available Two megawatt-class gyrotrons at frequencies of 110 GHz and 170 GHz have recently been fabricated at CPI. The 110 GHz gyrotron is designed to produce 1.2 MW of output power for 10-second pulses, and will be used for electron cyclotron heating and current drive on the DIII-D tokamak at General Atomics. This gyrotron has completed factory testing and has been delivered to General Atomics for installation and additional testing. The 170 GHz gyrotron, though specified as a 500 kW CW system, has been designed with the goal of generating up to 1 MW CW. Oak Ridge National Laboratory will use this gyrotron in ITER ECH transmission line testing. This gyrotron has been fabricated and is awaiting factory testing, Design features of each gyrotron are described, and test data for the 110 GHz gyrotron are presented.

  8. Performance of long-pulse source reference target-moderator-reflector configurations

    International Nuclear Information System (INIS)

    We have calculated the performance of five similar target-moderator-reflector geometries that are reasonably well optimized for long-pulse source applications. For all cases, the moderators are fully coupled; that is, no poisons, decouplers, or liner are used. For each case, the energy- and time-dependent characteristics of the moderator source brightness have been parameterized using empirical functions. These parameterizations have been made available to users of the Monte Carlo neutron scattering instrument design code MCLIB for use in evaluating the performance of neutron scattering instruments on a long-pulse source. (author) 7 figs., 2 tabs., 5 refs

  9. Development of an ion source for long-pulse (30-s) neutral beam injection

    Energy Technology Data Exchange (ETDEWEB)

    Menon, M.M.; Barber, G.C.; Blue, C.W.; Dagenhart, W.K.; Gardner, W.L.; Haselton, H.H.; Moeller, J.A.; Ponte, N.S.; Ryan, P.M.; Schecter, D.E.

    1982-01-01

    This paper describes the development of a long-pulse positive ion source that has been designed to provide high brightness deuterium beams (divergence approx. = 0.25/sup 0/ rms, current density approx. = 0.15 A cm/sup -2/) of 40 to 45 A, at a beam energy of 80 keV, for pulse lengths up to 30 s. The design and construction of the ion source components are described with particular emphasis placed on the long-pulse cathode assembly and ion accelerator.

  10. Improving Reliability of High Power Quasi-CW Laser Diode Arrays Operating in Long Pulse Mode

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

    2006-01-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data of the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  11. ECH system and its application to long pulse discharge in large helical device

    International Nuclear Information System (INIS)

    We have developed and constructed an ECH system for the large helical device (LHD). The ECH system consists of 0.5 MW, 84 GHz range and 168 GHz gyrotrons, high voltage power supplies, long distance transmission lines, and in-vessel quasi-optical antennas. It has been improved step by step. At the third campaign of LHD experiments, three 84 GHz range (two 82.6 GHz and one 84 GHz) and three 168 GHz gyrotrons are operated and ECH power can be injected from four antennas vertically and two horizontally. This complicated system is remotely controlled and monitored by fully GUI (Graphical User Interface) control panels realized on PC via TCP (transmission control protocol) communication. Over 10000 shots of gyrotron power have been injected steadily into the LHD during the experimental campaigns on this system. One line of the system (84 GHz line) is specially prepared for the experiments of steady state plasma production. Using this line, plasma sustainment for 2 min was successfully achieved by only ECH power. Injected ECH power was 50 kW with 95% duty factor. The electron density and temperature of the sustained plasma are measured to be 0.3-0.5x1018 m-3 and ∼650 eV. Ion temperature measured by Doppler broadening of the impurity radiation line was kept constant at ∼300 eV during RF injection

  12. ECH system and its application to long pulse discharge in large helical device

    Energy Technology Data Exchange (ETDEWEB)

    Shimozuma, T.; Kubo, S.; Sato, M.; Idei, H.; Takita, Y.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Yoshimura, Y.; Ohkubo, K.; Funaba, H.; Inagaki, S.; Kobuchi, T.; Masuzaki, S.; Muto, S.; Shoji, M.; Suzuki, H.; Noda, N.; Nakamura, Y.; Kawahata, K.; Ohyabu, N.; Motojima, O

    2001-01-01

    We have developed and constructed an ECH system for the large helical device (LHD). The ECH system consists of 0.5 MW, 84 GHz range and 168 GHz gyrotrons, high voltage power supplies, long distance transmission lines, and in-vessel quasi-optical antennas. It has been improved step by step. At the third campaign of LHD experiments, three 84 GHz range (two 82.6 GHz and one 84 GHz) and three 168 GHz gyrotrons are operated and ECH power can be injected from four antennas vertically and two horizontally. This complicated system is remotely controlled and monitored by fully GUI (Graphical User Interface) control panels realized on PC via TCP (transmission control protocol) communication. Over 10000 shots of gyrotron power have been injected steadily into the LHD during the experimental campaigns on this system. One line of the system (84 GHz line) is specially prepared for the experiments of steady state plasma production. Using this line, plasma sustainment for 2 min was successfully achieved by only ECH power. Injected ECH power was 50 kW with 95% duty factor. The electron density and temperature of the sustained plasma are measured to be 0.3-0.5x10{sup 18} m{sup -3} and {approx}650 eV. Ion temperature measured by Doppler broadening of the impurity radiation line was kept constant at {approx}300 eV during RF injection.

  13. Beam divergence studies on a long-pulse XeCl excimer laser

    NARCIS (Netherlands)

    Hofstra, R.M.; Goor, van F.A.; Witteman, W.J.; Letardi, Tommaso; Weber, Horst

    1996-01-01

    The focusability of a long pulse XeCl excimer laser has been improved using confocal positive branch unstable resonators where the outcoupling is done through the convex mirror. For the outcoupler different reflectivity profiles are used. A near diffraction limited output beam is obtained from hard

  14. Long-pulsed dye laser vs. intense pulsed light for the treatment of facial telangiectasias: a randomized controlled trial

    DEFF Research Database (Denmark)

    Nymann, Peter; Hedelund, Lene; Haedersdal, M

    2010-01-01

    This study aims to compare the efficacy and adverse effects of long-pulsed dye laser (LPDL) and intense pulsed light (IPL) in the treatment of facial telangiectasias.......This study aims to compare the efficacy and adverse effects of long-pulsed dye laser (LPDL) and intense pulsed light (IPL) in the treatment of facial telangiectasias....

  15. State-of-the-art of high power gyro-devices and free electron masers. Update 2005

    International Nuclear Information System (INIS)

    Gyrotron oscillators (gyromonotrons) are mainly used as high power millimeter wave sources for electron cyclotron resonance heating (ECRH), electron cyclotron current drive (ECCD), stability control and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. The maximum pulse length of commercially available 140 GHz, megawatt-class gyrotrons employing synthetic diamond output windows is 30 minutes (CPI and European FZK-CRPP-CEA-TED collaboration). The world record parameters of the European 140 GHz gyrotron are: 0.92 MW output power at 30 min. pulse duration, 97.5% Gaussian mode purity and 43% efficiency, employing a single-stage depressed collector for energy recovery. This results in an energy content of 1.66 GJ. A maximum output power of 1.2 MW in 4.1 s pulses was generated with the JAERI-TOSHIBA 110 GHz gyrotron. The Russian and the Japan 170 GHz ITER gyrotrons achieved 0.5 MW with pulse durations of 80 s and 500 s, respectively. Diagnostic gyrotrons deliver Pout=40 kW with τ=40 μs at frequencies up to 650 GHz (η=4%). Gyrotron oscillators have also been successfully used in materials processing. Such technological applications require gyrotrons with the following parameters: f≥24 GHz, Pout=4-50 kW, CW, η≥30%. This paper gives an update of the experimental achievements related to the development of high power gyrotron oscillators for long pulse or CW operation and pulsed gyrotrons for plasma diagnostics. In addition, this work gives a short overview of the present development status of coaxial-cavity gyrotrons, gyrotrons for technological applications, relativistic gyrotrons, quasi-optical gyrotrons, fast- and slow-wave cyclotron autoresonance masers (CARMs), gyroklystrons, gyro-TWT amplifiers, gyrotwystron amplifiers, gyro-BWO's, gyropeniotrons, magnicons, gyroharmonic converters, free electron masers (FEMs) and of vacuum windows for such high-power mm-wave sources. The highest CW powers produced by

  16. Designing A Mode Converter For Use With A Gyrotron

    Science.gov (United States)

    Hoppe, Daniel J.

    1995-01-01

    Report describes process of designing corrugated, circular-cross-section length of waveguide converting input electromagnetic radiation at frequency of 34.5 GHz in TM(11) mode to output radiation in HE(11) mode. TM(11)-mode input radiation supplied by gyrotron generating continuous-wave power of 200 kW at 34.5 GHz in TE(01) mode followed by TE(01)-to-TM(11) mode converter. Together, gyrotron and mode converters constitute prototype high-power transmitter for long-distance free-space communication.

  17. Phase locking and bandwidth in a gyrotron oscillator

    Science.gov (United States)

    Latham, P. E.; Granatstein, V. L.; Carmel, Y.

    1993-06-01

    For imaging radar and for satellite and space communication (e.g. NASA's deep space network), it is important that the bandwidth be as large as possible. Here we derive a formalism for computing the phase locking bandwidth that can be achieved in a gyrotron oscillator while varying the beam voltage. As an example, a second harmonic TE02/03 gyrotron is considered. For this device, the effective bandwidth can be increased by a factor of about 3 compared with the fixed voltage case by allowing the beam voltage to change together with the input locking signal.

  18. Oscillating virtual cathode, large-orbit gyrotron and driver

    Energy Technology Data Exchange (ETDEWEB)

    VanHaaften, F.W.; Hoeberling, R.F.; Fazio, M.V.

    1986-01-01

    Studies using an oscillating virtual cathode (vircator) and a large-orbit gyrotron to generate microwave levels of several hundred megawatts are being conducted at the Los Alamos National Laboratory (LANL). A pulse level of approx.1 MV, with length approaching 1 ..mu..s at a repetition rate of a few hertz, is anticipated for extension of these studies from the present single-shot mode with 100-ns pulse width. The increased pulse width is needed to test longer pulse length microwave sources. Pulse forming network (PFN), transformer-coupled drivers have been studied and are part of the subject of this paper. The large-orbit gyrotron is discussed here.

  19. Suppression of parasitic space-charge oscillations in a gyrotron

    Science.gov (United States)

    Louksha, O. I.; Piosczyk, B.; Sominski, G. G.; Thumm, M.; Samsonov, D. B.

    2006-10-01

    We study the influence of nonuniform electric and magnetic fields in the helical-beam compression region on the low-frequency parasitic space-charge oscillations for a moderate-power (˜ 100 kW) 4-mm gyrotron. Suppression of the oscillations is achieved by optimization of both the cathode-unit geometry in the magnetron-injector gun and the magnetic-field distribution in the region near the cavity input. The obtained data are evidence of possible effective operation of the gyrotron at elevated pitch-factor values α > 1.5 even for emitters with no highest emission uniformity (δje ≈ 30%).

  20. Initial operation of high power ICRF system for long pulse in EAST

    Energy Technology Data Exchange (ETDEWEB)

    Qin, C. M., E-mail: chmq@ipp.ac.cn; Zhao, Y. P.; Zhang, X. J.; Wan, B. N.; Gong, X. Z.; Mao, Y. Z.; Yuan, S.; Chen, G. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2015-12-10

    The ICRF heating system on EAST upgraded by active cooling aims for long pulse operation. In this paper, the main technical features of the ICRF system are described. One of a major challenges for long pulse operation is RF-edge interactions induced impurity production and heat loading. In EAST, ICRF antenna protections and Faraday screen bars damaged due to LH electron beam are found. Preliminary results for the analysis of the interaction between LHCD and ICRF antenna are discussed. Increase of metal impurities in the plasma during RF pulse and in a larger core radiation are also shown. These RF-edge interactions at EAST and some preliminary results for the optimizing RF performance will be presented.

  1. The performance of neutron spectrometers at a long-pulse spallation source

    International Nuclear Information System (INIS)

    At a recent workshop at Lawrence Berkeley National Laboratory, members of the international neutron scattering community discussed the performance to be anticipated from neutron scattering instruments installed at a 1 MW long-pulse spallation source (LPSS). Also the report of this workshop is long, its principal conclusions can be easily summarised and almost as easily understood. This article presents such a synthesis for a 60 Hz LPSS with 1 msec proton pulses. We discuss some of the limitation of the workshop conclusions and suggest a simple analysis of the performance differences that might be expected between short- and long-pulse sources both of which exploit coupled moderators. (author) 5 figs., 1 tab., 5 refs

  2. New Edge Coherent Mode Providing Continuous Transport in Long Pulse H-mode Plasmas

    DEFF Research Database (Denmark)

    Wang, H.Q.; Xu, G.S.; Wan, B.N.;

    2014-01-01

    An electrostatic coherent mode near the electron diamagnetic frequency (20–90 kHz) is observed in the steep-gradient pedestal region of long pulse H-mode plasmas in the Experimental Advanced Super-conducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond-coated reciproc......An electrostatic coherent mode near the electron diamagnetic frequency (20–90 kHz) is observed in the steep-gradient pedestal region of long pulse H-mode plasmas in the Experimental Advanced Super-conducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond...... the nature of dissipative trapped electron mode, as evidenced by gyrokinetic turbulence simulations....

  3. Initial operation of high power ICRF system for long pulse in EAST

    International Nuclear Information System (INIS)

    The ICRF heating system on EAST upgraded by active cooling aims for long pulse operation. In this paper, the main technical features of the ICRF system are described. One of a major challenges for long pulse operation is RF-edge interactions induced impurity production and heat loading. In EAST, ICRF antenna protections and Faraday screen bars damaged due to LH electron beam are found. Preliminary results for the analysis of the interaction between LHCD and ICRF antenna are discussed. Increase of metal impurities in the plasma during RF pulse and in a larger core radiation are also shown. These RF-edge interactions at EAST and some preliminary results for the optimizing RF performance will be presented

  4. Measurement of soft x-ray image by using CCD camera for long pulse discharge

    International Nuclear Information System (INIS)

    A soft x-ray imaging was made a CCD camera installed to a tangential port in LHD. The large number of pixels (1024x512) of with CCD gives a good spatial resolution of 1.8 mm. The tangential soft x-ray image is obtained during long pulse discharge on LHD with a time resolution of 0.5 s. The shift of x-ray emission profile is found for plasmas with different magnetic axes. (J.P.N.)

  5. Laser ion source with long pulse width for RHIC-EBIS

    International Nuclear Information System (INIS)

    The Electron Beam Ion Source (EBIS) at Brookhaven National Laboratory is a new heavy ion-projector for RHIC and NASA Space Radiation Laboratory. Laser Ion Source (LIS) with solenoid can supply many kinds of ion from solid targets and is suitable for long pulse length with low current as ion provider for RHIC-EBIS. In order to understand a plasma behavior for fringe field of solenoid, we measure current, pulse width and total ion charges by a new ion probe. The experimental result indicates that the solenoid confines the laser ablation plasma transversely. Laser ion source needs long pulse length with limited current as primary ion provider for RHIC-EBIS. New ion probe can measure current distribution for the radial positions along z axis. The beam pulse length is not effected by magnetic field strength. However, the currents and charges decay with the distance from the end of solenoid. These results indicate that solenoid field has important role for plasma confinement not longitudinally but transversely and solenoid is able to have long pulse length with sufficient total ion charges. Moreover, the results are useful for a design of the extraction system for RHIC-EBIS.

  6. Development of long pulse radiofrequency heating and current drive systems and scenarios for WEST

    International Nuclear Information System (INIS)

    The longstanding expertise of the Tore Supra Team in long pulse radiofrequency (RF) heating and current drive systems will now be exploited in WEST (tungsten-W Environment in Steady-state Tokamak). WEST will allow an integrated long pulse tokamak programme for testing W-divertor components at ITER-relevant heat flux (10-20 MW/m2), while treating crucial aspects for ITER-operation, such as avoidance of W-accumulation in long discharges, monitoring and control of heat fluxes on the metallic plasma facing components (PFCs) and coupling of RF waves in H-mode plasmas. Scenario modelling using the METIS-code shows that ITER-relevant heat fluxes are compatible with the sustainment of long pulse H-mode discharges, at high power (up to 15 MW/30s at IP = 0.8 MA) or high fluence (up to 10 MW, up to 1000s at IP = 0.6 MA), all based on RF heating and current drive using Ion Cyclotron Resonance Heating (ICRH) and Lower Hybrid Current Drive (LHCD). To allow coupling to H-mode plasmas, three ELM-resilient ICRH antennas have been designed for WEST. They will be fabricated and provided as in-kind contribution by ASIPP (Hefei), within the framework of the Associated Laboratory IRFM-ASIPP. Furthermore, the ICRH generator has been upgraded to allow high power operation (9 MW/30s) at high reflected power (VSWR = 2). The WEST ICRH system is thus the first ever ICRH system combining continuous wave (CW) operation at high power and load tolerance capability for coupling on H-modes. The nominal operating frequencies are 53±2 MHz and 55.5± 2 MHz, in order to allow flexibility in the location of the resonance layer around the magnetic axis. The LHCD system, with capability to inject 7 MW/1000s, is an indispensable tool for long pulse scenarios. The LH power deposition and current profiles have been modelled with the recent 'Tail LH' model in C3PO/LUKE, which has proven to reproduce well the experimental LHCD results on Tore Supra, as well as on EAST. The simulations show that the

  7. Research on advanced high power gyrotrons at FZK

    International Nuclear Information System (INIS)

    The experimental 170 GHz coaxial cavity gyrotron for ITER has been assembled and installed in the SC magnet. The operation started in May 2004 with performing the alignment and conditioning of the tube. The main goal of the experiments is to verify the design of components for a 2 MW, CW industrial prototype

  8. Status of the new multi-frequency ECRH system for ASDEX Upgrade

    DEFF Research Database (Denmark)

    Wagner, D.; Grünwald, G.; Leuterer, F.;

    2008-01-01

    Currently, a new multi-frequency ECRH system is under construction at the ASDEX Upgrade tokamak experiment. This system employs, for the first time in a fusion device, multi-frequency gyrotrons, step-tunable in the range 105-140 GHz. The first two gyrotrons, working at 105 and 140 GHz, were insta...

  9. A novel vacuum window for megawatt gyrotrons

    Science.gov (United States)

    Haldeman, George Stephenson

    2001-08-01

    This thesis describes a new microwave output window for megawatt power level, 110 GHz gyrotrons. The window uses two spherically polished sapphire elements separated by a nearly uniform gap of about 1 mm. Pressurized, microwave transparent coolant flows through this gap and across the transmitting aperture, removing absorbed energy at the element face. The design differs from previous face- cooled windows because the sapphire elements have a modestly curved dome, rather than flat shape. This curved shape increases the element's capability to withstand coolant pressures without significantly increasing stresses from differential heating. Consequently, window power can be increased either through enhanced, high pressure cooling or by using thinner elements with reduced microwave absorption. A model was developed to predict window power capability as a function of design geometry. This model predicted an increase from 0.5 to 2.1 MW when flat elements were changed to curved. Both designs used full size, 100mm clear apertures, but the curved elements with 214 mm curvature radii were 1.3 rather than 1.75 mm thick. The model was also used to design a half size prototype experiment. This 50 mm clear aperture system used 60 mm OD x 0.47 mm thick x 107 mm surface radius elements. An initial piece was fabricated and statically tested to a pressure of 1.1 MPa well above the 0.5 MPa analytically predicted to be required for megawatt operation. The complete window structure was then fabricated, including instrumentation to simulate microwave heating and to measure induced temperatures and strains. Test results demonstrated an equivalent continuous Gaussian beam power capability of 700 kW using a coolant flow of 1.1 lps. Scaling from this measurement, fall size boiling limited power is expected to be 1.1 MW for a Gaussian microwave intensity profile, or 2.3 MW for a shaped profile typical of previous flat, face-cooled designs. (Copies available exclusively from MIT Libraries, Rm

  10. A comparison between short pulse spallation source and long pulse spallation source

    Energy Technology Data Exchange (ETDEWEB)

    Aizawa, Kazuya; Watanabe, Noboru; Suzuki, Jun-ichi; Niimura, Nobuo; Morii, Yukio; Katano, Susumu; Osakabe, Toyotaka; Teshigawara, Makoto [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Mezei, F.

    1997-11-01

    The performance for a 5 MW short pulse spallation source (SPSS) and a 4.5 MW long pulse spallation source (LPSS) in a JAERI program which is based on the availability of a 1.5 GeV superconducting linac with a 30 mA peak current for both proton and H{sup -} beams is discussed. We have examined the superiority of SPSS to LPSS. While a LPSS facility is a second option, we propose an SPSS facility as a first option. (author)

  11. Heat treatment of long pulse operation for the JAERI ERL-FEL

    International Nuclear Information System (INIS)

    RF power sources are replaced from all-solid-state amplifiers to IOT amplifiers for the superconducting accelerators (SCAs) and a vacuum tube amplifier for the SHB of the JAERI ERL-FEL. A long pulse operation increased the pressure in the cryostat of the SCA. The single-cell SCA can be operated in 9% duty according to the time constant of the pressure decay in the cryostat. SHB can be operated in 4% duty which is limited by the frequency range of the tuners. The result of the ABAQUS calculation shows the more duty operation. (author)

  12. Design of long-pulse fast wave current drive antennas for DIII-D

    Science.gov (United States)

    Baity, F. W.; Batchelor, D. B.; Bills, K. C.; Fogelman, C. H.; Jaeger, E. F.; Ping, J. L.; Riemer, B. W.; Ryan, P. M.; Stallings, D. C.; Taylor, D. J.; Yugo, J. J.

    1994-10-01

    Two new long-pulse fast wave current drive (FWCD) antennas will be installed on DIII-D in early 1994. These antennas will increase the available FWCD power from 2 MW to 6 MW for pulse lengths of up to 2 s, and to 4 MW for up to 10 s. Power for the new antennas is from two ASDEX-type 30- to 120-MHz transmitters. When operated at 90° phasing into a low-density plasma (˜4×1019m-3) with hot electrons (˜10 keV), these two new antennas are predicted to drive approximately 1 MA of plasma current.

  13. Long pulse H- beam extraction with a rf driven ion source on a high power level

    International Nuclear Information System (INIS)

    IPP Garching is investigating the applicability of rf driven negative ion sources for the neutral beam injection of International Thermonuclear Experimental Reactor. The setup of the tested source was improved to enable long pulses up to 100 kW rf power. The efficiency of negative ion production decreases at high power. The extracted H- currents as well as the symmetry of the plasma density close to the plasma grid and of the beam divergence depend on the magnetic filter field. The pulse duration is limited by the increase in coextracted electrons, which depends on the rf power and the caesium conditions on the plasma grid.

  14. Recent Tests on 117.5 GHz and 170 GHz Gyrotrons

    Directory of Open Access Journals (Sweden)

    Felch K.

    2015-01-01

    Full Text Available Two megawatt-class gyrotrons at frequencies of 117.5 GHz and 170 GHz have recently been fabricated and tested at CPI. The 117.5 GHz gyrotron was designed to produce up to 1.8 MW for 10-second pulses, and will be used for electron cyclotron heating and current drive on the DIII-D tokamak at General Atomics. The 170 GHz gyrotron is specified as a 500 kW CW system, but has been designed with the goal of generating up to 1 MW CW. Oak Ridge National Laboratory will use the gyrotron in ITER ECH transmission line testing.

  15. Small-angle scattering instruments on a 1 MW long pulse spallation source

    International Nuclear Information System (INIS)

    We have designed and optimized two small-angle neutron scattering instruments for installation at a 1 MW long pulse spallation source. The first of these instruments measures a Q-domain from 0.002 to 0.44 A-1, and the second instrument from 0.00069-0.17 A-1, Design characteristics were determined and optimization was done using a Monte Carlo instrument simulation package under development at Los alamos. A performance comparison was made between these instruments with D11 at the ILL by evaluating the scattered intensity and rms resolution for the instrument response function at different Q values for various instrument configurations needed to spn a Q-range of 0.0007-0.44 A-1. We concluded that the first of these instruments outperforms D11 in both intensity and resolution over most of the Q-domain and that the second is comparable to D11. Comparisons were also made of the performance of the optimized long pulse instruments with different reflectors and with a short pulse source, from which we concluded that there is an optimal moderator-reflector combination, and that a short pulse does not substantially improve the instrument performance. (author) 7 figs., 2 tabs., 9 refs

  16. Towards high-power long-pulse operation on Tore Supra

    International Nuclear Information System (INIS)

    The Tore Supra tokamak was given the main mission to investigate the route towards long pulse plasma discharges. This includes the problem of heat exhaust and particle control (via the development of high-performance plasma facing components), and in parallel the physics of fully non inductive discharges and its optimization with respect to the confinement. Tore Supra is thus equipped with a superconducting toroidal magnet (maximum magnetic field on axis 4.5T), a full set of actively cooled plasma facing components (PFC), and a heating and current drive capability based on high power RIF systems connected to actively cooled antennas. The encouraging results already obtained, as well as recent progress in PFC, allowed us to envisage a significant improvement in the heat exhaust capability of Tore Supra. The so-called CIEL-project consists in a complete upgrade of the inner chamber of Tore Supra, planned to be installed during the year 2000. The present paper deals with the experimental and modeling activity linked to the preparation of the long-pulse high-power discharges using the present Tore Supra equipment: heating and current drive scenarios, power coupling, confinement and transport studies, discharge control... An overview of the results obtained in that field is presented, as well as the progress required in the coming years, and the expected performance, for the CIEL phase, in terms of current drive and confinement. (author)

  17. A repetitive long-pulse power generator based on pulse forming network and linear transformer driver.

    Science.gov (United States)

    Li, Mingjia; Kang, Qiang; Tan, Jie; Zhang, Faqiang; Luo, Min; Xiang, Fei

    2016-06-01

    A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ∼50 ns and a flat top of ∼100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ∼560 kV, output current amplitude of ∼10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 10(4) pulses. Meanwhile, the continuous operating time of the generator is up to 60 s. PMID:27370479

  18. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

    International Nuclear Information System (INIS)

    A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory

  19. A repetitive long-pulse power generator based on pulse forming network and linear transformer driver

    Science.gov (United States)

    Li, Mingjia; Kang, Qiang; Tan, Jie; Zhang, Faqiang; Luo, Min; Xiang, Fei

    2016-06-01

    A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ˜50 ns and a flat top of ˜100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ˜560 kV, output current amplitude of ˜10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 104 pulses. Meanwhile, the continuous operating time of the generator is up to 60 s.

  20. Occlusion Effect of a Long-pulsed 532nm Laser on Veins

    Institute of Scientific and Technical Information of China (English)

    ZHANGLai-ming; YANGGui-long; LIDian-jun; LUQi-peng; GUHua-dong; ZHULin-lin; ZHAOZhen-wu; LIXin; WANGJing-ping; TANGYu-guo; GUOJin

    2005-01-01

    Laser treatment represents an attractive option to other methods of vessel diseases especially varicose veins. A long pulse (30-50ms) 532nm laser was used in our experiments, with the pulse duration matching the thermal relaxation time of the vessels and the green laser matching the absorption spectrum peak of the blood.Laser irradiates nude vein vessels directly or exterior skin to finish operation faster and to acquire the practical data for upper enteron varicose vein treatment in several animal experiments performed in vivo. The 5Jenergy pulse allows us to finely occlude rabbit or dog's vein vessels up to 2 mm in diameter when irradiating them off external skin. Blood vessels are occluded at once, and later biopsy specimens show the immediate and long-term lasting occlusion effect. While vessels are irradiated directly, they are usually irradiated to perforate, detailed causes are still under investigation. Animal experiments showed that the long pulse green laser therapy is a safe and effective solution to the vein's occlusion, which promises such laser with high energy of each pulse and 30-50 ms duration is an ideal candidate for vessel diseases treatment.

  1. Long-pulse Nd:YAG 1064-nm laser treatment for onychomycosis

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rui-na; WANG Dong-kun; ZHUO Feng-lin; DUAN Xiao-han; ZHANG Xiao-yan; ZHAO Jun-ying

    2012-01-01

    Background Recent research shows that lasers can inhibit fungal growth and that Nd:YAG 1064-nm lasers can penetrate as deep as the lower nail plate.The aim of this study was to observe the effect of a long-pulse Nd:YAG 1064-nm laser on 154 nails of 33 patients with clinically and mycologically proven onychomycosis.Methods Thirty-three patients with 154 nails affected by onychomycosis were randomly assigned to two groups,with the 154 nails divided into three sub-groups (Ⅱ degree,Ⅲ degree,and Ⅳ degree) according to the Scoring Clinical Index of Onychomycosis.The 15 patients (78 nails) in group 1 were given eight sessions with a one-week interval,and the 18patients (76 nails) in group 2 were given four sessions with a one-week interval.Results In group 1,the effective rates at 8 weeks,16 weeks,and 24 weeks were 63%,62%,and 51%,respectively,and the effective rates in group 2 were 68%,67%,and 53% respectively.The treatment effect was not significantly different between any sub-group pair (P >0.05).Conclusions Long pulse Nd:YAG 1064-nm laser was effective for onychomycosis.It is a simple and effective method without significant complications or side effects and is expected to become an alternative or replacement therapy for onychomycosis.

  2. Investigation of an X-band gigawatt long pulse multi-beam relativistic klystron amplifier

    International Nuclear Information System (INIS)

    To achieve a gigawatt-level long pulse radiation power in X-band, a multi-beam relativistic klystron amplifier is proposed and studied experimentally. By introducing 18 electron drift tubes and extended interaction cavities, the power capacity of the device is increased. A radiation power of 1.23 GW with efficiency of 41% and amplifier gain of 46 dB is obtained in the particle-in-cell simulation. Under conditions of a 10 Hz repeat frequency and an input RF power of 30 kW, a radiation power of 0.9 GW, frequency of 9.405 GHz, pulse duration of 105 ns, and efficiency of 30% is generated in the experiment, and the amplifier gain is about 45 dB. Both the simulation and the experiment prove that the multi-beam relativistic klystron amplifier can generate a long pulse GW-level radiation power in X-band

  3. Dynamics of high power and long pulse laser propagation and its control in underdense plasmas

    Science.gov (United States)

    Nakatsutsumi, M.; Fuchs, J.; Antici, P.; Audebert, P.; Bourgeois, N.; Grech, M.; Kodama, R.; Lin, T.; Marqués, J. R.; Riazuelo, G.; Romagnani, L.; Tikhonchuk, V.

    2006-10-01

    The study of intense laser pulse propagation through long underdense plasmas is of crucial importance for inertial confinement fusion (ICF). We have performed a systematic study of long pulse beams (τL=400ps,I=10^10˜10^12Wcm-2) propagating through the underdense plasmas (ne=10^19˜10^20cm-3), by controlling two filaments created from the pulses with variable delay and intensity ratio. These experiments have been performed at the LULI laser facility. The results show that the earlier pulse affects the propagation characteristics of the later pulse. The 2D time-resolved sampling camera provides the ability to examine the possibility of enhanced propagation, collimation, and guiding of a trailing pulse induced by an earlier pulse. These facts are of interest for ICF and other applications. In particular, this study opens perspectives, through shaping the pulses temporally, for the control of propagation of long pulses in the low density plasmas that are present within ICF hohlraums.

  4. The performance of neutron scattering spectrometers at a long-pulse spallation source

    International Nuclear Information System (INIS)

    The first conclusion the author wants to draw is that comparison of the performance of neutron scattering spectrometers at CW and pulsed sources is simpler for long-pulsed sources than it is for the short-pulse variety. Even though detailed instrument design and assessment will require Monte Carlo simulations (which have already been performed at Los Alamos for SANS and reflectometry), simple arguments are sufficient to assess the approximate performance of spectrometers at an LPSS and to support the contention that a 1 MW long-pulse source can provide attractive performance, especially for instrumentation designed for soft-condensed-matter science. Because coupled moderators can be exploited at such a source, its time average cold flux is equivalent to that of a research reactor with a power of about 15 MW, so only a factor of 4 gain from source pulsing is necessary to obtain performance that is comparable with the ILL. In favorable cases, the gain from pulsing can be even more than this, approaching the limit set by the peak flux, giving about 4 times the performance of the ILL. Because of its low duty factor, an LPSS provides the greatest performance gains for relatively low resolution experiments with cold neutrons. It should thus be considered complementary to short pulse sources which are most effective for high resolution experiments using thermal or epithermal neutrons

  5. Advances in long pulse operation at high radio frequency power in Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Goniche, M.; Dumont, R.; Bourdelle, C.; Decker, J.; Delpech, L.; Ekedahl, A.; Guilhem, D.; Guimarães-Filho, Z.; Litaudon, X.; Lotte, Ph.; Maget, P.; Mazon, D.; Saoutic, B. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)

    2014-06-15

    The lower hybrid current drive (LHCD) system of Tore Supra has been upgraded for long pulse operation at higher power (7–8 MW). The two launchers have coupled on plasma 3.8 MW and 2.7 MW separately. This new power capability allows extending the operational domain of Tore Supra for long pulses at higher current and density. 38 long (20 s –155 s) discharges with very low loop voltage (V{sub L} = 30-60 mV) were performed with combined LHCD (5-5.7 MW) and ICRH (1–3 MW) powers, with up to 1 GJ of injected energy. Higher LHCD efficiency, with respect to the previous long discharges, is reported. MHD stability of these discharges is very sensitive to the LHCD power and parallel wave index, in particular in the preforming phase. For theses evanescent loop voltage plasmas, the ICRH power, in excess of 1 MW, is found to have a beneficial effect on the MHD stability.

  6. An 8-GW long-pulse generator based on Tesla transformer and pulse forming network.

    Science.gov (United States)

    Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

    2014-06-01

    A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

  7. Solid-state gyrotron body power supply, test results

    Energy Technology Data Exchange (ETDEWEB)

    Santinelli, M. [Association Euratom-ENEA, ENEA CR Frascati, 00044 Frascati (Italy)], E-mail: santinelli@frascati.enea.it; Claesen, R.; Coletti, A. [Association Euratom-ENEA, ENEA CR Frascati, 00044 Frascati (Italy); Bonicelli, T.; Mondino, P.L. [EFDA, EFDA CSU Garching, D-85748 Garching (Germany); Pretelli, M.; Rinaldi, L.; Sita, L.; Taddia, G. [OCEM SpA, Via 2 Agosto 1980 no. 11, 40016 San Giorgio di Piano (Italy)

    2007-10-15

    A 170 GHz, 2 MW, steady-state gyrotron is being developed in collaboration between European research associations and industries to be used for the electron cyclotron resonance heating (ECRH) system of ITER, the gyrotron is presently in the prototype state. EFDA entrusted ENEA with the design of a new power supply for the gyrotron's body; in which, the traditional power vacuum tubes are replaced with solid-state components (IGBT); furthermore ENEA had the task of developing the new body power supply (BPS), following the initial conceptual design. The BPS is formed by 50 identical bidirectional (in current) modules, connected in series; the BPS's control system regulates the output voltage by changing the modulation index. OCEM Spa, under ENEA's supervision, has manufactured the BPS. Tests, done at the start of this year, showed the substantial agreement between the initial technical specifications and the values achieved. Particularly the ramp-up/down-emergency time (50-10 {mu}s), the accuracy ({+-}0.5%), the sine wave modulation (45-20 kV at 5 kHz) and the maximum phase shift (<10 deg.) have been tested. In the article, the new stair-way modulation (SWM) scheme will be sketched and the test results will be described in detail.

  8. Investigations and advanced concepts on gyrotron interaction modeling and simulations

    Science.gov (United States)

    Avramidis, K. A.

    2015-12-01

    In gyrotron theory, the interaction between the electron beam and the high frequency electromagnetic field is commonly modeled using the slow variables approach. The slow variables are quantities that vary slowly in time in comparison to the electron cyclotron frequency. They represent the electron momentum and the high frequency field of the resonant TE modes in the gyrotron cavity. For their definition, some reference frequencies need to be introduced. These include the so-called averaging frequency, used to define the slow variable corresponding to the electron momentum, and the carrier frequencies, used to define the slow variables corresponding to the field envelopes of the modes. From the mathematical point of view, the choice of the reference frequencies is, to some extent, arbitrary. However, from the numerical point of view, there are arguments that point toward specific choices, in the sense that these choices are advantageous in terms of simulation speed and accuracy. In this paper, the typical monochromatic gyrotron operation is considered, and the numerical integration of the interaction equations is performed by the trajectory approach, since it is the fastest, and therefore it is the one that is most commonly used. The influence of the choice of the reference frequencies on the interaction simulations is studied using theoretical arguments, as well as numerical simulations. From these investigations, appropriate choices for the values of the reference frequencies are identified. In addition, novel, advanced concepts for the definitions of these frequencies are addressed, and their benefits are demonstrated numerically.

  9. Inelastic scattering research at a 1 MW long pulse spallation neutron source

    International Nuclear Information System (INIS)

    The brief was, with respect to the LPSS bench mark design supplied (60 Hz, 1 MW, Imsec proton pulse, with a split, non-fissile target and 4 moderators in a flux trap geometry design), to identify a set of instruments, and to assess their performance with respect to existing spectrometers on other sources. Any modifications to the existing instruments which would make them more effective on the bench-mark source, or conversely, any modifications to the source bench-mark required by the proposed instruments were to be identified, as were any uncertainties in the estimated performances, or any R ampersand D needed to make the proposed instruments viable. Any new instrument concepts specifically matched to the long pulse itself were to be identified and assessed. This process was to result in an indicative list of instruments for the source. A figure of around 10 spectrometers was to be aimed for

  10. High power density and long pulse operation with Tore Supra ICRF facility

    Energy Technology Data Exchange (ETDEWEB)

    Bremond, S. E-mail: sbremond@cea.fr; Agarici, G.; Beaumont, B.; Lombard, G.; Millon, L.; Mollard, P.; Volpe, D.; Vulliez, K.; Becoulet, A.; Colas, L.; Saoutic, B

    2003-09-01

    Ten years after the first ion cyclotron range of frequency (ICRF) heated Tore Supra (TS) plasma shot, and as TS facility, now equipped with the new 'CIEL' high power handing in-vessel components (This SOFT), is progressing towards long pulse performances, the main results and experience gained from the ICRF system are reviewed. An overview of the present status of TS ICRF facility is given, with highlights on the main modifications made to the initial plant and associated results. TS ICRF system achievements are then reported from a large ICRF heated pulses database covering ten experimental campaigns (1991-2001). The main technological issues encountered, especially those relevant to next step ICRF system design, are also discussed. Finally, in view of extended pulse length performances on TS, the present limitations of the ICRF facility and future plans are outlined.

  11. A Long-Pulse Modulator for the TESLA Test Facility (TTF)

    CERN Document Server

    Kaesler, W

    2004-01-01

    The long-pulse (1.6 ms) klystron modulator for TTF is a hardtube pulser using a Bouncer-circuit for droop compensation. It is built up with new advanced components representing industrial standards. The on-/off switch is a rugged 12 kV IGCT-stack with a fast 4kA turn-off capability. The 100 kJ storage capacitor bank contains only three capacitors with self-healing, segmented PP-foil technology. A new 100 kA solid-state switch based on light triggered thyristors (LTT) replaced the standard ignitrons as crowbar switches. The 300 kW high voltage power supply is based on modern switched mode technology.

  12. Counter-facing plasma focus system as an efficient and long-pulse EUV light source

    Science.gov (United States)

    Kuwabara, H.; Hayashi, K.; Kuroda, Y.; Nose, H.; Hotozuka, K.; Nakajima, M.; Horioka, K.

    2011-04-01

    A plasma focus system composed of a pair of counter-facing coaxial plasma guns is proposed as a long-pulse and efficient EUV light source. A proof-of-concept experiment demonstrated that with an assist of breakdown and outer electrode connections, current sheets evolved into a configuration for stable plasma confinement at the center of the electrode. The current sheets could successively compress and confine the high energy density plasma every half period of the discharge current, enabling highly repetitive light emissions in extreme ultraviolet region with time duration in at least ten microseconds for Xe plasma. Also, we confirmed operations of our system for Li plasma. We estimated the highest EUV energy in Li plasma operation at 93mJ/4π sr per 2% bandwidth per pulse.

  13. Design Concepts For A Long Pulse Upgrade For The DIII-D Fast Wave Antenna Array

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, Philip Michael [ORNL; Baity Jr, F Wallace [ORNL; Caughman, John B [ORNL; Goulding, Richard Howell [ORNL; Hosea, J. [Princeton Plasma Physics Laboratory (PPPL); Greenough, Nevell [Princeton Plasma Physics Laboratory (PPPL); Nagy, Alex [Princeton Plasma Physics Laboratory (PPPL); Pinsker, R. [General Atomics; Rasmussen, David A [ORNL

    2009-01-01

    A goal in the 5-year plan for the fast wave program on DIII-D is to couple a total of 3.6 MW of RF power into a long pulse, H-mode plasma for central electron heating. The present short-pulse 285/300 antenna array would need to be replaced with one capable of at least 1.2 MW, 10 s operation at 60 MHz into an H-mode (low resistive loading) plasma condition. The primary design under consideration uses a poloidally-segmented strap (3 sections) for reduced strap voltage near the plasma/Faraday screen region. Internal capacitance makes the antenna structure self-resonant at 60 MHz, strongly reducing peak E-fields in the vacuum coax and feed throughs.

  14. High Gain and Frequency Ultra-Stable Integrators for ICC and Long Pulse ITER Applications

    Science.gov (United States)

    Miller, Kenneth; Ziemba, Timothy; Prager, James

    2012-10-01

    Eagle Harbor Technologies has developed a high gain and frequency ultra-stable integrator for small scale concept experiments and long pulse ITER applications. The Phase I integrator has a 10 μs RC time with a frequency response greater than 10 MHz. The device has been operated for the 3600 s with a drift error less than 600 μV, which exceeds the ITER specification. Longer period operation is also possible (> 30 hours). Additionally, this integrator has an extremely large dynamic range thereby increasing the effective bit depth of a digitizer. These integrators allow for both the fast and slow magnetic/plasma dynamics to be resolved with a single diagnostic. Data will be presented demonstrating the success of the Phase I program, and the Phase II work plan will be discussed. Work has begun to incorporate the integrators into legacy (CAMAC) and modern (National Instruments) DAQ systems.

  15. Methods of first wall structural analysis with applications to the long pulse commercial tokamak reactor design

    International Nuclear Information System (INIS)

    Methods of analysis for fusion first wall design are developed. Several design limits have been evaluated and combined to present trade-offs in the form of design windows. These considerations include limits related to thermal fatigue, primary membrane strength, displacement under loading, ratcheting, radiation damage, and plasma-wall interactions. Special emphasis is placed on the investigation of thermal fatigue using a two dimensional treatment of a tubular first wall configuration. The work is motivated by the proposal of the Ultra Long Pulse Commercial Reactor (ULTR), a machine capable of delivering plasma burn pulses of up to 24 hours in length. The present work looks in detail at the impact of pertinent characteristics of the ULTR design such as pulse length, coolant pressure, first wall thickness and first wall lifetime on the structural effects considered. Computer programs are developed and consider several major structural effects on a cylindrical first wall element for both 316 stainless steel and vanadium alloy

  16. Magnet Design and Analysis of a 40 Tesla Long Pulse System Energized by a Battery Bank

    Science.gov (United States)

    Lv, Y. L.; Peng, T.; Wang, G. B.; Ding, T. H.; Han, X. T.; Pan, Y.; Li, L.

    2013-03-01

    A 40 tesla long pulse magnet and a battery bank as the power supply have been designed. This is now under construction at the Wuhan National High Magnetic Field Center. The 22 mm bore magnet will generate smooth pulses with duration 1 s and rise time 0.5 s. The battery bank consists of 945 12V/200 Ah lead-acid battery cells. The magnet and battery bank were optimized by codes developed in-house and by ANSYS. The coil was made from soft copper with internal reinforcement by fiber-epoxy composite; it is divided into two sections connected in series. The inner section consists of helix coils with each layer reinforced by Zylon composite. The outer section will be wound from copper sheet and externally reinforced by carbon fiber composite.

  17. Design of long-pulse fast wave current drive antennas for DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Baity, F.W.; Batchelor, D.B.; Bills, K.C.; Fogelman, C.H.; Jaeger, E.F.; Ping, J.L.; Riemer, B.W.; Ryan, P.M.; Stallings, D.C.; Taylor, D.J.; Yugo, J.J. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States))

    1994-10-15

    Two new long-pulse fast wave current drive (FWCD) antennas will be installed on DIII-D in early 1994. These antennas will increase the available FWCD power from 2 MW to 6 MW for pulse lengths of up to 2 s, and to 4 MW for up to 10 s. Power for the new antennas is from two ASDEX-type 30- to 120-MHz transmitters. When operated at 90[degree] phasing into a low-density plasma ([similar to]4[times]10[sup 19]m[sup [minus]3]) with hot electrons ([similar to]10 keV), these two new antennas are predicted to drive approximately 1 MA of plasma current.

  18. Effects of magnetic configuration on divertor power and particle deposition for long pulse operation in EAST

    International Nuclear Information System (INIS)

    The magnetic configuration exhibits a strong influence on the dynamics of Edge Localized Modes (ELMs), as demonstrated in the EAST superconducting tokamak. We find that poloidal drifts play an important role in particle deposition during the ELMs, leading to a strong up/down asymmetry in the double null divertor configuration, favoring the upper divertor for normal toroidal field, Bt, i.e., with the ion ∇B drift towards the bottom, while the heat flux distribution appears to be rather uniform during ELMs. These observations are well reproduced by the boundary plasma turbulence code, BOUT++. As divertor pumping was only available at the bottom, the preferential particle flow towards the bottom divertor associated with reverse Bt led to a preferred scenario for long pulse operation in EAST

  19. Infrared monitoring of 110 GHz gyrotron windows at DIII-D

    International Nuclear Information System (INIS)

    The combination of low millimeter wave losses and excellent thermal conductivity with good mechanical properties make artificial chemical vapor deposition (CVD) diamonds a compelling choice for 1 MW 110 GHz gyrotron windows. Five gyrotrons are currently operating at the DIII-D tokamak. Three Gycom gyrotrons have boron nitride (BN) ceramic windows. Due to temperature increases of the windows up to about 930 deg. C, the pulse duration of these tubes is limited to 2 s for output power near 800 kW. Two Communications and Power Industries (CPI) gyrotrons with diamond windows are also installed and operating. The diamond disks of these windows and the construction of their water-cooling assemblies are different. This paper reviews the infrared (IR) measurements of both types of gyrotron windows, with emphasis on the two diamond designs. (authors)

  20. Infrared Monitoring of 110 GHz Gyrotron Windows at Diii-D

    Science.gov (United States)

    Gorelov, Y.; Lohr, J.; Callis, R. W.; Ponce, D.

    2003-02-01

    The combination of low millimeter wave losses and excellent thermal conductivity with good mechanical properties make artificial chemical vapor deposition (CVD) diamonds a compelling choice for 1 MW 110 GHz gyrotron windows. Five gyrotrons are currently operating at the DIII-D tokamak. Three Gycom gyrotrons have boron nitride (BN) ceramic windows. Due to temperature increases of the windows up to about 930°C, the pulse duration of these tubes is limited to 2 s for output power near 800 kW. Two Communications and Power Industries (CPI) gyrotrons with diamond windows are also installed and operating. The diamond disks of these windows and the construction of their water-cooling assemblies are different. This paper reviews the infrared (IR) measurements of both types of gyrotron windows, with emphasis on the two diamond designs.

  1. Possibilities for Continuous Frequency Tuning in Terahertz Gyrotrons with Nontunable Electrodynamic Systems

    Science.gov (United States)

    Bratman, V. L.; Savilov, A. V.; Chang, T. H.

    2016-02-01

    Large ohmic losses in the cavities of terahertz gyrotrons may lead to the overlapping of the axial mode spectra. In a number of gyrotron experiments, this effect has been used to provide a fairly broadband frequency tuning by changing appropriately the operating magnetic field and/or accelerating voltage of the gyrotron. Similar to the systems with nonfixed axial structure of the RF electromagnetic field and low diffraction quality, which are due to weak reflections of the operating wave from the collector end of the electrodynamic system, this changing leads to a monotonic change in the axial index of the operating wave and transition from the gyrotron regime to the gyro-BWO regime. According to a theoretical comparison of these two methods performed on the basis of generalization of self-consistent gyrotron equations with allowance for variations in the axial electron momenta, low-reflection systems can provide a higher efficiency and monotonicity of the frequency tuning.

  2. ICPP: Physics and Design Interplay Phenomena in a Long Pulse Tokamak: Tore Supra

    Science.gov (United States)

    Chatelier, Michel

    2000-10-01

    The Tore Supra Tokamak has been built with the aim of running steady state powerful long pulse discharges. It has been equipped with relevant technology such as a superconducting magnet, high frequency additional heating systems with long pulse capability, to heat up the plasma and drive the current, and actively cooled plasma facing components to remove steadily the large power flow at the plasma boundary. Due to this configuration, a number of physics processes differ from the conventional situation with inertially cooled plasma facing components that have to be carefully analysed, since they can have consequences on the design and the availability of future devices. Three examples are listed below. - Intense beams of well confined multi-MeV runaway electrons are formed when plasma discharge recovers after a current disruption, which eventually penetrate deep inside the wall and can drill holes in the water pipes. - Suprathermal electrons are generated by lower hybrid frequency waves, used for non inductive current drive in the plasma bulk. These electrons can be transported to the edge without having been slowed down. They impact on very localised areas where the heat deposition is so large that the metal layer between CFC and water can be melted. - Carbon blooms are generally not observed in Tore Supra, because the wall is maintained at low temperature in normal operating conditions. When local destruction of CFC-copper bond occurs, the surface temperature rises, but on a too small area for any significant impurity source to be generated. Bond destruction protects the water circuit from being melted. The excursion in surface temperature to very high values triggers a new heat flow equilibrium to the wall which depends also on the local electron temperature.

  3. Research on a 170 GHz, 2 MW coaxial cavity gyrotron with inner-outer corrugation

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Shenyong, E-mail: houshenyong@sohu.com [Yangtze Normal University, Chongqing, 408001 (China); Yu, Sheng; Li, Hongfu [University of Electronics Science and Technology of China, Chengdu 610054 (China)

    2015-03-15

    In this paper, a coaxial cavity gyrotron with inner-outer corrugation is researched. The electron kineto-equations and the first order transmission line equations of the gyrotron are derived from Lorentz force equation and the transmission line theory, respectively. And then, a 2 MW, 170 GHz coaxial cavity gyrotron with inner-outer corrugation is designed. By means of numerical calculation, the beam-wave interaction of the coaxial cavity gyrotron with inner-outer corrugation is investigated. Results show that the efficient and the outpower of the gyrotron are 42.3% and 2.38 MW, respectively.

  4. High power 303 GHz gyrotron for CTS in LHD

    Science.gov (United States)

    Yamaguchi, Y.; Kasa, J.; Saito, T.; Tatematsu, Y.; Kotera, M.; Kubo, S.; Shimozuma, T.; Tanaka, K.; Nishiura, M.

    2015-10-01

    A high-power pulsed gyrotron is under development for 300 GHz-band collective Thomson scattering (CTS) diagnostics in the Large Helical Device (LHD). High-density plasmas in the LHD require a probe wave with power exceeding 100 kW in the sub-terahertz region to obtain sufficient signal intensity and large scattering angles. At the same time, the frequency bandwidth should be less than several tens of megahertz to protect the CTS receiver using a notch filter against stray radiations. Moreover, duty cycles of ~ 10% are desired for the time domain analysis of the CTS spectrum. At present, a 77 GHz gyrotron for electron cyclotron heating is used as a CTS wave source in the LHD. However, the use of such a low-frequency wave suffers from refraction, cutoff and absorption at the electron cyclotron resonance layer. Additionally, the signal detection is severely affected by background noise from electron cyclotron emission. To resolve those problems, high-power gyrotrons in the 300 GHz range have been developed. In this frequency range, avoiding mode competition is critical to realizing high-power and stable oscillation. A moderately over-moded cavity was investigated to isolate a desired mode from neighbouring modes. After successful tests with a prototype tube, the practical one was constructed with a cavity for TE22,2 operation mode, a triode electron gun forming intense laminar electron beams, and an internal mode convertor. We have experimentally confirmed single mode oscillation of the TE22,2 mode at the frequency of 303.3 GHz. The spectrum peak is sufficiently narrow. The output power of 290 kW has been obtained at the moment.

  5. The Development of 460 GHz gyrotrons for 700 MHz DNP-NMR spectroscopy

    Science.gov (United States)

    Idehara, T.; Tatematsu, Y.; Yamaguchi, Y.; Khutoryan, E. M.; Kuleshov, A. N.; Ueda, K.; Matsuki, Y.; Fujiwara, T.

    2015-07-01

    Two demountable gyrotrons with internal mode converters were developded as sub-THz radiation sources for 700 MHz DNP (Dynamic Nuclear Polarization) enhanced NMR spectroscopy. Experimental study on the DNP-NMR spectroscopy will be carried out in Osaka University, Institute for Protein Research, as a collaboration with FIR UF. Both gyrotrons operate near 460 GHz and the output CW power measured at the end of transmission system made by circular waveguides is typically 20 to 30 watts. One of them named Gyrotron FU CW GVI (we are using "Gyrotron FU CW GO-1" as an official name in Osaka University) is designed to have a special function of high speed frequency modulation δ f within 100 MHz band. This will expand excitable band width of ESR and increase the number of electron spins contributing to DNP. The other gyrotron, Gyrotron FU CW GVIA ("Gyrotron FU CW GO-II") has a function of frequency tunability Δ f in the range of wider than 1.5 GHz, which is achieved in steady state by changing magnetic field intensity. This function should be used for adjusting the output frequency at the optimal value to achieve the highest enhancement factor of DNP.

  6. Influence of construction concepts on training behavior of gyrotron magnets

    International Nuclear Information System (INIS)

    A series of 60 NbTi gyrotron magnets intended mainly for high frequency plasma heating complexes at Tokamak T-10 and Tokamak T-15, and prototypes and later improved versions for the same applications within ITER project, were developed and tested. A variety of constructional and technological concepts was applied. As a result of empirical experience in parallel with the application of established theoretical models to the magnet development, a remarkable improvement in winding mechanical stability was reached. The differences in magnet winding construction are related to operational as well as training and quench behaviour. (Author)

  7. Beam divergence studies on a hard edge unstable resonators for a long pulse XeCl excimer laser

    NARCIS (Netherlands)

    Hofstra, R.M.; Goor, van F.A.; Witteman, W.J.

    1997-01-01

    The focusability of a long pulse XeCl excimer laser has been improved using confocal positive branch unstable resonators where the outcoupling is done through the convex mirror. A nearly diffraction limited output beam is obtained from hard edge unstable resonators. An improvement of the far field e

  8. A 2 MW, 170 GHz coaxial cavity gyrotron - experimental verification of the design of main components

    International Nuclear Information System (INIS)

    A 2 MW, CW, 170 GHz coaxial cavity gyrotron is under development in cooperation between European Research Institutions (FZK Karlsruhe, CRPP Lausanne, HUT Helsinki) and the European tube industry (TED, Velizy, France). The design of critical components has recently been examined experimentally at FZK Karlsruhe with a short pulse (∼ few ms) coaxial cavity gyrotron. This gyrotron uses the same cavity and the same quasioptical (q.o.) RF-output system as designed for the industrial prototype and a very similar electron gun

  9. Numerical simulation of different pulse width of long pulsed laser on aluminum alloy

    Science.gov (United States)

    Li, Mingxin; Jin, Guangyong; Zhang, Wei; Chen, Guibo; Bi, Juan

    2015-03-01

    Established a physical model to simulate the melt ejection induced by long pulsed laser on aluminum alloy and use the finite element method to simulate the whole process. This simulation is based on the interaction between single pulsed laser with different pulse width and different peak energy and aluminum alloy material. By comparing the theoretical simulation data and the actual test data, we discover that: the theoretical simulation curve is well consistent with the actual experimental curve, this two-dimensional model is with high reliability; when the temperature at the center of aluminum alloy surface increases and evaporation happens after the surface temperature at the center of aluminum alloy surface reaches boiling point and later the aluminum alloy material sustains in the status of equilibrium vaporization; the keyhole appears on the surface of the target, an increment of the keyhole, the maximum temperature at the center of aluminum alloy surface gradually moves inwardly. This research may provide the theoretical references to the understanding of the interaction between millisecond pulsed laser and many kinds of materials, as well as be beneficial to the application of the laser materials processing and military field.

  10. Investigation of the phase stability of an X-band long pulse multibeam relativistic klystron amplifier

    Science.gov (United States)

    Liu, Zhenbang; Huang, Hua; Jin, Xiao; Lei, Lurong; Zhu, Lei; Li, Lele; Li, Shifeng; Yan, Wenkang; He, Hu

    2016-09-01

    To realize coherent high power microwave combining, an X-band long pulse multibeam relativistic klystron amplifier is designed, and the relative phase stability is investigated by three dimensions particle in cell simulation and high power microwave experiment. The simulation shows that the relative phase difference can be stabilized at gigawatt level radiation power. But the relative phase jitter increases in the experiment, then some measures are proposed to improve the stability of relative phase difference and avoid pulse shortening. A 0.98 GW radiation power with pulse duration of 160 ns is obtained in the experiment, the pulse shortening is avoided. The relative phase difference fluctuation between output microwave and input RF signal is less than ±25° in a single shot with duration of 100 ns. Then, the experiment of pulse repetition is carried out, and an output microwave with 0.98 GW radiation power at 25 Hz repetition rate is obtained. The power conversion efficiency is about 35% with pulse duration of 160 ns. The relative phase difference is less than ±30° at 25 Hz repetition rate in 100 ns.

  11. First lasing of the Dutch fusion-FEM in the long-pulse configuration

    Energy Technology Data Exchange (ETDEWEB)

    Militsyn, B.L. E-mail: militsyn@rijnh.nl; Bongers, W.A.; Bratman, V.L.; Caplan, M.; Denisov, G.G.; Geer, C.A.J. van der; Manintveld, P.; Oomens, A.A.M.; Plomp, J.; Pluygers, J.; Poelman, A.J.; Riet, M.; Savilov, A.V.; Smeets, P.H.M.; Tito, C.J.; Turk, G.H.B.; Varfolomeev, A.A.; Urbanus, W.H

    2002-05-01

    The Dutch Fusion-FEM is the prototype of a high-power, long-pulse, rapid-tunable free-electron maser. The target is to generate mm-wave power in a frequency range of 130-260 GHz, e.g. for tokamak heating and diagnostics experiments in fusion devices. For these applications a high system efficiency is needed. The electron beam is first DC-accelerated to the FEL interaction region. The unused electron beam energy is recovered by a DC-decelerator and a three-stage depressed collector. In short-pulse regime, without energy recovery system, 730 kW, 200 GHz of net output power was generated. Single-frequency operation and tunability have been demonstrated. In the present set-up, with the energy recovery system being operational, initial experiments showed a net output power of 110 kW on average and 140 kW peak power at a pulse length of 40 {mu}s. During the full-pulse length, a stable-frequency operation around 170 GHz has been observed.

  12. Advances in lower hybrid current drive for tokamak long pulse operation. Technology and physics

    International Nuclear Information System (INIS)

    The paper gives a picture of the present status and understanding of technology and physics of Lower Hybrid Current Drive for long pulse operation in tokamaks, including the development of continuous wave (CW) high power klystrons, and its evolutions towards ITER. 3.7 GH / 700 kW CW klystrons produced in series by Thales Electron Devices are now in operation on Tore Supra. First series of eight klystrons delivered more than 4 MW to sustain non-inductive plasmas during 50 s. Moreover, a prototype of 500 kW CW klystron operating at 5 GHz developed for KSTAR by Toshiba Electron Tubes and Devices, and foreseen for ITER, is able to produce RF output powers of 300 kW / 800 s and 450 kW / 20 s on matched load. The situation on wave coupling and antennas is reported, with the latest Tore Supra results of the new CW Passive-Active Multi-junction (PAM) launcher: the antenna concept foreseen for ITER. First experiments with the PAM antenna in Tore Supra have provided extremely encouraging results in terms of power handling and coupling. Relevant ITER power density of ∼25 MW/m2 (2.7 MW of power injected into the plasma) has been maintained over ∼80 s. In addition, LH power of 2.7 MW has been coupled at a plasma-antenna distance of 10 cm. (author)

  13. Application of Fusion Gyrotrons to Enhanced Geothermal Systems (EGS)

    Science.gov (United States)

    Woskov, P.; Einstein, H.; Oglesby, K.

    2013-10-01

    The potential size of geothermal energy resources is second only to fusion energy. Advances are needed in drilling technology and heat reservoir formation to realize this potential. Millimeter-wave (MMW) gyrotrons and related technologies developed for fusion energy research could contribute to enabling EGS. Directed MMW energy can be used to advance rock penetration capabilities, borehole casing, and fracking. MMWs are ideally suited because they can penetrate through small particulate extraction plumes, can be efficiently guided long distances in borehole dimensions, and continuous megawatt sources are commercially available. Laboratory experiments with a 10 kW, 28 GHz CPI gyrotron have shown that granite rock can be fractured and melted with power intensities of about 1 kW/cm2 and minute exposure times. Observed melted rock MMW emissivity and estimated thermodynamics suggest that penetrating hot, hard crystalline rock formations may be economic with fusion research developed MMW sources. Supported by USDOE, Office of Energy Efficiency and Renewable Energy and Impact Technologies, LLC.

  14. A Two Frequency 1.5 MW Gyrotron Experiment

    Science.gov (United States)

    Tax, David; Guss, William; Shapiro, Michael; Temkin, Richard; Rock, Ben; Vernon, Ronald; Neilson, Jeffrey

    2012-10-01

    Megawatt gyrotrons are an important microwave source for electron cyclotron heating and current drive (ECH/ECCD) in fusion plasmas due to their ability to produce megawatts of power at millimeter wave frequencies. The MIT gyrotron operates nominally at 96 kV and 40 A with 3 μs pulses and has previously demonstrated 1.5 MW of output power with > 50 % efficiency at 110 GHz with a depressed collector. A new cavity has been designed for 1.5 MW operation at two distinct frequencies: 110 GHz in the TE22,6 mode and 124.5 GHz in the TE24,7 mode. A new internal mode converter (IMC) consisting of a dimpled wall launcher and four smooth curved mirrors has also been designed and was optimized for both modes. Simulations of the IMC indicate that > 98 % Gaussian beam content could be achieved for each mode. Cold test results for the components will be presented as well as the current status of the hot test experiment.

  15. Numerical study on a 0.4 THz second harmonic gyrotron with high power

    International Nuclear Information System (INIS)

    Terahertz and sub-terahertz science and technology are promising topics today. However, it is difficult to obtain high power source of terahertz wave. In this paper, the mode competition and beam-wave interaction in a gradually tapered cavity are studied to achieve high efficiency of a 0.4THz second harmonic gyrotron in practice. In order to attain high power and stable radiation, the TE32,5 mode is selected as the operating mode of the desired gyrotron to realize single mode oscillation. The issues of studying on the high-order mode gyrotrons are solved effectively by transforming the generalized telegraphist's equations. The efficiency and output power of the gyrotron under different conditions have been calculated by the code, which is based on the transformed equations. Consequently, the results show that single mode second harmonic radiation with power of over 150 kW at frequency of 0.4 THz could be achieved

  16. A long-pulse repetitive operation magnetically insulated transmission line oscillator.

    Science.gov (United States)

    Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang

    2014-05-01

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO. PMID:24880374

  17. Proceedings of the workshop on neutron instrumentation for a long-pulse spallation source

    International Nuclear Information System (INIS)

    This workshop was carried out under the auspices of the Lawrence Berkeley National Laboratory Pulsed Spallation Source activity and its Pulsed Spallation Source Committee (PSSC). One of our activities has been the sponsorship of workshops related to neutron production by pulsed sources. At the Crystal City PSSC meeting a decision was made to hold a workshop on the instrumentation opportunities at a long-pulse spallation source (LPSS). The enclosed material represents the results of deliberations of the three working groups into which the participants were divided, covering elastic scattering, inelastic scattering and fundamental physics, as well as contributions from individual participants. We hope that the material in this report will be useful to the neutron scattering community as it develops a road-map for future neutron sources. The workshop was held at LBNL in mid-April with about sixty very dedicated participants from the US and abroad. This report presents the charge for the workshop: Based on the bench mark source parameters provided by Gary Russell, determine how a suite of spectrometers in each of the three working group's area of expertise would perform at an LPSS and compare this performance with that of similar spectrometers at a continuous source or a short-pulse source. Identify and discuss modifications to these spectrometers that would enhance their performance at an LPSS. Identify any uncertainties in the analysis of spectrometer performance that require further research. Describe what R ampersand D is needed to resolve these issues. Discuss how the performance of instruments would be affected by changes in source parameters such as repetition rate, proton pulse length, and the characteristic time of pulse tails. Identify beneficial changes that could become goals for target/moderator designers. Identify novel methods that might be applied at an LPSS. Selected papers are indexed separately for inclusion in the Energy Science and Technology

  18. A long-pulse repetitive operation magnetically insulated transmission line oscillator

    International Nuclear Information System (INIS)

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO

  19. A long-pulse repetitive operation magnetically insulated transmission line oscillator.

    Science.gov (United States)

    Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang

    2014-05-01

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

  20. Cold test of cylindrical open resonator for 42 GHz, 200 kW gyrotron

    Indian Academy of Sciences (India)

    Vivek Yadav; Sudeep Sharan; Hasina Khatun; Nitin Kumar; M K Alaria; B Jha; S C Deorani; A K Sinha; P K Jain

    2013-12-01

    This paper presents experimental results for cold testing of a gyrotron open resonator. Experiments were carried out to measure resonant frequency and their particular quality factor for TE mode at the frequency 42 GHz. The perturbation technique was used to determine the axial, radial and azimuthal electric field profile for identification of TE031 mode at operating frequency 42 GHz. The good agreement between experimental results and theoretical studies was found. The results verify the design and fabrication of the specific gyrotron cavity.

  1. Design of an electronically tunable millimeter wave Gyrotron Backward Wave Oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, M.

    1987-01-01

    A non-linear self-consistent computer simulation code is used to analyze the saturated output of the Gyrotron Backward Wave Oscillator (Gyro BWO) which can be used as a tunable driver for a 250 GHz FEL amplifier. Simulations show that the Gyrotron BWO using a Pierce/Wiggler gun configuration can produce at least 10 kW of microwave power over the range 249 GHz to 265 GHz by varying beam voltage alone.

  2. Gyrotron physics from linear to chaotic regimes: experiment and numerical modeling

    OpenAIRE

    Braunmüller, Falk Hans

    2016-01-01

    Gyrotrons belong to the family of high-power coherent radiation sources known as Electron Cyclotron Masers (ECMs) and are based on the physical mechanism of the ECM-instability, converting electron rotational kinetic energy into coherent electromagnetic radiation. The worldwide gyrotron R&D is mainly driven by the application in heating a magnetically confined fusion plasma, which requires coherent radiation sources with MW power-level in the sub-THz frequency range. In the last two decades,...

  3. 1.5 MW, 110 GHz Gyrotron with a Depressed Collector

    Science.gov (United States)

    Choi, Eunmi; Anderson, James; Shapiro, Michael; Jagadishwar, Sirigiri; Temkin, Richard

    2004-11-01

    A 1.5 MW, 110 GHz gyrotron is under development for electron cyclotron resonance plasma heating at DIII-D. Research conducted at MIT in short pulse operation is aimed at providing data on the operation of the gyrotron at very high efficiency. The 1.5 MW gyrotron design is based on previous successful results from the 1 MW gyrotrons built by Communication and Power Industries (CPI). A TE_22,6 mode cavity is utilized with an electron beam voltage of 96 kV and a beam current of 40 A. Recently we have successfully run the gyrotron in the axial configuration, and the experimental peak power was 1.44 MW at 37 % efficiency, when operating in the TE_22,6 mode. We have rebuilt this experiment in a configuration which has an internal mode converter and depressed collector, which should enhance the efficiency (> 50 %). The internal mode converter of the TE_22,6 mode to a Gaussian beam consists of an irregular waveguide launcher and four quasi-optical mirrors. A new cavity that provides greatly reduced Ohmic heating on the wall has been designed to enhance the gyrotron efficiency. This cavity will be tested in the next stage of the experiment.

  4. Optimization of operation of a three-electrode gyrotron with the use of a flow-type calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Kharchev, Nikolay K.; Batanov, German M.; Kolik, Leonid V.; Malakhov, Dmitrii V.; Petrov, Aleksandr Ye.; Sarksyan, Karen A.; Skvortsova, Nina N.; Stepakhin, Vladimir D. [Prokhorov General Physics Institute, Vavilova ul. 38, Moscow 119991 (Russian Federation); Belousov, Vladimir I. [Institute of Applied Physics, Ul' yanova ul. 46, Nizhnii Novgorod 603950 (Russian Federation); Malygin, Sergei A.; Tai, Yevgenii M. [GYCOM Company, Ul' yanova ul. 46, Nizhnii Novgorod 603155 (Russian Federation)

    2013-01-15

    Results are presented for measurements of microwave power of the Borets-75/0.8 gyrotron with recovery of residual electron energy, which were performed by a flow-type calorimeter. This gyrotron is a part of the ECR plasma heating complex put into operation in 2010 at the L-2M stellarator. The new calorimeter is capable of measuring microwave power up to 0.5 MW. Monitoring of the microwave power makes it possible to control the parameters of the gyrotron power supply unit (its voltage and current) and the magnetic field of the cryomagnet in order to optimize the gyrotron operation and arrive at maximum efficiency.

  5. Experimental demonstration of brighter sodium resonant scattering with 1.7 GHz sideband repumping for long pulse laser

    Science.gov (United States)

    Li, Lihang; Zhang, Shaopeng; Hua, Weihong; Wang, Hongyan; Ning, Yu; Xu, Xiaojun

    2014-08-01

    Adaptive Optics (AO) based on artificial beacons is the key to achieve high resolution images from large ground-based telescopes. Long pulsed lasers are preferable to create sodium laser guide stars (LGS) as they allow for Rayleigh blanking. However, these lasers may increase the effective light intensity irradiated at the sodium layer, which may lead to transition saturation, and then decline the normalized return flux efficiency. The return flux might be boosted by optical repumping, which could make full use of the advantages of optical pumping without trapping the atoms to the F=1 ground state. In this paper, we study the optical repumping effect by using a small scale long pulsed sodium laser developed in Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences, whose pulse format may be pretty suitable for large telescopes. An electro-optic phase modulator is used to produce 1.713 GHz sidebands from the D2a center wavelength with the fraction of 20%. As for a vacuum sodium cell at the temperature of 40°C, when the effective laser intensity increases from 4.53×102 W/m2 to 6.99×105 W/ m2, resonant fluorescence with and without repumping is measured. The result illustrates that the resonant scattering brightness with repumping can be as over 3 times as without it when the light intensity changes between 4.53×102 W/m2 to 5 ×104 W/ m2. The saturated phenomenon is also observed. This gives direct evidence that repumping could improve the performance of sodium laser guide stars based on TIPC long pulsed lasers. To our knowledge, this is the first experimental demonstration of the repumping effect with the TIPC type long pulsed laser in laboratory.

  6. Development of long pulse RF heating and current drive for H-mode scenarios with metallic walls in WEST

    Energy Technology Data Exchange (ETDEWEB)

    Ekedahl, Annika, E-mail: annika.ekedahl@cea.fr; Bourdelle, Clarisse; Artaud, Jean-François; Bernard, Jean-Michel; Bufferand, Hugo; Colas, Laurent; Decker, Joan; Delpech, Léna; Dumont, Rémi; Goniche, Marc; Helou, Walid; Hillairet, Julien; Lombard, Gilles; Magne, Roland; Mollard, Patrick; Nardon, Eric; Peysson, Yves; Tsitrone, Emmanuelle [CEA, IRFM, F-13108 Saint Paul-lez-Durance (France)

    2015-12-10

    The longstanding expertise of the Tore Supra team in long pulse heating and current drive with radiofrequency (RF) systems will now be exploited in the WEST device (tungsten-W Environment in Steady-state Tokamak) [1]. WEST will allow an integrated long pulse tokamak programme for testing W-divertor components at ITER-relevant heat flux (10-20 MW/m{sup 2}), while treating crucial aspects for ITER-operation, such as avoidance of W-accumulation in long discharges, monitoring and control of heat fluxes on the metallic plasma facing components (PFCs) and coupling of RF waves in H-mode plasmas. Scenario modelling using the METIS-code shows that ITER-relevant heat fluxes are compatible with the sustainment of long pulse H-mode discharges, at high power (up to 15 MW / 30 s at I{sub P} = 0.8 MA) or high fluence (up to 10 MW / 1000 s at I{sub P} = 0.6 MA) [2], all based on RF heating and current drive using Ion Cyclotron Resonance Heating (ICRH) and Lower Hybrid Current Drive (LHCD). This paper gives a description of the ICRH and LHCD systems in WEST, together with the modelling of the power deposition of the RF waves in the WEST-scenarios.

  7. Particle control in high power, high density long pulse operation on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Bucalossi, J.; Brosset, C.; Dufour, E.; Loarer, T.; Monier-Garbet, P.; Pegourie, B.; Tsitrone, E.; Basiuk, V.; Bremond, S.; Chantant, M.; Colas, L.; Commaux, N.; Geraud, A.; Guirlet, R.; Gunn, J.; Hertout, P.; Hoang, G. T.; Kazarian, F.; Mazon, D.; Maget, P.; Mitteau, R.; Moreau, P.; Saint-Laurent, F.; Schunke, B.; Vallet, J. C.

    2005-07-01

    Long pulse operation, and the related issues such as non inductive current drive, particle control and power exhaust, is a crucial point to investigate for next step machines. In the Tore Supra tokamak, equipped with superconducting magnets and actively cooled plasma facing components discharge up to 6 minutes, coupling 1 GJ of energy to the plasma, have already been obtained with 3 MW of LHCD at low density (%50 n{sub C}W). A new scenario has been recently developed combining ICRH and LHCD up to a total power of 8.5 MW at high density (90% n{sub G}W), limited in time to 60 s by the capability of the ICRH heating systems (500 MJ of injected/extracted energy). This paper describes the new operating conditions and compares the results obtained in both scenarios with a special focus on particle control. The density is still maintained by a feedback loop on the gas injection system and do not exhibit any uncontrolled excursions. The radiated power fraction is stable and remains below 30% all along the discharges. In comparison with the previous low density long duration discharges, the gas injection rate necessary to maintain the stationary plasma density is increased by a factor up to 3. The edge electron temperature and density measured by a reciprocating probes are also significantly different, signifying as expected a higher recycling flux. On the other hand, particle balance analyses based on pressure measurements show that the absolute in vessel retention rate is roughly equivalent in both scenarios. This indicates that the retention mechanisms could be dominated by wall processes such as diffusion in carbon porosities rather than plasma processes, dependent on edge conditions, such as codeposition. Moreover, analysis of carbon deposits originating from different locations inside the vessel reveal relatively low deuterium content, unable to account for the large deuterium in-vessel retention worked out from particle balance. Finally, particle control with more

  8. Gyrotron development at the Instituto de Pesquisas Espaciais

    International Nuclear Information System (INIS)

    The conceptual design of a 35GHz gyrotron operating in the TE021 mode, intended for plasma heating experiments, is presented. The electrooptical system is synthesized from the electron beam parameters in the cavity region and the electrodynamical system includes a conventional resonator consisting of truncated cones. The starting and operating characteristics are calculated by integrating the exact equation of electron motion under the action of an RF fiel with fixed spatial distribution. For the moment, the experimental activities, in addition to providing all the infrastructure for the laboratory, are concentrated on the construction of a system of magnetic coils, able to generated a 15kG magnetic induction with a fluctuation of 0.1% over an extension of 13cm, on the manufacture of cavities by using electroforming techniques and on the development of techniques for the construction of electron guns. (author)

  9. Gain/bandwidth predictions for travelling-wave gyrotron

    Science.gov (United States)

    Sangster, A. J.

    1980-10-01

    Small signal gain computations based on a Pierce description of the traveling-wave gyrotron have been performed for cases involving beam voltages in the range 70-300 kV. Interactions at both the first and the second harmonics of the cyclotron resonance frequency have been considered in order to identify a range of operating parameters for the gyro-traveling-wave amplifier configuration which will potentially produce gain and bandwidth figures of significance to radar and communication systems operating at millimeter-wave frequencies. It is shown that when operated fundamentally and well away from cutoff, the gyro-traveling-wave amplifier can be magnetically tuned over a wide frequency range, with instantaneous bandwidths in the range 4-8% depending on the beam voltage; at voltages in excess of 200 kV, instantaneous bandwidths approaching 10% can be achieved.

  10. Fault-Protected Laser Diode Drivers for Improving the Performance and Lifetime of Multiple-Millisecond, Long-Pulse LDAs for NASA LIDAR Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project will develop and deliver revolutionary driver technology with intelligent fault protection for driving long-pulse (> 2msec), quasi-CW laser...

  11. The 110 GHz Gyrotron Installation on DIII--D: Status and Experimental Results

    Science.gov (United States)

    Lohr, John; Ponce, Dan; Callis, R. W.; Popov, L.; Zerbini, M.; Cahalan, P.

    1997-11-01

    The 110 GHz installation on DIII--D consists of two gyrotrons each of which operates at generated power levels between 0.5 and 1.0 MW for pulse lengths up to 2.0 s. The gyrotrons are connected to DIII--D by windowless evacuated transmission lines. The greatest experience to date has been accumulated with the Gycom Centaur gyrotron, a diode tube which has been operated reliably at generated rf power levels in excess of 0.80 MW for pulse durations of 2.0 s. This tube has been modulated at 100% depth at frequencies up to 1 kHz. The second gyrotron is a Communications and Power Industries model VGT-8011A, a triode geometry, which is in initial testing. For this gyrotron, collector power loading has been measured, the beam steering has been set and pulse/power extension is in progress. DIII--D tests of the system performance are ongoing and initial tokamak experiments on transport, H--mode physics and scaling have begun.

  12. Temperature and thermal stress fields during the pulse train of long-pulse laser irradiating aluminium alloy plate

    Science.gov (United States)

    Zhang, Wei; Jin, Guangyong; Gu, Xiu-ying

    2014-12-01

    Based on Von Mises yield criterion and elasto-plastic constitutive equations, an axisymmetric finite element model of a Gaussian laser beam irradiating a metal substrate was established. In the model of finite element, the finite difference hybrid algorithm is used to solve the problem of transient temperature field and stress field. Taking nonlinear thermal and mechanical properties into account, transient distributions of temperature field and stress fields generated by the pulse train of long-pulse laser in a piece of aluminium alloy plate were computed by the model. Moreover,distributions as well as histories of temperature and stress fields were obtained. Finite element analysis software COMSOL is used to simulate the Temperature and thermal stress fields during the pulse train of long-pulse laser irradiating 7A04 aluminium alloy plate. By the analysis of the results, it is found that Mises equivalent stress on the target surface distribute within the scope of the center of a certain radius. However, the stress is becoming smaller where far away from the center. Futhermore, the Mises equivalent stress almost does not effect on stress damage while the Mises equivalent stress is far less than the yield strength of aluminum alloy targets. Because of the good thermal conductivity of 7A04 aluminum alloy, thermal diffusion is extremely quick after laser irradiate. As a result, for the multi-pulsed laser, 7A04 aluminum alloy will not produce obvious temperature accumulation when the laser frequency is less than or equal to 10 Hz. The result of this paper provides theoretical foundation not only for research of theories of 7A04 aluminium alloy and its numerical simulation under laser radiation but also for long-pulse laser technology and widening its application scope.

  13. Counter-facing plasma focus system as a repetitive and/or long-pulse high energy density plasma source

    Science.gov (United States)

    Aoyama, Yutaka; Nakajima, Mitsuo; Horioka, Kazuhiko

    2009-11-01

    A plasma focus system composed of a pair of counter-facing coaxial plasma guns is proposed as a long-pulse and/or repetitive high energy density plasma source. A proof-of-concept experiment demonstrated that with an assist of breakdown and outer electrode connections, current sheets evolved into a configuration for stable plasma confinement at the center of the electrodes. The current sheets could successively compress and confine the high energy density plasma every half period of the discharge current, enabling highly repetitive light emissions in extreme ultraviolet region with time durations in at least ten microseconds.

  14. Treatment of venous lesions of the lips and perioral area with a long-pulsed Nd:YAG laser.

    Science.gov (United States)

    John, H E; Phen, H S; Mahaffey, P J

    2016-05-01

    The conventional treatments for venous lesions of the lip have been excision, cryotherapy, infrared coagulation, and sclerotherapy. We report the use of a long-pulsed Nd:YAG laser in 31 consecutive patients. At a mean follow up of 12 months (6 weeks to 3 years), 27 (87%) had no evidence of recurrence and one had a small contracted scar. The treatment is effective for both small and large lesions, and operation or other ablative techniques are no longer indicated, or considerably less relevant. PMID:26233280

  15. Effect of defects on long-pulse laser-induced damage of two kinds of optical thin films.

    Science.gov (United States)

    Wang, Bin; Qin, Yuan; Ni, Xiaowu; Shen, Zhonghua; Lu, Jian

    2010-10-10

    In order to study the effect of defects on the laser-induced damage of different optical thin films, we carried out damage experiments on two kinds of thin films with a 1 ms long-pulse laser. Surface-defect and subsurface-defect damage models were used to explain the damage morphology. The two-dimensional finite element method was applied to calculate the temperature and thermal-stress fields of these two films. The results show that damages of the two films are due to surface and subsurface defects, respectively. Furthermore, the different dominant defects for thin films of different structures are discussed.

  16. Progress in long-pulse production of powerful negative ion beams for JT-60SA and ITER

    Science.gov (United States)

    Kojima, A.; Umeda, N.; Hanada, M.; Yoshida, M.; Kashiwagi, M.; Tobari, H.; Watanabe, K.; Akino, N.; Komata, M.; Mogaki, K.; Sasaki, S.; Seki, N.; Nemoto, S.; Shimizu, T.; Endo, Y.; Ohasa, K.; Dairaku, M.; Yamanaka, H.; Grisham, L. R.

    2015-06-01

    Significant progress in the extension of pulse durations of powerful negative ion beams has been made to realize the neutral beam injectors for JT-60SA and ITER. In order to overcome common issues of the long-pulse production/acceleration of negative ion beams in JT-60SA and ITER, new technologies have been developed in the JT-60SA ion source and the MeV accelerator in Japan Atomic Energy Agency. As for the long-pulse production of high-current negative ions for the JT-60SA ion source, the pulse durations have been successfully increased from 30 s at 13 A on JT-60U to 100 s at 15 A by modifying the JT-60SA ion source, which satisfies the required pulse duration of 100 s and 70% of the rated beam current for JT-60SA. This progress was based on the R&D efforts for the temperature control of the plasma grid and uniform negative ion productions with the modified tent-shaped filter field configuration. Moreover, each parameter of the required beam energy, current and pulse has been achieved individually by these R&D efforts. The developed techniques are useful to design the ITER ion source because the sustainment of the caesium coverage in the large extraction area is one of the common issues between JT-60SA and ITER. As for the long-pulse acceleration of high power density beams in the MeV accelerator for ITER, the pulse duration of MeV-class negative ion beams has been extended by more than 2 orders of magnitude by modifying the extraction grid with a high cooling capability and a high transmission of negative ions. A long-pulse acceleration of 60 s has been achieved at 70 MW m-2 (683 keV, 100 A m-2) which has reached the power density of JT-60SA level of 65 MW m-2. No degradations of the voltage holding capability of the acceleration voltage and the beam optics due to the distortion of the acceleration grids have been observed in this power density level. These results are the longest pulse durations of high-current and high-power-density negative ion beams in the

  17. A 250 GHz gyrotron with a 3 GHz tuning bandwidth for dynamic nuclear polarization.

    Science.gov (United States)

    Barnes, Alexander B; Nanni, Emilio A; Herzfeld, Judith; Griffin, Robert G; Temkin, Richard J

    2012-08-01

    We describe the design and implementation of a novel tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power. The tuning bandwidth and power are sufficient to generate a >1 MHz nutation frequency across the entire nitroxide EPR lineshape for cross effect DNP, as well as to excite solid effect transitions utilizing other radicals, without the need for sweeping the NMR magnetic field. Substantially improved tunability is achieved by implementing a long (23 mm) interaction cavity that can excite higher order axial modes by changing either the magnetic field of the gyrotron or the cathode potential. This interaction cavity excites the rotating TE(₅,₂,q) mode, and an internal mode converter outputs a high-quality microwave beam with >94% Gaussian content. The gyrotron was integrated into a DNP spectrometer, resulting in a measured DNP enhancement of 54 on the membrane protein bacteriorhodopsin. PMID:22743211

  18. A 250 GHz gyrotron with a 3 GHz tuning bandwidth for dynamic nuclear polarization

    Science.gov (United States)

    Barnes, Alexander B.; Nanni, Emilio A.; Herzfeld, Judith; Griffin, Robert G.; Temkin, Richard J.

    2012-08-01

    We describe the design and implementation of a novel tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power. The tuning bandwidth and power are sufficient to generate a >1 MHz nutation frequency across the entire nitroxide EPR lineshape for cross effect DNP, as well as to excite solid effect transitions utilizing other radicals, without the need for sweeping the NMR magnetic field. Substantially improved tunability is achieved by implementing a long (23 mm) interaction cavity that can excite higher order axial modes by changing either the magnetic field of the gyrotron or the cathode potential. This interaction cavity excites the rotating TE5,2,q mode, and an internal mode converter outputs a high-quality microwave beam with >94% Gaussian content. The gyrotron was integrated into a DNP spectrometer, resulting in a measured DNP enhancement of 54 on the membrane protein bacteriorhodopsin.

  19. Experimental tests of a 263 GHz gyrotron for spectroscopic applications and diagnostics of various media

    Energy Technology Data Exchange (ETDEWEB)

    Glyavin, M. Yu., E-mail: glyavin@appl.sci-nnov.ru; Denisov, G. G.; Zapevalov, V. E. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Gycom Ltd., Nizhny Novgorod (Russian Federation); Chirkov, A. V.; Fokin, A. P.; Kholoptsev, V. V.; Kuftin, A. N.; Luchinin, A. G.; Golubyatnikov, G. Yu.; Malygin, V. I.; Morozkin, M. V.; Manuilov, V. N.; Proyavin, M. D.; Sedov, A. S.; Tsvetkov, A. I. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Sokolov, E. V.; Tai, E. M. [Gycom Ltd., Nizhny Novgorod (Russian Federation)

    2015-05-15

    A 263 GHz continuous-wave (CW) gyrotron was developed at the IAP RAS for future applications as a microwave power source in Dynamic Nuclear Polarization / Nuclear magnetic resonance (DNP/NMR) spectrometers. A new experimental facility with a computerized control was built to test this and subsequent gyrotrons. We obtained the maximum CW power up to 1 kW in the 15 kV/0.4 A operation regime. The power about 10 W, which is sufficient for many spectroscopic applications, was realized in the low current 14 kV/0.02 A regime. The possibility of frequency tuning by variation of the coolant temperature about 4 MHz/1 °C was demonstrated. The spectral width of the gyrotron radiation was about 10{sup −6}.

  20. High power operation of Gaussian beam gyrotron with CVD diamond window for JT-60U

    International Nuclear Information System (INIS)

    A 110 GHz-Gaussian beam output gyrotron with CVD (Chemical Vapor Deposition) diamond window was developed for the electron cyclotron heating and current drive on JT-60U. A stable Gaussian output beam power of 1.1 MW-0.1 s was obtained with the efficiency of 39% with depressed collector operation. Due to Gaussian beam output from the gyrotron, the coupling efficiency to HE11 mode in the mirror optical unit was 94%. Moreover, the transmission efficiency of 89% for HE11 mode was performed at the power level of 1 MW on the 40 m-transmission test line of φ31.751 mm corrugated waveguide and 8-miter bends included 1-pair of polarizer. The gyrotron and transmission line were installed into JT-60U system and 0.6 MW-0.3 s power was successfully injected into JT-60U plasmas as an initial operation

  1. Control of the Superconducting Magnets current Power Supplies of the TJ-II Gyrotrons

    International Nuclear Information System (INIS)

    The TJ-II ECRH heating system consists of two gyrotrons, which can deliver a maximum power of 300 kW at a frequency of 53.2 GHz. Another 28 GHz gyrotron is going to be used in the Bernstein waves heating system. In order to get the required frequency, the gyrotrons need and homogeneous magnetic field of several tesla, which is generated by a superconducting coil field by a current source. This document describes the current source control as well as the high precision ammeters control. These ammeters measure the current in the superconducting coils. The user interface and the programming of the control system are described. The communication between devices is also explained. (author) 9 Refs

  2. Development of a 33 kV, 20 A long pulse converter modulator for high average power klystron.

    Science.gov (United States)

    Reghu, T; Mandloi, V; Shrivastava, Purushottam

    2014-05-01

    Research, design, and development of high average power, long pulse modulators for the proposed Indian Spallation Neutron Source are underway at Raja Ramanna Centre for Advanced Technology. With this objective, a prototype of long pulse modulator capable of delivering 33 kV, 20 A at 5 Hz repetition rate has been designed and developed. Three Insulated Gate Bipolar Transistors (IGBT) based switching modules driving high frequency, high voltage transformers have been used to generate high voltage output. The IGBT based switching modules are shifted in phase by 120° with respect to each other. The switching frequency is 25 kHz. Pulses of 1.6 ms pulse width, 80 μs rise time, and 70 μs fall time have been achieved at the modulator output. A droop of ±0.6% is achieved using a simple segmented digital droop correction technique. The total fault energy transferred to the load during fault has been measured by conducting wire burn tests and is found to be within 3.5 J. PMID:24880410

  3. Development of a 33 kV, 20 A long pulse converter modulator for high average power klystron

    Energy Technology Data Exchange (ETDEWEB)

    Reghu, T.; Mandloi, V.; Shrivastava, Purushottam [Pulsed High Power Microwave Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, M.P. (India)

    2014-05-15

    Research, design, and development of high average power, long pulse modulators for the proposed Indian Spallation Neutron Source are underway at Raja Ramanna Centre for Advanced Technology. With this objective, a prototype of long pulse modulator capable of delivering 33 kV, 20 A at 5 Hz repetition rate has been designed and developed. Three Insulated Gate Bipolar Transistors (IGBT) based switching modules driving high frequency, high voltage transformers have been used to generate high voltage output. The IGBT based switching modules are shifted in phase by 120° with respect to each other. The switching frequency is 25 kHz. Pulses of 1.6 ms pulse width, 80 μs rise time, and 70 μs fall time have been achieved at the modulator output. A droop of ±0.6% is achieved using a simple segmented digital droop correction technique. The total fault energy transferred to the load during fault has been measured by conducting wire burn tests and is found to be within 3.5 J.

  4. Development of a 33 kV, 20 A long pulse converter modulator for high average power klystron

    Science.gov (United States)

    Reghu, T.; Mandloi, V.; Shrivastava, Purushottam

    2014-05-01

    Research, design, and development of high average power, long pulse modulators for the proposed Indian Spallation Neutron Source are underway at Raja Ramanna Centre for Advanced Technology. With this objective, a prototype of long pulse modulator capable of delivering 33 kV, 20 A at 5 Hz repetition rate has been designed and developed. Three Insulated Gate Bipolar Transistors (IGBT) based switching modules driving high frequency, high voltage transformers have been used to generate high voltage output. The IGBT based switching modules are shifted in phase by 120° with respect to each other. The switching frequency is 25 kHz. Pulses of 1.6 ms pulse width, 80 μs rise time, and 70 μs fall time have been achieved at the modulator output. A droop of ±0.6% is achieved using a simple segmented digital droop correction technique. The total fault energy transferred to the load during fault has been measured by conducting wire burn tests and is found to be within 3.5 J.

  5. Status of the 2 MW, 170 GHz coaxial cavity gyrotron for ITER

    International Nuclear Information System (INIS)

    Full text: A 170 GHz coaxial cavity gyrotron with 2 MW output power in continuous wave (CW) operation is under development in cooperation between European research centres together with European industry. A first industrial prototype of such a gyrotron has already been fabricated and delivered to CRPP Lausanne, where a suitable test facility has been constructed. Due to a delay in fabrication the delivery of the gyrotron magnet is expected in May 2007. Thus experimental tests are expected for the second half of this year. In parallel to the industrial activities, experimental operation with a short pulse (∼ few ms) 170 GHz coaxial gyrotron ('pre-prototype') which uses the same main components as designed for the industrial tube has been continued. The mechanism of parasitic low frequency (LF) oscillations around 260 MHz has been identified. Based on this identification, small modifications of the geometry of the coaxial insert have been made. As a result the starting current for the LF oscillations has been increased by a factor of about 3 causing a strong reduction of the LF amplitude. Measurements with a prototype of a microwave load, which has been designed and fabricated for operation with the 2 MW prototype tube, have been performed. In addition to the distribution of the microwave power absorbed on the wall, the amount of power reflected back into the gyrotron has been measured and its influence on gyrotron performance has been investigated. The performance of the quasi optical (q.o.) RF output system presently installed in the industrial prototype tube is insufficient, mainly because of the low Gaussian content of the RF output beam. As a first step a new launcher with a different wall corrugation and a new adapted phase correcting mirror has been designed and fabricated. According to simulations an increase of the Gaussian content to about 87% is expected. This q.o. RF output system has been installed in the pre-prototype tube for performing hot

  6. Stable, high efficiency gyrotron backward-wave oscillator

    Science.gov (United States)

    Fan, C. T.; Chang, T. H.; Pao, K. F.; Chu, K. R.; Chen, S. H.

    2007-09-01

    Stability issues have been a major concern for the realization of broadband tunability of the gyrotron backward-wave oscillator (gyro-BWO). Multimode, time-dependent simulations are employed to examine the stability properties of the gyro-BWO. It is shown that the gyro-BWO is susceptible to both nonstationary oscillations and axial mode competition in the course of frequency tuning. Regions of nonstationary oscillations and axial mode competition are displayed in the form of stability maps over wide-ranging parameter spaces. These maps serve as a guide for the identification and optimization of stable windows for broadband tuning. Results indicate that a shorter interaction length provides greater stability without efficiency degradation. These theoretical predictions have been verified in a Ka-band gyro-BWO experiment using both short and long interaction lengths. In the case of a short interaction length, continuous and smooth tunability, in magnetic field and in beam voltage, was demonstrated with the high interaction efficiency reported so far. A maximum 3-dB tuning range of 1.3GHz with a peak power of 149kW at 29.8% efficiency was achieved. In a comparative experiment with a longer interaction length, the experimental data are characterized by piecewise-stable tuning curves separated by region(s) of nonstationary oscillations, as predicted by theory.

  7. Gyrotrons for High-Power Terahertz Science and Technology at FIR UF

    CERN Document Server

    Idehara, Toshitaka

    2016-01-01

    In this paper, we present the recent progress in the development of a series of gyrotrons at FIR UF that have opened the road to many novel applications in the high-power Terahertz science and technology. The current status of the research in this actively developing field is illustrated by the most representative examples in which the developed gyrotrons are used as powerful and frequency tunable sources of coherent radiation operating in a CW regime. Among them are high-precision spectroscopic techniques (most notably DNP-NMR, ESR, XDMR, and studies of the hyperfine splitting of the energy levels of positronium), treatment and characterization of advanced materials, new medical technologies.

  8. Infrared measurements of the synthetic diamond window of a 110 GHz high power Gyrotron

    International Nuclear Information System (INIS)

    Artificially grown diamond has extremely low absorption for microwaves in the millimeter wave range, making this material an attractive candidate for output windows on high power gyrotrons. Several windows have failed in this application due to higher than expected losses. Infrared measurements of the window temperature on a high power gyrotron operating at 110 GHz have been performed. The peak central temperature and time to equilibrium during the rf pulse were consistent with the low loss properties of the material determined from low power cavity measurements

  9. Design of 95 GHz, 2 MW Gyrotron for Communication and Security Applications

    Science.gov (United States)

    Kumar, Nitin; Singh, Udaybir; Singh, T. P.; Sinha, A. K.

    2011-02-01

    The design and the numerical simulation of the 95 GHz, 2 MW gyrotron for various kinds of communication, sensing and security applications is presented. The gyrotron is designed for the TE24,8 operating mode. Various in-house developed and commercially available computer codes are used for the design purpose. A 4.25 MW electron gun is designed for the 2 MW of output power. The mode selection, cold cavity and the beam-wave interaction analysis are discussed for the design of weakly tapered open resonator type of interaction cavity. The parametric analysis of the interaction cavity and the electron gun is also presented.

  10. Continuous-Wave Operation of a Frequency-Tunable 460-GHz Second-Harmonic Gyrotron for Enhanced Nuclear Magnetic Resonance

    OpenAIRE

    Torrezan, Antonio C.; Han, Seong-Tae; Mastovsky, Ivan; Shapiro, Michael A; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Griffin, Robert G.; Barnes, Alexander B.

    2010-01-01

    The design, operation, and characterization of a continuous-wave (CW) tunable second-harmonic 460-GHz gyrotron are reported. The gyrotron is intended to be used as a submillimeter-wave source for 700-MHz nuclear magnetic resonance experiments with sensitivity enhanced by dynamic nuclear polarization. The gyrotron operates in the whispering-gallery mode TE11,2 and has generated 16 W of output power with a 13-kV 100-mA electron beam. The start oscillation current measured over a range of magnet...

  11. Measurement of Radiation Frequency of Gyrotron by GaAs Schottky Barrier Diodes Coupled with Thin-Film Slot Antenna

    Science.gov (United States)

    Kosuke Hayashi,; Takashi Furuya,; Takashi Tachiki,; Takashi Uchida,; Toshitaka Idehara,; Yoshizumi Yasuoka,

    2010-03-01

    Thin-film slot-antenna-coupled GaAs Schottky barrier diodes (SBDs) used at the 180 GHz band were fabricated by microfabrication techniques, and the radiation frequency of a gyrotron at the University of Fukui (Gyrotron FU CW IV) was measured. In second-harmonic mixing using a local oscillator (LO) wave of 88.0899 GHz, an intermediate frequency (IF) signal of 102.8 MHz was observed and the radiation frequency of the gyrotron was found to be 176.077 GHz.

  12. Services-oriented architecture for adaptive and intelligent data acquisition and processing systems in long pulse fusion experiments

    International Nuclear Information System (INIS)

    Advanced software tools for implementing nodes in distributed data acquisition systems (DDAQ) are essential for implementing long duration experiments. Nodes need local processing capabilities for implementing 'on line' and 'real time' analysis. Data reduction techniques and pattern recognitions solutions can be implemented in ITMS (Intelligent Test and Measurement System). User's processing algorithms are implemented in a high level graphical language (LabVIEW). DAQ must be integrated in complex network using SOA solutions. JINI provides this mechanism and simplifies use, setup, supervision and software update. Advanced timing and synchronization are essential tools in the next generation of advanced DAQs and SCXML is a 'powerful' tool for implementing Intelligent DAQ systems for long pulse fusion experiments

  13. Investigation into the electromagnetic impulses from long-pulse laser illuminating solid targets inside a laser facility

    Science.gov (United States)

    Yi, Tao; Yang, Jinwen; Yang, Ming; Wang, Chuanke; Yang, Weiming; Li, Tingshuai; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun; Xiao, Shaoqiu

    2016-06-01

    Emission of the electromagnetic pulses (EMP) due to laser-target interaction in laser facility had been evaluated using a cone antenna in this work. The microwave in frequencies ranging from several hundreds of MHz to 2 GHz was recorded when long-pulse lasers with several thousands of joules illuminated the solid targets, meanwhile the voltage signals from 1 V to 4 V were captured as functions of laser energy and backlight laser, where the corresponding electric field strengths were obtained by simulating the cone antenna in combination with conducting a mathematical process (Tiknohov Regularization with L curve). All the typical coupled voltage oscillations displayed multiple peaks and had duration of up to 80 ns before decaying into noise and mechanisms of the EMP generation was schematically interpreted in basis of the practical measuring environments. The resultant data were expected to offer basic know-how to achieve inertial confinement fusion.

  14. Investigation into the electromagnetic impulses from long-pulse laser illuminating solid targets inside a laser facility

    Science.gov (United States)

    Yi, Tao; Yang, Jinwen; Yang, Ming; Wang, Chuanke; Yang, Weiming; Li, Tingshuai; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun; Xiao, Shaoqiu

    2016-09-01

    Emission of the electromagnetic pulses (EMP) due to laser-target interaction in laser facility had been evaluated using a cone antenna in this work. The microwave in frequencies ranging from several hundreds of MHz to 2 GHz was recorded when long-pulse lasers with several thousands of joules illuminated the solid targets, meanwhile the voltage signals from 1 V to 4 V were captured as functions of laser energy and backlight laser, where the corresponding electric field strengths were obtained by simulating the cone antenna in combination with conducting a mathematical process (Tiknohov Regularization with L curve). All the typical coupled voltage oscillations displayed multiple peaks and had duration of up to 80 ns before decaying into noise and mechanisms of the EMP generation was schematically interpreted in basis of the practical measuring environments. The resultant data were expected to offer basic know-how to achieve inertial confinement fusion.

  15. A Fully-Sealed Carbon-Nanotube Cold-Cathode Terahertz Gyrotron

    Science.gov (United States)

    Yuan, Xuesong; Zhu, Weiwei; Zhang, Yu; Xu, Ningsheng; Yan, Yang; Wu, Jianqiang; Shen, Yan; Chen, Jun; She, Juncong; Deng, Shaozhi

    2016-09-01

    Gigahertz to terahertz radiation sources based on cold-cathode vacuum electron technology are pursued, because its unique characteristics of instant switch-on and power saving are important to military and space applications. Gigahertz gyrotron was reported using carbon nanotube (CNT) cold-cathode. It is reported here in first time that a fully-sealed CNT cold-cathode 0.22 THz-gyrotron is realized, typically with output power of 500 mW. To achieve this, we have studied mechanisms responsible for CNTs growth on curved shape metal surface, field emission from the sidewall of a CNT, and crystallized interface junction between CNT and substrate material. We have obtained uniform growth of CNTs on and direct growth from cone-cylinder stainless-steel electrode surface, and field emission from both tips and sidewalls of CNTs. It is essential for the success of a CNT terahertz gyrotron to have such high quality, high emitting performance CNTs. Also, we have developed a magnetic injection electron gun using CNT cold-cathode to exploit the advantages of such a conventional gun design, so that a large area emitting surface is utilized to deliver large current for electron beam. The results indicate that higher output power and higher radiation frequency terahertz gyrotron may be made using CNT cold-cathode electron gun.

  16. Start-Up Scenario in Gyrotrons with a Nonstationary Microwave-Field Structure

    Science.gov (United States)

    Nusinovich, G. S.; Yeddulla, M.; Antonsen, T. M., Jr.; Vlasov, A. N.

    2006-03-01

    Megawatt class gyrotrons operate in very high-order modes. Therefore, control of a gyrotron oscillator’s start-up is important for excitation of the desired mode in the presence of the many undesired modes. Analysis of such scenario using the self-consistent code MAGY [M. Botton , IEEE Trans. Plasma Sci. 26,ITPSBD0093-3813 882 (1998)10.1109/27.700860] reveals that during start-up not only mode amplitudes vary in time, but also their axial structure can be time dependent. Simulations done for a 1.5 MW gyrotron show that the excitation of a single operating TE22,6 mode can exhibit a sort of intermittency when, first, it is excited as a mode whose axial structure extends outside the interaction cavity, then it ceases and then reappears as a mode mostly localized in the cavity. This phenomenon makes it necessary to analyze start-up scenarios in such gyrotrons with the use of codes that account for the possible evolution of field profiles.

  17. CONDITIONING AND PROTECTION CIRCUITRY FOR EXTERNAL MODULATION OF A PREPROGRAMMED GYROTRON CATHODE VOLTAGE COMMAND WAVEFORM

    Energy Technology Data Exchange (ETDEWEB)

    PONCE,D; FERRON,J.R; LEGG,R.A

    2003-10-01

    OAK-B135 The modulating voltages applied to the DIII-D gyrotrons are controlled by reference signals which are synthesized by arbitrary waveform generators.These generators allow ECH operators to pre-program reference waveforms consisting of ramps, flat tops, and various modulation shapes. This capability is independent of the DIII-D central timing and waveform facilities, which provides the ECH operators operational flexibility. The waveform generators include an amplitude modulation input, providing a means to control the pre-programmed waveform externally. This input is being used to allow the DIII-D plasma control system (PCS) to control gyrotron power in response top selected feedback signals. As the PCS control signal could potentially modulate the gyrotrons beyond operational limits or otherwise in a manner leading to recalcitrant rf generation, the control signal is conditioned so that its effect upon the ECH pre-programmed reference waveform is limited by conditions set by the ECH operators. The design of the circuitry which restricts the range over which the PCS control signal may modulate the reference waveform will be discussed. Test and DIII-D experimental results demonstrating the utility and effectiveness of gyrotron power modulated by the PCS will be presented.

  18. Simulation tools for computer-aided design and numerical investigations of high-power gyrotrons

    Science.gov (United States)

    Damyanova, M.; Balabanova, E.; Kern, S.; Illy, S.; Sabchevski, S.; Thumm, M.; Vasileva, E.; Zhelyazkov, I.

    2012-03-01

    Modelling and simulation are essential tools for computer-aided design (CAD), analysis and optimization of high-power gyrotrons used as radiation sources for electron cyclotron resonance heating (ECRH) and current drive (ECCD) of magnetically confined plasmas in the thermonuclear reactor ITER. In this communication, we present the current status of our simulation tools and discuss their further development.

  19. To the theory of high-power gyrotrons with uptapered resonators

    International Nuclear Information System (INIS)

    In high-power gyrotrons it is desirable to combine an optimal resonator length with the optimal value of the resonator quality factor. In resonators with the constant radius of the central part, the possibilities of this combination are limited because the quality factor of the resonator sharply increases with its length. Therefore the attempts to increase the length for maximizing the efficiency leads to such increase in the quality factor which makes the optimal current too small. Resonators with slightly uptapered profiles offer more flexibility in this regard. In such resonators, one can separate optimization of the interaction length from optimization of the quality factor because the quality factor determined by diffractive losses can be reduced by increasing the angle of uptapering. In the present paper, these issues are analyzed by studying as a typical high-power 17 GHz gyrotron which is currently under development in Europe for ITER (http://en.wikipedia.org/wiki/ITER). The effect of a slight uptapering of the resonator wall on the efficiency enhancement and the purity of the radiation spectrum in the process of the gyrotron start-up and power modulation are studied. Results show that optimal modification of the shape of a slightly uptapered resonator may result in increasing the gyrotron power from 1052 to 1360 kW.

  20. A Fully-Sealed Carbon-Nanotube Cold-Cathode Terahertz Gyrotron.

    Science.gov (United States)

    Yuan, Xuesong; Zhu, Weiwei; Zhang, Yu; Xu, Ningsheng; Yan, Yang; Wu, Jianqiang; Shen, Yan; Chen, Jun; She, Juncong; Deng, Shaozhi

    2016-01-01

    Gigahertz to terahertz radiation sources based on cold-cathode vacuum electron technology are pursued, because its unique characteristics of instant switch-on and power saving are important to military and space applications. Gigahertz gyrotron was reported using carbon nanotube (CNT) cold-cathode. It is reported here in first time that a fully-sealed CNT cold-cathode 0.22 THz-gyrotron is realized, typically with output power of 500 mW. To achieve this, we have studied mechanisms responsible for CNTs growth on curved shape metal surface, field emission from the sidewall of a CNT, and crystallized interface junction between CNT and substrate material. We have obtained uniform growth of CNTs on and direct growth from cone-cylinder stainless-steel electrode surface, and field emission from both tips and sidewalls of CNTs. It is essential for the success of a CNT terahertz gyrotron to have such high quality, high emitting performance CNTs. Also, we have developed a magnetic injection electron gun using CNT cold-cathode to exploit the advantages of such a conventional gun design, so that a large area emitting surface is utilized to deliver large current for electron beam. The results indicate that higher output power and higher radiation frequency terahertz gyrotron may be made using CNT cold-cathode electron gun. PMID:27609247

  1. Effects of electron beam parameters and velocity spread on radio frequency output of a photonic band gap cavity gyrotron oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ashutosh, E-mail: asingh.rs.ece@iitbhu.ac.in [Faculty of Physical Sciences, Institute of Natural Sciences and Humanities, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Uttar Pradesh 225003 (India); Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Jain, P. K. [Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2015-09-15

    In this paper, the effects of electron beam parameters and velocity spread on the RF behavior of a metallic photonic band gap (PBG) cavity gyrotron operating at 35 GHz with TE{sub 041}–like mode have been theoretically demonstrated. PBG cavity is used here to achieve a single mode operation of the overmoded cavity. The nonlinear time-dependent multimode analysis has been used to observe the beam-wave interaction behavior of the PBG cavity gyrotron, and a commercially available PIC code “CST Particle Studio” has been reconfigured to obtain 3D simulation results in order to validate the analytical values. The output power for this typical PBG gyrotron has been obtained ∼108 kW with ∼15.5% efficiency in a well confined TE{sub 041}–like mode, while all other competing modes have significantly low values of power output. The output power and efficiency of a gyrotron depend highly on the electron beam parameters and velocity spread. The influence of several electron beam parameters, e.g., beam voltage, beam current, beam velocity pitch factor, and DC magnetic field, on the PBG gyrotron operations has been investigated. This study would be helpful in optimising the electron beam parameters and estimating accurate RF output power of the high frequency PBG cavity based gyrotron oscillators.

  2. Gyrotron: an application of the relativistic bunching of electrons to the generation of intense millimeter microwave radiation

    International Nuclear Information System (INIS)

    The cyclotron maser or gyrotron is capable of generating high power microwaves at millimeter wave frequencies for applications in fusion heating, radar astronomy and communications. Analytic and numerical simulation models are developed that describe the behavior of these devices under realistic laboratory conditions including the effects of circuit geometry, beam thermal spread, and mode competition. In Chapter 2, a generalized linear theory for the gyrotron is presented in the form of an integro-differential equation that can be solved within various circuit geometries thus describing gyro-amplifiers, gyro-oscillatory and gyroklystrons. In Chapter 3 a complete description of a finite size electromagnetic particle simulation model is presented that describes gyrotrons operating in a TE/sub mn/ waveguide mode. In Chapter 4 simulations and theoretical analysis are made of gyrotron amplifiers operating in the TE/sub 01/ mode. In Chapter 5 the linear eigenmodes and eigenfrequencies of gyrotron oscillators are examined. In Chapter 6 the experimental development of a GHz gyrotron is presented. Theoretical and numerical predictions of oscillation thresholds and efficiencies compare favorably with experimental data

  3. Intense pulsed light vs. long-pulsed dye laser treatment of telangiectasia after radiotherapy for breast cancer: a randomized split-lesion trial of two different treatments

    DEFF Research Database (Denmark)

    Nymann, P.; Hedelund, L.; Hædersdal, Merete

    2009-01-01

    Background Chronic radiodermatitis is a common sequela of treatment for breast cancer and potentially a psychologically distressing factor for the affected women. Objectives To evaluate the efficacy and adverse effects of treatments with a long-pulsed dye laser (LPDL) vs. intense pulsed light (IPL...

  4. Mechanical baseline design of the common long pulse source for the neutral beam systems of TFTR, Doublet III-D, and MFTF-B

    International Nuclear Information System (INIS)

    The Common Long Pulse Source (CLPS) is designed to meet the differing long pulse neutral beam requirements of TFTR, Doublet III-D, and MFTF-B. The mechanical baseline design to meet these requirements is described along with supporting engineering data collected during the testing of the prototype LBL 10 x 40 Long Pulse Accelerator (LPA) and the Long Pulse Plasma Source (LPS). The CLPS is a scaled up design of the LPA and LPS and can be configured for 120 keV, 70 A D2 non-focused, and, 80 keV, 80 A H2 or 50 A D2 with a 10 m focal length. The two configurations use identical major components, such as accelerator grids, supporting structures, insulators and plasma sources. Ion beam optics are analytically modeled and the results are presented along with the electric field gradients and thermal calculations for various components. A low technology plasma source back plate electron dump design has been adopted. A full scale model of CLPS was constructed, and the baseline design has been transferred to industry. 7 refs., 5 figs

  5. Long-pulse beam acceleration of MeV-class H(-) ion beams for ITER NB accelerator.

    Science.gov (United States)

    Umeda, N; Kashiwagi, M; Taniguchi, M; Tobari, H; Watanabe, K; Dairaku, M; Yamanaka, H; Inoue, T; Kojima, A; Hanada, M

    2014-02-01

    In order to realize neutral beam systems in International Thermonuclear Experimental Reactor whose target is to produce a 1 MeV, 200 A/m(2) during 3600 s D(-) ion beam, the electrostatic five-stages negative ion accelerator so-called "MeV accelerator" has been developed at Japan Atomic Energy Agency. To extend pulse length, heat load of the acceleration grids was reduced by controlling the ion beam trajectory. Namely, the beam deflection due to the residual magnetic field of filter magnet was suppressed with the newly developed extractor with a 0.5 mm off-set aperture displacement. The new extractor improved the deflection angle from 6 mrad to 1 mrad, resulting in the reduction of direct interception of negative ions from 23% to 15% of the total acceleration power, respectively. As a result, the pulse length of 130 A/m(2), 881 keV H(-) ion beam has been successfully extended from a previous value of 0.4 s to 8.7 s. This is the first long pulse negative ion beam acceleration over 100 MW/m(2).

  6. Service-oriented architecture of adaptive, intelligent data acquisition and processing systems for long-pulse fusion experiments

    International Nuclear Information System (INIS)

    The data acquisition systems used in long-pulse fusion experiments need to implement data reduction and pattern recognition algorithms in real time. In order to accomplish these operations, it is essential to employ software tools that allow for hot swap capabilities throughout the temporal evolution of the experiments. This is very important because processing needs are not equal during different phases of the experiment. The intelligent test and measurement system (ITMS) developed by UPM and CIEMAT is an example of a technology for implementing scalable data acquisition and processing systems based on PXI and CompactPCI hardware. In the ITMS platform, a set of software tools allows the user to define the processing algorithms associated with the different experimental phases using state machines driven by software events. These state machines are specified using the State Chart XML (SCXML) language. The software tools are developed using JAVA, JINI, an SCXML engine and several LabVIEW applications. Within this schema, it is possible to execute data acquisition and processing applications in an adaptive way. The power of SCXML semantics and the ability to work with XML user-defined data types allow for very easy programming of the ITMS platform. With this approach, the ITMS platform is a suitable solution for implementing scalable data acquisition and processing systems based on a service-oriented model with the ability to easily implement remote participation applications.

  7. Services oriented architecture for adaptive and intelligent data acquisition and processing systems in long pulse fusion experiments

    International Nuclear Information System (INIS)

    Data acquisition systems used in long pulse fusion experiments require to implement data reduction and pattern recognition algorithms in real time. In order to accomplish these operations is essential to dispose software tools that allow hot swap capabilities throughout the temporal evolution of the experiments. This is very important because the processing needs are not equal in the different experiment's phases. The intelligent test and measurement system (ITMS) developed by UPM and CIEMAT is an example of technology for implementing scalable data acquisition and processing systems based in PXI and compact PCI hardware. In the ITMS platform a set of software tools allows the user to define the processing associated with the different experiment's phases using state machines driven by software events. These state machines are specified using State Chart XML (SCXML) language. The software tools are developed using: JAVA, JINI, a SCXML engine and several LabVIEW applications. With this schema it is possible to execute data acquisition and processing applications in an adaptive way. The powerful of SCXML semantics and the possibility of to work with XML user defined data types allow a very easy programming of ITMS platform. With this approach ITMS platform is a suitable solution for implementing scalable data acquisition and processing systems, based in a services oriented model, with ease possibility for implement remote participation applications. (authors)

  8. Service-oriented architecture of adaptive, intelligent data acquisition and processing systems for long-pulse fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, J. [Grupo de Investigacion en Instrumentacion y Acustica Aplicada. Universidad Politecnica de Madrid, Crta. Valencia Km-7 Madrid 28031 (Spain); Ruiz, M., E-mail: mariano.ruiz@upm.e [Grupo de Investigacion en Instrumentacion y Acustica Aplicada. Universidad Politecnica de Madrid, Crta. Valencia Km-7 Madrid 28031 (Spain); Barrera, E.; Lopez, J.M.; Arcas, G. de [Grupo de Investigacion en Instrumentacion y Acustica Aplicada. Universidad Politecnica de Madrid, Crta. Valencia Km-7 Madrid 28031 (Spain); Vega, J. [Asociacion EURATOM/CIEMAT para Fusion, Madrid (Spain)

    2010-07-15

    The data acquisition systems used in long-pulse fusion experiments need to implement data reduction and pattern recognition algorithms in real time. In order to accomplish these operations, it is essential to employ software tools that allow for hot swap capabilities throughout the temporal evolution of the experiments. This is very important because processing needs are not equal during different phases of the experiment. The intelligent test and measurement system (ITMS) developed by UPM and CIEMAT is an example of a technology for implementing scalable data acquisition and processing systems based on PXI and CompactPCI hardware. In the ITMS platform, a set of software tools allows the user to define the processing algorithms associated with the different experimental phases using state machines driven by software events. These state machines are specified using the State Chart XML (SCXML) language. The software tools are developed using JAVA, JINI, an SCXML engine and several LabVIEW applications. Within this schema, it is possible to execute data acquisition and processing applications in an adaptive way. The power of SCXML semantics and the ability to work with XML user-defined data types allow for very easy programming of the ITMS platform. With this approach, the ITMS platform is a suitable solution for implementing scalable data acquisition and processing systems based on a service-oriented model with the ability to easily implement remote participation applications.

  9. Experimental tests of Rayleigh-Taylor stabilization mechanisms with long pulse gas-filled halfraums on OMEGA

    Science.gov (United States)

    Casner, A.; Huser, G.; Vandenboomgaerde, M.; Liberatore, S.; Masse, L.; Galmiche, D.

    2008-11-01

    Mitigation of Rayleigh-Taylor instabilities growth is a key issue on the road toward ignition. The graded doped ablator is a common concept for NIF [1] and LMJ [2] point designs. A complementary stabilization mechanism based on anisotropic thermal diffusion was theoretically underlined [3] for the ablative Rayleigh-Taylor instability. We will present the first ever experimental tests of these mechanisms. Indirect drive experiments were performed on the OMEGA laser facility with a long-pulse platform. We used in fact gas-filled halfraums and stack 15 drive beams along 2 cones to create a 7 ns long radiation drive. Halfraum energetics with E-IDI-300 phase plates was validated by dedicated shots along P5/P8 and is fairly reproduced by the simulations. These drive measurements allowed also to determine the graded doped planar emulator whose layers thicknesses and composition should be carefully optimized . Side-on and face-on data acquired with germanium-doped plastic samples (modulations wavelength 35 and 50 microns) will be presented and compared with FCI2 hydrocodes simulations. [1] S.W. Haan et al., Phys. Plasmas 12, 056316 (2005). [2] C C-Cl'erouin et al 2008 J. Phys.: Conf. Ser. 112 022023 [3] L. Masse., Phys. Rev. Lett. 98, 245001 (2007).

  10. Comparison of Different Methods for Calculating Gyrotron Quasi-Optical Mode Converters

    Science.gov (United States)

    Gashturi, A. P.; Chirkov, A. V.; Denisov, G. G.; Paveliev, A. B.

    2013-01-01

    This paper presents the use of combination of three methods for calculation and synthesis of high-efficiency microwave mode converters, such as radiators of gyrotrons. The analytical method yields immediate estimates of mode converter dimensions, the Scalar Integral Equation (SIE) allows one to synthesize efficiently the optimal profile of the mode converter, and the most accurate Electric Field Integral Equation (EFIE) is used to check all transmission characteristics of the converter including calculations of reflection and cross-polarization. The combination of these three methods is an optimal for the mode converter design. Just so the launcher was designed for a quasi-optical mode converter used in the 60 GHz gyrotron in the TE7,3 operating mode. The simulation results agree well with the measured data. The paper also presents for the first time an accurate derivation of the SIE method.

  11. Gyrotrons for High-Power Terahertz Science and Technology at FIR UF

    Science.gov (United States)

    Idehara, Toshitaka; Sabchevski, Svilen Petrov

    2016-10-01

    In this review paper, we present the recent progress in the development of a series of gyrotrons at the Research Center for Development of Far-Infrared Region, University of Fukui, that have opened the road to many novel applications in the high-power terahertz science and technology. The current status of the research in this actively developing field is illustrated by the most representative examples in which the developed gyrotrons are used as powerful and frequency-tunable sources of coherent radiation operating in a continuous-wave regime. Among them are high-precision spectroscopic techniques (most notably dynamic nuclear polarization-nuclear magnetic resonance, electron spin resonance, X-ray detected magnetic resonance, and studies of the hyperfine splitting of the energy levels of positronium), treatment and characterization of advanced materials, and new medical technologies.

  12. Problem-Oriented Simulation Packages and Computational Infrastructure for Numerical Studies of Powerful Gyrotrons

    Science.gov (United States)

    Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.

    2016-05-01

    Powerful gyrotrons are necessary as sources of strong microwaves for electron cyclotron resonance heating (ECRH) and electron cyclotron current drive (ECCD) of magnetically confined plasmas in various reactors (most notably ITER) for controlled thermonuclear fusion. Adequate physical models and efficient problem-oriented software packages are essential tools for numerical studies, analysis, optimization and computer-aided design (CAD) of such high-performance gyrotrons operating in a CW mode and delivering output power of the order of 1-2 MW. In this report we present the current status of our simulation tools (physical models, numerical codes, pre- and post-processing programs, etc.) as well as the computational infrastructure on which they are being developed, maintained and executed.

  13. Development and simulation of RF components for high power millimeter wave gyrotrons

    International Nuclear Information System (INIS)

    To test gyrotron RF components, efficient low-power generators for rotating high-order modes of high purity are necessary. Designs of generators for the TE15,3 mode at 84 GHz and for the TE31,8 mode at 168 GHz are presented and some preliminary test results are discussed. In addition, Toshiba gyrotron cavities at 168 GHz were analyzed for leakage of RF power in the beam tunnel. To decrease RF power leakage, the declination angle of the cut-off cavity cross section has to be decreased. A TE15,3 waveguide nonlinear uptaper is analyzed at 84 GHz as well as 168 GHz uptapers. Since the calculated conversion losses are slightly higher than designed value, an optimization of those uptapers may be required. (author)

  14. High-frequency gyrotrons and their application to tokamak plasma heating

    International Nuclear Information System (INIS)

    A comprehensive analysis of high frequency (100 to 200 GHz) and high power (> 100 kW) gyrotrons has been conducted. It is shown that high frequencies will be required in order for electron cyclotron radiation to propagate to the center of a compact tokamak power reactor. High power levels will be needed in order to ignite the plasma with a reasonable number of gyrotron units. In the first part of this research, a set of analytic expressions, valid for all TE cavity modes and all harmonics, is derived for the starting current and frequency detuning using the Vlasov-Maxwell equations in the weakly relativistic limit. The use of an optical cavity is also investigated

  15. Time-domain theory of gyrotron traveling wave amplifiers operating at grazing incidence

    International Nuclear Information System (INIS)

    Time-domain theory of the gyrotron traveling wave tube (gyro-TWT) operating at grazing incidence has been developed. The theory is based on a description of wave propagation by a parabolic equation. The results of the simulations are compared with experimental results of the observation of subnanosecond pulse amplification in a gyro-TWT consisting of three gain sections separated by severs. The theory developed can also be used successfully for a description of amplification of monochromatic signals

  16. Time domain analysis of a gyrotron traveling wave amplifier with misaligned electron beam

    International Nuclear Information System (INIS)

    This article develops a time-domain theory to study the beam-wave interaction in gyrotron traveling wave amplifier (gyro-TWA) with a misaligned electron beam. The effects of beam misalignment on the TE01 mode gyro-TWA operating at the fundamental are discussed. Numerical results show that the effect of misalignment is less obvious when the input power is larger, and the influences of misalignment on the stable gain and the stable time are basically opposite

  17. A 250 GHz Gyrotron with a 3 GHz Tuning Bandwidth for Dynamic Nuclear Polarization

    OpenAIRE

    Barnes, Alexander B.; Nanni, Emilio A.; Herzfeld, Judith; Griffin, Robert G.; Temkin, Richard J.

    2012-01-01

    We describe the design and implementation of a novel tunable 250 GHz gyrotron oscillator with >10 W output power over most of a 3 GHz band and >35 W peak power. The tuning bandwidth and power are sufficient to generate a >1 MHz nutation frequency across the entire nitroxide EPR lineshape for cross effect DNP, as well as to excite solid effect transitions utilizing other radicals, without the need for sweeping the NMR magnetic field. Substantially improved tunability is achieved by implementin...

  18. Modelling and simulation of new generation powerful gyrotrons for the fusion research

    Energy Technology Data Exchange (ETDEWEB)

    Sabchevski, S [Institute of Electronics, Bulgarian Academy of Sciences, BG-1784 Sofia (Bulgaria); Zhelyazkov, I [Faculty of Physics, Sofia University, BG-1164 Sofia (Bulgaria)

    2007-04-15

    One of the important issues related with the cyclotron resonance heating (CRH) and current drive of fusion plasmas in thermonuclear reactors (tokamaks and stellarators) is the development of multi-megawatt class gyrotrons. There are generally three stages of the implementation of that task, notably (i) elaborating a novel generation of software tools for the physical modelling and simulation of such kind of gyrotrons, (ii) their computer aided design (CAD) and construction on the basis of the simulation's results, and finally, (iii) gyrotrons' testing in real experimental conditions. This tutorial paper concerns the first item-the development of software tools. In co-operation with the Institute for Pulsed Power and Microwave Technology at the Forschungszentrum Karlsruhe, Germany, and Centre de Recherches en Physique des Plasmas at Ecole Polytechnique Federale de Lausanne, Switzerland, we work on the conceptual design of the software tools under development. The basic conclusions are that the numerical codes for gyrotrons' modelling should possess the following essential characteristics: (a) portability, (b) extensibility, (c) to be oriented toward the solution of practical problems (i.e., elaborating of computer programs that can be used in the design process), (d) to be based on self-consistent 3D physical models, which take into account the departure from axial symmetry, and (e) ability to simulate time dependent processes (electrostatic PIC simulation) alongside with a trajectory analysis (ray tracing simulation). Here, we discuss how various existing numerical codes have to be improved and implemented via the advanced programming technologies for state-of-the-art computer systems including clusters, grid, parallel platforms, and supercomputers.

  19. Diffraction and Scattering in Launchers of Quasi-Optical Mode Converters for Gyrotrons

    OpenAIRE

    Flamm, Jens Hanspeter

    2012-01-01

    In this work different methods for the calculation of diffraction and scattering in launchers of quasi-optical mode converters for gyrotrons are compared, ranked and extended. The extension gives the opportunity to take a tapered average radius of the waveguide antenna into account. The comparison and the extension of the fast field calculation methods for component synthesis opens the possibility to reduce diffraction and stray radiation of reliable and powerful millimeter wave sources.

  20. Final Report for "Gyrotron Design and Evaluation using New Particle-in-Cell Capability"

    Energy Technology Data Exchange (ETDEWEB)

    David N Smithe

    2008-05-28

    ITER will depend on high power CW gyrotrons to deliver power to the plasma at ECR frequencies. However, gyrotrons can suffer from undesirable low frequency oscillations (LFO’s) which are known to interfere with the gun-region diagnostics and data collection, and are also expected to produce undesirable energy and velocity spread in the beam. The origins and processes leading to these oscillations are poorly understood, and existing gyrotron R&D tools, such as static gun solvers and interaction region models, are not designed to look at time-dependant oscillatory behavior. We have applied a time-domain particle-in-cell method to investigate the LFO phenomenon. Our company is at the forefront of smooth-curved-boundary treatment of the electromagnetic fields and particle emission surfaces, and such methods are necessary to simulate the adiabatically trapped and reflected electrons thought to be driving the oscillations. This approach provides the means for understanding, in microscopic detail, the underlying physical processes driving the low-frequency oscillations. In the Phase I project, an electron gun region from an existing gyrotron, known to observe LFO’s, was selected as a proof-of-principle geometry, and was modeled with the curved-geometry time-domain simulation tool, in order to establish the feasibility of simulating LFO physics with this tool on office-scale, and larger, parallel cluster computers. Generally, it was found to be feasible to model the simulation geometry, emission, and magnetic features of the electron gun. Ultimately, the tool will be used to investigate the origins and life cycle within the trapped particle population. This tool also provides the foundations and validation for potential application of the software to numerous other time-dependant beam and rf source problems in the commercial arena.

  1. The Gyrotron: AN Application of the Relativistic Bunching of Electrons to the Generation of Intense Millimeter Microwave Radiation

    Science.gov (United States)

    Caplan, Malcolm

    The cyclotron maser or gyrotron is capable of generating high power microwaves at millimeter wave frequencies for applications in fusion heating, radar astronomy and communications. Analytic and numerical simulation models are developed which describe the behavior of these devices under realistic laboratory conditions including the effects of circuit geometry, beam thermal spread and mode competition. In Chapter 2, a generalized linear theory for the gyrotron is presented in the form of an integro-differential equation which can be solved within various circuit geometries thus describing gyro-amplifiers, gyro-oscillators and gyroklystrons. In Chapter 3 a complete description of a finite size electromagnetic particle simulation model is presented which describes gyrotrons operating in a TE(,mn) waveguide mode. The resulting computer code is a "stretched" version of a 1-3/2 D particle code which apart from modelling transient self-consistent wave beam dynamics includes the essential effects of arbitrary conducting boundaries without requiring a full 2D simulation. The code also allows simultaneous multi-mode interaction. In Chapter 4 simulations and theoretical analysis are made of gyrotron amplifiers operating in the TE(,01) mode to predict bandwidth gain and efficiency with particular attention to the stabilization of absolute instabilities through frequency selective loss. In Chapter 5 the linear eigenmodes and eigenfrequencies of gyrotron oscillators are examined including the effects of beam loading and circuit geometry. Oscillation threshold currents are obtained. The design analysis and predicted efficiencies of gyrotron oscillators operating in the TE(,021) mode with output powers of at least 200 kW are obtained from particle simulations. In Chapter 6 the experimental development of a GHz gyrotron is presented including the design of the magnetron injection gun, circuit, collector and window. Theoretical and numerical predictions of oscillation thresholds and

  2. Low Noise Amplifiers for 140 Ghz Wide-Band Cryogenic Receivers

    Science.gov (United States)

    Larkoski, Patricia V.; Kangaslahti, Pekka; Samoska, Lorene; Lai, Richard; Sarkozy, Stephen

    2013-01-01

    We report S-parameter and noise measurements for three different Indium Phosphide 35-nanometer-gate-length High Electron Mobility Transistor (HEMT) Low Noise Amplifier (LNA) designs operating in the frequency range centered on 140 gigahertz. When packaged in a Waveguide Rectangular-6.1 waveguide housing, the LNAs have an average measured noise figure of 3.0 decibels - 3.6 decibels over the 122-170 gigahertz band. One LNA was cooled to 20 degrees Kelvin and a record low noise temperature of 46 Kelvin, or 0.64 decibels noise figure, was measured at 152 gigahertz. These amplifiers can be used to develop receivers for instruments that operate in the 130-170 gigahertz atmospheric window, which is an important frequency band for ground-based astronomy and millimeter-wave imaging applications.

  3. A Research of 140-GHz Folded Rectangular Gro ove Waveguide Traveling-Wave Tub e

    Institute of Scientific and Technical Information of China (English)

    ZHANG Minghao; WEI Yanyu; YUE Lingna; GUO Guo; WANG Yuanyuan; SHI Xianbao; WANG Wenxiang

    2015-01-01

    A two-section Folded rectangular groove waveguide (FRGWG) Slow wave structure (SWS) Travel-ing wave tube (TWT) with large dimension of beam tunnel is studied. Compared with the Folded waveguide (FWG) under the same size parameters conditions, the interac-tion impedance and center frequency of the FRGWG are higher. The advantage is that a beam tunnel with large dimension can be applied to the FRGWG without the influence caused by signal decrease, reflection and oscil-lation. The microwave amplification capability based on beam-wave interaction is obtained through the particle-in-cell method. This circuit structure can produce an output power of over 100W ranging from 136 to 142GHz when the operation voltage and beam current are set as 18.4kV and 150mA, respectively, for a 95mm long circuit.

  4. Experimental Study Of A 1.5-mw, 110-ghz Gyrotron Oscillator

    CERN Document Server

    Anderson, J P

    2005-01-01

    This thesis reports the design, construction and testing of a 1.5 MW, 110 GHz gyrotron oscillator. This high power microwave tube has been proposed as the next evolutionary step for gyrotrons used to provide electron cyclotron heating required in fusion devices. A short pulse gyrotron based on the industrial tube design was built at MIT for experimental studies. The experiments are the first demonstration of such high powers at 110 GHz. Using a 96 kV, 40 A electron beam, over 1.4 MW was axially extracted in the design (TE22,6) mode in 3 μs pulses, corresponding to a microwave efficiency of 37%. The beam alpha, the ratio of transverse to axial velocity in the electron beam, was measured with a probe. At the high efficiency operating point the beam alpha was measured as 1.33. This value of alpha is less than the design value of 1.4, possibly accounting for the slightly reduced experimental efficiency. The output power and efficiency, as a function of magnetic field, beam voltage, and beam current, are in...

  5. A 0.33-THz second-harmonic frequency-tunable gyrotron

    Science.gov (United States)

    Zheng-Di, Li; Chao-Hai, Du; Xiang-Bo, Qi; Li, Luo; Pu-Kun, Liu

    2016-02-01

    Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interaction mechanism about propagating waves, featured by wave competition and wave cooperation, is presented and provides a new insight into the beam-wave interaction. The two different features revealed in the two different operation regions of low-order axial modes (LOAMs) and high-order axial modes (HOAMs) respectively determine the characteristic of the overall performance of the device essentially. The device performance is obtained by the simulation based on the time-domain nonlinear theory and shows that using a 12-kV/150-mA electron beam and TE-3,4 mode, the second harmonic gyrotron can generate terahertz radiations with frequency-tuning ranges of about 0.85 GHz and 0.60 GHz via magnetic field and beam voltage tuning, respectively. Additionally, some non-stationary phenomena in the mode startup process are also analyzed. The investigation in this paper presents guidance for future developing high-performance frequency-tunable gyrotrons toward terahertz applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471007, 61531002, 61522101, and 11275206) and the Seeding Grant for Medicine and Information Science of Peking University, China (Grant No. 2014-MI-01).

  6. Configuration and supervision of advanced distributed data acquisition and processing systems for long pulse experiments using JINI technology

    International Nuclear Information System (INIS)

    The development of tools for managing the capabilities and functionalities of distributed data acquisition systems is essential in long pulse fusion experiments. The intelligent test and measurement system (ITMS) developed by UPM and CIEMAT is a technology that permits implementation of a scalable data acquisition and processing system based on PXI or CompactPCI hardware. Several applications based on JINI technology have been developed to enable use of this platform for extensive implementation of distributed data acquisition and processing systems. JINI provides a framework for developing service-oriented, distributed applications. The applications are based on the paradigm of a JINI federation that supports mechanisms for publication, discovering, subscription, and links to remote services. The model we implemented in the ITMS platform included services in the system CPU (SCPU) and peripheral CPUs (PCPUs). The resulting system demonstrated the following capabilities: (1) setup of the data acquisition and processing to apply to the signals, (2) information about the evolution of the data acquisition, (3) information about the applied data processing and (4) detection and distribution of the events detected by the ITMS software applications. With this approach, software applications running on the ITMS platform can be understood, from the perspective of their implementation details, as a set of dynamic, accessible, and transparent services. The search for services is performed using the publication and subscription mechanisms of the JINI specification. The configuration and supervision applications were developed using remotely accessible (LAN or WAN) objects. The consequence of this approach is a hardware and software architecture that provides a transparent model of remote configuration and supervision, and thereby a means to simplify the implementation of a distributed data acquisition system with scalable and dynamic local processing capability developed in a

  7. Configuration and supervision of advanced distributed data acquisition and processing systems for long pulse experiments using JINI technology

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Joaquin; Ruiz, Mariano [Grupo de Investigacion en Instrumentacion y Acustica Aplicada, Universidad Politecnica de Madrid (UPM), Ctra. Valencia Km-7, 28031, Madrid (Spain); Barrera, Eduardo [Grupo de Investigacion en Instrumentacion y Acustica Aplicada, Universidad Politecnica de Madrid (UPM), Ctra. Valencia Km-7, 28031, Madrid (Spain)], E-mail: eduardo.barrera@upm.es; Lopez, Juan Manuel; de Arcas, Guillermo [Grupo de Investigacion en Instrumentacion y Acustica Aplicada, Universidad Politecnica de Madrid (UPM), Ctra. Valencia Km-7, 28031, Madrid (Spain); Vega, Jesus [Asociacion EURATOM/CIEMAT para Fusion, Avda. Complutense 22, 28040, Madrid (Spain)

    2009-06-15

    The development of tools for managing the capabilities and functionalities of distributed data acquisition systems is essential in long pulse fusion experiments. The intelligent test and measurement system (ITMS) developed by UPM and CIEMAT is a technology that permits implementation of a scalable data acquisition and processing system based on PXI or CompactPCI hardware. Several applications based on JINI technology have been developed to enable use of this platform for extensive implementation of distributed data acquisition and processing systems. JINI provides a framework for developing service-oriented, distributed applications. The applications are based on the paradigm of a JINI federation that supports mechanisms for publication, discovering, subscription, and links to remote services. The model we implemented in the ITMS platform included services in the system CPU (SCPU) and peripheral CPUs (PCPUs). The resulting system demonstrated the following capabilities: (1) setup of the data acquisition and processing to apply to the signals, (2) information about the evolution of the data acquisition, (3) information about the applied data processing and (4) detection and distribution of the events detected by the ITMS software applications. With this approach, software applications running on the ITMS platform can be understood, from the perspective of their implementation details, as a set of dynamic, accessible, and transparent services. The search for services is performed using the publication and subscription mechanisms of the JINI specification. The configuration and supervision applications were developed using remotely accessible (LAN or WAN) objects. The consequence of this approach is a hardware and software architecture that provides a transparent model of remote configuration and supervision, and thereby a means to simplify the implementation of a distributed data acquisition system with scalable and dynamic local processing capability developed in a

  8. Experimental Research on a 1.5 MW, 110 GHz Gyrotron with a Smooth Mirror Internal Mode Converter

    Science.gov (United States)

    Tax, D. S.; Mastovsky, I.; Shapiro, M. A.; Temkin, R. J.; Torrezan, A. C.

    2010-11-01

    Megawatt gyrotrons are important for electron cyclotron heating (ECH) of fusion plasmas, including ITER. These gyrotrons should operate with high efficiency to reduce the prime power required and to ensure good reliability. The gyrotron efficiency is affected both by the physical principles that govern the device and the performance of components like the internal mode converter (IMC), which must convert the electromagnetic cavity mode into a Gaussian beam. An IMC consisting of a helically-cut launcher and three smooth curved mirrors, which is less susceptible to alignment errors than an IMC using mirrors with phase correcting surfaces, was recently tested on a 1.5 MW, 110 GHz, 3μs pulsed gyrotron operating in the TE22,6 mode, and an output beam with 95.8 ± 0.5 % Gaussian beam content was measured in both hot and cold tests. We are also examining the issue of mode competition in the gyrotron, which can limit the achievable output power and efficiency. The sequence of competing modes excited during the rise time of the voltage pulse has been measured and results are compared with the numerical simulation code MAGY. These results should provide a good test of the accuracy of the code.

  9. On the dependence of the efficiency of a 240 GHz high-power gyrotron on the displacement of the electron beam and on the azimuthal index

    Energy Technology Data Exchange (ETDEWEB)

    Dumbrajs, O. [Institute of Solid State Physics (ISSP), Association EUROATOM-University of Latvia, Kengaraga iela 8, LV-1063 Riga (Latvia); Avramidis, K. A.; Franck, J.; Jelonnek, J. [Karlsruhe Institute of Technology (KIT), Institute for Pulsed Power and Microwave Technology (IHM), Association EURATOM-KIT, Kaiserstrasse 12, 76131 Karlsruhe (Germany)

    2014-01-15

    Two issues in the cavity design for a Megawatt-class, 240 GHz gyrotron are addressed. Those are first, the effect of a misaligned electron beam on the gyrotron efficiency and second, a possible azimuthal instability of the gyrotron. The aforementioned effects are important for any gyrotron operation, but could be more critical in the operation of Megawatt-class gyrotrons at frequencies above 200 GHz, which will be the anticipated requirement of DEMO. The target is to provide some basic trends to be considered during the refinement and optimization of the design. Self-consistent calculations are the base for simulations wherever possible. However, in cases for which self-consistent models were not available, fixed-field results are presented. In those cases, the conservative nature of the results should be kept in mind.

  10. On the dependence of the efficiency of a 240 GHz high-power gyrotron on the displacement of the electron beam and on the azimuthal index

    International Nuclear Information System (INIS)

    Two issues in the cavity design for a Megawatt-class, 240 GHz gyrotron are addressed. Those are first, the effect of a misaligned electron beam on the gyrotron efficiency and second, a possible azimuthal instability of the gyrotron. The aforementioned effects are important for any gyrotron operation, but could be more critical in the operation of Megawatt-class gyrotrons at frequencies above 200 GHz, which will be the anticipated requirement of DEMO. The target is to provide some basic trends to be considered during the refinement and optimization of the design. Self-consistent calculations are the base for simulations wherever possible. However, in cases for which self-consistent models were not available, fixed-field results are presented. In those cases, the conservative nature of the results should be kept in mind

  11. 2.2 MW Operation of the European Coaxial-Cavity Pre-Prototype Gyrotron for ITER

    International Nuclear Information System (INIS)

    Full text: A 2 MW, CW, 170 GHz coaxial-cavity gyrotron for electron cyclotron heating and current drive in the International Thermonuclear Experimental Reactor (ITER) is under development within an European Gyrotron Consortium (EGYC*). To support the development of the industrial prototype of a CW gyrotron, a short pulse tube (pre-prototype) is used at KIT (former FZK) for experimental verification of the design of critical components, such as electron gun, beam tunnel, cavity and quasi-optical (q.o.) RF-output coupler. Significant progress was achieved recently. In particular, RF output power of up to 2.2 MW with 30% output efficiency has been obtained in single-mode operation at 170 GHz. Furthermore, an excellent quality of the RF output beam with ∼ 96% fundamental Gaussian mode content has been obtained by using a new quasi-optical RF output system. The verification of these results with computer simulations will be presented. (author)

  12. 500-fold enhancement of in situ 13C liquid state NMR using gyrotron-driven temperature-jump DNP

    Science.gov (United States)

    Yoon, Dongyoung; Soundararajan, Murari; Caspers, Christian; Braunmueller, Falk; Genoud, Jérémy; Alberti, Stefano; Ansermet, Jean-Philippe

    2016-09-01

    A 550-fold increase in the liquid state 13C NMR signal of a 50 μL sample was obtained by first hyperpolarizing the sample at 20 K using a gyrotron (260 GHz), then, switching its frequency in order to apply 100 W for 1.5 s so as to melt the sample, finally, turning off the gyrotron to acquire the 13C NMR signal. The sample stays in its NMR resonator, so the sequence can be repeated with rapid cooling as the entire cryostat stays cold. DNP and thawing of the sample are performed only by the switchable and tunable gyrotron without external devices. Rapid transition from DNP to thawing in one second time scale was necessary especially in order to enhance liquid 1H NMR signal.

  13. Study of a cylindrical cavity gyrotron, influence of power reflection and of the oscillation of a travelling mode

    International Nuclear Information System (INIS)

    The quality factor and oscillating mode of a gyrotron cavity are essential parameters to consider when trying to obtain a high power (>500 kW), high efficiency (∼50%) microwave source, which oscillates in a stable manner in the principal mode of the cavity. The study and development of an 8 GHz gyrotron whose resonant cavity is formed by a cylindrical waveguide of slowly varying radius, is undertaken. The study is principally concerned with the phenomena associated with the low quality factor of the TEo011 mode of the cavity. (author) figs., tabs., 102 refs

  14. Coupler for coupling gyrotron whispering gallery mode RF into HE11 waveguide

    Science.gov (United States)

    Neilson, Jeffrey M

    2015-02-24

    A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.

  15. Preliminary design of 1 MW, Ku-band gyrotron traveling-wave amplifier

    Institute of Scientific and Technical Information of China (English)

    Chongqing JIAO

    2009-01-01

    The preliminary design results ofa 1-MW, Ku-band gyrotron traveling wave amplifier (gyro-TWA) are presented. Operating at the second cyclotron harmonic of the TE11 mode, the amplifier characterizes good stability even in the case of no distributed losses loaded, which could potentially allow it to be operated at high average power. Large signal simulation shows that the amplifier can generate a saturated peak power of about 1 MW with efficiency of 26.6%, gain of 31 dB, and 3-dB bandwidth of about 1 GHz when driven by a 100 kV, 40 A electron beam with 5% axial velocity spread.

  16. Experiment for Over 200 kW Oscillation of a 295 GHz Pulse Gyrotron

    OpenAIRE

    YAMAGUCHI, YuuSuke; SAITO, Teruo; TATEMATSU, Yoshinori; IKEUCHI, Shinji; KASA, Jun; KOTERA, Masaki; Ogawa, Isamu; Idehara, Toshitaka; Kubo, Shin; SHIMOZUMA, Takashi; NISHIURA, Masaki; Tanaka, Kenji

    2013-01-01

    A high-power sub-THz gyrotron is under development as a power source of collective Thomson scatteringdiagnostic of fusion plasmas. It operates at a fundamental harmonic frequency of 295 GHz. A cavity whichrealizes stable and efficient single mode oscillation, an electron gun with an intense laminar electron beam, andan internal mode convertor are designed. A maximum oscillation power of 234kW is achieved with a Gaussianlike radiation pattern. The duration of 130kW pulse is extended up to 30 m...

  17. Experiment for over 200 kW oscillation of a 295 GHz pulse gyrotron

    International Nuclear Information System (INIS)

    A high-power sub-THz gyrotron is under development as a power source of collective Thomson scattering diagnostic of fusion plasmas. It operates at a fundamental harmonic frequency of 295 GHz. A cavity which realizes stable and efficient single mode oscillation, an electron gun with an intense laminar electron beam, and an internal mode convertor are designed. A maximum oscillation power of 234 kW is achieved with a Gaussian like radiation pattern. The duration of 130 kW pulse is extended up to 30 microseconds, which is limited by the configuration of power supply. (author)

  18. Development of problem-oriented software packages for numerical studies and computer-aided design (CAD) of gyrotrons

    Science.gov (United States)

    Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.

    2016-03-01

    Gyrotrons are the most powerful sources of coherent CW (continuous wave) radiation in the frequency range situated between the long-wavelength edge of the infrared light (far-infrared region) and the microwaves, i.e., in the region of the electromagnetic spectrum which is usually called the THz-gap (or T-gap), since the output power of other devices (e.g., solid-state oscillators) operating in this interval is by several orders of magnitude lower. In the recent years, the unique capabilities of the sub-THz and THz gyrotrons have opened the road to many novel and future prospective applications in various physical studies and advanced high-power terahertz technologies. In this paper, we present the current status and functionality of the problem-oriented software packages (most notably GYROSIM and GYREOSS) used for numerical studies, computer-aided design (CAD) and optimization of gyrotrons for diverse applications. They consist of a hierarchy of codes specialized to modelling and simulation of different subsystems of the gyrotrons (EOS, resonant cavity, etc.) and are based on adequate physical models, efficient numerical methods and algorithms.

  19. The Role of Lithium Conditioning in Achieving High Performance, Long Pulse H-mode Discharges in the NSTX and EAST Devices

    Energy Technology Data Exchange (ETDEWEB)

    Maingi, Rajesh [PPPL; Mansfield, D. K. [PPPL; Gong, X. Z. [IPPCAS; Sun, Z. [IPPCAS; Bell, M. G. [PPPL

    2014-10-01

    In this paper, the role of lithium wall conditioning on the achievement of high performance, long pulse discharges in the National Spherical Torus Experiment (NSTX) and the Experimental Advanced Superconducting Tokamak (EAST) is documented. Common observations include recycling reduction and elimination of ELMs. In NSTX, lithium conditioning typically resulted in ELM-free operation with impurity accumulation, which was ameliorated e.g. with pulsed 3D fields to trigger controlled ELMs. Active lithium conditioning in EAST discharges has overcome this problem, producing an ELM-free Hmode with controlled density and impurities.

  20. Simulation of a suite of generic long-pulse neutron instruments to optimize the time structure of the European Spallation Source

    DEFF Research Database (Denmark)

    Lefmann, Kim; Klenø, Kaspar H.; Birk, Jonas Okkels;

    2013-01-01

    between 10 Hz and 25 Hz. The relative change in performance with time structure is given for each instrument, and an unweighted average is calculated. The performance of the instrument suite is proportional to (a) the peak flux and (b) the duty cycle to a power of approximately 0.3. This information......We here describe the result of simulations of 15 generic neutron instruments for the long-pulsed European Spallation Source. All instruments have been simulated for 20 different settings of the source time structure, corresponding to pulse lengths between 1 ms and 2 ms; and repetition frequencies...

  1. Combined Hyperthermia and Photodynamic Therapy Using a Sub-THz Gyrotron as a Radiation Source

    Science.gov (United States)

    Miyoshi, Norio; Idehara, Toshitaka; Khutoryan, Eduard; Fukunaga, Yukihiro; Bibin, Andriana Bintang; Ito, Shinji; Sabchevski, Svilen Petrov

    2016-08-01

    In this paper, we present results of a hyperthermia treatment of malignant tumors using a gyrotron as a radiation source for heating of the cancerous tissue. They clearly demonstrate the efficiency of the irradiation by sub-THz waves, which leads to steady decrease of the volume of the tumor and finally to its disappearance. A combination of hyperthermia and photodynamic therapy (PDT) that utilizes a novel multifunctional photosensitizer has also been explored. In the latter case, the results are even more convincing and promising. In particular, while after a hyperthermia treatment sometimes a regrowth of the tumor is being observed, in the case of combined hyperthermia and PDT such regrowth has never been noticed. Another combined therapy is based on a preheating of the tumor by gyrotron radiation to temperatures lower than the hyperthermia temperature of 43 °C and followed then by PDT. The results show that such combination significantly increases the efficiency of the treatment. We consider this phenomenon as a synergy effect since it is absent when hyperthermia and PDT are applied separately, and manifests itself only when both methods are combined.

  2. Safety and protection of 8T NbTi gyrotron magnet in persistent mode

    International Nuclear Information System (INIS)

    Successful series of 5T cryomagnetic systems for additional high frequency plasma heating in Tokamaks T10 and T15, produced in Czechoslovakia during the last decade with the authors participation in magnet design and testing encouraged them to continue in further development of gyrotron magnets for further generation with operational field B0 = 8T. Approximately of the size and dimensions as was the case of previous 5T series, the 8T gyrotron magnet was designed as a part of preliminary work with preparations for ITER project. To achieve high mechanical stability of the superconducting winding, numerical stress-strain analyzes of winding structure and appropriate technology of epoxy impregnation were applied. To improve winding mechanical stability, initially round φ1 mm varnish insulated conductor was flattened to ''race track'' cross section (1.25 x 0.75 mm2 for inner section, respectively, 1.31 x 0.65 mm2 for the rest of magnet). Stainless steel road (φ1mm) of the bandage was flattened in the same way too (up to 1.14 x 0.77 mm2). Danger of creating a hot spot region has been limited by radial magnet sectioning and sections shunting by low ohmic shunts. Superconducting switch was protected by couple of antiparallel silicon diodes mounted between magnet flanges in parallel to it. High threshold voltages of diodes at 4.2K allow to run up system with relatively high speed without any limitation on sign of magnet field polarity

  3. Simulation of transient behavior in a pulse-line-driven gyrotron oscillator

    Science.gov (United States)

    Lin, A. T.; Lin, Chih-Chien; Yang, Z. H.; Chu, K. R.; Fliflet, A. W.

    1988-04-01

    Results are reported for a set of slow-time-scale single-mode and fast-time-scale single-mode and multimode simulations of the transient-mode excitation phenomena in a short-pulse high-peak-power Ka-band gyrotron oscillator experiment. Both the slow- and fast-time-scale single-mode simulations are generally in good agreement with each other and, within experimental uncertainties, with the experimental observations of the time dependence and magnetic-field dependence of 35-GHz emission in the TE62 mode. However, the multimode simulations suggest the presence of mode suppression, mode beating, and other nonlinear multimode phenomena that could not easily be observed in the experiment, and generally agree less well with the experimental measurements than the single-mode simulations. The multimode simulations also suggest that steady-state behavior may not be obtainable with the highly time-dependent voltage waveform employed in the experiment, and indicate the importance of carrying out future high-voltage gyrotron experiments with less highly transient voltage waveforms.

  4. Beam-wave interaction behavior of a 35 GHz metal PBG cavity gyrotron

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ashutosh, E-mail: asingh.rs.ece@iitbhu.ac.in [Faculty of Physical Sciences, Institute of Natural Sciences and Humanities Shri Ramswaroop Memorial University, Lucknow-Deva Road, Uttar Pradesh-225003 (India); Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi-221005 (India); Jain, P. K. [Center of Research in Microwave Tubes, Department of Electronics Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi-221005 (India)

    2014-09-15

    The RF behavior of a 35 GHz photonic band gap (PBG) cavity gyrotron operating in TE{sub 041}-like mode has been presented to demonstrate its single mode operation capability. In this PBG cavity gyrotron, the conventional tapered cylindrical cavity is replaced by a metal PBG cavity as its RF interaction structure. The beam-wave interaction behavior has been explored using time dependent multimode nonlinear analysis as well as through 3D PIC simulation. Metal PBG cavity is treated here similar to that of a conventional cylindrical cavity for the desired mode confinement. The applied DC magnetic field profile has been considered uniform along the PBG cavity length both in analysis as well as in simulation. Electrons energy and phase along the interaction length of the PBG cavity facilitates bunching mechanism as well as energy transfer phenomena from the electron beam to the RF field. The RF output power for the TE{sub 041}-like design mode as well as nearby competing modes have been estimated and found above to 100 kW in TE{sub 041}-like mode with ∼15% efficiency. Results obtained from the analysis and the PIC simulation are found in agreement within 8% variation, and also it supports the single mode operation, as the PBG cavity does not switch into other parasitic modes in considerably large range of varying DC magnetic field, contrary to the conventional cylindrical cavity interaction structure.

  5. Characteristics of a superconducting magnet using a persistent current for a 110 GHz gyrotron

    Energy Technology Data Exchange (ETDEWEB)

    Maebara, Sunao; Kasugai, Atsushi; Sakamoto, Keishi; Tsuneoka, Masaki; Imai, Tsuyoshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    1996-03-01

    A superconducting magnet (SCM) using a persistent current for a 110 GHz gyrotron was developed to reduce liquid-helium loss, the boiled-off rate of 0.13 liter/hour was attained in a persistent current operation. It shows that the continuous operation for 50 days is capable without additional liquid-helium supply. Moreover, the 3040 liter in a year is used for a gyrotron test during five months and for the maintenance during seven months and liquid-helium savings of 65% was successfully demonstrated. The SCM is capable to excite the maximum magnetic field of 5.0 T in the persistent current mode. A mirror ratio between resonant cavity and magnetron injection gun (MIG) is 20 for operating the main coils in the persistent mode, since cavity coils and gun coils are connected in series. Auxiliary coils are equipped independently to control the mirror ratio, the mirror ratio of 13.6 - 37.0 at the 110 GHz is available. A two-stage refrigerator using helium gas was also installed and made liquid-nitrogen for cooling thermal shield of 80 K free. By developing this new type SCM, the number of routine works was drastically decreased in one time per 22-50 days, while routine works of a few times per week was needed up to now. (author).

  6. Electrical and thermo-mechanical analysis of beam recovery system for megawatt power gyrotron

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Ranajoy, E-mail: joy_trm@yahoo.com [Central Electronics Engineering Research Institute (CEERI), Pilani, Rajasthan 333031 (India); Sahu, Naveen Kr [Central Electronics Engineering Research Institute (CEERI), Pilani, Rajasthan 333031 (India); Khan, Arani Ali [Department of Electronics and Communication, Indian Institute of Technology, Kharagpur (India); Khatun, Hasina; Sinha, A.K. [Central Electronics Engineering Research Institute (CEERI), Pilani, Rajasthan 333031 (India)

    2013-05-15

    Highlights: • Electrical design of single stage depressed collector for high power gyrotron tube. • Efficiency enhancement by collecting spent beam. • Optimization of geometry and magnetic field for optimized beam spread. • Optimization of cooling duct system for better thermal management. -- Abstract: The paper presents the electrical and thermo-mechanical design of single stage beam recovery system for 120 GHz, 1 MW gyrotron. The electrical study shows that the cylindrical shape single stage beam recovery system enhances the efficiency by 66.26%. The maximum power deposited to collector in depressed collector operation is 0.48 MW for electronic efficiency, 30% and 1.44 MW for DC electron beam. The thermo-mechanical analysis has been performed to evaluate the water cooling system. The cooling system has capability of accommodating a peak wall loading, 0.9 kW/cm{sup 2} at flow rate of 1500 l/min for safe operating time, 60 ms. Further, a high voltage analysis is also carried out to appraise the electric field distribution in the collector.

  7. Nonlinear study of mode locking in a quasi-optical gyrotron

    Science.gov (United States)

    Wu, Hao; McCurdy, Alan H.

    1996-10-01

    Nonlinear, time-dependent multimode calculations have been carried out to study mode locking in quasi-optical gyrotron oscillators. The calculations are based on the rate equation model of modal growth and saturation. The slow-time formalism is used for particle motion and both the time varying electric and magnetic fields are included. It is found that radiation pulses of width 400 ps can be generated in nonlinear regime. The gyrotron features an open resonator of length 100 cm formed by a pair of spherical mirrors and a single pencil electron beam guided by external magnetic field in transverse direction to the axis of symmetry of the cavity. The strong current modulation is provided at frequency of 300 MHz, the nominal model spacing between two odd modes in such a cavity. Eight odd modes are found to be locked to generate extremely short radiation pulses. Application for short pulse radiation in millimeter and submillimeter wavelength range include radar, plasma diagnosis, time domain metrology and communication systems. Parametric dependencies investigated include static magnetic field, beam current and beam voltage, as well as the drive signal amplitudes and frequencies. The work is geared towards support of a proof of principle experiment to generate high power radiation pulses of short duration via synchronous mode locking.

  8. Continuous-Wave Operation of a Frequency-Tunable 460-GHz Second-Harmonic Gyrotron for Enhanced Nuclear Magnetic Resonance.

    Science.gov (United States)

    Torrezan, Antonio C; Han, Seong-Tae; Mastovsky, Ivan; Shapiro, Michael A; Sirigiri, Jagadishwar R; Temkin, Richard J; Barnes, Alexander B; Griffin, Robert G

    2010-06-01

    The design, operation, and characterization of a continuous-wave (CW) tunable second-harmonic 460-GHz gyrotron are reported. The gyrotron is intended to be used as a submillimeter-wave source for 700-MHz nuclear magnetic resonance experiments with sensitivity enhanced by dynamic nuclear polarization. The gyrotron operates in the whispering-gallery mode TE(11,2) and has generated 16 W of output power with a 13-kV 100-mA electron beam. The start oscillation current measured over a range of magnetic field values is in good agreement with theoretical start currents obtained from linear theory for successive high-order axial modes TE(11,2,q). The minimum start current is 27 mA. Power and frequency tuning measurements as a function of the electron cyclotron frequency have also been carried out. A smooth frequency tuning range of 1 GHz was obtained for the operating second-harmonic mode either by magnetic field tuning or beam voltage tuning. Long-term CW operation was evaluated during an uninterrupted period of 48 h, where the gyrotron output power and frequency were kept stable to within ±0.7% and ±6 ppm, respectively, by a computerized control system. Proper operation of an internal quasi-optical mode converter implemented to transform the operating whispering-gallery mode to a Gaussian-like beam was also verified. Based on the images of the gyrotron output beam taken with a pyroelectric camera, the Gaussian-like mode content of the output beam was computed to be 92% with an ellipticity of 12%. PMID:21243088

  9. Plasma wall interaction in long-pulse helium discharge in LHD – Microscopic modification of the wall surface and its impact on particle balance and impurity generation

    International Nuclear Information System (INIS)

    Ultra-long-pulse helium discharge with ion and electron cyclotron heating (ICH + ECH) in the Large Helical Device (LHD) was achieved in a 48 min plasma (ne ∼ 1.2 × 1019 m−3, Ti,e ∼ 2 keV) with an average heating power of 1.2 MW. The temperature of the first-wall surface during discharges remained at nearly room temperature. However, even in ultra-long-pulse helium discharge, the discharge conditions cannot be said to be in a steady-state, because of two major issues interrupting the steady-state condition. One is the “dynamic change of the wall pumping rate” and the other is the “termination of the discharge with the exfoliation of the mixed-material deposition layers.” Microscopic modifications, such as helium radiation damage and the formation of the mixed-material deposition layers composed of C (∼98%) and Fe (∼2%), on the plasma facing components (PFMs) were clarified to possibly influence the major issues

  10. A highly efficient and compact long pulse Nd:YAG rod laser with 540 J of pulse energy for welding application.

    Science.gov (United States)

    Choubey, Ambar; Vishwakarma, S C; Misra, Pushkar; Jain, R K; Agrawal, D K; Arya, R; Upadhyaya, B N; Oak, S M

    2013-07-01

    We have developed an efficient and high average power flash lamp pumped long pulse Nd:YAG laser capable of generating 1 kW of average output power with maximum 540 J of single pulse energy and 20 kW of peak power. The laser pulse duration can be varied from 1 to 40 ms and repetition rate from 1 to 100 Hz. A compact and robust laser pump chamber and resonator was designed to achieve this high average and peak power. It was found that this laser system provides highest single pulse energy as compared to other long pulsed Nd:YAG laser systems of similar rating. A slope efficiency of 5.4% has been achieved, which is on higher side for typical lamp pumped solid-state lasers. This system will be highly useful in laser welding of materials such as aluminium and titanium. We have achieved 4 mm deep penetration welding of these metals under optimized conditions of output power, pulse energy, and pulse duration. The laser resonator was optimized to provide stable operation from single shot to 100 Hz of repetition rate. The beam quality factor was measured to be M(2) ~ 91 and pulse-to-pulse stability of ±3% for the multimode operation. The laser beam was efficiently coupled through an optical fiber of 600 μm core diameter and 0.22 numerical aperture with power transmission of 90%. PMID:23902045

  11. Comparative study of efficacy of 30% Salicylic acid peel VsLong-pulsed 1064 nm Nd:YAG laser for treatment of Keratosis Pilaris

    Directory of Open Access Journals (Sweden)

    Zonunsanga

    2015-04-01

    Full Text Available Introduction: Keratosis pilaris(KP is a disorder of keratinization of hair follicles characterized by keratin plugs in the hair follicles with perifollicular erythema. It may be inherited with X-Linked Dominant, or may be sporadic. Aim of the study: to compare the efficacy of 30% Salicylic acid and Long pulsed 1064nm Nd:YAG laser for treatment of keratosis pilaris. Materials and Methods: Out of 20 patients, 10 patients were given 30% Salicylic acid peel (after washing their face every 15 days for 2 months. Another 15 patients were given the 1064 nm Nd:YAG Long pulse, Spot size: 10 mm, Pulse width: 30 ms every 4-6 weeks for 4 sitting. Results: Among salicylic acid treated group, only 2 out of 10 showed improvement between 50-75%, and were slightly satisfied; none showed >75% improvement, and 8 out of 10 failed to show >50% improvement and were considered as failure of the therapy. Among the Nd:YAG treated group, 3 out of 10 showed 50-75% improvement and were slightly satisfied;none showed > 75% improvement, 7 out 10 failed to show successful results i.e. >50% improvement. Conclusion: Both of the treatments are not much effective and do not give consistent and satisfactory results for treatment of keratosis pilaris.

  12. Power-stabilization of high frequency gyrotrons using a double PID feedback control for applications to many high power THz spectroscopy

    OpenAIRE

    Kuleshov, Alexei; Ueda, Keisuke; Idehara, Toshitaka

    2013-01-01

    High stabilization of the output power of high frequency gyrotrons for high power THzspectroscopy is an important issue in order to extend the applications of gyrotrons to wider subjects.For this objective, we tried a PID feedback control on a heater current of a triode magnetroninjection gun (MIG) for stabilization of an electron beam current and an additional PID control ofan anode voltage of the gun for direct stabilization of output power. This double PID controlachieves effective respons...

  13. Formation of Multicharged Metal Ions in Vacuum Arc Plasma Heated by Gyrotron Radiation%Formation of Multicharged Metal Ions in Vacuum Arc Plasma Heated by Gyrotron Radiation

    Institute of Scientific and Technical Information of China (English)

    G. Yu. YUSHKOV; K. P. SAVKIN; A. G. NIKOLAEV; E. M. OKS; A.V. VODOPYANOV; I. V. IZOTOV; D. A. MANSFELD

    2011-01-01

    A new method for the generation of high charged state metal ion beams is developed. This method is based on microwave heating of vacuum arc plasma in a magnetic trap under electron cyclotron resonance (ECR) conditions. Two gyrotrons for plasma heating were used, which were with the following parameters. The first is with a wave frequency of 37.5 GHz, a pulse duration of 1 ms and power of 100 kW, another is with 75 GHz, 0.15 ms and 400 kW. Two different magnetic traps were considered for vacuum arc plasma confinement. The first one is a simple mirror trap. Such system was already investigated and could provide high charge state ions. The second trap was with a cusp magnetic field configuration with native "minimum-B" field structure. Two different ways of metal plasma injection into the magnetic trap were used. The first one is an axial injection from an arc source located out of the trap, and the second is a radial injection from four arc sources mounted at the center of the trap. Both traps provide up to 200 eMA of ion beam current for platinum ions with highest charge state 10+. Ion beams were successfully extracted from the plasma and accelerated by a voltage of up to 20 kV.

  14. ECRH transmission system

    International Nuclear Information System (INIS)

    The M.I.T. gyrotron group operates a 140 GHz, short pulse (1μs) gyrotron with output power, at present, of up to 175 kW. Output radiation has been obtained in several modes, including TE03 at 140 GHz, TE23 at 137 GHz, TE42 at 128 GHz and TE52 at 145 GHz. Studies have been carried out of the mode purity, both in frequency and in space, of gyrotron output radiation. These studies investigate parasitic mode excitation and mode conversion of gyrotron output power. Far field patterns of gyrotron radiation have been investigated to determine mode symmetry and purity. These results are useful in estimating the efficiency of various transmission systems. Finally, a new approach to quasi-optical transmission lines and mode converters, using axisymmetric optics, is suggested

  15. High-power, stable Ka/V dual-band gyrotron traveling-wave tube amplifier

    Science.gov (United States)

    Hung, Chien-Lun

    2012-05-01

    A dual-band amplifier can reduce the size, cost, and weight of a transmitter in dual-band radar and communication systems. This study proposes and theoretically investigates a gyrotron traveling-wave tube (gyro-TWT) amplifier capable of dual-band operation. Possible oscillations in the coaxial interaction waveguide are stabilized by the lossy inner cylinder. Under stable operating conditions, the gyro-TWT is predicted to provide a peak power of 375 kW with 71 dB saturated gain and 3.8 GHz bandwidth in the Ka-band and a peak power of 150 kW with 35 dB saturated gain and 1.7 GHz bandwidth in the V-band.

  16. 1 megawatt, 100 GHz gyrotron study. Final report, March 21-September 1, 1983

    International Nuclear Information System (INIS)

    This report provides the results of a design study on a gyrotron device employing a new type of hollow gyrobeam formation system and having a capability for delivering megawatt CW power at 100 GHz to an ECRH-heated, magnetically-confined plasma. The conceptual basis for the beam formation system is the tilt-angle gun (TAG) in which a conically-shaped electron beam is formed in a magnetically-shielded region and is then injected into the stray-field region of the main magnetic focusing system. Because fluid coolants can be accessed through the central pole of the TAG-type gun, rf interaction can be contemplated with cavity configurations not practical with the conventional MIG-type gyrobeam formation systems

  17. Infrared surface temperature measurements for long pulse operation, and real time feedback control in Tore-Supra, an actively cooled Tokamak

    International Nuclear Information System (INIS)

    Tore-Supra has a steady-state magnetic field using super-conducting magnets and water-cooled plasma facing components for high performances long pulse plasma discharges. When not actively cooled, plasma-facing components can only accumulate a limited amount of energy since the temperature increase continuously (T proportional to √(t)) during the discharge until radiation cooling is equal to the incoming heat flux (T > 1800 K). Such an environment is found in most today Tokamaks. In the present paper we report the recent results of Tore-Supra, especially the design of the new generation of infrared endoscopes to measure the surface temperature of the plasma facing components. The Tore-Supra infrared thermography system is composed of 7 infrared endoscopes, this system is described in details in the paper, the new JET infrared thermography system is presented and some insights of the ITER set of visible/infrared endoscope is given. (authors)

  18. Efficient delivery of 60 J pulse energy of long pulse Nd:YAG laser through 200 m core diameter optical fibre

    Indian Academy of Sciences (India)

    Ravindra Singh; Ambar Choubey; R K Jain; S C Vishwakarma; D K Agrawal; Sabir Ali; B N Upadhyaya; S M Oak

    2014-02-01

    Most of today’s industrial Nd:YAG lasers use fibre-optic beam delivery. In such lasers, fibre core diameter is an important consideration in deploying a beam delivery system. Using a smaller core diameter fibre allows higher irradiances at focus position, less degradation of beam quality, and a larger stand-off distance. In this work, we have put efforts to efficiently deliver the laser output of ‘ceramic reflector’-based long pulse Nd:YAG laser through a 200 m core diameter optical fibre and successfully delivered up to 60 J of pulse energy with 90% transmission efficiency, using a GRADIUM (axial gradient) plano-convex lens to sharply focus down the beam on the end face of the optical fibre and fibre end faces have been cleaved to achieve higher surface damage thresholds.

  19. Long-pulsed dye laser versus intense pulsed light for photodamaged skin: A randomized split-face trial with blinded response evaluation

    DEFF Research Database (Denmark)

    Jorgensen, G.F.; Hedelund, L.; Haedersdal, M.

    2008-01-01

    assigned to left and right sides. Primary end-points were telangiectasias, irregular pigmentation and preferred treatment. Secondary end-points were skin texture, rhytids, pain, and adverse effects. Efficacy was evaluated by patient self-assessments and by blinded clinical on-site and photographic...... evaluations at 1, 3, and 6 months postoperatively. Adverse effects were evaluated by blinded clinical on-site evaluations. Results: Telangiectasia improved from LPDL and IPL treatments with superior vessel clearance from LPDL treatments (postoperative side-to-side evaluations, patient self-assessments, P ...Objective: In a randomized controlled split-face trial to evaluate efficacy and adverse effects from rejuvenation with long-pulsed dye laser (LPDL) versus intense pulsed light (IPL). Materials and Methods: Twenty female volunteers with Fitzpatrick skin types I-III, classes I-II rhytids...

  20. Initial measurements of plasma current and electron density profiles using a polarimeter/interferometer (POINT) for long pulse operation in EAST (invited)

    Science.gov (United States)

    Liu, H. Q.; Qian, J. P.; Jie, Y. X.; Ding, W. X.; Brower, D. L.; Zou, Z. Y.; Li, W. M.; Lian, H.; Wang, S. X.; Yang, Y.; Zeng, L.; Lan, T.; Yao, Y.; Hu, L. Q.; Zhang, X. D.; Wan, B. N.

    2016-11-01

    A double-pass, radially viewing, far-infrared laser-based POlarimeter-INTerferometer (POINT) system utilizing the three-wave technique has been implemented for diagnosing the plasma current and electron density profiles in the Experimental Advanced Superconducting Tokamak (EAST). POINT has been operated routinely during the most recent experimental campaign and provides continuous 11 chord line-integrated Faraday effect and density measurement throughout the entire plasma discharge for all heating schemes and all plasma conditions (including ITER relevant scenario development). Reliability of both the polarimetric and interferometric measurements is demonstrated in 25 s plasmas with H-mode and 102 s long-pulse discharges. Current density, safety factor (q), and electron density profiles are reconstructed using equilibrium fitting code (EFIT) with POINT constraints for the plasma core.

  1. Infrared surface temperature measurements for long pulse operation, and real time feedback control in Tore-Supra, an actively cooled Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Guilhem, D.; Adjeroud, B.; Balorin, C.; Buravand, Y.; Bertrand, B.; Bondil, J.L.; Desgranges, C.; Gauthier, E.; Lipa, M.; Messina, P.; Missirlian, M.; Mitteau, R.; Moulin, D.; Pocheau, C.; Portafaix, C.; Reichle, R.; Roche, H.; Saille, A.; Vallet, S

    2004-07-01

    Tore-Supra has a steady-state magnetic field using super-conducting magnets and water-cooled plasma facing components for high performances long pulse plasma discharges. When not actively cooled, plasma-facing components can only accumulate a limited amount of energy since the temperature increase continuously (T proportional to {radical}(t)) during the discharge until radiation cooling is equal to the incoming heat flux (T > 1800 K). Such an environment is found in most today Tokamaks. In the present paper we report the recent results of Tore-Supra, especially the design of the new generation of infrared endoscopes to measure the surface temperature of the plasma facing components. The Tore-Supra infrared thermography system is composed of 7 infrared endoscopes, this system is described in details in the paper, the new JET infrared thermography system is presented and some insights of the ITER set of visible/infrared endoscope is given. (authors)

  2. Systematic cavity design approach for a multi-frequency gyrotron for DEMO and study of its RF behavior

    Science.gov (United States)

    Kalaria, P. C.; Avramidis, K. A.; Franck, J.; Gantenbein, G.; Illy, S.; Pagonakis, I. Gr.; Thumm, M.; Jelonnek, J.

    2016-09-01

    High frequency (>230 GHz) megawatt-class gyrotrons are planned as RF sources for electron cyclotron resonance heating and current drive in DEMOnstration fusion power plants (DEMOs). In this paper, for the first time, a feasibility study of a 236 GHz DEMO gyrotron is presented by considering all relevant design goals and the possible technical limitations. A mode-selection procedure is proposed in order to satisfy the multi-frequency and frequency-step tunability requirements. An effective systematic design approach for the optimal design of a gradually tapered cavity is presented. The RF-behavior of the proposed cavity is verified rigorously, supporting 920 kW of stable output power with an interaction efficiency of 36% including the considerations of realistic beam parameters.

  3. Development of a dual frequency (110/138 GHz gyrotron for JT-60SA and its extension to an oscillation at 82 GHz

    Directory of Open Access Journals (Sweden)

    Kobayashia Takayuki

    2015-01-01

    Full Text Available A dual-frequency gyrotron, which can generate 110 GHz and 138 GHz waves independently, is being developed in JAEA to enable electron cyclotron heating (ECH and current drive (ECCD in a wider range of plasma discharge conditions of JT-60SA. Conditioning operation of the gyrotron toward 1 MW for 100 s, which is the target output power and pulse length for JT-60SA, is in progress without significant problems. Oscillations of 1 MW for 10 s and 0.5 MW for 198 s were obtained, so far, at both frequencies. Cooling water temperatures in the gyrotron and matching optics unit were saturated in the 198 s oscillation, and the observed maximum water temperature is sufficiently low. In addition to the above activity on the dual-frequency gyrotron development, an oscillation (0.3 MW for 20 ms at 82 GHz was demonstrated as an additional frequency of the dual-frequency gyrotron. A possibility of the use of fundamental harmonic wave at 82 GHz in JT-60SA has been shown.

  4. Theoretical study on mode competition between fundamental and second harmonic modes in a 0.42 THz gyrotron with gradually tapered complex cavity

    International Nuclear Information System (INIS)

    In this paper, the nonlinear dynamics of mode competition in the complex cavity gyrotron are studied by using multi-frequency, time-dependent theory with the cold-cavity longitudinal profile approximation. Based on the theory, a code is written to simulate the mode competition in the gradually tapered complex cavity gyrotron operating at second harmonic oscillation. The simulations tracking seven competition modes show that single mode oscillation of the desired mode TE17.4 at 150 kW level can be expected with proper choice of operating parameters. Through studying on mode competition, it is proved that the complex cavity has a good capability for suppressing the mode competition. Meanwhile, it is found that TE17.3 could be excited in the first cavity as a competition mode when the gyrotron operating at large beam current, which leads to that TE17.3 and TE17.4 with different frequencies can coexist stably in the complex cavity gyrotron with very close amplitudes. Thus, the complex cavity might be used for multi-frequency output gyrotron

  5. Analyses of advanced concepts in multi-stage gyro-amplifiers and startup in high power gyro-oscillators

    Science.gov (United States)

    Sinitsyn, Oleksandr V.

    Gyrotrons are well recognized sources of high-power coherent electromagnetic radiation. The power that gyrotrons can radiate in the millimeter- and submillimeter-wavelength regions exceeds the power of classical microwave tubes by many orders of magnitude. In this work, the author considers some problems related to the operation of gyro-devices and methods of their solution. In particular, the self-excitation conditions for parasitic backward waves and effect of distributed losses on the small-signal gain of gyro-TWTs are analyzed. The corresponding small-signal theory describing two-stage gyro-traveling-wave tubes (gyro-TWTs) with the first stage having distributed losses is presented. The theory is illustrated by using it for the description of operation of a Ka-band gyro-TWT designed at the Naval Research Laboratory. Also, the results of nonlinear studies of this tube are presented and compared with the ones obtained by the use of MAGY, a multi-frequency, self-consistent code developed at the University of Maryland. An attempt to build a large signal theory of gyro-TWTs with tapered geometry and magnetic field profile is made and first results are obtained for a 250 GHz gyro-TWT. A comparative small-signal analysis of conventional four-cavity and three-stage clustered-cavity gyroklystrons is performed. The corresponding point-gap models for these devices are presented. The efficiency, gain, bandwidth and gain-bandwidth product are analyzed for each scheme. Advantages of the clustered-cavity over the conventional design are discussed. The startup scenarios in high-power gyrotrons and the most important physical effects associated with them are considered. The work presents the results of startup simulations for a 140 GHz, MW-class gyrotron developed by Communications and Power Industries (CPI) for electron-cyclotron resonance heating (ECRH) and current drive experiments on the "Wendelstein 7-X" stellarator plasma. Also presented are the results for a 110 GHz, 1

  6. Towards coherent combining of X-band high power microwaves: phase-locked long pulse radiations by a relativistic triaxial klystron amplifier

    Science.gov (United States)

    Ju, Jinchuan; Zhang, Jun; Qi, Zumin; Yang, Jianhua; Shu, Ting; Zhang, Jiande; Zhong, Huihuang

    2016-01-01

    The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high power microwave (HPM) generator, and this issue becomes more challenging for high frequency bands. Coherent power combining therefore provides an alternative approach to achieve an equivalent peak power of the order of ∼100 GW, which consequently provides opportunities to explore microwave related physics at extremes. The triaxial klystron amplifier (TKA) is a promising candidate for coherent power combing in high frequency bands owing to its intrinsic merit of high power capacity, nevertheless phase-locked long pulse radiation from TKA has not yet been obtained experimentally as the coaxial structure of TKA can easily lead to self-excitation of parasitic modes. In this paper, we present investigations into an X-band TKA capable of producing 1.1 GW HPMs with pulse duration of about 103 ns at the frequency of 9.375 GHz in experiment. Furthermore, the shot-to-shot fluctuation standard deviation of the phase shifts between the input and output microwaves is demonstrated to be less than 10°. The reported achievements open up prospects for accomplishing coherent power combining of X-band HPMs in the near future, and might also excite new development interests concerning high frequency TKAs. PMID:27481661

  7. Calculation and analysis of the number of return photons from sodium laser beacon excited by the long pulse laser with circular polarization

    International Nuclear Information System (INIS)

    The number of return photons from sodium laser beacon (SLB) greatly suffers down-pumping, recoil, and geomagnetic field when the long pulse laser with circular polarization interacts with sodium atoms in the mesosphere. Considering recoil and down-pumping effects on the number of return photons from SLB, the spontaneous radiation rates are obtained by numerical computations and fittings. Furthermore, combining with the geomagnetic field effects, a new expression is achieved for calculating the number of return photons. By using this expression and considering the stochastic distribution of laser intensity in the mesosphere under different turbulence models for atmosphere, the number of return photons excited by the narrow-band single mode laser and that by the narrow-band three-mode laser are respectively calculated. The results show that the narrow-band three-mode laser with a specific spectrum structure has a higher spontaneous radiation rate and more return photons than a narrow-band single mode laser. Of note, the effect of the atmospheric turbulence on the number of return photons is remarkable. Calculation results indicate that the number of return photons under the HV5/7 model for atmospheric turbulence is much higher than that under the Greenwood and ModHV models. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  8. Extensive angiokeratoma circumscriptum - successful treatment with 595-nm variable-pulse pulsed dye laser and 755-nm long-pulse pulsed alexandrite laser.

    Science.gov (United States)

    Baumgartner, Ján; Šimaljaková, Mária; Babál, Pavel

    2016-06-01

    Angiokeratomas are rare vascular mucocutaneous lesions characterized by small-vessel ectasias in the upper dermis with reactive epidermal changes. Angiokeratoma circumscriptum (AC) is the rarest among the five types in the current classification of angiokeratoma. We present a case of an extensive AC in 19-year-old women with Fitzpatrick skin type I of the left lower extremity, characterized by a significant morphological heterogeneity of the lesions, intermittent bleeding, and negative psychological impact. Histopathological examination after deep biopsy was consistent with that of angiokeratoma. The association with metabolic diseases (Fabry disease) was excluded by ophthalmological, biochemical, and genetic examinations. Nuclear magnetic resonance imaging has not detected deep vascular hyperplasia pathognomic for verrucous hemangioma. The combined treatment with 595-nm variable-pulse pulsed dye laser (VPPDL) and 755-nm long-pulse pulsed alexandrite laser (LPPAL) with dynamic cooling device led to significant removal of the pathological vascular tissue of AC. Only a slight degree of secondary reactions (dyspigmentations and texture changes) occurred. No recurrence was observed after postoperative interval of 9 months. We recommend VPPDL and LPPAL for the treatment of extensive AC. PMID:26736060

  9. Towards coherent combining of X-band high power microwaves: phase-locked long pulse radiations by a relativistic triaxial klystron amplifier

    Science.gov (United States)

    Ju, Jinchuan; Zhang, Jun; Qi, Zumin; Yang, Jianhua; Shu, Ting; Zhang, Jiande; Zhong, Huihuang

    2016-08-01

    The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high power microwave (HPM) generator, and this issue becomes more challenging for high frequency bands. Coherent power combining therefore provides an alternative approach to achieve an equivalent peak power of the order of ∼100 GW, which consequently provides opportunities to explore microwave related physics at extremes. The triaxial klystron amplifier (TKA) is a promising candidate for coherent power combing in high frequency bands owing to its intrinsic merit of high power capacity, nevertheless phase-locked long pulse radiation from TKA has not yet been obtained experimentally as the coaxial structure of TKA can easily lead to self-excitation of parasitic modes. In this paper, we present investigations into an X-band TKA capable of producing 1.1 GW HPMs with pulse duration of about 103 ns at the frequency of 9.375 GHz in experiment. Furthermore, the shot-to-shot fluctuation standard deviation of the phase shifts between the input and output microwaves is demonstrated to be less than 10°. The reported achievements open up prospects for accomplishing coherent power combining of X-band HPMs in the near future, and might also excite new development interests concerning high frequency TKAs.

  10. Development of a long-pulse (30-s), high-energy (120-keV) ion source for neutral-beam applications

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, C.C.; Barber, G.C.; Blue, C.W.

    1983-01-01

    Multimegawatt neutral beams of hydrogen or deuterium atoms are needed for fusion machine applications such as MFTB-B, TFTR-U, DIII-U, and FED (INTOR or ETR). For these applications, a duoPIGatron ion source is being developed to produce high-brightness deuterium beams at a beam energy of approx. 120 keV for pulse lengths up to 30 s. A long-pulse plasma generator with active water cooling has been operated at an arc level of 1200 A with 30-s pulse durations. The plasma density and uniformity are sufficient for supplying a 60-A beam of hydrogen ions to a 13- by 43-cm accelerator. A 10- by 25-cm tetrode accelerator has been operated to form 120-keV hydrogen ion beams. Using the two-dimensional (2-D) ion extraction code developed at Oak Ridge National Laboratory (ORNL), a 13- by 43-cm tetrode accelerator has been designed and is being fabricated. The aperture shapes of accelerator grids are optimized for 120-keV beam energy.

  11. Low-voltage harmonic multiplying gyrotron traveling-wave amplifier in G band

    International Nuclear Information System (INIS)

    Harmonic multiplying operation in a gyrotron traveling-wave amplifier (gyro-TWA) permits for magnetic field reduction and frequency multiplication. Lowering a beam voltage is an important step toward miniaturization of a harmonic multiplying gyro-TWA. However, the additional degree of freedom that is provided by the multitude cyclotron harmonics in a low-voltage harmonic multiplying gyro-TWA still easily generates various competing modes. An improved mode-selective circuit, using circular waveguides with various radii, can provide the rejection points within the frequency range to suppress competing modes. Simulated results reveal that the mode-selective circuit can provide an attenuation of more than 14 dB to suppress the competing modes. Furthermore, the performance of the gyro-TWA is analyzed for studying the sensitivity of the saturated output power and full width at half maximum bandwidth of the gyro-TWA to the beam voltage and the magnetic field. A stable low-voltage harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 24 kW at 200.4 GHz, corresponding to a saturated gain of 56 dB at an interaction efficiency of 20%. The full width at half maximum bandwidth is 3.0 GHz

  12. G-band harmonic multiplying gyrotron traveling-wave amplifier with a mode-selective circuit

    International Nuclear Information System (INIS)

    Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) permit for magnetic field reduction and frequency multiplication. A high-order-mode harmonic multiplying gyro-TWA with large circuit dimensions and low ohmic loss can achieve a high average power. By amplifying a fundamental harmonic TE01 drive wave, the second harmonic component of the beam current initiates a TE02 wave to be amplified. Wall losses can suppress some competing modes because they act as an effective sink of the energy of the modes. However, such wall losses do not suppress all competing modes as the fields are contracted in the copper section in the gyro-TWA. An improved mode-selective circuit, using circular waveguides with the specified radii, can provide the rejection points within the frequency range to suppress the competing modes. The simulated results reveal that the mode-selective circuit can provide an attenuation of more than 10 dB to suppress the competing modes (TE21, TE51, TE22, and TE03). A G-band second harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 50 kW at 198.8 GHz, corresponding to a saturated gain of 55 dB at an interaction efficiency of 10%. The full width at half maximum bandwidth is 5 GHz

  13. Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

    International Nuclear Information System (INIS)

    A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by “fresh” electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam

  14. Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

    Science.gov (United States)

    Ginzburg, N. S.; Zotova, I. V.; Sergeev, A. S.; Zaslavsky, V. Yu.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V.

    2015-11-01

    A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by "fresh" electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam.

  15. Intense high-frequency gyrotron-based microwave beams for material processing

    Energy Technology Data Exchange (ETDEWEB)

    Hardek, T.W.; Cooke, W.D.; Katz, J.D.; Perry, W.L.; Rees, D.E.

    1997-03-01

    Microwave processing of materials has traditionally utilized frequencies in the 0.915 and 2.45 GHz regions. Microwave power sources are readily available at these frequencies but the relatively long wavelengths can present challenges in uniformly heating materials. An additional difficulty is the poor coupling of ceramic based materials to the microwave energy. Los Alamos National Laboratory scientists, working in conjunction with the National Center for Manufacturing Sciences (NCMS), have assembled a high-frequency demonstration processing facility utilizing gyrotron based RF sources. The facility is primarily intended to demonstrate the unique features available at frequencies as high as 84 GHz. The authors can readily provide quasi-optical, 37 GHz beams at continuous wave (CW) power levels in the 10 kW range. They have also provided beams at 84 GHz at 10 kW CW power levels. They are presently preparing a facility to demonstrate the sintering of ceramics at 30 GHz. This paper presents an overview of the present demonstration processing facility and describes some of the features they have available now and will have available in the near future.

  16. Analysis and design of double-anode magnetron injection gun for 170 GHz gyrotron

    International Nuclear Information System (INIS)

    Based on adiabatic compression theory and electro-optical theory, a double-anode magnetron injection gun for 170 GHz gyrotron was designed. By theoretical analysis and calculations, using simulation software to simulate and optimize the electron gun, and got the result that the velocity ratio of electron beam was 1.31, the transverse velocity spread was 3.5% and the axial velocity spread was 7.1%, the beam current was 51 A. The effects of the cathode magnetic field, the control Jantage and the second anode Jantage on the properties of electron beam were discussed and found that electron beam were very sensitive with these factors. When cathode magnetic field increased, the velocity ratio of electron beam decreased, the axial velocity spread increased first and then decreased, the transverse velocity spread decreased first and then increased. The increase of the first anode Jantage could improve the velocity ratio and velocity spread of electron beam. The closer the anode angle and cathode angle, the smaller axial velocity spread. The transverse velocity spread became smaller while the anode angle changed toward the direction of reducing the distance between anode could cathode. When the two anode Jantage did not change, the increase of the distance between cathode and anode could minish the velocity spread of electron beam but the velocity ratio decreased at the same time. (authors)

  17. Dynamic nuclear polarization at 9 T using a novel 250 GHz gyrotron microwave source

    Science.gov (United States)

    Bajaj, V. S.; Farrar, C. T.; Hornstein, M. K.; Mastovsky, I.; Vieregg, J.; Bryant, J.; Eléna, B.; Kreischer, K. E.; Temkin, R. J.; Griffin, R. G.

    2011-12-01

    In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9 T (250 GHz for g = 2 electrons, 380 MHz for 1H). In these experiments, 1H enhancements of up to 170 ± 50 have been observed in 1- 13C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in 15N spectra of unoriented pf1-bacteriophage. Finally, enhancements of ˜17 have been obtained in two-dimensional 13C- 13C chemical shift correlation spectra of the amino acid U- 13C, 15N-proline during magic angle spinning (MAS), demonstrating the stability of the DNP experiment for sustained acquisition and for quantitative experiments incorporating dipolar recoupling. In all cases, we have exploited the thermal mixing DNP mechanism with the nitroxide radical 4-amino-TEMPO as the paramagnetic dopant. These are the highest frequency DNP experiments performed to date and indicate that significant signal enhancements can be realized using the thermal mixing mechanism even at elevated magnetic fields. In large measure, this is due to the high microwave power output of the 250 GHz gyrotron oscillator used in these experiments.

  18. Low-order-mode harmonic multiplying gyrotron traveling-wave amplifier in W band

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Y. S.; Chen, C. H.; Yang, S. J.; Lai, C. H.; Lin, T. Y.; Lo, Y. C.; Hong, J. W. [Department of Electro-Optical Engineering, Southern Taiwan University, Tainan, Taiwan (China); Hung, C. L. [Department of Communication Engineering, National Penghu University of Science and Technology, Penghu, Taiwan (China); Chang, T. H. [Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)

    2012-09-15

    Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) allow for magnetic field reduction and frequency multiplication. To avoid absolute instabilities, this work proposes a W-band harmonic multiplying gyro-TWA operating at low-order modes. By amplifying a fundamental harmonic TE{sub 11} drive wave, the second harmonic component of the beam current initiates a TE{sub 21} wave to be amplified. Absolute instabilities in the gyro-TWA are suppressed by shortening the interaction circuit and increasing wall losses. Simulation results reveal that compared with Ka-band gyro-TWTs, the lower wall losses effectively suppress absolute instabilities in the W-band gyro-TWA. However, a global reflective oscillation occurs as the wall losses decrease. Increasing the length or resistivity of the lossy section can reduce the feedback of the oscillation to stabilize the amplifier. The W-band harmonic multiplying gyro-TWA is predicted to yield a peak output power of 111 kW at 98 GHz with an efficiency of 25%, a saturated gain of 26 dB, and a bandwidth of 1.6 GHz for a 60 kV, 7.5 A electron beam with an axial velocity spread of 8%.

  19. Low-voltage harmonic multiplying gyrotron traveling-wave amplifier in G band

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Y. S.; Guo, Y. W.; Kao, B. H.; Chen, C. H.; Wang, Z. W. [Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, Tainan, Taiwan (China); Hung, C. L. [Department of Communication Engineering, National Penghu University of Science and Technology, Penghu, Taiwan (China); Chang, T. H. [Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)

    2015-12-15

    Harmonic multiplying operation in a gyrotron traveling-wave amplifier (gyro-TWA) permits for magnetic field reduction and frequency multiplication. Lowering a beam voltage is an important step toward miniaturization of a harmonic multiplying gyro-TWA. However, the additional degree of freedom that is provided by the multitude cyclotron harmonics in a low-voltage harmonic multiplying gyro-TWA still easily generates various competing modes. An improved mode-selective circuit, using circular waveguides with various radii, can provide the rejection points within the frequency range to suppress competing modes. Simulated results reveal that the mode-selective circuit can provide an attenuation of more than 14 dB to suppress the competing modes. Furthermore, the performance of the gyro-TWA is analyzed for studying the sensitivity of the saturated output power and full width at half maximum bandwidth of the gyro-TWA to the beam voltage and the magnetic field. A stable low-voltage harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 24 kW at 200.4 GHz, corresponding to a saturated gain of 56 dB at an interaction efficiency of 20%. The full width at half maximum bandwidth is 3.0 GHz.

  20. Mechanisms of amplification of ultrashort electromagnetic pulses in gyrotron traveling wave tube with helically corrugated waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, N. S., E-mail: ginzburg@appl.sci-nnov.ru; Zaslavsky, V. Yu. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul' yanov Str., 603950 Nizhny Novgorod (Russian Federation); Nizhny Novgorod State University, 23 Gagarin Ave., 603950 Nizhny Novgorod (Russian Federation); Zotova, I. V.; Sergeev, A. S.; Zheleznov, I. V.; Samsonov, S. V.; Mishakin, S. V. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ul' yanov Str., 603950 Nizhny Novgorod (Russian Federation)

    2015-11-15

    A time-domain self consistent theory of a gyrotron traveling wave tube with a helically corrugated operating waveguide has been developed. Based on this model, the process of short pulse amplification was studied in regimes of grazing and intersection of the dispersion curves of the electromagnetic wave and the electron beam. In the first case, the possibility of amplification without pulse form distortion was demonstrated for the pulse spectrum width of the order of the gain bandwidth. In the second case, when the electrons' axial velocity was smaller than the wave's group velocity, it was shown that the slippage of the incident signal with respect to the electron beam provides feeding of the signal by “fresh” electrons without initial modulation. As a result, the amplitude of the output pulse can exceed the amplitude of its saturated value for the case of the grazing regime, and, for optimal parameters, the peak output power can be even larger than the kinetic power of the electron beam.

  1. Three-Dimensional Numerical Simulation of a 30-GHz Gyrotron Resonator With an Explicit High-Order Discontinuous-Galerkin-Based Parallel Particle-In-Cell Method

    DEFF Research Database (Denmark)

    Stock, Andreas; Neudorfer, Jonathan; Riedlinger, Marc;

    2012-01-01

    and the operating setup. For the first time, we apply a fully electromagnetic (EM) transient 3-D high-order discontinuous Galerkin particle-in-cell method solving the complete self-consistent nonlinear Vlasov–Maxwell equations to simulate a 30-GHz high-power millimeter-wave gyrotron resonator without physical......Fast design codes for the simulation of the particle–field interaction in the interior of gyrotron resonators are available. They procure their rapidity by making strong physical simplifications and approximations, which are not known to be valid for many variations of the geometry...

  2. Development of a dual frequency (110/138 GHz) gyrotron for JT-60SA and its extension to an oscillation at 82 GHz

    OpenAIRE

    Kobayashia Takayuki; Moriyama Shinichi; Isayama Akihiko; Sawahata Masayuki; Terakado Masayuki; Hiranai Shinichi; Wada Kenji; Sato Yoshikatsu; Hinata Jun; Yokokura Kenji; Hoshino Katsumichi; Sakamoto Keishi

    2015-01-01

    A dual-frequency gyrotron, which can generate 110 GHz and 138 GHz waves independently, is being developed in JAEA to enable electron cyclotron heating (ECH) and current drive (ECCD) in a wider range of plasma discharge conditions of JT-60SA. Conditioning operation of the gyrotron toward 1 MW for 100 s, which is the target output power and pulse length for JT-60SA, is in progress without significant problems. Oscillations of 1 MW for 10 s and 0.5 MW for 198 s were obtained, so far, at both fre...

  3. Suppression of the Oscillatory Modes of a Space Charge in the Magnetron Injection Guns of Technological Gyrotrons

    Science.gov (United States)

    Glyavin, M. Yu.; Kuntsevich, A. D.; Manuilov, V. N.

    2015-01-01

    We present the results of based on the PIC method numerical simulation of the dynamic processes of trapping of electrons into the adiabatic trap of a technological gyrotron for different configurations of the electric and magnetic fields in the electron beam formation region. The electrode geometry providing a low reflection coefficient of the magnetic mirror to suppress oscillatory modes in the space-charge cloud and ensure the stability of the electron beam with a high fraction of oscillatory energy in such a system has been found.

  4. Development program for a 200 kW, CW gyrotron. Quarterly report No. 16, April-June 1983

    International Nuclear Information System (INIS)

    The objective of this program is the design and development of a millimeter-wave device to produce 200 kW of continuous wave power at 60 GHz. The device, a gyrotron oscillator, will be compatible with power delivery to an electron-cyclotron heated plasma. Smooth control of rf power over a 17 dB range is required, and the device should be capable of operation into a severely time-varying load mismatch. Progress is presented in the testing, analyses and understanding of S/N 1B behavior and in preparing S/N 3 for test in the coming report period

  5. Intense Pulsed light Versus 1,064 Long-Pulsed Neodymium: Yttrium–Aluminum– Garnet Laser in the Treatment of Facial Acne Vulgaris

    Science.gov (United States)

    Mohamed, Essam Elden; Tawfik, Khaled

    2016-01-01

    Introduction Laser and light-based procedures provide a good and safe modality for treatment of active acne lesions when used properly. Aim To compare the clinical efficacy of intense pulsed light (IPL) versus 1,064 long-pulsed Neodymium:Yttrium–Aluminum– Garnet (Nd: YAG) in treatment of facial acne vulgaris. Materials and Methods Seventy four patients recruited between June 2013 and August 2014 was enrolled in this controlled, single-blind, split-face clinical trial. All participants received 3 sessions of IPL on the right side of the face and 1,064-nm Nd:YAG on the left side of the face at 4-weeks intervals. Final assessment was made by comparison of the changes in the count of inflammatory acne lesions (inflammatory papules, pustules, nodules and cyst) and non-inflammatory acne lesions (Comedones) and the acne severity score between both therapies, based on standardized photography. Results At the final visit, the inflammatory acne lesions were reduced on the IPL and 1,064-nm Nd:YAG treated sides by 67.1% and 70.2% respectively (p0.05 for each). For both therapies, there was significant difference in the improvement on inflammatory acne lesions in comparison to non-inflammatory lesions (p0.05 for each). Conclusion Both IPL and 1,064-nm Nd:YAG laser are effective in treatment of inflammatory facial acne vulgaris. There is no significant difference between the effects of both therapies on facial acne lesions. PMID:27630934

  6. Summary on Electron Cyclotron Technology

    International Nuclear Information System (INIS)

    In EC 12, held in Aix-en-Provence on 13-15 May 2002, 24 papers addressed ECH technology oriented work. There were five status reports on systems currently in operation, being designed or in construction (JT60 (110 GHz), JET-EP (113 GHz), TS (118 GHz), TEXTOR and W7-X (40 GHz)), eight papers on power gyrotron development, six on subsystems or components development, three on windows, two on remote steering. About the systems still not operative, the cancellation of the JET DEP experiment is regrettable. On the other hand the W7-X ECH is perhaps the Stellarator subsystem in the most advanced state of development, and it can be already considered a future valuable test bench for the ITER EC system. In the area of gyrotron development, the best performance in terms of energy output and pulse length has been obtained by the 140 GHz FZK/EPFL/TED tube developed for W7-X, with pulses in the range of ∼ 0.5 MW for ∼ 200 s. Frequency and pulse performance of this tube are already in the range of ITER relevance. The sources at the nominal ITER frequency (170 GHz) have reached the nominal power level (∼1 MW) only for short pulses. However, the progress toward long pulses was delayed by accidents (loss of vacuum conditions because of overheating of an uncooled component in the Toshiba device and break of a diamond window in the Gycom tube). The reasons for these accidents are known and remedial actions already performed. A substantial progress on long pulse operation should be expected this year. An important progress achieved in gyrotron development is the control of stray radiation in the matching box by the use of radiation windows. Power modulation has become a recognized requirement for gyrotron sources. A further progress is however needed in order to preserve the nominal efficiency also at low power level, also in order to prevent thermal overloading of the collector. The electrical efficiency of the tubes is acceptable (∼ 50%) in short pulse but it generally de

  7. 60 GHz gyrotron development program. Final report, April 1979-June 1984

    International Nuclear Information System (INIS)

    The original objective of this program was to develop a microwave amplifier or oscillator capable of producing 200 kW CW power output at 110 GHz. The use of cyclotron resonance interaction was pursued, and the design phases of this effort are discussed. Later, however, the program's objective was changed to develop a family of oscillators capable of producing 200 kw of peak output power at 60 GHz. Gyrotron behavior studies were performed at 28 GHz to obtain generic design information as quickly as possible. The first experimental device at 60 GHz produced over 200 kw of peak power at a pulse duration of 20 μs. Heating problems and mode interference were encountered. The second experimental tube incorporated an optimized gun location but also suffered from mode interference. The third experimental tube included modifications that reduced mode interference. It demonstrated 200 kw of peak output at 100 ms pulse duration. The fourth experimental tube, which used an older rf circuit design but in a CW configuration, produced 71.5 kW CW. The fifth experimental tube incorporated a thinner double-disc output window which improved window bandwidth and reduced window loss. This tube also incorporated modifications to the drift tunnel and cavity coupling, which had proven successful in the third experimental pulse tube tests. It produced 123 kW of CW output power at 60 GHz rf load coolant boiling and tube window failure terminated the tests. A new waterload was designed and constructed, and alternative window designs were explored

  8. Microwave generation for magnetic fusion energy applications, Task B

    International Nuclear Information System (INIS)

    One of the main issues in the development of high power gyrotrons is the present discrepancy between the theoretically predicted efficiency and that observed in the experiments. Recent 140 GHz experiments by MIT employed three cavities; two of the cavities have different interaction lengths and the third cavity is a complex two-section cavity. In all cases, the maximum experimental efficiency is well below the theoretically predicted one. A better theoretical understanding of the causes of these discrepancies is essential to the scaling of gyrotrons to higher power and higher frequency. We continued our investigation with the objective of determining whether mode competition and velocity spread in the electron beam could in some way be influencing the current result from the MIT 140 GHz gyrotrons experiments and determining to what extent these effects would influence operation of a 1 MW, 280 GHz, TE42,7 gyrotron as conceived at MIT. In our investigations, we used two models, the ''fixed axial field profile'' model and the ''self-consistent determination of the axial field profile'' model. With the ''fixed axial field profile'' model we studied the effect of thermal spread on the efficiency of gyrotrons operation, mode competition between unequally spaced modes, and we simulated the start up of the MIT 140 GHz gyrotrons. Our main conclusions from all these studies are discussed in this paper

  9. Development Program for a 200-kW, c-w gyrotron. Quarterly report No. 14, October-December 1982

    International Nuclear Information System (INIS)

    The objective of this program is the design and development of a millimeter-wave device to produce 200 kW of continuous-wave power at 60 GHz. The device, a gyrotron oscillator, will be compatible with power delivery to an electron-cyclotron plasma. Smooth control of RF power output over a 17 dB range is required, and the device should be capable of operation into a severe time-varying load mismatch. Continued testing of S/N 1 A was limited by boiling in the water load. An efficiency of 48.9 percent was achieved at 3.3 amps cathode current. Extensive experimentation with eclectic water-load configurations was performed and significant progress was made toward a permanent load configuration. Testing was completed on S/N 2. This gyrotron had a limited operating range due to a nonconcentric cathode. After regunning, initial tests on S/N 2A produced 150 kW RF on the diagnostic modulator. Further investigation of a beam instability problem, which occurs under certain magnetic-field conditions, was performed on S/N 2A. Corrective action has been taken on S/N 3 to suppress this oscillation

  10. Repetitive characteristics of solid state high power long pulse generator%固态化高功率长脉冲驱动源重频特性

    Institute of Scientific and Technical Information of China (English)

    高景明; 杨汉武; 李嵩; 晏龙波; 钱宝良; 张军

    2016-01-01

    A solid state high power long pulse generator has been designed and constructed based on the key technologies of magnetic switch,low impedance pulse forming line,and inductive voltage adder,which was verified by single mode operation for peak power of 2 GW.For repetitive operation,a repetitive primary power supply of moderate voltage level was developed,the two stage magnetic pulse compressor was improved from aspects of reset and insulation,the pulsed charging was optimized where the inductive voltage adder was utilized for pulsed voltage step-up as well as for pulse charging and on-line direct current (DC)re-set was achieved by reasonable design of reset current path.At present,the experimental results achieved on a dummy load are output pulsed power of 2.1 GW,pulse width of 1 70 ns,repetitive rate of 20 Hz,operation time of 1 s and good for repeatability. For further improvement,the pseudospark switch would be replaced by serial connected thyristors to accomplish all solid-state de-sign.%基于固态化磁开关、低阻抗脉冲形成网络和感应电压叠加等关键技术,提出并研制了一台固态化高功率长脉冲驱动源。在前期通过2 GW 单次实验验证技术方案的基础上,研制了中等电压等级的重复频率初级电源;改进了两级磁脉冲压缩系统的复位和绝缘特性;优化了系统整体电路结构,利用感应电压叠加器完成充电磁开关和脉冲升压的双重功能;设计了合理的复位路径,实现了各部分磁芯的在线直流复位;并开展了重频运行研究。在电阻负载上获得了输出功率2.1 GW、脉宽约170 ns、重复频率20 Hz 及运行时间1 s 的实验结果,脉冲波形的重叠一致性好。

  11. Effects of tapering structures on the characteristics of a coaxial-waveguide gyrotron backward-wave oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Hung, C. L. [Department of Communication Engineering, National Penghu University of Science and Technology, Penghu 880, Taiwan (China); Chang, T. H. [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China); Yeh, Y. S. [Department of Electro-Optical Engineering, Southern Taiwan University, Tainan 710, Taiwan (China)

    2011-10-15

    This study analyzes the characteristics of a gyrotron backward-wave oscillator (gyro-BWO) with a longitudinally tapered coaxial-waveguide by using a single-mode, self-consistent nonlinear code. Simulation results indicate that although tapering the inner wall or the outer wall can significantly raise the start-oscillation current, the former is more suitable for mode selection than the latter because an increase of the start-oscillation current by a tapered inner wall heavily depends on the chosen C value (i.e., the average ratio of the outer radius to the inner radius over the axial waveguide length). Selective suppression of the competing mode by tapering the inner wall is numerically demonstrated. Moreover, efficiency of the coaxial gyro-BWO is increased by tapering the outer wall. Properly down-tapering the outer wall ensures that the coaxial gyro-BWO can reach a maximum efficiency over twice that with a uniform one.

  12. Optimizing the coupling of output of a quasi-optical gyrotron owing to a diffraction grating with ellipsoidal support

    International Nuclear Information System (INIS)

    The output scheme of a quasi-optical gyrotron has been optimized in order to produce a gaussian output microwave beam suitable for transmission over long distances. The technique which has been applied consists of substituting one of the mirrors of the Fabry-Perot resonator in which the particle-wave interaction takes place by a diffraction grating placed in the -1 order Littrow mount and designed such that only orders -1 and 0 can propagate. In such a configuration, the diffraction angle of the order -1 coincides exactly with the incidence direction, thus providing a feedback in the cavity, whereas the order 0 constitutes the output of the resonator. A theoretical study of the power content in each diffracted order of a planar grating of infinite extent with equally spaced linear grooves as a function of the grating parameters has been performed. It has been shown that parameter domains can be found, which provide appropriate efficiencies in both orders for an application on a quasi-optical gyrotron. The Littrow condition was then adapted in order to match the spherical wavefronts of a gaussian beam incident on a possibly non-planar surface. The grooves become thus curvilinear and are no longer equally spaced. Measurements made on a cold test stand have confirmed the validity of the Littrow condition extension and allowed to determine its limits. It has also been shown that this type of cavity provides a mode having an optimal gaussian content and giving a minimal cavity transmission. The angular dispersion of the grating leads to a higher cavity transmission and to a slightly lower gaussian content for the adjacent resonator modes. The fundamental eigenmode electric field profile has been measured inside the cavity and is similar to that of an equivalent resonator made with two spherical mirrors. (author) figs., tabs., 141 refs

  13. Generation of electron beams in cyclotron motion and its interaction with electromagnetic fields in weakly irregular cavities: a study applied to conceptual elaboration of a 35 GHz gyrotron

    International Nuclear Information System (INIS)

    It is presented an investigation of different phenomena that occur in the gyrotron: 1) generation and transport of helical electron beams, 2) interaction of electrons in cyclotron motion with a transverse electric mode in resonant cavities operating near cutoff and 3) electron deposition over the collector active region. An exact ballistic model, which points out the nonlinear attributes of the relativistic equation of electron cyclotron motion and that includes a complex formulation for the longitudinal electric field distribution in weakly irregular waveguides, is used. Physically realizable RF field profiles are studied with the objective of maximizing gyrotron efficiency. For this purpose, an investigation is made of the resonant properties of truncated cones cavities and a new resonator type, with a profile described in terms of a continuous function, is developed. High perpendicular efficiencies (ηperpendicularMAX=0.86) have been calculated for interaction at the fundamental 1cyclotron harmonic and for uniform external magnetic field. A maximum efficiency scaling parameter S has been introduced, by which scaling relations ηperpendicularMAX= ηperpendicularMAX (S) are applicable to a variety of field profiles. The conceptual design of a 35 GHz gyrotron gives emphasis to selection criteria of operating parameters in compliance with technical constraints and with the requirement of soft self-excited oscillations. The proposed gyrotron operates in the azimuthally symetrical mode TE021 and is able to produce, with an electronic efficiency of 40%, an output power of 100 kW, in pulses of 20 ms, with a duty factor of 0.04%. (author)

  14. Occlusion Effect of a Long-pulsed 532nm Laser on Veins%长脉冲532nm激光器对静脉血管的封闭效应

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lai-ming; TANG Yu-guo; GUO Jin; YANG Gui-long; LI Dian-jun; LU Qi-peng; GU Hua-dong; ZHU Lin-lin; ZHAO Zhen-wu; LI Xin; WANG Jing-ping

    2005-01-01

    Laser treatment represents an attractive option to other methods of vessel diseases especially varicose veins. A long pulse (30~50ms) 532nm laser was used in our experiments, with the pulse duration matching the thermal relaxation time of the vessels and the green laser matching the absorption spectrum peak of the blood. Laser irradiates nude vein vessels directly or exterior skin to finish operation faster and to acquire the practical data for upper enteron varicose vein treatment in several animal experiments performed in vivo. The 5Jenergy pulse allows us to finely occlude rabbit or dog's vein vessels up to 2 mm in diameter when irradiating them off external skin. Blood vessels are occluded at once, and later biopsy specimens show the immediate and long-term lasting occlusion effect.While vessels are irradiated directly, they are usually irradiated to perforate, detailed causes are still under investigation. Animal experiments showed that the long pulse green laser therapy is a safe and effective solution to the vein's occlusion, which promises such laser with high energy of each pulse and 30~50 ms duration is an ideal candidate for vessel diseases treatment.

  15. Control of the Superconducting Magnets current Power Supplies of the TJ-II Gyrotrons; Control de las Fuentes de Corriente de las Bobinas Superconductoras de los Girotrones del TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Ros, A.; Fernandez, A.; Tolkachev, A.; Catalan, G.

    2006-07-01

    The TJ-II ECRH heating system consists of two gyrotrons, which can deliver a maximum power of 300 kW at a frequency of 53.2 GHz. Another 28 GHz gyrotron is going to be used in the Bernstein waves heating system. In order to get the required frequency, the gyrotrons need and homogeneous magnetic field of several tesla, which is generated by a superconducting coil field by a current source. This document describes the current source control as well as the high precision ammeters control. These ammeters measure the current in the superconducting coils. The user interface and the programming of the control system are described. The communication between devices is also explained. (author) 9 Refs.

  16. A Stable 0.2-THz Coaxial-Waveguide Gyrotron Traveling-Wave-Tube Amplifier with Distributed Losses

    Science.gov (United States)

    Hung, C. L.; Yeh, Y. S.; Chang, T. H.; Fang, R. S.

    2016-08-01

    For high-power operation, a THz gyrotron traveling-wave-tube (gyro-TWT) amplifier must operate in a high-order waveguide mode to enlarge the transverse dimension of an interaction waveguide. However, a gyro-TWT amplifier operating in a high-order waveguide mode is susceptible to spurious oscillations. To improve the device stability, in this study, we investigate the possibility of using a coaxial waveguide with distributed losses as the interaction structure. For the same required attenuation, all threatening oscillating modes can be suppressed using different combinations of losses of inner and outer cylinders. This provides flexibility in designing distributed losses when considering the ohmic loading of the interaction structure. We predict that the 0.2-THz gyro-TWT can stably produce a peak power of 14 kW with an efficiency of 23 %, a 3-dB bandwidth of 3.5 GHz, and a saturated gain of 50 dB for a 20-kV 3-A electron beam with a 5 % velocity spread and 1.0 velocity ratio.

  17. Design and measurement of a TE13 input converter for high order mode gyrotron travelling wave amplifiers

    Science.gov (United States)

    Wang, Yan; Liu, Guo; Shu, Guoxiang; Yan, Ran; Wang, Li; Agurgo Balfour, E.; Fu, Hao; Luo, Yong; Wang, Shafei

    2016-03-01

    A technique to launch a circular TE13 mode to interact with the helical electron beam of a gyrotron travelling wave amplifier is proposed and verified by simulation and cold test in this paper. The high order (HOM) TE13 mode is excited by a broadband Y-type power divider with the aid of a cylindrical waveguide system. Using grooves and convex strips loaded at the lateral planes of the output cylindrical waveguide, the electric fields of the potential competing TE32 and TE71 modes are suppressed to allow the transmission of the dominant TE13 mode. The converter performance for different structural dimensions of grooves and convex strips is studied in detail and excellent results have been achieved. Simulation predicts that the average transmission is ˜-1.8 dB with a 3 dB bandwidth of 7.2 GHz (91.5-98.7 GHz) and port reflection is less than -15 dB. The conversion efficiency to the TE32 and TE71 modes are, respectively, under -15 dB and -24 dB in the operating frequency band. Such an HOM converter operating at W-band has been fabricated and cold tested with the radiation boundary. Measurement from the vector network analyzer cold test and microwave simulations show a good reflection performance for the converter.

  18. Stability analysis of a two-stage tapered gyrotron traveling-wave tube amplifier with distributed losses

    Energy Technology Data Exchange (ETDEWEB)

    Hung, C. L. [Department of Communication Engineering, National Penghu University of Science and Technology, Penghu 880, Taiwan (China); Lian, Y. H.; Cheng, N. H. [Graduate Institute of Electrical Engineering and Computer Science, National Penghu University of Science and Technology, Penghu 880, Taiwan (China); Yeh, Y. S. [Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan (China); Chang, T. H. [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China)

    2012-11-15

    The two-stage tapered gyrotron traveling-wave tube (gyro-TWT) amplifier has achieved wide bandwidth in the millimeter wave range. However, possible oscillations in each stage limit this amplifier's operating beam current and thus its output power. To further enhance the amplifier's stability, distributed losses are applied to the interaction circuit of the two-stage tapered gyro-TWT. A self-consistent particle-tracing code is used for analyzing the beam-wave interactions. The stability analysis includes the effects of the wall losses and the length of each stage on the possible oscillations. Simulation results reveal that the distributed-loss method effectively stabilizes all the oscillations in the two stages. Under stable operating conditions, the device is predicted to produce a peak power of 60 kW with an efficiency of 29% and a saturated gain of 52 dB in the Ka-band. The 3-dB bandwidth is 5.7 GHz, which is approximately 16% of the center frequency.

  19. High power rf amplifiers for accelerator applications: The large orbit gyrotron and the high current, space charge enhanced relativistic klystron

    Energy Technology Data Exchange (ETDEWEB)

    Stringfield, R.M.; Fazio, M.V.; Rickel, D.G.; Kwan, T.J.T.; Peratt, A.L.; Kinross-Wright, J.; Van Haaften, F.W.; Hoeberling, R.F.; Faehl, R.; Carlsten, B.; Destler, W.W.; Warner, L.B.

    1990-01-01

    Los Alamos is investigating a number of high power microwave sources for their potential to power advanced accelerators. Included in this investigation are the large orbit gyrotron amplifier and oscillator (LOG) and the relativistic klystron amplifier (RKA). LOG amplifier development is newly underway. Electron beam power levels of 3 GW, 70 ns duration, are planned, with anticipated conversion efficiencies into RF on the order of 20 percent. Ongoing investigations on this device include experimental improvement of the electron beam optics, and computational studies of resonator design and RF extraction. Recent RKA studies have operated at electron beam powers into the device of 1.35 GW in microsecond duration pulses. The device has yielded modulated electron beam power approaching 300 MW using 3--5 kW of RF input drive. RF powers extracted into waveguide have been up to 70 MW, suggesting that more power is available from the device that we have converted to-date in the extractor. We have examined several aspects of operation, including beam bunching phenomena and RF power extraction techniques. In addition, investigations of the amplifier gain as a function of input drive, electron beam parameters and axial magnetic field strength also have been explored. The effect of ions formed during device operation also has been considered.

  20. 长脉冲1064 nmNd:YAG激光治疗皮肤血管性疾病%Long pulsed 1064nm Nd: YAG Laser Treatment of Dermovascular Disease

    Institute of Scientific and Technical Information of China (English)

    黄伟

    2010-01-01

    目的 探讨应用长脉冲1064 nm Nd:YAG激光治疗皮肤血管性疾病的治疗效果.方法 自2005年2月至2009年2月,应用长脉冲1064 nm Nd:YAG激光治疗皮肤血管性疾病285例,对鲜红斑痣、草莓样血管瘤、混合性血管瘤、皮肤毛细血管扩张、血管痣及充血性增生瘢痕等皮肤血管性疾病,根据皮损的不同性质选定不同能量的光束进行照射,视情况重复治疗1~5次.治疗结束6个月后随访,评价治疗效果.结果 285例中,有效245例,有效率为85.9%,治愈153例,治愈率为53.7%,出现色素性改变52例(18.2%),均在数月至半年后恢复,遗留浅表性瘢痕10例(3.51%),增生性瘢痕2例(0.7%).结论 长脉冲长脉冲1064 nm Nd:YAG激光治疗皮肤血管性疾病具有起效快、疗效显著、不良反应小的优点,具有重要的临床应用价值.%Objective Evaluation Of long pulsed 1064nmNd: YAG laser treatment of dermovascular disease treatment effects. Methods A total of 285 cases of dermovascular disease were treated with long pulsed 1064nmNd: YAG laser including port wine stains, strawberry hemangiomas, expanded capillary and congested hypertrophic scar. from February 2005 to February 2009.During the management, different energy levels were decided on the basis of the reaction of each lesion and the treatment repeated 1 to 5 times. The treatment effect were evaluated after six months follow-up. Results 245 cases (85.9%) in 285 cases patients gained effective therapy. 153 cases (53.7%) obtained healing. There are 52 cases (18.2%) with temple pigment alteration after the courses of treatment which can recover in several months or haff a year, superficial depressed scar wereremained in 10 patients (3.51%),two patients (0.7%) showed hyperplastic scar. Conclusion Treatment of dermovascular disease with long pulsed 1064 nm Nd: YAG laser has the qualities of quick and remarkable action and few side effect. This method has important clinical application value.

  1. Preparation of Steady State Operation of the Wendelstein 7-X Stellarator

    International Nuclear Information System (INIS)

    Full text: Wendelstein 7-X has been designed to demonstrate the steady state capability of the stellarator concept. At 10 MW of heating power a pulse duration of 30 minutes is envisaged. Short pulses of additional heating power are foreseen to access beta and equilibrium limits and study fast ion confinement and fast ion driven instabilities. The large variety of time scales is strongly affecting the design of plasma diagnostics, heating and fuelling systems, data acquisition and device control. For steady state heating ten 1 MW continuous wave gyrotrons are foreseen, operating at 140 GHz second harmonic heating at 2.5 T. Using a system of mirrors, relaying the micro waves through air to Wendelstein 7-X, a very high transmission efficiency has been achieved. Front steering mirrors, one for each gyrotron, individually change the poloidal and toroidal launch angles, thus controlling the radial deposition and current drive. Recent modifications to the gyrotron design include an improved power handling in the collector using a rotating transverse magnetic field. The main heating scenarios are 2nd harmonic X-mode (X2) heating below the cut-off density of 1.2 x 1020 m-3 and 2nd harmonic O-mode (O2) heating at higher densities. Owing to non-absorbed power, significant levels of stray radiation are expected for O2-heating, during the transition from X2- to O2-heating, and also during plasma start-up with electron cyclotron resonance waves. Therefore all in-vessel components have to be qualified and if necessary protected to withstand up to 50 kW/m2 of continuous micro-wave power flux. Many diagnostic techniques require a specific adaptation or even new developments to cope with steady state operation. Besides the measurement of fast events, also the long times scales have to be covered. As a consequence not only data rates increase, but the total amount of data. This requires special efforts for real time plasma control, and for continuous data acquisition and data

  2. SYL1500型长脉冲绿激光治疗蜘蛛痣的临床观察%Therapeutic effects of SYL1500 green long pulse laser in treatment of spider moles

    Institute of Scientific and Technical Information of China (English)

    宋洋; 张迪; 姜萍

    2013-01-01

    Objectives :To study the therapeutic effects of SYL1500 green long pulse laser intreating spider moles .Methods :Pulse laser penetrate the skin quickly ,arriving at the dermal layer .The hemoglobins of the blood vessels absorp selectively 532 nm pulse laser .Results :The cure rate was 100 percent at half -year follow - up resulting in blood vessels shrinks .Conclusions :This technique was proved to be effective safe ,quick ,easy to operate and little risk of scarring without recurrence .%目的:观察SYL1500型长脉冲绿激光治疗蜘蛛痣的疗效。方法:快速穿透表皮,到达真皮的病变血管,发生病变的血管中血红蛋白选择性吸收532nm的脉冲激光,病变的血管被急剧加热,使得病变血管收缩。结果:经1年随访,无复发,治愈率100%。结论:操作简单,瞄准精确,不易形成疤痕,治愈率高,疗程短,不复发,快速安全。

  3. Long-pulse Supercontinuum Light Sources

    DEFF Research Database (Denmark)

    Moselund, Peter M.

    A Supercontinuum (SC) is a broad spectrum generated from a narrow light source through non-linear effects. This thesis describes SC generation based on 1064 nm ps pulses in PCF fibres. We investigate how the SC spectrum can be modified and intensity noise reduced by feeding back part of the SC...

  4. Automated Microwave Complex on the Basis of a Continuous-Wave Gyrotron with an Operating Frequency of 263 GHz and an Output Power of 1 kW

    Science.gov (United States)

    Glyavin, M. Yu.; Morozkin, M. V.; Tsvetkov, A. I.; Lubyako, L. V.; Golubiatnikov, G. Yu.; Kuftin, A. N.; Zapevalov, V. E.; V. Kholoptsev, V.; Eremeev, A. G.; Sedov, A. S.; Malygin, V. I.; Chirkov, A. V.; Fokin, A. P.; Sokolov, E. V.; Denisov, G. G.

    2016-02-01

    We study experimentally the automated microwave complex for microwave spectroscopy and diagnostics of various media, which was developed at the Institute of Applied Physics of the Russian Academy of Sciences in cooperation with GYCOM Ltd. on the basis of a gyrotron with a frequency of 263 GHz and operated at the first gyrofrequency harmonic. In the process of the experiments, a controllable output power of 0 .1 -1 kW was achieved with an efficiency of up to 17 % in the continuous-wave generation regime. The measured radiation spectrum with a relative width of about 10 -6 and the frequency values measured at various parameters of the device are presented. The results of measuring the parameters of the wave beam, which was formed by a built-in quasioptical converter, as well as the data obtained by measuring the heat loss in the cavity and the vacuum output window are analyzed.

  5. Rapid Sintering of Silica Xerogel Ceramic Derived from Sago Waste Ash Using Sub-millimeter Wave Heating with a 300 GHz CW Gyrotron

    Science.gov (United States)

    Aripin, Haji; Mitsudo, Seitaro; Sudiana, I. Nyoman; Tani, Shinji; Sako, Katsuhide; Fujii, Yutaka; Saito, Teruo; Idehara, Toshitaka; Sabchevski, Sliven

    2011-06-01

    In this paper, we present and discuss experimental results from a microwave sintering of a silica-glass ceramic, produced from a silica xerogel extracted from a sago waste ash. As a radiation source for the microwave heating a sub-millimeter wave gyrotron (Gyrotron FU CW I) with an output frequency of 300 GHz has been used. The powders of silica xerogel have been dry pressed and then sintered at temperatures ranging from 300°C to 1500°C. The influence of the sintering temperature on the technological properties such as porosity and bulk density was studied in detail. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy have been used in order to study the structure of the produced silica glass-ceramics. It has been found that the silica xerogel crystallizes at a temperature of 800°C, which is about 200°C lower than the one observed in the conventional process. The silica xerogel samples sintered by their irradiation with a sub-millimeter wave at 900°C for 18 minutes are fully crystallized into a silica glass-ceramic with a density of about 2.2 g/cm3 and cristobalite as a major crystalline phase. The results obtained in this study allow one to conclude that the microwave sintering with sub-millimeter waves is an appropriate technological process for production of silica glass-ceramics from a silica xerogel and is characterized with such advantages as shorter times of the thermal cycle, lower sintering temperatures and higher quality of the final product.

  6. Qualifying plasma diagnostics for a high power microwave background of ECRH heated discharges

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, M.; Baldzuhn, J.; Endler, M.; Laux, M.; Zhang, D.; Laqua, H.P.; Noke, F.; Purps, F.; Ewert, K. [Max-Planck Institut fur Plasmaphysik, EURATOM Association, D-17491 Greifswald (Germany); Oosterbeek, J.W. [Technische Universiteit Eindhoven, Den Doelch 2, 5612 AZ Eindhoven (Netherlands); Jimenez, R. [Associacion EURATOM/CIEMAT, av. Complutense 22, 28040, Madrid (Spain)

    2011-07-01

    Microwave background radiation resulting from multiple reflected unabsorbed ECRH / ECCD power may cause severe problems for microwave absorbing in-vessel components such as gaskets, bellows, windows, isolators and cable insulations in particular during long pulse operation. For qualifying in-vessel components of W7-X in the environment of an isotropic 140 GHz radiation the Microwave Stray Radiation Launch facility, MISTRAL is operated at IPP. Power flux densities of 10-40 kW/m{sup 2} are obtained with a pulsed power gyrotron launching the microwave via a corrugated transmission line and a vacuum window to the MISTRAL vessel. The focus of the program was on cable isolations as required e.g. for in-vessel magnetic diagnostics. Sufficient shielding is obtained in nearly closed metal pipes only. Cryo pumps require a temperature < 12 K where Hydrogen desorption starts. The cryo pumps are usually shielded from plasma radiation by so called chevron structures. It is investigated whether coating of these chevrons with a microwave absorbing layer yields a sufficient reduction of the stray radiation level to ensure cryo pump operation. Diagnostic windows have been tested also. Although the temperature rise even of uncooled ZnSe and quartz windows at 10 kW/m{sup 2} is uncritical with respect to damage the associated refractive index changes may be too high for some diagnostic purposes e.g. for interferometry. A possible shielding are meshes or {mu}W absorbing coatings. Integrated diagnostic mock-ups such as for the diamagnetic loop, the inner Rogowski coils, Mirnov coils and the bolometer head also have been tested

  7. Design of megawatt gyrotrons

    International Nuclear Information System (INIS)

    The design parameters of a 120 GHz gyromonotron capable of output powers in excess of 1 MW are determined. A nonlinear model of the interaction between the beam and rf field is used in which the efficiency is a function of only three normalized variables. By expressing the technological constraints in terms of these variables, permissible design parameters yielding high efficiency operation can be calculated. Constraints that are considered include ohmic heating of the walls, voltage depression of the beam, reduced coupling between the beam and rf field due to beam thickness, and efficiency degradation due to space charge forces within the beam. An analysis of the tradeoffs between current and voltage at the 1 MW level indicates that lower order modes can be utilized at lower voltages, but the constraints based on current limitations are difficult to satisfy. An 80 kV, 29 A design is presented that achieves a total efficiency of 44%. The primary uncertainty of these designs is the severity of competition due to parasitic modes. However, a number of isolated asymmetric modes appear capable of single mode emission at 1 MW based on present experimental results. Multimegawatt operation is also considered. It is shown that powers exceeding 20 MW are possible if single mode operation can be achieved in very high order modes. The methodology presented in this paper is general and can be easily adapted to other frequencies and output powers

  8. 170 GHz回旋管电子枪的设计%Design of the magnetron injection gun for 170 GHz gyrotron

    Institute of Scientific and Technical Information of China (English)

    曾旭; 王峨锋; 刘本田; 李志良; 冯进军

    2013-01-01

    A 170 GHz gryotron is an ideal power source for the Electron Cyclotron Resonance Heating (ECRH) in the plasma fusion. The required output power from a single gyrotron tube at 170 GHz operating frequency for ECRH application is 1 MW or more. For generating the high output power,a Magnetron Injection Gun(MIG) which can provide the electron beam with large enough transverse energy for interacting with the transverse filed of the electromagnetic wave is designed. Ideal parameters of the double-anode MIG are obtained according to the adiabatic compression theory and the correlative simulation software. The designed MIG can provide the necessary beams for the 170 GHz fundamental harmonic gyrotron under 80 kV of voltage and 40 A of current with the guidance center radius of 8.27 mm and the pitch factor of 1.5.%  170 GHz回旋管是等离子体核聚变中电子回旋谐振加热的理想功率源,在功率上要求具有1 MW以上的输出功率。要产生这么大的输出功率,就需要具有足够大横向能量的电子注与高频场的横向电场进行互作用,因此要对电子枪进行专门的设计。利用绝热压缩理论及相关的仿真软件对双阳极磁控注入电子枪进行了设计,得到了较好的电子注参数。所设计的电子枪能在工作电压80 kV、工作电流40 A 的条件下为170 GHz 基波回旋管提供所需的回旋电子注,其引导中心半径为8.27 mm,横纵速度比1.5。

  9. Backscattering of gyrotron radiation and short-wavelength turbulence during electron cyclotron resonance plasma heating in the L-2M stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Batanov, G. M.; Borzosekov, V. D., E-mail: tinborz@gmail.com; Kovrizhnykh, L. M.; Kolik, L. V.; Konchekov, E. M.; Malakhov, D. V.; Petrov, A. E.; Sarksyan, K. A.; Skvortsova, N. N.; Stepakhin, V. D.; Kharchev, N. K. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2013-06-15

    Backscattering of gyrotron radiation ({theta} = {pi}) by short-wavelength density fluctuations (k{sub Up-Tack} = 30 cm{sup -1}) in the plasma of the L-2M stellarator was studied under conditions of electron cyclotron resonance (ECR) plasma heating at the second harmonic of the electron gyrofrequency (75 GHz). The scattering of the O-wave emerging due to the splitting of the linearly polarized gyrotron radiation into the X- and O-waves was analyzed. The signal obtained after homodyne detection of scattered radiation is a result of interference of the reference signal, the quasi-steady component, and the fast oscillating component. The coefficients of reflection of the quasi-steady component, R{sub =}{sup 2}(Y), and fast oscillating component, R{sub {approx}}{sup 2}(Y), of scattered radiation are estimated. The growth of the R{sub {approx}}{sup 2}(Y) coefficient from 3.7 Multiplication-Sign 10{sup -4} to 5.2 Multiplication-Sign 10{sup -4} with increasing ECR heating power from 190 to 430 kW is found to correlate with the decrease in the energy lifetime from 1.9 to 1.46 ms. The relative density of short-wavelength fluctuations is estimated to be Left-Pointing-Angle-Bracket n{sub {approx}}{sup 2} Right-Pointing-Angle-Bracket / Left-Pointing-Angle-Bracket n{sub e}{sup 2} Right-Pointing-Angle-Bracket = 3 Multiplication-Sign 10{sup -7}. It is shown that the frequencies of short-wavelength fluctuations are in the range 10-150 kHz. The recorded short-wavelength fluctuations can be interpreted as structural turbulence, the energy of which comprises {approx}10% of the total fluctuations energy. Simulations of transport processes show that neoclassical heat fluxes are much smaller than anomalous ones. It is suggested that short-wavelength turbulence plays a decisive role in the anomalous heat transport.

  10. 片状石墨增强树脂基复合材料的耐激光烧蚀性能研究%Ablation Capability of Flake Graphite Reinforced Barium-phenolic Resin Composite under Long Pulse Laser Irradiation

    Institute of Scientific and Technical Information of China (English)

    于庆春; 万红

    2012-01-01

    The carbon fiber reinforced phenolic resin composite is widely used as a thermal protection material because of its excellent thermal ablation. A novel flake graphite reinforced barium-phenolic resin composite was made by roller coating technology and its thermal ablation capability under long pulse laser irradiation was studied. The results show that the thermal ablation rate of the flake graphite reinforced barium-resin composite is 32.8 ug/J at 1700 W/cm2 irradiation power density, which is much lower than that of the carbon fiber reinforced barium-resin composite or barium-phenolic resin obviously. The anti-ablative mechanism of the flake graphite reinforced barium-phenolic resin composite is investigated by the observation of its microstructure and the calculation of the laser en-. Ergy coupling with the material. It is found that the flake graphite is arrayed homogeneous alignment as sandwich among the composite. When the laser radiation gets on the composite, the flake graphite plays as a mirror and reflects part of the laser, and then the laser radiation energy deposition on the composite is reduced. It is also found that the size of the flake graphite also affects the ablation capability. The composite with the flake graphite diameter of about 0.5 mm has the lowest thermal ablation rate.%采用刷涂的方法制备了一种新型的片状石墨增强钡酚醛树脂基复合材料,并采用重频激光辐照的方法,对其耐烧蚀性能进行了研究.研究结果表明:片状石墨增强钡酚醛树脂基复合材料在平均功率密度为1700 J/cm2的重频激光辐照下的热烧蚀率为32.8 μg/J,耐激光烧蚀性能明显高于碳纤维增强的钡酚醛树脂基复合材料和钡酚醛树脂;片状石墨增强钡酚醛树脂基复合材料中的片状石墨呈近平行的层状分布方式,在激光辐照过程中能对入射激光起到平面反射作用,从而有效地降低激光辐照的能量沉积;片状石墨的片型对复合材料

  11. Further Characterization of 394-GHz Gyrotron FU CW GII with Additional PID Control System for 600-MHz DNP-SSNMR Spectroscopy

    Science.gov (United States)

    Ueda, Keisuke; Matsuki, Yoh; Fujiwara, Toshimichi; Tatematsu, Yoshinori; Ogawa, Isamu; Idehara, Toshitaka

    2016-09-01

    A 394-GHz gyrotron, FU CW GII, has been designed at the University of Fukui, Japan, for dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) experiments at 600-MHz 1H resonant frequency. After installation at the Institute for Protein Research (IPR), Osaka University, Japan, a PID feedback control system was equipped to regulate the electron gun heater current for stabilization of the electron beam current, which ultimately achieved stabilization of output power when operating in continuous wave (CW) mode. During exploration to further optimize operating conditions, a continuous tuning bandwidth of approximately 1 GHz was observed by varying the operating voltage at a fixed magnetic field. In the frequency range required for positive DNP enhancement, the output power was improved by increasing the magnetic field and the operating voltage from their initial operational settings. In addition, fine tuning of output frequency by varying the cavity cooling water temperature was demonstrated. These operating conditions and ancillary enhancements are expected to contribute to further enhancement of SSNMR signal.

  12. Further Characterization of 394-GHz Gyrotron FU CW GII with Additional PID Control System for 600-MHz DNP-SSNMR Spectroscopy

    Science.gov (United States)

    Ueda, Keisuke; Matsuki, Yoh; Fujiwara, Toshimichi; Tatematsu, Yoshinori; Ogawa, Isamu; Idehara, Toshitaka

    2016-04-01

    A 394-GHz gyrotron, FU CW GII, has been designed at the University of Fukui, Japan, for dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) experiments at 600-MHz 1H resonant frequency. After installation at the Institute for Protein Research (IPR), Osaka University, Japan, a PID feedback control system was equipped to regulate the electron gun heater current for stabilization of the electron beam current, which ultimately achieved stabilization of output power when operating in continuous wave (CW) mode. During exploration to further optimize operating conditions, a continuous tuning bandwidth of approximately 1 GHz was observed by varying the operating voltage at a fixed magnetic field. In the frequency range required for positive DNP enhancement, the output power was improved by increasing the magnetic field and the operating voltage from their initial operational settings. In addition, fine tuning of output frequency by varying the cavity cooling water temperature was demonstrated. These operating conditions and ancillary enhancements are expected to contribute to further enhancement of SSNMR signal.

  13. 94 GHz TE02模回旋管Vlasov模式变换器的设计与模拟%Design and Simulation of Vlasov Mode Converter for 94 GHz TE02 Mode Gyrotron

    Institute of Scientific and Technical Information of China (English)

    王斌; 杜朝海; 刘濮鲲; 耿志辉; 徐寿喜

    2011-01-01

    该文研究并设计了一个由Vlasov阶梯型开口辐射器、椭圆面反射器和抛物面反射器组成的TE02模回旋管准光模式变换器.首先采用几何光学研究了阶梯型开口辐射器、椭圆面反射器和抛物面反射器的具体形状,再利用矢量绕射理论分析了其工作过程,最后结合 94 GHz TE02模回旋管的具体参数,编写仿真程序详细讨论了工作模式在此模式变换器中的变换过程.模拟结果表明,94 GHz回旋管中的TE02模在输出窗处被转换为能量集中的准高斯波束,转换效率为78.35%.%The quasi-optical mode converter for the TE02 mode gyrotron, consisting of a Vlasov stepped-cut launcher,an elliptical reflector and a parabolic reflector, was designed, fabricated and studied. Firstly, the stepped-cut launcher, the elliptical reflector and the parabolic reflector were analytically evaluated with geometric optics. Next, the operation process of the converter was analyzed with vector diffra fion theory. And finally,operation of the mode conversion was simulated,based on the physical model of Vlasov mede converter for 94 GHz TE02 mode gyrotron. The simulated results show that the TE02 mode inside the 94 GHz gyrotron was converted into a higly Gaussian-like beam at the output window, and that the conversion efficiency was 78.35%.

  14. 长脉冲1064nm激光联合口服皮质激素治疗婴幼儿血管瘤的疗效评价%Treatment of infantile hemangiomas with long pulsed 1064nm laser and oral corticosteroids

    Institute of Scientific and Technical Information of China (English)

    闫俊杰; 江银华; 田克斌

    2012-01-01

    目的:探讨激光联合口服皮质激素治疗婴幼儿血管瘤的可行性,并对其疗效作初步评价.方法:对102例处于增殖期的血管瘤患儿,分别给予激光治疗、激光与皮质激素联合治疗.治疗前超声检查病灶深度,按深度是否超过1cm,分为深部型与表浅型.激光为1064nm长脉冲可调脉宽激光,治疗1-3次,皮质激素服用一个疗程.采用SAS6.12软件包对所得数据进行Ridit分析.结果:100例完成治疗,随访率为98%.激光治疗治愈12例(24.00%)、显效18例(36.00%),有效率为60.00%;激光与皮质激素联合治疗治愈14例(26.92%)、显效27例(51.92%),有效率为78.84%,2种治疗方法疗效具有显著差异(P<0.05).在表浅病灶组,激光治疗治愈8例(34.78%)、显效10例(43.48%),有效率为78.26%;激光与皮质激素联合治疗治愈7例(33.33%)、显效8例(38.10%),有效率为71.43%,2种治疗方法疗效无显著差异(P>0.05).在深部病灶组,激光治疗治愈4例(14.81%)、显效8例(29.63%),有效率为44.44%;激光与皮质激素联合治疗治愈7例(22.58%)、显效19例(61.29%),有效率为83.87%,2种治疗方法疗效具有显著差异(P<0.05).结论:长脉冲1064nm激光与口服皮质激素联合治疗深部型增殖期血管瘤是一种有效的方法.%PURPOSE: To evaluate the clinical therapeutic efficacy on infantile hemangiomas using long pulsed 1064nm laser and oral corticosteroid. METHODS: One hundred and two infantile hemangiomas in the proliferating phase state were treated with long pulsed 1064nm laser, long pulsed 1064nm laser and oral corticosteroid .Color Doppler was used to detect the depth of tumor. Laser treatment was conducted for 1 to 3 sessions,and oral corticosteroid was one course for 12 weeks. The results were analyzed with SAS6.12 software package for Ridit test. RESULTS: Total response treated with long pulsed 1064nm laser, long pulsed 1064nm laser and oral corticosteroid were

  15. Observations of Regular Filamentary Plasma Arrays in High-Pressure Gas Breakdown by 1.5 MW, 110 GHz Gyrotron Pulses

    Science.gov (United States)

    Hidaka, Yoshiteru

    2008-11-01

    Formation of regular two-dimensional plasma filamentary arrays has been observed in long open-shuttered images of air breakdown at atmospheric pressure [Y. Hidaka et al., Phys. Rev. Lett. 100, 035003 (2008)]. The breakdown was generated by a focused linearly-polarized Gaussian beam from a 1.5-MW, 110-GHz gyrotron with a 3-microsecond pulse length. Each plasma filament is elongated in the electric field direction and separated roughly one-quarter wavelength from each other in the H-plane. The development of this array structure can be explained as a result of diffraction of the beam around the highly conductive filaments. The diffraction generates a new electric field profile in which a high intensity region emerges about a quarter wavelength upstream from an existing filament. A new plasma filament is likely to appear at the intensified spot. The same process continues and results in the formation of the observed array. Electromagnetic wave simulations that model plasma filaments as metallic posts agree quite well with the hypothesis above. With a nanoseconds-gated ICCD camera, we directly confirmed that only a few rows of the observed array are bright at any one moment, as well as that the light emitting region propagates towards the microwave source. Further experimental breakdown research has been carried out with nitrogen, helium, and SF6 at different pressures. Although each species exhibits qualitatively different structures, in general, a lumpy plasma at high pressures transforms into a more familiar, diffuse plasma as pressure is decreased. The propagation velocity of the ionization front has been also estimated both from the ICCD images and a photodiode array. The velocity is on the order of 10 km/s, and increases as the pressure decreases and the power density increases.

  16. Maturing ECRF technology for plasma control

    International Nuclear Information System (INIS)

    The availability of high power, (∼1 MW) long pulse length (effectively cw), high frequency, (>100 GHz) gyrotrons has opened the opportunity for enhanced scientific results on magnetic confinement devices for fusion research worldwide. This has led to successful experiments on electron cyclotron heating, electron cyclotron current drive, non-inductive tokamak operation, tokamak energy transport, suppression of instabilities and advanced profile control leading to enhanced performance. The key development in the gyrotron community that has led to the realization of high power long pulse gyrotrons is the availability of edge cooled synthetic diamond gyrotron output windows, which have low loss and excellent thermal and mechanical properties. In addition to the emergence of reliable high power gyrotrons, ancillary equipment for efficient microwave transmission over distances of hundreds of meters, polarization control, diagnostics, and flexible launch geometry have all been developed and proven in regular service. (author)

  17. 长脉冲激光对组成CCD图像传感器的MOS光敏单元的硬破坏机理研究%Mechanism for long pulse laser-induced hard damage to the MOS pixel of CCD image sensor

    Institute of Scientific and Technical Information of China (English)

    毕娟; 张喜和; 倪晓武

    2011-01-01

    The interaction process between 1.06μm wavelength Nd:YAG long pulse laser with a millisecond pulse width and the MOS pixel of frame transfer area CCD image sensor and its hard damage mechanism are studied by the finite element method.The thermal-mechanical coupled modeling for long pulse laser irradiation of a MOS pixel is established,and the distributions of temperature and stress are obtained.The results show that the spallations between O layer and S layer appear due to the S layer radial stress on the surface exceeding the compressive strength under the action of the long pulse laser,then it will extend to the entire layer before melting by radial stress,axial stress and hoop stress.Hard damage of pixel occurs as spallation,and one pixel or an array of pixels in the laser irradiation area of CCD sensor is completely in failure.This paper could provide foundation for both laser-induced damage and protection of CCD image sensor.%以帧转移型面阵CCD图像传感器为例,采用有限元法研究了波长1.06μm,脉宽ms量级长脉冲Nd:YAG激光与组成CCD传感器的MOS光敏单元的作用过程及硬破坏机理.建立了长脉冲激光辐照MOS光敏单元的热力耦合模型,模拟了MOS光敏单元的温度分布和应力分布.研究结果表明:在长脉冲激光作用下,由于S层表面径向压应力超过其抗压强度引起MOS光敏单元出现了OS层间分裂,进而受径向、环向和轴向压应力的共同作用下,在光敏单元还未熔融时,层间分裂就扩大至光敏单元的整个OS层间.OS层间完全分裂会使光敏单元发生硬破坏,并造成CCD传感器中激光照射区的单个或一列光敏单元的功能完全失效.文章的研究结果可为CCD图像传感器的激光损伤及防护提供必要的理论依据.

  18. Clinical Research of High Dose Long-pulsed Laser on Venous Malformations in Deep Skin Under the Condition of Controlling Low Temperature%控低温大剂量长脉冲激光治疗皮肤深部静脉畸形的临床研究

    Institute of Scientific and Technical Information of China (English)

    陈深; 严煜林; 韦妮波; 郑凤丽; 官英勇; 李伟强

    2014-01-01

    Objective:To explore the therapeutic effects and adverse reactions of high dose long-pulsed laser on venous malformation in deep skin under the condition of controlling low temperature. Method:Patients were divided into two groups,one group were treated with long-pulsed laser under usual temperature, and the other group were treated with long-pulsed laser under the conditions of controlling low temperature. Observing the therapeutic effect and adverse reaction of two groups under different conditions. Results:Compared with usual temperature,treatment dose can increase 10~20 J /cm2,continuous intensity of treatment and total energy can increase 10 times,pain and side effect were less under the condition of controlling low temperature. After 6 to 10 times of treatment,there were 42.00 percent of cure rate,33.33 percent of show efficiency rate,21.07 percent of effective rate,94.74 percent of the total effective rate and 10.11 percent of adverse reaction rate. Conclusion:Venous malformations in deep skin can be treated with high dose long-pulsed laser under the condition of controlling low temperature. It can improve curative effect,and reduce pain and adverse reactions. So it should be widely used in clinic.%目的:探讨皮肤深部静脉畸形在瘤体控低温条件下应用长脉冲激光治疗的疗效和不良反应。方法:将皮肤深部静脉畸形分别采用常温和瘤体控低温条件下进行长脉冲激光治疗,观察两组瘤体在不同条件下其治疗效果和不良反应。结果:瘤体在控低温技术比常温下应用长脉冲激光治疗,其治疗剂量可以增大10~20 J/cm2,连续治疗强度和总能量可增大10倍,患者本人的痛觉感减轻,不良反应更少。经过8~10次治疗,治愈率为42%,显效率为33.33%,有效率为21.07%,总有效率为94.74%,不良反应率10.11%。结论:皮肤深部静脉畸形在瘤体控低温条件下可使用大剂量长脉冲激光治疗,疗效满意,痛

  19. Therapeutic Effect of Long-pulsed 1064nm Nd:Laser with Optimal Pulse Technology on Infantile Hemangiomas in Maxillofacial Region%长脉冲1064nmNd:YAG激光联合优化脉冲光治疗颌面部婴幼儿血管瘤的临床分析

    Institute of Scientific and Technical Information of China (English)

    陈深; 严煜林; 郑凤丽; 韦妮波; 李伟强; 覃朝莲

    2013-01-01

    Objective To explore the therapeutic effects and adverse reactions of long-pulsed 1064nm Nd:laser with optimal pulse technology on infantile hemangiomas in maxillofacial region. Methods Patients were treated with long-pulsed 1064nm Nd:laser with optimal pulse technology,and personalized treatment parameters were selected depending on the location,size,color,texture of the tumors.“Tumor of abnormal”is when reaching optimal therapeutic dosage,tumor cells and organization structure change and even destroy their nature of state after treated with laser and optimal pulse light. Results After 2 to 6 times of treatment, there are 66.18% cure rate,29.41% efficiency rate,4.41% effective rate and 7.35% adverse reaction rate. Conclusion Long-pulsed 1064nm Nd:laser with optimal pulse technology can exert their advantages,such as long-pulsed laser and optimal pulse light,so the combination therapy is perfect,with less adverse reaction. It should be used in clinic,and be an early intervention treatment.%目的:探讨长脉冲1064nmNd:YAG激光联合优化脉冲光治疗颌面部婴幼儿血管瘤的治疗效果和不良反应。方法:应用长脉冲激光联合优化脉冲光对颌面部婴幼儿血管瘤进行治疗,根据瘤体的位置、大小、色泽、质地等选择个性化治疗参数,每次治疗达到最佳治疗剂量,就是应用激光、优化脉冲光照射后使瘤体内细胞、组织结构的状态和本质产生改变甚至被破坏,即出现“瘤态变”为治疗标准。结果:经过2~6次治疗,治愈率为66.18%,显效率为29.41%,有效率为4.41%。不良反应率7.35%。结论:长脉冲1064nmNd:YAG激光联合优化脉冲光治疗婴幼儿血管瘤能分别发挥长脉冲激光和优化脉冲光的各自优点,联合治疗效果更好,不良反应少,宜在临床中推广使用,应早期干预治疗。

  20. 170 GHz兆瓦级同轴回旋振荡管的分析计算%Analysis and calculation of a 170 GHz megawatt-level coaxial gyrotron

    Institute of Scientific and Technical Information of China (English)

    覃觅觅; 罗勇; 杨阔; 黄勇

    2014-01-01

    回旋管是最有希望应用于正在实施的国际热核实验反应堆计划的微波源器件,然而研究设计符合要求的回旋管还存在很多困难需要解决.对170 GHz兆瓦级光滑同轴回旋管的注-波互作用进行了研究.选取模式谱相对稀疏的TE31,12作为工作模式,利用Matlab编制源程序,计算了同轴回旋管的注-波耦合系数、起振电流.在考虑电子速度零散、腔壁电阻率和单模近似的基础上,对光滑同轴谐振腔的优化设计和注-波互作用进行了仿真,给出了磁场、电压、电流和内导体倾角等参量与回旋管效率的关系.结果表明,电压和磁场对回旋管效率影响较大,电子速度零散对回旋管效率影响较小,因而可降低电子枪的设计要求.此外,优化内导体倾角和同轴谐振腔结构参数可提高注-波互作用效率,降低电子速度零散对互作用效率的影响,获得了约50%的电子效率及1.7 MW输出功率.%Gyrotrons are the most promising microwave source devices that can be used in the International Thermonuclear Experimental Reactor, but there are many diffculties to be solved in study and design of gyrotrons to meet the require-ments. In this paper, the beam-wave interactions of a 170 GHz megawatt-level smooth-wall coaxial gyrotron are studied numerically. In order to attain high effciency and stable radiation, TE31,12 mode that lies in a relative sparse spectrum is selected as the operating mode, and the beam-wave coupling coeffcient and start oscillation current are calculated by a set of source codes developed by Matlab. Taking into account the electronic velocity spread and cavity wall resistivity, and based on a single-mode approximation, the optimization design and simulation of beam-wave interaction of a 170 GHz megawatt smooth-wall coaxial gyrotron have been fulfilled. The relationships between effciency and magnetic field, and the voltage, current, taper angle of insert, and other parameters are

  1. Ech System on the Diii-D Tokamak

    Science.gov (United States)

    Gorelov, I. A.; Lohr, J.; Cengher, M.; Ponce, D.

    2009-04-01

    A significant upgrade to the 110 GHz DIII-D ECH system was completed last year. Two additional Communication and Power Industries (CPI) diode gyrotrons were installed and tested to half the designed pulse length of 10 s. For the 2008 experimental campaign, the DIII-D system comprised five long pulse CPI gyrotrons. One additional high voltage power supply is being tested to support operation of up to 6 gyrotrons simultaneously at full parameters. The five gyrotrons in operation have chemical-vapor-deposition (CVD) diamond windows that are monitored by infrared camera during full parameter testing and operation during plasma experiments. A sixth CPI gyrotron has been repaired after collector failure and is being conditioned for high power at DIII-D. New equipment for gyrotron collector heat load monitoring was tested and used to measure the collector power deposition profile. A new fast fault processing system based on FPGA technology is being commissioned.

  2. A MAGICTRAC [Microwave Antenna for Whispering-Gallery-Mode Conversion using a Twist Reflector Antenna Converter] design for the MTX [Microwave Tokamak Experiment] transport system

    International Nuclear Information System (INIS)

    A design of a MAGICTRAC (Microwave Antenna for Whispering-Gallery-Mode Conversion using a Twist Reflector Antenna Converter) device is presented for use on the MTX (Microwave Tokamak Experiment) transport system. The MAGICTRAC device, consisting of a mode converting waveguide taper and three metal reflectors, transforms the TE15,2 circular waveguide mode output of a VARIAN Associates 140 GHz gyrotron into a free-space Gaussian-like beam with >95% efficiency. Dimensions of the MAGICTRAC are chosen to produce a beam matched to the MTX quasi-optical transport system

  3. 长脉冲1064nm Nd:YAG激光治疗婴幼儿皮肤血管瘤215例疗效分析%A clinical effect analysis of long-pulsed 1064 nm Nd:YAG laser in the treatment of 215 infancy hemangiomas

    Institute of Scientific and Technical Information of China (English)

    曹丽华; 张美华; 吕东; 秦萍萍; 周洋

    2012-01-01

    Objectives: To observe the clinical effects of long-pulsed 1 064 nm Nd:YAG laser in the treatment of heman-giomas of skin in infant and investigate its related factors. Methods: Total 215 cases were treated with long-pulsed 1 064 nm Nd:YAG laser according to different disease types, including 19 cases of port wine stains, 179 cases of strawberry heman-giomas and 17 cases of mixed hemangiomas. The association between clinical effect and types, size, location and times of treatment of hemangiomas was also analyzed. Results: Among 215 cases, 133 were cured, 67 gained marked effect, 8 gaining effective therapy and 7 ineffective. The cure rate and total efficacy rate were 61.9% and 93.1%, respectively. The effect was related with the type, size and treatment times of hemangiomas. However, the location of hemangiomas was not associated with the therapy effect. The side-effect rate was 48.8% with temporary hyper-pigmentation, 8.3% with temporary hypo-pigmentation, 4.6% with superficial scar and 3.7% with hair reduction or disappearance. Conclusion: The long-pulsed 1 064nm Nd:YAG laser is an effective, safe and low side-effect treatment for infancy hemangiomas.%目的:观察长脉冲1064nm Nd:YAG激光治疗婴幼儿皮肤血管瘤临床疗效,并探讨影响疗效的相关因素.方法:应用长脉冲1 064 nm Nd:YAG激光治疗婴幼儿皮肤血管瘤215例,其中鲜红斑痣19例,草莓状血管瘤179例,混合型血管瘤17例.分析其疗效与病变类型、瘤体大小、病变部位及治疗次数的关系.结果:215例患儿中治愈133例,显效67例,有效8例,无效7例,痊愈率和有效率分别为61.9%和93.1%.疗效与血管瘤的病变类型、瘤体的大小以及治疗次数有关,但与其病变部位无明显相关性.治疗后暂时性色素沉着、暂时性色素减退、浅表性瘢痕、头部毛发减少或消失的发生率分别为48.8%、8.3%、4.6%和3.7%.结论:长脉冲1064nm Nd:YAG激光治疗婴幼儿皮肤血管瘤疗效好,

  4. Treatment of Treatment of Facial Telangiectasia Associated with Hormone-dependent Dermatitis by Long-pulsed 1064nm Nd:YAG Laser%长脉冲1064nm Nd:YAG激光治疗面部激素依赖性皮炎伴发的毛细缸管扩张

    Institute of Scientific and Technical Information of China (English)

    金燕; 郭永刚; 李文志

    2011-01-01

    目的:观察长脉冲1064nm Nd:YAG激光治疗面部激素依赖性皮炎伴发毛细血管扩张的临床治疗效果.方法:治疗参数选用:光斑直径3mm,平均脉宽(13.5±3.4)ms,平均能量密度(267.2±3.1)J/cm2.结果:37例女性患者,平均治疗2.3次,面部毛细血管扩张平均密度由(2.76±1.03)根/cm2下降至(0.42± 0.27)根/cm2,临床疗效显著.治疗后,皮肤恢复至基本正常状态,无瘢痕、色素改变,皮炎反复发作的现象消失.结论:长脉冲1064nm Nd:YAG激光治疗面部激素依赖性皮炎伴有的毛细血管扩张具有较好临床治疗效果,方法值得进行更广泛的临床实践与深入研究.%Objective To observe the clinic therapeutic effect of facial Telangiectasia Associated with Hormone-dependent Dermatitis by long-pulsed 1064nm Nd: YAG laser. Methods The facial telangiectasia were treated by laser with 3mm spot diameter,the average pulse width (13,5±3.4) ms and the average energy density (267.2±3.1) J/cm2.Results 37 cases of female patients were cured by 2.3 average treatment times. The average density of facial telangiectasia were decreased from (2.76±1.03) vessels / cm2 to (0.42± 0.27) root / cm2. The clinical effect is significant.After treatment, no scars, no pigmentation occurred and the dermatitis disappeared. Conclusion There is a good result with facial Telangiectasia Associated with Hormone-dependent Dermatitis treated by long pulse 1064nm Nd:YAG laser. This approach deserves more extensive clinical practice and in-depth study.

  5. Efficacy of long-pulse Nd:YAG 1064 nm laser combined with occlusive dressing with salicylic acid in the treatment of onychomycosis%长脉宽Nd:YAG 1064 nm激光联合水杨酸封包治疗甲真菌病的疗效评价

    Institute of Scientific and Technical Information of China (English)

    陈梅; 张敬东; 董正邦

    2015-01-01

    Objective:To assess the efficacy of long-pulse Nd:YAG 1064 nm laser combined with occlu-sive dressing with salicylic acid in the treatment of onychomycosis. Methods: Sixty six patients with onycho-mycosis were randomly divided into the treatment group ( 34 patients, 68 disease nails) and control group ( 32 patients, 72 disease nails) . The disease nails in each group were divided into the SCIO≤9 group and the 90.05) . The effective rates of disease nails with a score of 90.05);对于9

  6. Long pulse EBW start-up experiments in MAST

    International Nuclear Information System (INIS)

    Start-up technique reported here relies on a double mode conversion (MC) for electron Bernstein wave (EBW) excitation. It consists of MC of the ordinary (O) mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X) mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance (ECR) and experiences a subsequent X to EBW MC near the upper hybrid resonance (UHR). Finally the excited EBW mode is totally absorbed at the Doppler shifted ECR. The absorption of EBW remains high even in cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [1]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results were extended to longer RF pulses showing further increase of plasma currents generated by RF power alone. A record current of 73kA has been achieved with 450ms RF pulse of similar power. The current drive enhancement was mainly achieved due to RF pulse extension and further optimisation of the start-up scenario

  7. DARHT-II Long-Pulse Beam-Dynamics Experiments

    CERN Document Server

    Ekdahl, Carl; Bartsch, Richard; Bender, Howard; Briggs, Richard J; Broste, William; Carlson, Carl; Caudill, Larry; Chan, Kwok-Chi D; Chen Yu Jiuan; Dalmas, Dale; Durtschi, Grant; Eversole, Steven; Eylon, Shmuel; Fawley, William M; Frayer, Daniel; Gallegos, Robert J; Harrison, James; Henestroza, Enrique; Holzscheiter, M H; Houck, Timothy L; Hughes, Thomas P; Jacquez, Edward; Johnson, Douglas; Johnson, Jeffrey; Jones, Kenneth; McCuistian, Brian T; Meidinger, Alfred; Montoya, Nicholas; Mostrom, Chris; Moy, Kenneth; Nath, Subrata; Nielsen, Kurt; Oro, David; Rodriguez, Leroy; Rodriguez, Patrick; Rowton, Larry J; Sanchez, Manolito; Scarpetti, Raymond; Schauer, Martin; Schulze, Martin E; Simmons, David; Studebaker, Jan; Sturgess, Ronald; Sullivan, Gary; Swinney, Charles; Tang, Yan; Temple, Rodney; Tipton, Angela; Tom, C Y; Vernon Smith, H; Yu, Simon

    2005-01-01

    When completed, the DARHT-II linear induction accelerator (LIA) will produce a 2-kA, 18-MeV electron beam with more than 1500-ns current/energy "flat-top." In initial tests DARHT-II has already accelerated beams with current pulse lengths from 500-ns to 1200-ns full-width at half maximum (FWHM) with more than1.2-kA, 12.5-MeV peak current and energy. Experiments are now underway with a ~2000-ns pulse length, but reduced current and energy. These pulse lengths are all significantly longer than any other multi-MeV LIA, and they define a novel regime for high-current beam dynamics, especially with regard to beam stability. Although the initial tests demonstrated absence of BBU, the pulse lengths were too short to test the predicted protection against ion-hose instability. The present experiments are designed to resolve these and other beam-dynamics issues with a ~2000-ns pulse length beam.

  8. Event recognition using signal spectrograms in long pulse experiments.

    Science.gov (United States)

    González, J; Ruiz, M; Vega, J; Barrera, E; Arcas, G; López, J M

    2010-10-01

    As discharge duration increases, real-time complex analysis of the signal becomes more important. In this context, data acquisition and processing systems must provide models for designing experiments which use event oriented plasma control. One example of advanced data analysis is signal classification. The off-line statistical analysis of a large number of discharges provides information to develop algorithms for the determination of the plasma parameters from measurements of magnetohydrodinamic waves, for example, to detect density fluctuations induced by the Alfvén cascades using morphological patterns. The need to apply different algorithms to the signals and to address different processing algorithms using the previous results necessitates the use of an event-based experiment. The Intelligent Test and Measurement System platform is an example of architecture designed to implement distributed data acquisition and real-time processing systems. The processing algorithm sequence is modeled using an event-based paradigm. The adaptive capacity of this model is based on the logic defined by the use of state machines in SCXML. The Intelligent Test and Measurement System platform mixes a local multiprocessing model with a distributed deployment of services based on Jini. PMID:21033990

  9. Analysis of melt ejection during long pulsed laser drilling

    Science.gov (United States)

    Ting-Zhong, Zhang; Zhi-Chao, Jia; Hai-Chao, Cui; De-Hua, Zhu; Xiao-Wu, Ni; Jian, Lu

    2016-05-01

    In pulsed laser drilling, melt ejection greatly influences the keyhole shape and its quality as well, but its mechanism has not been well understood. In this paper, numerical simulation and experimental investigations based on 304 stainless steel and aluminum targets are performed to study the effects of material parameters on melt ejection. The numerical method is employed to predict the temperatures, velocity fields in the solid, liquid, and vapour front, and melt pool dynamics of targets as well. The experimental methods include the shadow-graphic technique, weight method, and optical microscope imaging, which are applied to real-time observations of melt ejection phenomena, measurements of collected melt and changes of target mass, observations of surface morphology and the cross-section of the keyhole, respectively. Numerical and experimental results show that the metallic material with high thermal diffusivity like aluminum is prone to have a thick liquid zone and a large quantity of melt ejection. Additionally, to the best of our knowledge, the liquid zone is used to illustrate the relations between melt ejection and material thermal diffusivity for the first time. The research result in this paper is useful for manufacturing optimization and quality control in laser-material interaction. Project supported by the Natural Science Foundation of Jiangsu Province, China (Grant No. KYLX_0341) and the National Natural Science Foundation of China (Grant No. 61405147).

  10. Event recognition using signal spectrograms in long pulse experiments

    International Nuclear Information System (INIS)

    As discharge duration increases, real-time complex analysis of the signal becomes more important. In this context, data acquisition and processing systems must provide models for designing experiments which use event oriented plasma control. One example of advanced data analysis is signal classification. The off-line statistical analysis of a large number of discharges provides information to develop algorithms for the determination of the plasma parameters from measurements of magnetohydrodinamic waves, for example, to detect density fluctuations induced by the Alfven cascades using morphological patterns. The need to apply different algorithms to the signals and to address different processing algorithms using the previous results necessitates the use of an event-based experiment. The Intelligent Test and Measurement System platform is an example of architecture designed to implement distributed data acquisition and real-time processing systems. The processing algorithm sequence is modeled using an event-based paradigm. The adaptive capacity of this model is based on the logic defined by the use of state machines in SCXML. The Intelligent Test and Measurement System platform mixes a local multiprocessing model with a distributed deployment of services based on Jini.

  11. Ti:sapphire laser with long-pulse lamp pumping

    Science.gov (United States)

    Koselja, Michael P.; Kubelka, Jiri; Kvapil, Jiri

    1992-06-01

    Lamp pumping of Ti:Sapphire has some advantages over laser pumping and represents some interest due to possible applications. The paper will present laser behavior of Ti:Sapphire under very long lamp pulse pumping. Pulse lamp duration (FWHM) was more than 100 times greater than the lifetime of Ti3+. Output energy with no tuning element was achieved greater than 1.5 J with 0.12% electrical-to-optical efficiency. Dimensions of the rod used was 7 mm in diameter and 148 mm in length. The doping level of Ti3+ was 0.09% Ti2O3 in the rod. Tuning characteristics with different tuning elements are also presented. Further development to obtain CW lamp pumping operation will be discussed.

  12. Long Pulse EBW Start-up Experiments in MAST

    Directory of Open Access Journals (Sweden)

    Shevchenko V.F.

    2015-01-01

    Full Text Available Start-up technique reported here relies on a double mode conversion (MC for electron Bernstein wave (EBW excitation. It consists of MC of the ordinary (O mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance (ECR and experiences a subsequent X to EBW MC near the upper hybrid resonance (UHR. Finally the excited EBW mode is totally absorbed at the Doppler shifted ECR. The absorption of EBW remains high even in cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [1]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results were extended to longer RF pulses showing further increase of plasma currents generated by RF power alone. A record current of 73kA has been achieved with 450ms RF pulse of similar power. The current drive enhancement was mainly achieved due to RF pulse extension and further optimisation of the start-up scenario.

  13. Long Pulse EBW Start-up Experiments in MAST

    CERN Document Server

    Shevchenko, V F; Caughman, J B; Diem, S; Mailloux, J; Brien, M R O; Peng, M; Saveliev, A N; Takase, Y; Tanaka, H; Taylor, G

    2015-01-01

    The non-solenoid start-up technique reported here relies on a double mode conversion for electron Bernstein wave (EBW) excitation. It consists of the mode conversion of the ordinary mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X) mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance and experiences a subsequent X to EBW mode conversion near the upper hybrid resonance. Finally the excited EBW mode is totally absorbed at the Doppler shifted electron cyclotron resonance. The absorption of EBW remains high even in cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [V. Shevchenko et al, Nuclear Fusion 50, 022004 (2010)]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results ...

  14. Long Pulse Operation on Tore-Supra: Towards Steady State

    International Nuclear Information System (INIS)

    The experimental programme of Tore Supra is devoted to the study of technology and physics issues associated to long-duration high performance discharges. This new domain of operation requires simultaneously and in steady state: heat removal capability, particle exhaust, fully non-inductive current drive, advanced technology integration and real time plasma control. The long discharge allows for addressing new time scale physic such as the wall particle retention and erosion. Moreover, the physics of fully non-inductive discharges is full of novelty, namely: the MHD stability, the slow spontaneous oscillation of the central electron temperature or the outstanding inward particle pinch

  15. Experimental studies towards long pulse steady state operation in LHD

    NARCIS (Netherlands)

    Noda, N.; Nakamura, Y.; Takeiri, Y.; Mutoh, T.; Kumazawa, R.; Sato, M.; Kawahata, K.; Yamada, S.; Shimozuma, T.; Oka, Y.; Iiyoshi, A.; Sakamoto, R.; Kubota, Y.; Masuzaki, S.; Inagaki, S.; Morisaki, T.; Suzuki, H.; Ohyabu, N.; Adachi, K.; Akaishi, K.; Ashikawa, N.; Chikaraishi, H.; de Vries, P. C.; Emoto, M.; Funaba, H.; Goto, M.; Hamaguchi, S.; Ida, K.; Idei, H.; Ikeda, K.; Imagawa, S.; Inoue, N.; Isobe, M.; Iwamoto, A.; Kado, S.; Kaneko, O.; Kitagawa, S.; Khlopenkov, K.; Kobuchi, T.; Komori, A.; Kubo, S.; Liang, Y.; Maekawa, R.; Minami, T.; Mito, T.; Miyazawa, J.; Morita, S.; Murai, K.; Murakami, S.; Muto, S.; Nagayama, Y.; Nakanishi, H.; Narihara, K.; Nishimura, A.; Nishimura, K.; Nishizawa, A.; Notake, T.; Ohdachi, S.; Okamoto, M.; Osakabe, M.; Ozaki, T.; Pavlichenko, R. O.; Peterson, B. J.; Sagara, A.; Saito, K.; Sakakibara, S.; Sasao, H.; Sasao, M.; Sato, K.; Seki, T.; Shoji, M.; Sugama, H.; Takahata, K.; Takechi, M.; Tamura, H.; Tamura, N.; Tanaka, K.; Toi, K.; Tokuzawa, T.; Torii, Y.; Tsumori, K.; Watanabe, K. Y.; Watanabe, T.; Watari, T.; Yanagi, N.; Yamada, I.; Yamada, H.; Yamaguchi, S.; Yamamoto, S.; Yamamoto, T.; Yokoyama, M.; Yoshimura, Y.; Ohtake, I.; Akiyama, R.; Haba, K.; Iima, M.; Kodaira, J.; Tsuzuki, K.; Itoh, K.; Matsuoka, K.; Ohkubo, K.; Satoh, S.; Satow, T.; Sudo, S.; Tanahashi, S.; Yamazaki, K.; Motojima, O.; Hamada, Y.; Fujiwara, M.

    2001-01-01

    In the Large Helical Device, stable discharges lasting longer than one minute have been obtained using the complete heating scheme, including ECH. The plasma is sustained with NBI or ICRF of 0.5-1 MW. The central plasma temperature is higher than 1.5 keV with a density of (1-2) x 10(19) m(-3) mainta

  16. Évaluation de technologies organiques faibles pertes et d’impression plastique 3D afin de contribuer au développement de solutions antennaires innovantes dans la bande 60 GHz – 140GHz.

    OpenAIRE

    Bisognin, Aimeric

    2015-01-01

    The improvement of the capabilities of wireless communication devices (smartphone, tablets …) which require higher and higher data rate, leads to a significant increase of the data traffic needed by each end user. This strong consumer demand for higher data-rate and coverage is stressing a lot the capacity of existing cellular networks. In order to cope with this challenge, one of the most promising solution consists in a network densification based on the deployment of low-power and short-ra...

  17. 长脉冲1064nm Nd:YAG激光治疗兔耳增生性瘢痕的实验研究%Therapeutic efficacy of long-pulsed 1064 mn Nd:YAG laser on hyperplastic scar in rabbit ear model

    Institute of Scientific and Technical Information of China (English)

    尹冬云; 曹莫; 刘柳

    2011-01-01

    Objective To evaluate the therapeutic effect of long-pulsed Nd:YAG 1064 laser on hyperplastic scars by using a rabbit ear model.Methods Five female and five male New Zealand long-ear white rabbits weighting 2.0-2.5 kg were used in this experiment.Four square full-thickness skin wounds sized 1.5 cm x1.5 cm were created on the ventral surface of each ear to develop a model of hyperplastic scar.Finally,a total of 74 hyperplastic scars developed on the 80 wounds,and the scars on the left and right ears served as the control (unirradiated) and treatment (irradiated with long-pulsed 1064 nm Nd:YAG laser) group,respectively.After 30 days of irradiation,the color and texture of scars were observed and the scar thickness was measured by color Doppler ultrasonogTaphy.Then,the scars were harvested followed by the analysis of density of fibroblasts and microvessels as well as the changes in collagen fibers in scars by HE staining,CD31 staining and Masson staining,respectively.Results A decrease was observed in the color,hardness and thickness of scars in the irradiated ears compared with the unirradiated ears.The average thickness of scars,microvessel density and fibroblast density in scars were significantly lower in the treatment group than in the control group(2.137vs.3.089 am,t=5.72,P<0.01;38.333/mm2vs.68.056/mm2,t=4.93,P<0.01;166.940/mm2vs.355.000/mm2,t=13.36.P<0.01).Masson staining revealed a disorganized arrangement of collagen fibers in the control group but a sparse and regular alignment in the treatment group.Conclusion Long-pulsed 1064 nm Nd:YAG laser may promote the shrinkage and suppress the hyperplasia of scars.%目的 通过建立兔耳增生性瘢痕模型,评价长脉冲1064 nm激光治疗增生性瘢痕的疗效.方法 选用新西兰长耳白兔10只,雌雄各半,体质量2.0~2.5 kg.在所有兔耳腹侧面建立增生性瘢痕模型,每只兔耳4处1.5 cm x 1.5 cm正方形造模.10只兔子共80个创面形成增生性瘢痕74处,将左侧和右侧兔耳

  18. Characteristics of the light emission from CVD diamond windows

    International Nuclear Information System (INIS)

    Video and infrared signals were registered from brazed and bare CVD diamond disks forming the windows of an evacuated transmission cell placed into the beam line of a high power gyrotron facility at 140 GHz (Maquette tube). Intense light emission forming spot-like patterns, that was observed under vacuum conditions, has a broad maximum around 770 nm, which is attributed to light emitting processes of non-purely thermal nature. Carbon residues, likely of amorphous structure, which can be formed by decomposition of organic fibres, such as cellulose, are shown to be one source of this spectacular phenomenon. Here, no critical limitation is seen for the performance of high power diamond windows. (authors)

  19. Advanced electron cyclotron heating systems for next-step fusion experiments

    International Nuclear Information System (INIS)

    Electron cyclotron heating (ECH) is one of the major candidates for heating and current drive on ITER (170GHz) and W7-X (140GHz). ECH is extremely attractive from physics and reactor engineering points of view, offering start-up assist, efficient and localized power deposition, simple and compact launching structures with high injected power density, and a simple interface with shielding and blanket. High unit power (1MW or greater) and high efficiency (35% or greater) single-mode continuous-wave (CW) gyrotron oscillators are under development in order to reduce significantly the systems costs by reducing the size of the auxiliary support systems. 140GHz gyrotrons with 0.55MW output power in the Gaussian free-space TEM0,0 mode with a pulse length τ up to 3.0s and efficiency η of 42% are already commercially available (Gycom). Improved internal quasi-optical mode transducers generate the TEM0,0 output mode with efficiencies of 90-95% and separate the electron beam from the r.f. beam, thus allowing the use of large CW relevant depressed collectors for energy recovery. Tube efficiencies around 50% have been already achieved at JAERI and KfK. Face cooled double-disk sapphire windows, cryogenically edge-cooled single-disk sapphire windows (liquid-nitrogen, liquid-neon or liquid-helium cooling), distributed windows (metal or ceramics) as well as diamond and silicon windows are under investigation in order to solve the window problem. Long-distance high-power millimeter wave transmission from the source to the plasma device with very low ohmic losses and high mode purity can be accomplished by (1) a closed, highly overmoded, circumferentially corrugated or dielectrically lined, tubular HE1,1-hybrid mode waveguide and (2) open quasi-optical TEM0,0 transmission through a gaussian beam waveguide using focusing reflectors as phase-correcting elements. (orig.)

  20. ECH Technology Development

    Energy Technology Data Exchange (ETDEWEB)

    Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2014-12-24

    Electron Cyclotron Heating (ECH) is needed for plasma heating, current drive, plasma stability control, and other applications in fusion energy sciences research. The program of fusion energy sciences supported by U. S. DOE, Office of Science, Fusion Energy Sciences relies on the development of ECH technology to meet the needs of several plasma devices working at the frontier of fusion energy sciences research. The largest operating ECH system in the world is at DIII-D, consisting of six 1 MW, 110 GHz gyrotrons capable of ten second pulsed operation, plus two newer gyrotrons. The ECH Technology Development research program investigated the options for upgrading the DIII-D 110 GHz ECH system. Options included extending present-day 1 MW technology to 1.3 – 1.5 MW power levels or developing an entirely new approach to achieve up to 2 MW of power per gyrotron. The research consisted of theoretical research and designs conducted by Communication and Power Industries of Palo Alto, CA working with MIT. Results of the study would be validated in a later phase by research on short pulse length gyrotrons at MIT and long pulse / cw gyrotrons in industry. This research follows a highly successful program of development that has led to the highly reliable, six megawatt ECH system at the DIII-D tokamak. Eventually, gyrotrons at the 1.5 megawatt to multi-megawatt power level will be needed for heating and current drive in large scale plasmas including ITER and DEMO.

  1. A Case Report of Telangiectatic Rosacea Treated with Long Pulsed Nd-YAG Laser

    Directory of Open Access Journals (Sweden)

    Can Ergin

    2016-02-01

    Full Text Available Rosacea is a chronic enflammatory skin disease characterized by facial erythema, telangiectasia, papules and pustules. A variety of topical and systemic medications are used in the treatment of the disease. Recently, erythema and telangiectasia in rosacea patients have been frequently treated with laser applications. Herein, we present a case of rosacea whose telangiectasia were successfully treated with Nd-YAG laser treatment. 

  2. Very long pulse high-RF power test of a lower hybrid frequency antenna module

    Energy Technology Data Exchange (ETDEWEB)

    Goniche, M.; Brossaud, J.; Barral, C.; Berger-By, G.; Bibet, Ph.; Poli, S.; Rey, G.; Tonon, G. [Association Euratom-CEA, Centre d`Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Seki, M.; Obara, K. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment] [and others

    1994-03-01

    Outgassing, induced by very long RF waves injection at high power density was studied in a module, able to be used for a lower hybrid frequency antenna. Good RF properties of the module are reported, however, resonance phenomena with strong absorption of RF power (15%) was observed at high temperature (T>400 deg C). A large outgassing data base is provided by the 75 shots cumulating 27 hours of RF injection. The comparison with previous experiments (Tore Supra and TdV prototype modules) confirm the effect of baking and results are consistent. Outgassing increases exponentially with -1/T, and a desorption model with an activation energy Ed {approx} 0.35 eV fits the data up to 400 deg C. In order to design vacuum pumping system for large lower hybrid frequency antenna, outgassing rates are given for different working temperatures. (author). 11 refs., 55 figs.

  3. Elastic scattering research at a 1 MW long pulse spallation neutron source

    International Nuclear Information System (INIS)

    The elastic scattering working group investigated instrumentation for powder diffraction, single-crystal diffraction, small-angle diffraction, and reflectometry. For this purpose, three subgroups were formed; one for powder diffraction and single-crystal diffraction, one for small-angle diffraction, and one for reflectometry. For the most part these subgroups worked separately, but for part of the time the reflectometry and small-angle diffraction subgroups met together to discuss areas of common interest. Contributors in each of these subgroups are indicated below along with the discussion of these subgroup deliberations

  4. Fundamental neutron physics at a 1 MW long pulse spallation neutron source

    International Nuclear Information System (INIS)

    Modern neutron sources and modern neutron science share a common origin in mid twentieth century scientific investigations concerned with the study of the fundamental interactions between elementary particles. Since the time of that common origin, neutron science and the study of elementary particles have evolved into quite disparate disciplines. The neutron became recognized as a powerful tool for the study of condensed matter with modern neutron sources being primarily used (and primarily justified) as tools for condensed matter research. The study of elementary particles has, of course, led to the development of rather different tools and is now dominated by activities carried out at extremely high energies. Notwithstanding this trend, the study of fundamental interactions using neutrons has continued and remains a vigorous activity at many contemporary neutron sources. This research, like neutron scattering research, has benefited enormously by the development of modern high flux neutron facilities. Future sources, particularly high power spallation sources, offer exciting possibilities for the continuation of this program of research

  5. The Physics of Long-Pulse Wire Array Z-Pinch Implosions

    Energy Technology Data Exchange (ETDEWEB)

    DOUGLAS,MELISSA R.; DEENEY,CHRISTOPHER; SPIELMAN,RICK B.; COVERDALE,CHRISTINE A.; RODERICK,N.F.; PETERSON,D.L.

    1999-12-14

    Recent improvements in z-pinch wire array load design at Sandia National Laboratories have led to a substantial increase in pinch performance as measured by radiated powers of up to 280 TW in 4 ns and 1.8 MJ of total radiated energy. Next generation, higher current machines will allow for larger mass arrays and comparable or higher velocity implosions to be reached, possibly extending these result.dis the current is pushed above 20 MA, conventional machine design based on a 100 ns implosion time results in higher voltages, hence higher cost and power flow risk. Another approach, which shifts the risk to the load configuration, is to increase the implosion time to minimize the voltage. This approach is being investigated in a series of experimental campaigns on the Saturn and Z machines. In this paper, both experimental and two dimensional computational modeling of the fist long implosion Z experiments will be presented. The experimental data shows broader pulses, lower powers, and larger pinch diameters compared to the corresponding short pulse data. By employing a nested array configuration, the pinch diameter was reduced by 50% with a corresponding increase in power of > 30%. Numerical simulations suggest load velocity is the dominating mechanism behind these results.

  6. A Case Report of Telangiectatic Rosacea Treated with Long Pulsed Nd-YAG Laser

    OpenAIRE

    Can Ergin

    2016-01-01

    Rosacea is a chronic enflammatory skin disease characterized by facial erythema, telangiectasia, papules and pustules. A variety of topical and systemic medications are used in the treatment of the disease. Recently, erythema and telangiectasia in rosacea patients have been frequently treated with laser applications. Herein, we present a case of rosacea whose telangiectasia were successfully treated with Nd-YAG laser treatment. 

  7. Characteristics of long-pulse and short-pulse spallation-source targets

    International Nuclear Information System (INIS)

    Generation of sharp neutron pulses is the desired output of a pulsed spallation neutron source (PSNS). These pulses should be approximately 10 μs. wide at half maximum, and preserve as much of the original flux as possible. A proposed PSNS has been designed to operate at an average proton beam power of 5 MW. The PSNS consists of a heavy metal target, surrounded by a reflector, and a selection of moderators. The moderators are connected to beam tubes in which the neutrons are transported to the experimental stations. Reflectors are generally made of good moderating material, in which neutrons leaking from the target are slowed down by elastic scattering, prior to moderation. It is proposed to investigate the possibility of using reflectors which slow neutrons down by inelastic scattering rather than elastic scattering. In a purely inelastic scattering medium neutron pulses leaking from the heavy metal target will tend to preserve their original shape in both energy and time. We will examine the effect of different reflectors and proton pulse lengths on the neutron pulses in the moderators. This study will be carried out using a simple target configuration. In this way effects introduced by complicated target arrangements can be avoided. All the analyses presented in this paper were carried out using the LAHET code system (LCS). This code system consists of two major modules: (1) LAHET, a modified version of the HETC intranuclear cascade code for evaluations above 20 MeV, and (2) HMCNP, a modified version of the well known MCNP transport code for calculations from 20 MeV down to thermal energies. Both modules employ a combinatorial surface/cell specification of the problem geometry which permits modeling of the target configurations with minimal approximations. In addition, HMCNP employs nuclear data from the ENDF/B files in essentially unapproximated point-wise form which avoid the complications associated with generation of group cross sections

  8. Evaluation of Long Pulsed-ND: Yag Laser in The Treatment of Onychomycosis

    International Nuclear Information System (INIS)

    Onychomycosis is a common persistent fungal infection of the nail bed, matrix or plate. It is the most common nail disorder in adults, accounting for one third of all fungal skin infections and up to 50 percent of all nail diseases worldwide including psoriasis, a topic dermatitis, nail trauma, contact irritants, and lichen planus (Schlefman, 1999 and Ghannoum, 2000). Toenails are affected more often than fingernails and the incidence is greater in older adults (Evans, 1998). Individuals who are especially susceptible include those with chronic diseases such as diabetes, circulatory problems, smokers, patients with psoriasis and those with diseases that suppress the immune system (e.g. HIV-positive patients, extremes of age, patients on long term corticosteroids therapy). Other risk factors include a family history, previous trauma to the nails, warm climate, and occlusive or tight footwear (Gupta et al., 2004). The causative agents of onychomycosis include dermatophytes, to a lesser extent non dermatophyte moulds and rarely, yeasts of the Candida species (Evans, 1998). Onychomycosis is classified clinically as distal and lateral subungual onychomycosis (DLSO), superficial white onychomycosis (SWO), proximal subungual onychomycosis (PSO), candidal onychomycosis and total dystrophic onychomycosis (Summerbell, 1989). Onychomycosis is very difficult and sometimes impossible to treat, and therapy is often long-term with high relapse rates 50-85 %. Several management and treatment regimens were designed to control and cure this disease such as palliative care, topical as well as systemic drugs (Gupta, 2003). Among the orally delivered systemic drugs terbinafine, itraconazole and fluconazole are most frequently used, but with several unpleasant side effects as headache, gastrointestinal symptoms, liver enzyme abnormalities (Scher, 1999). Nail debridement chemically or surgically is another treatment option, but it is considered by many to be primitive compared with topical or systemic treatment (Donald et al., 2002). The choice of therapy is influenced by the presentation and severity of the disease, other medications that the patient is taking, physician and patient preference, and cost (Gupta et al., 2003). A novel non-invasive approach for treatment of onychomycosis is the application of laser energy to the nail plate targeting the fungal cells themselves. By using a laser with a specific wavelength of laser light energy, the fungus could be directly targeted in the nail and heated to the point it is killed, but without burning the surrounding tissue and with leaving the skin and nail intact (Kozarev and Vizintin, 2010). The Nd-Yag (neodymium-doped yttrium aluminium garnet; Nd: Y3Al5O12) laser is such a device with a wavelength 1064 nm that will pass through the nail plate and into the nail bed resulting in superheating of the fungal material. Exposure of fungi to high temperatures inhibits their growth as well as causing cell damage and death (Hashimoto and Blumenthal, 1978). Several other types of lasers are introduced for the treatment of onychomycosis including diode laser (Landsman et al., 2010) femtosecond infrared titanium sapphire laser (Manevitch et al., 2010). A novel 0.65-millisecond pulsed Nd:YAG is also introduced for the treatment of onychomycosis (Mozena and Haverstock, 2010).

  9. Cloud hole-boring with long pulse CO sub 2 lasers

    Energy Technology Data Exchange (ETDEWEB)

    Quigley, G.P.; Webster, R.B.; York, G.W.

    1990-01-01

    Chemically generated CO{sub 2} laser pulses at 10.6 {mu}m have been used to clear a 5 cm diameter hole through a stratus-like cloud in a laboratory cloud chamber. The results show that 100% clearing can be achieved. The mechanism is shown to be droplet shattering followed by evaporation. Under the conditions of the experiment, the channel closure is dominated by turbulent mixing and not droplet recondensation. 14 refs., 9 figs.

  10. Processes in a dense long-pulse electron beam focused on a solid target

    International Nuclear Information System (INIS)

    The results obtained in beam-target experiments with dense medium-energy electron beam in the regime of long single pulses are presented. The measured power density of the focused beam at the target reached 20 MW/cm2 in these experiments. The processes caused by dense flows of secondary particles and by a dense target ablation plasma were studied in detail. Substantial target shielding occurs when the energy density at the target exceeds the value of about 1 kJ/cm2. The target plasma and the sputtered matter that is responsible for shielding affects also the beam structure, as well as the target etching rates. (J.U.). 3 figs., 5 refs

  11. Particle control in high power, high density long pulses on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Bucalossi, J.; Brosset, C.; Dufour, E.; Loarer, T.; Pegourie, B.; Tsitrone, E.; Basiuk, V.; Bremond, S.; Chantant, M.; Colas, L.; Commaux, N.; Geraud, A.; Grosman, A.; Guirlet, R.; Gunn, J.; Hertout, P.; Hoang, G.T.; Kazarian, F.; Mazon, D.; Maget, P.; Mitteau, R.; Monier-Garbet, P.; Moreau, P.; Saint-Laurent, F.; Schunke, B.; Vallet, J.C

    2005-07-01

    The plasma density and impurity level (Z(eff) {approx} 2) are perfectly controlled all along the 6 minute long discharges, the main limitation coming from the LH (lower hybrid) power source. After 60 s, the particle injection rate and the particle exhaust rate are constant. Therefore the retention rate, defined as the difference between these 2 quantities, is also constant at about 3.10{sup 20} D/s. These discharges were performed at low density and with LHCD (lower hybrid current drive). A new scenario has been recently developed combining ICRH (ion cyclotron resonance heating) and LHCD up to a total power of 10 MW at higher density and limited in time to 60 s by the capability of the ICRH heating systems. The infrared imaging protection system reveals lots of hot spots on the plasma facing components. These localized heat loads are attributed mainly to the fast particles which are accelerated in the near field generated by the IC and LH launchers. The gas injection rate necessary to maintain the plasma density in the high power high density scenarios (LHCD + ICRH) is substantially increased (up to a factor 3). Particle balance analysis based on pressure measurements shows that the absolute in-vessel retention rate, computed after 30 s of plasma is roughly equivalent in both scenarios (3.10{sup 20} D/s), whatever the ICRH power (from 0 to 4 MW) and the line integrated plasma density (from 2.5 to 4.10{sup 19} m{sup -2}) are. This result could indicate that the retention mechanisms could be dominated by wall processes such as diffusion in carbon porosities rather than plasma processes such as co-deposition, dependent on edge conditions. (A.C.)

  12. Speech perception with interaction-compensated simultaneous stimulation and long pulse durations in cochlear implant users.

    Science.gov (United States)

    Schatzer, Reinhold; Koroleva, Inna; Griessner, Andreas; Levin, Sergey; Kusovkov, Vladislav; Yanov, Yuri; Zierhofer, Clemens

    2015-04-01

    Early multi-channel designs in the history of cochlear implant development were based on a vocoder-type processing of frequency channels and presented bands of compressed analog stimulus waveforms simultaneously on multiple tonotopically arranged electrodes. The realization that the direct summation of electrical fields as a result of simultaneous electrode stimulation exacerbates interactions among the stimulation channels and limits cochlear implant outcome led to the breakthrough in the development of cochlear implants, the continuous interleaved (CIS) sampling coding strategy. By interleaving stimulation pulses across electrodes, CIS activates only a single electrode at each point in time, preventing a direct summation of electrical fields and hence the primary component of channel interactions. In this paper we show that a previously presented approach of simultaneous stimulation with channel interaction compensation (CIC) may also ameliorate the deleterious effects of simultaneous channel interaction on speech perception. In an acute study conducted in eleven experienced MED-EL implant users, configurations involving simultaneous stimulation with CIC and doubled pulse phase durations have been investigated. As pairs of electrodes were activated simultaneously and pulse durations were doubled, carrier rates remained the same. Comparison conditions involved both CIS and fine structure (FS) strategies, either with strictly sequential or paired-simultaneous stimulation. Results showed no statistical difference in the perception of sentences in noise and monosyllables for sequential and paired-simultaneous stimulation with doubled phase durations. This suggests that CIC can largely compensate for the effects of simultaneous channel interaction, for both CIS and FS coding strategies. A simultaneous stimulation paradigm has a number of potential advantages over a traditional sequential interleaved design. The flexibility gained when dropping the requirement of interleaving pulses across electrodes may be instrumental in designing coding strategies for a more accurate transmission of stimulus features such as temporal fine structure or interaural time delays to the auditory nerve. Also, longer pulse phase durations may be implemented while maintaining relatively high stimulation pulse rates. Utilizing longer pulse durations may relax requirements on implant compliance and facilitate the design of more energy-efficient implant receivers for a longer battery lifetime or a reduction in implant size. This article is part of a Special Issue entitled . PMID:25457654

  13. On the operation of a long-pulse KrCl excimer laser

    OpenAIRE

    Casper, Lars Christian

    2007-01-01

    High-power lasers pumped by a gas discharge are extensively used in industrial applications. Of particular importance are lasers pumped by an electric discharge in excimer gas mixtures because this allows the generation of powerful ultraviolet radiation (UV), with wavelengths below 350 nm. Due to the short wavelength, these lasers offer the unique possibility to structure materials on the sub-micron scale, when focused or with mask techniques. Also, the absorption of UV radiation is strong in...

  14. Development of imaging bolometers for long-pulse MFE experiments (invited)

    International Nuclear Information System (INIS)

    We have developed the concept of an imaging bolometer, capable of operation with 100 close-quote s of individual channels, while relying on optical (infrared) readout of the temperature rise in a thin foil. A thin gold foil (0.5 endash 5 μm thick) is sandwiched between pieces of copper. The copper mask (a large thermal mass) has a hole pattern drilled into it to form many open-quotes individual pixels,close quotes effectively forming many separate sensors. This segmented foil/mask combination is exposed on its front side to plasma radiation through a cooled pinhole camera geometry. Simultaneously, a high-resolution infrared camera monitors any temperature change on the backside of the thin foil. A sensitive infrared (IR) camera views the foil through an IR telescope/periscope system, and is shielded from the magnetic and nuclear radiation fields, either by distance and/or material shielding. A simple time-dependent design algorithm, using 1D heat transport to a cold boundary, has been written in MathCad, which allows us to select optimal material and geometries to match the expected plasma conditions. We have built a compact prototype with 149 channels, and tested it successfully both in a vacuum test stand in the laboratory, and on a plasma in the CHS at the National Institute for Fusion Science, subjecting it to electron cyclotron heated and neutral beam injection heated conditions. A water-cooled version has been built for the new LHD. Since the IR imaging bolometer uses only metal parts near the plasma, and has no need for wiring or wiring feedthrus, it is intrinsically radiation hard, and has direct application to ignition device to test engineering concepts (ITER), or ITER-class experiments. copyright 1999 American Institute of Physics

  15. Use of Helical Fields to Allow a Long Pulse Reversed Field Pinch

    Energy Technology Data Exchange (ETDEWEB)

    A. Boozer and N. Pomphrey

    2008-11-20

    The maintenance of the magnetic configuration of a Reversed Field Pinch (RFP) is an unsolved problem. Even a toroidal loop voltage does not suffice to maintain the magnetic configuration in axisymmetry but could if the plasma had helical shaping. The theoretical tools for plasma optimization using helical shaping have advanced, so an RFP could be relatively easily designed for optimal performance with a spatially constant toroidal loop voltage. A demonstration that interesting solutions exist is given.

  16. LONG-PULSE, HIGH-PERFORMANCE DISCHARGES IN THE DIII-D TOKAMAK

    Energy Technology Data Exchange (ETDEWEB)

    T.C. LUCE; M.R. WADE; P.A. POLITZER; S.L. ALLEN; M E. AUSTIN; D.R. BAKER; B.D. BRAY; D.P. BRENNAN; K.H. BURRELL; T.A. CASPER; M.S. CHU; J.D. De BOO; E.J. DOYLE; J.R. FERRON; A.M. GAROFALO; P.GOHIL; I.A. GORELOV; C.M. GREENFIELD; R.J. GROEBNER; W.W. HEIBRINK; C.-L. HSIEH; A.W. HYATT; R.JAYAKUMAR; J.E.KINSEY; R.J. LA HAYE; L.L.LAO; C.J.LASNIER; E.A. LAZARUS; A.W. LEONARD; Y.R.LIN-LIU; J.LOHR; M.A. MAKOWSKI; M.MURAKAMI; C.C.PETTY; R.I. PINSKER; R.PRATER; C.L. RETTIG; T.L. RHODES; B.W. RICE; E.J. STRAIT; T.S. TAYLOR; D.M. THOMAS; A.D. TURNBULL; J.G. WATKINS; W.P.WEST; K.-L. WONG

    2000-10-01

    Significant progress in obtaining high performance discharges for many energy confinement times in the DIII-D tokamak has been realized since the previous IAEA meeting. In relation to previous discharges, normalized performance {approx}10 has been sustained for >5 {tau}{sub E} with q{sub min} >1.5. (The normalized performance is measured by the product {beta}{sub N} H{sub 89} indicating the proximity to the conventional {beta} limits and energy confinement quality, respectively.) These H-mode discharges have an ELMing edge and {beta} {approx}{le} 5%. The limit to increasing {beta} is a resistive wall mode, rather than the tearing modes previously observed. Confinement remains good despite the increase in q. The global parameters were chosen to optimize the potential for fully non-inductive current sustainment at high performance, which is a key program goal for the DIII-D facility in the next two years. Measurement of the current density and loop voltage profiles indicate {approx}75% of the current in the present discharges is sustained non-inductively. The remaining ohmic current is localized near the half radius. The electron cyclotron heating system is being upgraded to replace this remaining current with ECCD. Density and {beta} control, which are essential for operating advanced tokamak discharges, were demonstrated in ELMing H-mode discharges with {beta}{sub N}H{sub 89} {approx} 7 for up to 6.3 s or {approx} 34 {tau}{sub E}. These discharges appear to be in resistive equilibrium with q{sub min} {approx} 1.05, in agreement with the current profile relaxation time of 1.8 s.

  17. RF-sheath assessment of ICRF antenna geometry for long pulses

    International Nuclear Information System (INIS)

    Monitoring powered ion cyclotron resonance frequency (ICRF) antennas in magnetic fusion devices has revealed localized modifications of the plasma edge in the antenna shadow, most of them probably related to an enhanced polarization of the scrape-off layer (SOL) through radio-frequency (RF) sheath rectification. Although tolerable on present short RF pulses, sheaths should be minimized, as they may hinder proper operation of steady-state antennas and other subsystems connected magnetically to them, such as lower hybrid grills. As a first step towards mitigating RF sheaths in the design of future antennas, the present paper analyses the spatial structure of sheath potential maps in their vicinity, in relation with the 3D topology of RF near fields and the geometry of antenna front faces. Various combinations of poloidal radiating straps are first considered, and results are confronted to those inferred from transmission line theory. The dependence of sheath potentials on RF voltages or RF currents is studied. The role of RF near-field symmetries along tilted field lines is stressed to interpret such effects as that of strap phasing. A generalization of the 'dipole effect' is proposed. With similar arguments, the behavior of Faraday screen corners, where hot spots concentrate on Tore-Supra (TS), is then studied. The merits of aligning the antenna structure with the tilted magnetic field are thus discussed. The effect of switching from TS (high RF voltage near corners) to ITER-like electrical configurations of the straps (high voltage near equatorial plane) is also analyzed. (authors)

  18. High-power microwave transmission and launching systems for fusion plasma heating systems

    International Nuclear Information System (INIS)

    Microwave power in the 30- to 300-GHz frequency range is becoming widely used for heating of plasma in present-day fusion energy magnetic confinement experiments. Microwave power is effective in ionizing plasma and heating electrons through the electron cyclotron heating (ECH) process. Since the power is absorbed in regions of the magnetic field where resonance occurs and launching antennas with narrow beam widths are possible, power deposition location can be highly controlled. This is important for maximizing the power utilization efficiency and improving plasma parameters. Development of the gyrotron oscillator tube has advanced in recent years so that a 1-MW continuous-wave, 140-GHz power source will soon be available. Gyrotron output power is typically in a circular waveguide propagating a circular electric mode (such as TE0,2) or a whispering-gallery mode (such as TE15,2), depending on frequency and power level. An alternative high-power microwave source currently under development is the free-electron laser (FEL), which may be capable of generating 2-10 MW of average power at frequencies of up to 500 GHz. The FEL has a rectangular output waveguide carrying the TE0,1 mode. Because of its higher complexity and cost, the high-average-power FEL is not yet as extensively developed as the gyrotron. In this paper, several types of operating ECH transmission systems are discussed, as well systems currently being developed. The trend in this area is toward higher power and frequency due to the improvements in plasma density and temperature possible. Every system requires a variety of components, such as mode converters, waveguide bends, launchers, and directional couplers. Some of these components are discussed here, along with ongoing work to improve their performance. 8 refs

  19. High power microwave transmission systems for electron cyclotron resonance plasma heating

    International Nuclear Information System (INIS)

    This progress report is for the fourth year of a grant from the US Department of Energy for the design, development, and fabrication of ECRF transmission and mode conversion systems to transport microwave power from a gyrotron to a magnetically confined plasma. The development and testing of new and improved components for such systems and underlying theory, where necessary, is the focus of this project. Devising and improving component testing and diagnostic techniques is also an important part of this effort. During the last year, we developed a preliminary design for a Te15,2--TE15,1 mode converter for the MIT 150 GHz gyrotron and considered its performance as the frequency and mode was step tuned. A preliminary design for a combined uptaper and TE15,2--TE15,1 converter for possible use with the Varian 140 GHz gyrotron was also developed. Work was begun on a combined TE15,n uptaper -- mode converter to produce a mode combination which would reduce microwave radiation into an azimuthal waveguide gap. Simple models for the radiation from TE0n and TM0n Vlasov launcher baffles were developed and compared with measurements which were taken in our radiation pattern measurement facility. Work began on testing possible methods for generating high azimuthal index rotating modes. Work on the further refinement of the method of mode content determination from open-end radiation pattern measurement was carried out. An investigation of the Wiener-Hopf method for obtaining open- end radiation patterns produced improved radiation patterns for the TE0n modes in a circular waveguide. 15 refs., 15 figs

  20. RF calculation and thermal-stress analysis of the ECRH launcher on EAST tokamak

    International Nuclear Information System (INIS)

    Highlights: • The new constructing 140 GHz/1 MW/1000 s ECRH system was briefly introduced and the structure of ECRH launcher was detailedly described. • The transmission characteristics of the RF propagation inside the launcher were calculated and the Gaussian beam radius in the resonance layer of plasma was optimized. • Temperature distribution and thermal-stress of mobile mirror were analyzed. • The inner equivalent diameter of water channel in the mobile mirror and the suggested water velocity were analyzed. - Abstract: EAST is a medium sized superconducting tokamak with major radius R = 1.8 m, minor radius a = 0.45 m, plasma current Ip ≤ 1 MA, toroidal field BT ≤ 3.5 T and expected plasma pulse length up to 1000 s. An electron cyclotron resonance heating (ECRH) launcher for four-beam injection is being installed on EAST tokamak. Four electron cyclotron wave beams which are generated from four sets of 140 GHz/1 MW/1000 s gyrotrons will be injected into the plasma by the spherical focusing mirrors and plane mobile mirrors. The focusing mirrors are spherical to focus Gaussian beams after reflection. Four plane mobile mirrors independently steer continuously in the poloidal and toroidal direction controlled by motors. With the suitable distance between mirrors and appropriate focal length of focusing mirror, the beam radius in the resonance layer of plasma is 31.145 mm. The heat from plasma radiation and metal losses is loaded on the mobile mirror. In order to decrease the temperature and thermal stress, the inner equivalent diameter of water channels is 8 mm and the suggested water velocity is 4 m/s

  1. Construction of a 35 GHz 100 kW gyrotron

    International Nuclear Information System (INIS)

    In this work a description of a 35 GHz 100 kW gyrocon is described which is under construction at the National Space Research Institute Plasma Laboratory. Project conceptual aspects are emphasized, specifically high current density thermionic cathodes, high time and spatial resolution intense magnetic fields generation, high-vacuum systems, techniques of ceramic-metal sealing, and high-voltage electrical modulator circuits. (author). 8 refs., 9 figs., 1 tab

  2. Research and Development of 2-frequency (110/138 GHz FADIS for JT-60SA ECHCD system

    Directory of Open Access Journals (Sweden)

    Idei H.

    2015-01-01

    Full Text Available A FAst DIrectional Switch (FADIS of 2-frequency (2-ƒ gyrotron system for the JT-60SA project is being developed under collaboration between Japan Atomic Energy Agency (JAEA and Kyushu University. At first, the frequency drift and dip in the gyrotron operation were measured to consider which kind of FADIS is preferred for application in the Electron Cyclotron Heating and Current Drive (ECHCD system for the JT- 60SA. Various types of the FADIS have been considered. A square corrugated waveguide diplexer system with double resonant rings was considered as one of the most attractive FADIS systems for stable high-power and long-pulse operations in the 2-ƒ JT-60SA ECHCD system.

  3. Tokamak burn cycle study: a data base for comparing long pulse and steady-state power reactors

    International Nuclear Information System (INIS)

    Several distinct operating modes (conventional ohmic, noninductive steady state, internal transformer, etc.) have been proposed for tokamaks. Our study focuses on capital costs and lifetime limitations of reactor subsystems in an attempt to quantify sensitivity to pulsed operation. Major problem areas considered include: thermal fatigue on first wall, limiter/divertor; thermal energy storage; fatigue and eddy current heating in toroidal field coils; electric power supply costs; and noninductive driver costs. We assume a high availability and low cost of energy will be mandatory for a commercial fusion reactor, and we characterize improvements in physics (current drive efficiency) and engineering (superior materials) which will help achieve these goals for different burn cycles

  4. Magnetic structure in the entrance region of spheromaks sustained by a magnetized coaxial plasma gun under long pulse operation

    International Nuclear Information System (INIS)

    The magnetic structure in coaxial-gun-sustained spheromaks has been investigated. The plasma gun has been operated with a small axial/radial bias magnetic flux as compared to the azimuthal magnetic flux produced by the discharge current. Stronger magnetic field is observed in the entrance region (ER) than in the flux conserver (FC). In both ER and FC, the magnetic structure is nearly axisymmetric. The axial magnetic field in ER is amplified up to about sixteen times as large as the bias magnetic field. This amplification is limited by the drastic change in the magnetic structure, which occurs when the discharge current becomes very large. The magnetic structure before the drastic change is interpreted with the Bessel function model. The μ estimation shows that the magnetic structure is mainly determined by the boundary geometry, not by the external magnetic flux and current. (author)

  5. Single-Grain Si TFTs Fabricated by Liquid-Si and Long-Pulse Excimer-Laser

    NARCIS (Netherlands)

    Ishihara, R.; Zhang, J.; Trifunovic, M.; Van der Zwan, M.; Takagishi, H.; Kawajiri, R.; Shimoda, T.; Beenakker, C.I.M.

    2012-01-01

    Solution process of silicon using liquid-Si is attractive for fabrication of high-speed flexible electronics. We have fabricated single-grain Si TFTs on location-controlled Si grains with longpulse excimer laser crystallization of spin-coated liquid Si film. The maximum grain diameter is 3.5μm, and

  6. Wideband long-pulse operation of an efficient electro-optic modulator at 10.6 microns

    Science.gov (United States)

    Harris, N. W.; Grimm, J. G.; Eng, R. S.

    1990-10-01

    A high-efficiency high-power bulk-type CdTe single-sideband electrooptic modulator operating at 10.6 microns was designed by dividing the modulator into two sections and driving each section separately so that the relative phase of the microwave drive and optical beam are identical at the entrance to each section. This was done at selected frequencies at high power and high efficiency and then over a wide instantaneous bandwidth at lower power. High conversion efficiency over a wide microwave band was demonstrated. The experimental data compared well with theoretical predictions, supporting the quantitative theory that predicts further bandwidth improvement with more separately driven modulator sections.

  7. Wideband long-pulse operation of an efficient electro-optic modulator at 10.6 microm.

    Science.gov (United States)

    Harris, N W; Grimm, J G; Eng, R S

    1990-10-15

    High conversion efficiency over a wide microwave band has been achieved in a high-power CdTe single-sideband electro-optic modulator working at 10.6 microm by dividing the modulator into two sections and driving each separately. PMID:19771027

  8. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    International Nuclear Information System (INIS)

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 (micro)s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  9. High-power CW and long-pulse lasers in the green wavelength regime for copper welding

    Science.gov (United States)

    Pricking, Sebastian; Huber, Rudolf; Klausmann, Konrad; Kaiser, Elke; Stolzenburg, Christian; Killi, Alexander

    2016-03-01

    We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we are able to extract up to 8 kW pulse power in the few-millisecond range at a wavelength of 515 nm with a duty cycle of 10%. Careful shaping and stabilization of the polarization and spectral properties leads to a high optical-to-optical efficiency larger than 55%. The beam parameter product is designed and measured to be below 5 mm·mrad which allows the transport by a fiber with a 100 μm core diameter. The fiber and beam guidance optics are adapted to the green wavelength, enabling low transmission losses and stable operation. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows us to produce weld spots with an unprecedented reproducibility in diameter and welding depth. With an optimized set of parameters we could achieve a splatter-free welding process of copper, which is crucial for welding electronic components. Furthermore, the surface condition does not influence the welding process when the green wavelength is used, which allows to skip any expensive preprocessing steps like tin-coating. With minor changes we could operate the laser in cw mode and achieved up to 1.7 kW of cw power at 515 nm with a beam parameter product of 2.5 mm·mrad. These parameters make the laser perfectly suitable for additional applications such as selective laser melting of copper.

  10. Using Adaptive Discrete-Time Gas Supply Control for Long Pulse Arc Discharge of Ion Source on NBI

    Institute of Scientific and Technical Information of China (English)

    SHENG Peng; HU Chundong; SONG Shihua; LIU Sheng; LIU Zhimin

    2008-01-01

    A control model of gas supply system is introduced for ion source and an adaptive discrete-time control algorithm to regulate the hydrogen injection.A real-time feedback control system (RFCS) is designed to control the gas supply for ion source based on the control model and the discrete-time control algorithm.The experimental results have proved that RFCS could regulate the gas supply smoothly,suppress the arc's abrupt over-current at the end of the ion source discharging,prolong the discharge pulse and stabilize the ion concentration.With RFCS,the ion source for neutral beam injection has reached its longest pulse with a length of 4.5 seconds in a stable status.

  11. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl A [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mccuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrato [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rowton, Lawrence [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Scarpetti, Raymond [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Hughes, Thomas [Los Alamos National Laboratory; Anaya, Richard [LLNL; Caporaso, George [LLNL; Chambers, Frank [LLNL; Chen, Yu - Jiuan [LLNL; Falabella, Steve [LLNL; Guethlein, Gary [LLNL; Raymond, Brett [LLNL; Richardson, Roger [LLNL; Trainham, C [NSTEC/STL; Watson, Jim [LLNL; Weir, John [LLNL; Genoni, Thomas [VOSS; Toma, Carsten [VOSS

    2009-01-01

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 {micro}s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  12. Late-time radiography of beryllium ignition-target ablators in long-pulse gas-filled hohlraums

    International Nuclear Information System (INIS)

    A multiple-laboratory campaign is underway to qualify beryllium as a fusion capsule ablator for the National Ignition Facility [Moses and Wuest, Fusion Sci. Technol. 43, 420 (2003)]. Although beryllium has many advantages over other ablator materials, individual crystals of beryllium have anisotropic properties, e.g., sound speed, elastic constants, and thermal expansion coefficients, which may seed hydrodynamic instabilities during the implosion phase of ignition experiments. Experiments based on modeling have begun at the OMEGA laser [Boehly, McCrory, Verdon et al., Fusion Eng. Design 44, 35 (1999)] to create a test bed for measuring instability growth rates with face-on radiography of perturbed beryllium samples with the goal of establishing a specification for microstructure in beryllium used as an ablator. The specification would include the size and distribution of sizes of grains and voids and the impurity content. The experimental platform is a 4 kJ laser-heated (for ∼6 ns) hohlraum that is well modeled for radiation temperature and for shock pressure and breakout timing through the driven beryllium sample. A 1 atm methane gas fill has been used to maintain a clear line of sight through the hohlraum for radiography with acceptable plasma backscatter losses. The peak radiation temperature is 145 eV; the pressure early in the laser pulse is 1 Mbar for over 1 ns. Radiographs of sinusoidally perturbed copper-doped (0.9% by atom) beryllium samples have been obtained more than 10 ns after drive initiation. With the current laser drive, a growth factor approaching ten has been measured for initial 2.5 μm perturbations with on-axis radiography

  13. Efficacy and safety of long-pulse pulsed dye laser delivered with compression versus cryotherapy for treatment of solar lentigines

    Directory of Open Access Journals (Sweden)

    Hassan Seirafi

    2011-01-01

    Full Text Available Background: Although cryotherapy is still the first-line therapy for solar lentigines, because of the side effects such as post-inflammatory hyperpigmentation (PIH, especially in patients with darker skin types, pigment-specific lasers should be considered as a therapy for initial treatment. Aim: The aim of this study is to evaluate the efficacy and safety of cryotherapy compared with 595-nm pulsed dye laser (PDL with cutaneous compression in the treatment of solar lentigines. Materials and Methods: Twenty-two patients (skin type II−IV with facial or hand lentigines participated in this study. Lesions of one side of the face or each hand were randomly assigned and treated with either cryotherapy or PDL. Treatments were performed with radiant exposures of 10 J/cm 2 , 7-mm spot size and 1.5 ms pulse duration with no epidermal cooling. Photographs were taken before treatment and 1-month later. The response rate and side effects were compared. Results: PDL was more likely to produce substantial lightening of the solar lentigines than cryotherapy, especially in skin type III and IV (n = 8, n = 9; P 0.05. PIH was seen only in cryotherapy group. PDL group had only minimal erythema. No purpura was observed. Conclusion: PDL with compression is superior to cryotherapy in the treatment of solar lentigines in darker skin types.

  14. Experiment Study of High-Speed Aluminum Flyers Driven by Long Pulse KrF Excimer Laser

    Institute of Scientific and Technical Information of China (English)

    TIAN; Bao-xian; LIANG; Jing; LI; Ye-jun; WANG; Zhao; HAN; Mao-lan

    2012-01-01

    <正>Laser ablation is an important method to drive high-speed flyers. In the flyer experiments, the technology of side-on shadowgraph was developed to measure the velocities of aluminum flyers. Experimental results of Al flyer track for 50 J and 100 J are shown in Fig. 1.

  15. Design and development of a prototype 25 kV, 10 A long pulse Marx modulator for high power klystron

    Science.gov (United States)

    Acharya, Mahesh; Shrivastava, Purushottam

    2016-02-01

    Research, design, and development of high average power modulators for the proposed Indian Spallation Neutron Source are in progress at Raja Ramanna Centre for Advanced Technology. With this objective, a prototype of 25 kV, 10 A, 1 ms Marx modulator at repetition rate of 1 Hz has been designed and developed which serves as a proof of principle and technology assessment stage for further development of high repetition rate high voltage high average power modulators. Insulated Gate Bipolar Transistor (IGBT) based modules of 2.8 kV switching capability have been used as main modules. The modulator had 8.2% droop in output voltage pulse without any droop compensation circuit. A droop compensation involving 15 corrector modules has been used to reduce the droop up to 1%. We have used IGBT based 250 V switches to realize the corrector module. A microcontroller based control unit was designed and developed for triggering the main and corrector modules. With this control unit, programmable output pulse has been achieved. Electrical isolation between high voltage circuits and control circuit has been achieved by the use of fiber optic based control signal transmission. Output pulses of 1 ms pulse width, 800 ns rise time, and 5 μs fall time have been achieved. The modulator has advantages of modular design, adjustable pulse width, adjustable rise time, and fall time.

  16. High power millimeter wave experiment of ITER relevant electron cyclotron heating and current drive system.

    Science.gov (United States)

    Takahashi, K; Kajiwara, K; Oda, Y; Kasugai, A; Kobayashi, N; Sakamoto, K; Doane, J; Olstad, R; Henderson, M

    2011-06-01

    High power, long pulse millimeter (mm) wave experiments of the RF test stand (RFTS) of Japan Atomic Energy Agency (JAEA) were performed. The system consists of a 1 MW/170 GHz gyrotron, a long and short distance transmission line (TL), and an equatorial launcher (EL) mock-up. The RFTS has an ITER-relevant configuration, i.e., consisted by a 1 MW-170 GHz gyrotron, a mm wave TL, and an EL mock-up. The TL is composed of a matching optics unit, evacuated circular corrugated waveguides, 6-miter bends, an in-line waveguide switch, and an isolation valve. The EL-mock-up is fabricated according to the current design of the ITER launcher. The Gaussian-like beam radiation with the steering capability of 20°-40° from the EL mock-up was also successfully proved. The high power, long pulse power transmission test was conducted with the metallic load replaced by the EL mock-up, and the transmission of 1 MW/800 s and 0.5 MW/1000 s was successfully demonstrated with no arcing and no damages. The transmission efficiency of the TL was 96%. The results prove the feasibility of the ITER electron cyclotron heating and current drive system.

  17. Integrated Operating Scenario to Achieve 100-Second, High Electron Temperature Discharge on EAST

    Science.gov (United States)

    Qian, Jinping; Gong, Xianzu; Wan, Baonian; Liu, Fukun; Wang, Mao; Xu, Handong; Hu, Chundong; Wang, Liang; Li, Erzhong; Zeng, Long; Ti, Ang; Shen, Biao; Lin, Shiyao; Shao, Linming; Zang, Qing; Liu, Haiqing; Zhang, Bin; Sun, Youwen; Xu, Guosheng; Liang, Yunfeng; Xiao, Bingjia; Hu, Liqun; Li, Jiangang; EAST Team

    2016-05-01

    Stationary long pulse plasma of high electron temperature was produced on EAST for the first time through an integrated control of plasma shape, divertor heat flux, particle exhaust, wall conditioning, impurity management, and the coupling of multiple heating and current drive power. A discharge with a lower single null divertor configuration was maintained for 103 s at a plasma current of 0.4 MA, q95 ≈7.0, a peak electron temperature of >4.5 keV, and a central density ne(0)˜2.5×1019 m-3. The plasma current was nearly non-inductive (Vloop heating at 140 GHz, and 0.4 MW modulated neutral deuterium beam injected at 60 kV. This progress demonstrated strong synergy of electron cyclotron and lower hybrid electron heating, current drive, and energy confinement of stationary plasma on EAST. It further introduced an example of integrated “hybrid” operating scenario of interest to ITER and CFETR. supported by the National Magnetic Confinement Fusion Science Foundation of China (Nos. 2015GB102000 and 2014GB103000)

  18. Integrated Operating Scenario to Achieve 100-Second, High Electron Temperature Discharge on EAST

    Institute of Scientific and Technical Information of China (English)

    QIAN Jinping; GONG Xianzu; WAN Baonian; LIU Fukun; WANG Mao; XU Handong; HU Chundong

    2016-01-01

    Stationary long pulse plasma of high electron temperature was produced on EAST for the first time through an integrated control of plasma shape,divertor heat flux,particle exhaust,wall conditioning,impurity management,and the coupling of multiple heating and current drive power.A discharge with a lower single null divertor configuration was maintained for 103 s at a plasma current of 0.4 MA,q95 ≈7.0,a peak electron temperature of >4.5 keV,and a central density ne(0)~ 2.5×1019 m-3.The plasma current was nearly non-inductive (Vloop <0.05 V,poloidal beta ~ 0.9) driven by a combination of 0.6 MW lower hybrid wave at 2.45 GHz,1.4 MW lower hybrid wave at 4.6 GHz,0.5 MW electron cyclotron heating at 140 GHz,and 0.4 MW modulated neutral deuterium beam injected at 60 kV.This progress demonstrated strong synergy of electron cyclotron and lower hybrid electron heating,current drive,and energy confinement of stationary plasma on EAST.It further introduced an example of integrated “hybrid” operating scenario of interest to ITER and CFETR.

  19. Overview on recent W7-AS results

    International Nuclear Information System (INIS)

    During the almost one year shutdown in 1999/2000 the Stellarator W7-AS underwent two major modifications: First, the limiters were replaced by ten divertor modules, and the diagnostic set associated with the plasma boundary and target plate regions was greatly expanded for divertor experiments. Extensive tests of the island divertor concept foreseen for W7-X were started in 2001. Partial plasma detachment is observed for magnetic field configurations with large edge islands and with high neutral beam heating power at core densities of 3x1020 m-3 . At somewhat lower densities stable discharges with good energy confinement and high radiation levels (mainly edge radiation) can be maintained up to pulse lengths of more than 1 s. Secondly, the previously counter tangential neutral beam injector box was shifted to a co-position. Thus, the heating efficiency is increased at low magnetic fields and high densities, where high-β experiments are usually performed, but where counter beam injection suffers from substantial fast ion losses. In first experiments - values up to about 3% were achieved at still only weak MHD-activity. Meanwhile 5 gyrotrons (70 and 140 GHz) are available on W7-AS with a total heating power of up to 2.5 MW. They were used to increase central electron temperatures up to 6.7 keV. The application of electron Bernstein waves was further investigated for plasma heating and as a plasma diagnostic. Heating of a high density divertor discharge and the measurement of electron temperature profiles are demonstrated. Copyright (2002) Australian National University- Research School of Physical Sciences and Engineering

  20. Hair removal in hirsute women with normal testosterone levels: a randomized controlled trial of long-pulsed diode laser vs. intense pulsed light

    DEFF Research Database (Denmark)

    Haak, C S; Jensen, Pernille Nymann; Pedersen, A T;

    2010-01-01

    Hirsutism is a common disorder in women of reproductive age, and androgen disturbances may aggravate the condition. Limited evidence exists regarding efficacy of hair removal in this specific population and no data are available for patients with verified normal testosterone levels....

  1. Fault-Protected Laser Diode Drivers for Improving the Performance and Lifetime of Multiple-Millisecond, Long-Pulse LDAs for NASA LIDAR Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project will develop and deliver to NASA revolutionary laser diode driver technology with intelligent fault protection for driving high power laser diode...

  2. Basic concept for an accelerator-driven subcritical system to be used as a long-pulse neutron source for Condensed Matter research

    Energy Technology Data Exchange (ETDEWEB)

    Vivanco, R., E-mail: raul.vivanco.sanchez@gmail.com [ESS-BILBAO, Parque Tecnológico Bizkaia, Laida Bidea, Edificio 207 B Planta Baja, 48160 Derio (Spain); Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Ghiglino, A.; Vicente, J.P. de; Sordo, F.; Terrón, S.; Magán, M. [ESS-BILBAO, Parque Tecnológico Bizkaia, Laida Bidea, Edificio 207 B Planta Baja, 48160 Derio (Spain); Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Perlado, J.M. [Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Bermejo, F.J. [Instituto de Estructura de la Materia, IEM-CSIC, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid (Spain)

    2014-12-11

    A model for an accelerator-driven subcritical system to be operated as a source of cold neutrons for Condensed Matter research is developed at the conceptual level. Its baseline layout relies upon proven accelerator, spalattion target and fuel array technologies, and consists in a proton accelerator able to deliver some 67.5 mA of proton beam with kinetic energy 0.6 GeV, a pulse length of 2.86 ms, and repetition rate of 14 Hz. The particle beam hits a target of conventional design that is surrounded by a multiplicative core made of fissile/fertile material, composed by a subcritical array of fuel bars made of aluminium Cermet cooled by light water poisoned with boric acid. Relatively low enriched uranium is chosen as fissile material. An optimisation of several parameters is carried out, using as components of the objective function several characteristics pertaining the cold neutron pulse. The results show that the optimal device will deliver up to 80% of the cold neutron flux expected for some of the ongoing projects using a significantly lower proton beam power than that managed in such projects. The total power developed within the core rises up to 22.8 MW, and the criticality range shifts to a final k{sub eff} value of around 0.9 after the 50 days cycle.

  3. New Radiation Input/Output Systems for Millimeter-Wave Gyrotron Traveling-Wave Tubes

    Science.gov (United States)

    Denisov, G. G.; Bogdashov, A. A.; Gachev, I. G.; Mishakin, S. V.; Samsonov, S. V.

    2016-03-01

    We consider in detail the method allowing one to input and output the microwave radiation produced by an elecrovacuum amplifier through the same barrier window, which was proposed earlier, in the context of its application in a traveling-wave tube based on a waveguide with a helically corrugated surface. Special attention is given to the splitter of differently polarized radiation, and the results of studying this splitter at wavelengths of about 6 and 1 mm theoretically and experimentally are presented.

  4. Klystrons, traveling wave tubes, magnetrons, crossed-field amplifiers, and gyrotrons

    CERN Document Server

    Gilmour, A S

    2011-01-01

    Microwave tubes are vacuum electron devices used for the generation and amplification of radio frequencies in the microwave range. An established technology area, the use of tubes remains essential in the field today for high-power applications. The culmination of the author's 50 years of industry experience, this authoritative resource offers you a thorough understanding of the operations and major classes of microwave tubes.Minimizing the use of advanced mathematics, the book places emphasis on clear qualitative explanations of phenomena. This practical reference serves as an excellent intro

  5. Dynamic nuclear polarization at 9 T using a novel 250 GHz gyrotron microwave source

    OpenAIRE

    Bajaj, V. S.; Farrar, C. T.; Hornstein, M.K.; Mastovsky, I.; Vieregg, J.; Bryant, J; Eléna, B.; Kreischer, K.E.; Temkin, R.J.; Griffin, R G

    2003-01-01

    In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9 T (250 GHz for g = 2 electrons, 380 MHz for [superscript 1]H). In these experiments, [superscript 1]H enhancements of up to 170 ± 50 have been observed in 1-[superscript 13]C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in [superscrip...

  6. Application of high power microwave vacuum electron devices

    International Nuclear Information System (INIS)

    High power microwave vacuum electron devices can work at high frequency, high peak and average power. They have been widely used in military and civil microwave electron systems, such as radar, communication,countermeasure, TV broadcast, particle accelerators, plasma heating devices of fusion, microwave sensing and microwave heating. In scientific research, high power microwave vacuum electron devices are used mainly on high energy particle accelerator and fusion research. The devices include high peak power klystron, CW and long pulse high power klystron, multi-beam klystron,and high power gyrotron. In national economy, high power microwave vacuum electron devices are used mainly on weather and navigation radar, medical and radiation accelerator, TV broadcast and communication system. The devices include high power pulse and CW klystron, extended interaction klystron, traveling wave tube (TWT), magnetron and induced output tube (IOT). The state of art, common technology problems and trends of high power microwave vacuum electron devices are introduced in this paper. (authors)

  7. Absorbing coatings for high power millimeter-wave devices and matched loads

    Energy Technology Data Exchange (ETDEWEB)

    Bin, W., E-mail: wbin@ifp.cnr.it [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA/CNR Association, Milano (Italy); Bruschi, A.; Cirant, S. [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA/CNR Association, Milano (Italy); Muzzini, V. [Istituto di Biologia Agro-ambientale e Forestale, Consiglio Nazionale delle Ricerche, Area di Ricerca di Roma 1, Monterotondo, Rome (Italy); Simonetto, A.; Spinicchia, N. [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA/CNR Association, Milano (Italy); Angella, G. [Istituto per l’Energetica e le Interfasi, Consiglio Nazionale delle Ricerche, Milano (Italy); Dell’Era, F. [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA/CNR Association, Milano (Italy); Gantenbein, G.; Leonhardt, W. [Institut für Hochleistungsimpuls-und Mikrowellentechnik, Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Nardone, A. [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA/CNR Association, Milano (Italy); Samartsev, A.; Schmid, M. [Institut für Hochleistungsimpuls-und Mikrowellentechnik, Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany)

    2013-10-15

    Highlights: ► An overview of the activity at IFP-CNR concerning the absorbing coatings is presented. ► The application of the absorbing ceramics to the IFP-CNR matched loads is described. ► B{sub 4}C is presented as a promising material for power absorption in the EC frequency range. ► The most important high power validation tests performed on coatings are described. ► Some results from simulations of the absorption capability of a double layer coating are shown. -- Abstract: In the electron cyclotron frequency range the handling of high power is critical. In some cases an unpredictable amount of stray radiation can reach some components or accumulate in localized regions, with risk of damages caused by thermal overloads, and any uncontrolled reflection represents a danger for the sources. A possibility to mitigate the problem consists in covering some regions exposed to radiation with absorbers. Enhanced absorption of stray radiation lowers requirements on active protection systems in microwave diagnostics. The released heat can be extracted by dedicated cooling systems. The chromium oxide (Cr{sub 2}O{sub 3}), largely tested at IFP-CNR, has been routinely used as internal coating for matched loads. The performances of a variable thickness coating has been tested at high power at Karlsruhe Institute of Technology (KIT), with a 140 GHz gyrotron of the W7-X ECRH system and an averaged power density absorbed at the coating surface higher than 1 MW/m{sup 2} for 3 min. Also boron carbide (B{sub 4}C) has been tested at low power and patented as a millimeter-wave absorber. In the paper, the results of some tests performed on these coatings are given, together with some simulations of the absorption capability based on low power measurements on samples. Finally, some calculations are presented for a coating obtained combining together Cr{sub 2}O{sub 3} and B{sub 4}C.

  8. X波段长脉冲高功率微波产生的实验研究%Experimental investigation of X-band long pulse high-power microwave generation

    Institute of Scientific and Technical Information of China (English)

    张军; 钟辉煌; 舒挺; 刘振祥; 黄科

    2008-01-01

    获得长脉冲高功率微波(HPM)输出是HPM源技术追求的重要目标之一.从物理机理上分析了影响慢波结构HPM器件实现长脉冲HPM输出的因素,并利用长脉冲脉冲功率源和过模慢波结构HPM器件,开展了X波段长脉冲HPM产生实验.实验中,采用介质-铜阴极,并在慢波结构表面镀Cr,在导引磁场约0.7 T、二极管电压约400 kV、电流约10 kA、束流脉宽200 ns的条件下,获得了功率500 MW、脉宽约100 ns、主模为TM01的X波段长脉冲HPM输出.对实验结果的分析表明,脉冲功率源与HPM器件的阻抗不匹配,是导致HPM器件输出微波脉宽比电子束脉宽短、以及HPM器件输出微波功率效率较低的主要原因.

  9. Experiment Study of Long Pulse Laser-Driven Flyer to High Velocity%长脉冲KrF激光驱动高速飞片实验研究

    Institute of Scientific and Technical Information of China (English)

    田宝贤; 梁晶; 王钊; 李业军; 汤秀章

    2012-01-01

    利用侧向阴影成像技术开展了激光驱动高速金属飞片实验研究,并介绍了飞片实验系统与条纹相机时空标定结果.实验在辐照激光波长248 nm、脉宽28 ns、能量100 J、功率密度1.8×1012 W/cm2的条件下加速带有50 μm烧蚀层的5 μm铝飞片至10 km/s左右.讨论了不同条件下加速过程的区别,分析了冲击波对飞片加速过程的影响,并从铝、钽飞片实验对比中发现激光烧蚀不同材料的能量转化效率是不同的.%The technology of side-on shadowgraph was developed to study the velocity of metal flyer driven by laser. The system of flyer experiment,the calibration of time and space axis of streak camera were introduced in the paper. With the laser of 248 nm wavelength, 28 ns pulse duration at laser energy of 100 J and laser intensity of 1. 8 × 1012 W/cm2, the 5 μm aluminum flyer with 50 μm ablation layer was accelerated to 10 km/s. The difference of accelerated process in different conditions was discussed and the effect of shock wave in flyer accelerated process was also analyzed in the paper. Through the comparison of Al and Ta experiment results, it is revealed that the energy conversion efficiency of laser material interaction is different for different materials.

  10. THE PERFORMANCE OF THE 8.4 MW MODULATOR/REGULATOR POWE SYSTEMS FOR THE ELECTRON CYCLOTRON HEATING FACILITY UPGRADE AT DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    S.G.E. PRONKO; S.W. DELAWARE; T.E. HARRIS; D. HOYT; D.H. KELLMAN; R.A. LEGG; M. LONTOC; A. NEREM; J.R. VALENTINE

    2000-11-01

    The DIII-D National Fusion Facility at General Atomics is completing the upgrade of its electron cyclotron heating (ECH) capability from the previous 3 MW at 110 GHz to 6 MW of generated microwave power. An 8.4 MW modulator/regulator (M/R) power system has been designed and constructed. Surplus hardware that was acquired from the Lawrence Livermore National Laboratory (LLNL) Mirror Fusion Test Facility (MFTF program) was used as part of the design foundation. The power system, with a nominal output of -80 kV and 80 A, can supply a pair of gyrotrons with up to 10 second long pulses that may or may not be modulated. The modulator/regulator was designed about the BBC CKQ200-4 tetrode, which was the key component acquired from the LLNL program. In order to meet the performance goals of the program, substantial design modifications were needed to be made on the grid driver amplifier and the closed-loop feedback regulator circuits. Also, a newly designed crowbar switch system, featuring a high speed, thyratron-like triggered gas switch, was implemented. The modulator/regulator performance to date has been demonstrated as having <0.06% peak-to-peak ripple and square wave modulation of 50% amplitude at 2 kHz. The key features of the design of the power system and its performance will be presented in this paper.

  11. Steady state operation of MW heating power using ICH and ECH in LHD

    International Nuclear Information System (INIS)

    Full text of publication follows. The steady-state operation (SSO) of high-performance plasma in the Large Helical Device (LHD) has been progressed steadily by increased heating power of more than 1 MW using ICH and ECH. In the 2012 year campaign, plasma performance of steady state operation was improved to higher density and temperature of 1*1019 m-3 and 2.5 keV for during 20 min. Plasma is sustained by newly installed ICH antenna (HAS antenna which can control the launching parallel wave number) and also using new gyrotron tubes of 77 GHz frequency. The higher wave number operation with dipole phasing of HAS antenna can sustain the higher density plasma steadily in comparison with monopole phasing operation. Typical plasma parameters of long pulse operation of around 20 minutes have been obtained. Bulk ions are helium and minority ion of ICRF heating mode is hydrogen. ECH of 77 GHz frequency is located at plasma center. The radial profiles of electron temperature and density of similar SSO plasma have also been obtained. SSO plasmas are terminated by various reasons. Major reason is arcing occurred inside the ICRF antennas. Local hot spots and erosions of divertor carbon plates are also observed. Particle and heat balances, behaviors of dust and flakes which also frequently terminate the steady state operations are studied and will be presented at the meeting. (authors)

  12. Modification of the collective Thomson scattering radiometer in the search for parametric decay on TEXTOR

    DEFF Research Database (Denmark)

    Nielsen, Stefan Kragh; Salewski, Mirko; Bongers, W.;

    2012-01-01

    Strong scattering of high-power millimeter waves at 140 GHz has been shown to take place in heating and current-drive experiments at TEXTOR when a tearing mode is present in the plasma. The scattering signal is at present supposed to be generated by the parametric decay instability. Here we descr...

  13. Study on High Frequency Gyrotron Microwave Sintering of Nanoceramics%高频回旋管微波烧结纳米陶瓷研究

    Institute of Scientific and Technical Information of China (English)

    范瑛; 韦力凡; 丰杰; 谭云; 鞠炳全; 张卫庄

    2004-01-01

    在高频回旋管微波烧结系统上进行纳米陶瓷烧结研究,制备出氧化锆单元及二元纳米陶瓷样品,对不同烧结工艺制备出的样品做了密度、硬度测试,利用XRD和扫描电镜分析陶瓷样品晶粒特性,以摸索适宜的烧结工艺.探讨了高频回旋管微波烧结纳米陶瓷的可行性.

  14. Korea Superconducting tokamak advanced research project - Development of heating system

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Byung Ho [Korea Atomic Energy Research Institute, Taejon (Korea)

    1998-10-01

    The heating and current drive systems for KSTAR based on multiple technologies (neutral beam, ion cyclotron, lower hybrid and electron cyclotron) have been designed to provide heating and current drive capabilities as well as flexibility in the control of current density and pressure profiles needed to meet the mission and research objectives of the machine. They are designed to operate for long-pulse lengths of up to 300 s. The NBI system initially delivers 8 MW of neutral beam power to the plasma from one co-directed beam line and shall be upgraded to provide 20 MW of neutral beam power with two co-directed beam lines plus one counter-directed beam line. It will be capable of being reconfigured such that the source arrangement is changed from horizontal to vertical stacking, with 6 MW beam power to the plasmas per beam line, in order to facilitate profile control. The RF system initially delivers 6 MW of rf power to the plasma, using a single four-strap antenna mounted in a midplane port. The system will be upgraded to proved 12 MW of rf power through 2 adjacent ports. In the first phase, we completed the basic design of RF system and the system have the capabilities to be operationable for pulse length up to 300 sec and in the 25-60 MHz frequency range. Lower hybrid system initially provides 1.5 MW LH rf power to the plasma at 3.7 GHz through a horizontal port, which has a capability to be operated for pulse length up to 300 sec, and shall be upgraded to provide 4.5 MW of LH rf power to the plasma. In the first phase, we completed the basic design of LHCD system which incorporate the TPX-type launcher and independently phase-changeable transmission system for the fully phased coupler. The ECH system will deliver up to 0.5 MW of power to the plasma for up to 0.5 sec. In the first phase, we completed the basic design of ECH system which includes an 84 GHz gyrotron system, a transmission system, and a launcher. The basic design of the low loss transmission system

  15. Annual report of Naka Fusion Research Establishment for the period from April 1, 1993 to March 31, 1994

    International Nuclear Information System (INIS)

    Research and development activities at Naka Fusion Research Establishment, JAERI, are reported for the period from April 1, 1993 to March 31, 1994. The main objectives of JT-60U experiments in FY1993 were to achieve and sustain high confinement regime with current drive. The JFT-2M experiments progressed in the systematic study of the plasma responses by applying an external helical field and also in the study of the boundary plasma with electric field or current in the scrape off layer (SOL) introduced by the divertor bias system. The study in Plasma Theory and Computation focused on the ion temperature gradient instability, the linear toroidal particle simulation, the MHD stability and the analyses of burning plasma. The progresses on DIII-D experiments were obtained in the studies of divertor radiation, cryopumping and VH-mode plasma. As for the fusion engineering research, further developments of a ceramic vacuum pump and a high-resolution quadrupole mass spectrometer (QMS) were made. A high energy H- beam of 400keV and 0.18A was produced with a current density of 13mA/cm2 for 1s. Many efforts were made in developing the long pulse gyrotron and the high efficiency collector potential depression (CPD) gyrotron in the radio-frequency (RF) technology area. The main progress in the Tritium Systems Test Assembly (under US/Japan collaboration) was to demonstrate the plasma exhaust stream under non-steady tokamak operation. Heating experiments of the development 1m long divertor module for ITER were performed at a heat flux of 15MW/m2 for 30sec. The R and D of the reactor structure were focused on the major components such as non-circular bellows, fail-safe first wall, etc.. The R and D of the blanket technology were focussed on the box structure for ITER shielding blanket and the out-of-reactor testing of ITER breeding blanket. (J.P.N.)

  16. Novel aspects of plasma control in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Humphreys, D.; Jackson, G.; Walker, M.; Welander, A. [General Atomics P.O. Box 85608, San Diego, California 92186-5608 (United States); Ambrosino, G.; Pironti, A. [CREATE/University of Naples Federico II, Napoli (Italy); Vries, P. de; Kim, S. H.; Snipes, J.; Winter, A.; Zabeo, L. [ITER Organization, St. Paul Lez durance Cedex (France); Felici, F. [Eindhoven University of Technology, Eindhoven (Netherlands); Kallenbach, A.; Raupp, G.; Treutterer, W. [Max-Planck Institut für Plasmaphysik, Garching (Germany); Kolemen, E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451 (United States); Lister, J.; Sauter, O. [Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Moreau, D. [CEA, IRFM, 13108 St. Paul-lez Durance (France); Schuster, E. [Lehigh University, Bethlehem, Pennsylvania (United States)

    2015-02-15

    ITER plasma control design solutions and performance requirements are strongly driven by its nuclear mission, aggressive commissioning constraints, and limited number of operational discharges. In addition, high plasma energy content, heat fluxes, neutron fluxes, and very long pulse operation place novel demands on control performance in many areas ranging from plasma boundary and divertor regulation to plasma kinetics and stability control. Both commissioning and experimental operations schedules provide limited time for tuning of control algorithms relative to operating devices. Although many aspects of the control solutions required by ITER have been well-demonstrated in present devices and even designed satisfactorily for ITER application, many elements unique to ITER including various crucial integration issues are presently under development. We describe selected novel aspects of plasma control in ITER, identifying unique parts of the control problem and highlighting some key areas of research remaining. Novel control areas described include control physics understanding (e.g., current profile regulation, tearing mode (TM) suppression), control mathematics (e.g., algorithmic and simulation approaches to high confidence robust performance), and integration solutions (e.g., methods for management of highly subscribed control resources). We identify unique aspects of the ITER TM suppression scheme, which will pulse gyrotrons to drive current within a magnetic island, and turn the drive off following suppression in order to minimize use of auxiliary power and maximize fusion gain. The potential role of active current profile control and approaches to design in ITER are discussed. Issues and approaches to fault handling algorithms are described, along with novel aspects of actuator sharing in ITER.

  17. Novel aspects of plasma control in ITER

    Science.gov (United States)

    Humphreys, D.; Ambrosino, G.; de Vries, P.; Felici, F.; Kim, S. H.; Jackson, G.; Kallenbach, A.; Kolemen, E.; Lister, J.; Moreau, D.; Pironti, A.; Raupp, G.; Sauter, O.; Schuster, E.; Snipes, J.; Treutterer, W.; Walker, M.; Welander, A.; Winter, A.; Zabeo, L.

    2015-02-01

    ITER plasma control design solutions and performance requirements are strongly driven by its nuclear mission, aggressive commissioning constraints, and limited number of operational discharges. In addition, high plasma energy content, heat fluxes, neutron fluxes, and very long pulse operation place novel demands on control performance in many areas ranging from plasma boundary and divertor regulation to plasma kinetics and stability control. Both commissioning and experimental operations schedules provide limited time for tuning of control algorithms relative to operating devices. Although many aspects of the control solutions required by ITER have been well-demonstrated in present devices and even designed satisfactorily for ITER application, many elements unique to ITER including various crucial integration issues are presently under development. We describe selected novel aspects of plasma control in ITER, identifying unique parts of the control problem and highlighting some key areas of research remaining. Novel control areas described include control physics understanding (e.g., current profile regulation, tearing mode (TM) suppression), control mathematics (e.g., algorithmic and simulation approaches to high confidence robust performance), and integration solutions (e.g., methods for management of highly subscribed control resources). We identify unique aspects of the ITER TM suppression scheme, which will pulse gyrotrons to drive current within a magnetic island, and turn the drive off following suppression in order to minimize use of auxiliary power and maximize fusion gain. The potential role of active current profile control and approaches to design in ITER are discussed. Issues and approaches to fault handling algorithms are described, along with novel aspects of actuator sharing in ITER.

  18. 100 GHz electrically tunable planar Bragg grating via nematic liquid crystal overlay towards reconfigurable WDM networks

    OpenAIRE

    Adikan, Faisal Rafiq Mahamd; Gates, James C.; Major, Huw E.; Gawith, Corin B.E.; Smith, Peter G. R.; Dyadyusha, Andriy; Kaczmarek, Malgosia; Sparrow, Ian J.G.

    2007-01-01

    Novel liquid crystal-based integrated optical devices with >140GHz electrical tuning are presented for application towards reconfigurable wavelength division multiplexing (WDM) networks. Initial results with Bragg wavelength tuning covering five 25GHz WDM channel spacing have been achieved with 170V (peak-to-peak) sinusoidal voltages applied across electro-patterned ITO-covered glass electrodes placed 60?m apart. These prototype devices were fabricated using direct UV grating writing, with an...

  19. Demonstration of 100 GHz electrically tunable liquid-crystal Bragg gratings for application in dynamic optical networks

    OpenAIRE

    Adikan, F.R.Mahamd; J.C.Gates; Dyadyusha, A.; Major, H.E.; Gawith, C.B.E.; Sparrow, I.J.G.; Emmerson, G.D.; Kaczmarek, M.; P.G.R.Smith

    2007-01-01

    We demonstrate liquid crystal-based integrated optical devices with >140GHz electrical tuning for potential applications in dynamic optical networks. Bragg wavelength tuning covering five 25GHz WDM channel spacings has been achieved with 170V (peak-to-peak) sinusoidal voltages applied across electro-patterned ITO-covered glass electrodes placed 60?m apart. This tunability range was limited only by the initial grating strength and supply voltage level. We also observed two distinct threshold b...

  20. GaAs single-drift flat-profile IMPATT diodes for CW operation at D band

    Science.gov (United States)

    Eisele, H.; Haddad, G. I.

    1992-01-01

    Single-drift flat-profile GaAs IMPATT diodes were designed for CW operation in the 140 GHz range. The diodes were fabricated from MBE grown material, mounted on diamond heatsinks, and tested in a radial line full height waveguide cavity. An RF output power of 15 mW with a corresponding DC to RF conversion efficiency of 1.5 percent was obtained at 135.3 GHz.

  1. Millimeter-wave brightness temperatures of military vehicles

    Science.gov (United States)

    Nemarich, Joseph; Cassidy, Thomas W.; Shiner, R.; Agravante, Hiroshi H.; Dixon, David; Moffa, Philip; Quon, Bill H.; Yujiri, Larry; Dahlstrom, R.

    1999-07-01

    Millimeter wave (MMW) radiometers operating at 97 and 140 GHz were used to obtain passive MMW images and brightness temperatures of military vehicles at various altitudes and depression angles. The line-scanning radiometer system used for the measurements is described, and several passive MMW images are presented. The upper-bound MMW brightness temperatures of a number of different types of vehicles in an open area were determined and shown to have similar values at various depression angles.

  2. Design of pill-box output window for high power Q-band gyrotron traveling wave tube%Q波段回旋行波管新型盒型输出窗的设计

    Institute of Scientific and Technical Information of China (English)

    陈辉; 王丽; 罗勇; 唐勇

    2015-01-01

    利用等效电路理论,初步设计了窗片厚度为1.32 mm的回旋行波管盒型输出窗,再加入感性膜片,更改窗片形状,最终设计出了能承受25 kW平均功率、相对带宽达到14%、窗片厚度达到1.7 mm的Q波段新型宽频带回旋行波管盒型输出窗;采用高频软件HFSS与有限元分析软件ANSYS协同仿真的新方法对回旋行波管盒型窗进行热特性研究表明,盒型窗理论上功率容量达到62 kW平均功率,说明输出窗窗片承受25 kW平均功率的可行性,窗片中心与边缘的温差为66℃,没有达到陶瓷窗片的临界温差158℃,验证了新型盒型窗设计的合理性.

  3. The DIII-D 3 MW, 110 GHz ECH system

    Science.gov (United States)

    Callis, R. W.; Lohr, J.; Ponce, D.; O'Neill, R. C.; Prater, R.; Luce, T. C.

    1999-09-01

    Three 110 GHz gyrotrons with nominal output power of 1 MW each have been installed and are operational on the DIII-D tokamak. One gyrotron is built by Gycom and has a nominal rating of 1 MW and a 2 s pulse length, with the pulse length being determined by the maximum temperature allowed on the edge cooled Boron Nitride window. The second and third gyrotrons were built by Communications and Power Industries (CPI). The first CPI gyrotron uses a double disc FC-75 cooled sapphire window which has a pulse length rating of 0.8 s at 1 MW, 2 s at 0.5 MW and 10 s at 0.35 MW. The second CPI gyrotron, utilizes a single disc chemical-vapor-deposition diamond window, that employs water cooling around the edge of the disc. Calculation predict that the diamond window should be capable of full 1 MW cw operation. All gyrotrons are connected to the tokamak by a low-loss-windowless evacuated transmission line using circular corrugated waveguide for propagation in the HE11 mode. Each waveguide system incorporates a two mirror launcher which can steer the rf beam poloidally from the center to the outer edge of the plasma. Central current drive experiments with the two gyrotrons with 1.5 MW of injected power drove about 0.17 MA. Results from using the three gyrotron systems will be reported as well as the plans to upgrade the system to 6 MW.

  4. Development of Mode Conversion Waveguides at KIT

    Directory of Open Access Journals (Sweden)

    Jin Jianbo

    2015-01-01

    Full Text Available The development of mode conversion waveguides (launchers for high power gyrotrons has gone through three stages at KIT. Formerly, harmonically deformed launchers have been used in the series gyrotrons developed for the stellarator W7-X. In 2009, a numerical method for the analysis and synthesis of mirror-line launchers was developed at KIT. Such a launcher with adapted mode-converting mirrors for a 2 MW TE34,19-mode, 170GHz coaxial-cavity gyrotron has been designed and tested, and also a mirror-line launcher for the 1MW EU ITER gyrotron has been designed. Recently, based on the Helmholtz-Kirchhoff integral theorem, a novel numerical method for the synthesis of hybrid-type gyrotron launchers has been developed. As an example, TE32,9 mode launchers operating at 170GHz that have been designed using the three different methods are being compared.

  5. Microwave generation for magnetic fusion energy applications

    International Nuclear Information System (INIS)

    This progress report encompasses work on three separate projects, all related to developing sources for electron cyclotron resonance heating of magnetic fusion plasmas. The report is therefore divided into three parts as follows: free electron lasers with small period wigglers; theory and modeling of high frequency, high power gyrotron operation; and depressed collectors for energy recovery in gyrotrons. Task A is experimental and eventually aims at developing CW sources for ECRH at frequencies as high as 600 GHz. Task B provides gyrotron theory and modeling in support of the gyrotron development programs at MIT and Varian. Task C was phased out in the current contract year but recent publications are included in this report in order to create a permanent record for the use of future researchers with interest in the topic of increasing gyrotron efficiency through the use of depressed collectors

  6. 大功率微波真空电子器件的应用%Application of high power microwave vacuum electron devices

    Institute of Scientific and Technical Information of China (English)

    丁耀根; 刘濮鲲; 张兆传; 王勇; 沈斌

    2011-01-01

    大功率微波真空电子器件具有工作频率高、峰值和平均功率大等特点,已广泛应用于微波电子系统,在科学研究和国民经济方面的应用越来越广泛.在科学研究方面,它主要应用在高能粒子加速器和可控热核聚变加热装置等大型科学装置上,主要包括高峰值功率速调管、连续波和长脉冲高功率速调管和高功率回旋管等器件.在国民经济方面,则主要应用于天气雷达、导航雷达、医用和工业辐照加速器、电视广播和通信等微波电子系统,主要包括大功率脉冲和连续波速调管、分布作用速调管、行波管、磁控管和感应输出管等.为此,介绍了这些微波真空电子器件的技术现状、共性技术问题和发展趋势.%High power microwave vacuum electron devices can work at high frequency, high peak and average power. They have been widely used in military and civil microwave electron systems, such as radar, communication, countermeasure, TV broadcast, particle accelerators, plasma heating devices of fusion, microwave sensing and microwave heating. In scientific research, high power microwave vacuum electron devices are used mainly on high energy particle accelerator and fusion research. The devices include high peak power klystron, CW and long pulse high power klystron, multi-beam klystron, and high power gy-rotron. In national economy, high power microwave vacuum electron devices are used mainly on weather and navigation radar, medical and radiation accelerator, TV broadcast and communication system. The devices include high power pulse and CW klystron, extended interaction klystron, traveling wave tube(TWT), magnetron and induced output tube(IOT). The state of art, common technology problems and trends of high power microwave vacuum electron devices are introduced in this paper.

  7. Design and operation of the power installation for the TCV ECR additional heating

    Energy Technology Data Exchange (ETDEWEB)

    Fasel, D.; Favre, A.; Goodman, T.; Henderson, M.; Isoz, P.F.; Perez, A.; Tran, M.Q. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Alex, J. [Thomcast AG, Turgi (Switzerland)

    1996-10-01

    Following a brief introduction to the TCV project, this paper concentrates on the Regulated High Voltage Power Supply (RHVPS) system chosen to supply the nine gyrotrons, distributed in three clusters, that will deliver 4.5 MW of Electron Cyclotron Resonance Heating (ECRH) to TCV plasmas. The configuration of these clusters is described in some detail, including the results of site test both with dummy load (80 kV, 85 A, 2 sec) and the gyrotrons themselves (70 kV, 25 A, 2 sec). Some details are also given of gyrotron auxiliaries, interlock circuitry, control and data acquisition, and integration into TCV control environment. (author) 4 figs., 1 tab., 4 refs.

  8. Millimeter-Wave Broadband Anti-Reflection Coatings Using Laser Ablation of Sub-Wavelength Structures

    CERN Document Server

    Matsumura, Tomotake; Wen, Qi; Hanany, Shaul; Koch, Jürgen; Suttman, Oliver; Schütz, Viktor

    2016-01-01

    We report on the first use of laser ablation to make sub-millimeter, broad-band, anti-reflection coatings (ARC) based on sub-wavelength structures (SWS) on alumina and sapphire. We used a 515 nm laser to produce pyramid-shaped structures with pitch of about 320 \\mu m and total height of near 800 \\mu m. Transmission measurements between 70 and 140 GHz are in agreement with simulations using electromagnetic propagation software. The simulations indicate that SWS ARC with the fabricated shape should have a fractional bandwidth response of $\\Delta \

  9. Broadband notch filter design for millimeter-wave plasma diagnostics

    DEFF Research Database (Denmark)

    Furtula, Vedran; Michelsen, Poul; Leipold, Frank;

    2010-01-01

    Notch filters are integrated in plasma diagnostic systems to protect millimeter-wave receivers from intensive stray radiation. Here we present a design of a notch filter with a center frequency of 140 GHz, a rejection bandwidth of ∼ 900 MHz, and a typical insertion loss below 2 dB in the passband...... in the cylindrical cavities is the fundamental TE11. The performance of the constructed filter is measured using a vector network analyzer monitoring a total bandwidth of 30 GHz. We compare the measurements with numerical simulations. © 2010 EURATOM...

  10. The Real-Time system for MHD activity control in the FTU tokamak

    Directory of Open Access Journals (Sweden)

    Minelli D.

    2012-09-01

    Full Text Available The Real-Time system for the control of the magnetohydrodynamics instabilities in FTU tokamak is presented. It is based on both a-priori information derived from statistical treatment of a database and Real-Time elaboration of live diagnostics data. The analysis codes are executed in different time threads based on multi-processors machines. The actuator is the 2×0.4MW 140 GHz ECRH system equipped with the new fast quasi-optical steerable launcher.

  11. EC-5 fifth international workshop on electron cyclotron emission and electron cyclotron heating

    Energy Technology Data Exchange (ETDEWEB)

    Prater, R.; Lohr, J. [eds.

    1985-12-31

    This report contains papers on the following topics: electron cyclotron emission measurements; electron cyclotron emission theory; electron cyclotron heating; gyrotron development; and ECH systems and waveguide development. These paper have been indexed separately elsewhere. (LSP).

  12. Dispersion of helically corrugated waveguides: Analytical, numerical, and experimental study

    Science.gov (United States)

    Burt, G.; Samsonov, S. V.; Ronald, K.; Denisov, G. G.; Young, A. R.; Bratman, V. L.; Phelps, A. D.; Cross, A. W.; Konoplev, I. V.; He, W.; Thomson, J.; Whyte, C. G.

    2004-10-01

    Helically corrugated waveguides have recently been studied for use in various applications such as interaction regions in gyrotron traveling-wave tubes and gyrotron backward-wave oscillators and as a dispersive medium for passive microwave pulse compression. The paper presents a summary of various methods that can be used for analysis of the wave dispersion of such waveguides. The results obtained from an analytical approach, simulations with the three-dimensional numerical code MAGIC, and cold microwave measurements are analyzed and compared.

  13. 300GHz 材料プロセッシング装置の開発

    OpenAIRE

    光藤, 誠太郎; 坂井, 和喜; 小林, 一生; 中野, 智彰; 出原, 敏孝; 斉藤, 輝雄

    2007-01-01

    High power THz-frequency material processing has great potential for the applications. The gyrotron is a microwave tube capable of delivering very high microwave power in the pulse and CW operation at the THz frequencies. The frequency of gyrotron is proportional to the intensity of magnetic field, because the operation results from the mechanism of “cyclotron resonance maser”. Therefore, in order to achieve high frequency operation, we need a high magnetic field which superconducting magne...

  14. Characterization of high-power RF structures using time-domain field codes

    International Nuclear Information System (INIS)

    We have modeled gyrotron windows and gyrotron amplifier sever structures for TE modes in the 100-150 GHz range and have computed the reflection and transmission characteristics from the field data. Good agreement with frequency domain codes and analytic analysis have been obtained for some simple geometries. We present results for realistic structures with lossy coatings and describe implementation of microwave diagnostics. (Author) 5 figs., 7 refs

  15. Progress of microwave collective Thomson scattering in LHD

    International Nuclear Information System (INIS)

    Microwave collective Thomson scattering (CTS) by using a 77 GHz gyrotron is routinely working in LHD and the improvements of the system is now underway. The targets of this diagnostic are measurements of energetic fast ion distribution and ion ratio. In the present system, 800kW 77 GHz gyrotron is injected horizontally and scattered radiation is received changing scattering angle. The system works with existence of electron cyclotron resonance layer. Thus, most of the power is absorbed at the layer like beam damping and stray radiation dramatically decreases. Gyrotron is modulated at 40 Hz, then, background ECE, which is signal in gyrotron off phase, is subtracted from scattered signal in gyrotron on phase. The perturbation of electron temperature due to the gyrotron injection is almost negligible. Temporal evolution of CTS spectrum is obtained by 32ch filter bank receiver through discharge and fine spectrum is obtained by 10 GHz sampling fast digitizer for 80 ms. Change of the width and asymmetry of CTS spectrum is observed after turning off of tangentially injected neutral beam (NB). This is qualitatively consistent with reduction of fast ion density. Preliminary data of ion ratio between hydrogen and helium are also obtained

  16. ECH on the MTX [Microwave Tokamak Experiment

    International Nuclear Information System (INIS)

    The Microwave Tokamak Experiment (MTX) at LLNL is investigating the heating of high density Tokamak plasmas using an intense pulse FEL. Our first experiments, now beginning, will study the absorption and plasma heating of single FEL pulses (20 ns pulse length and peak power up to 2 GW) at a frequency of 140 GHz. A later phase of experiments also at 140 GHz will study FEL heating at 5 kHz rate for a pulse train up to 50 pulses (35 ns pulse length and peak power up to 4 GW). Future operations are planned at 250 GHz with an average power of 2 MW for a pulse train of 0.5 s. The microwave output of the FEL is transported quasi-optically to the tokamak through a window-less, evacuated pipe of 20 in. diameter, using a six mirror system. Computational modelling of the non-linear absorption for the MTX geometry predicts single-pass absorption of 40% at a density and temperature of 1.8 /times/ 1020m/sup /minus/3/ and 1 keV, respectively. To measure plasma microwave absorption and backscatter, diagnostics are available to measure forward and reflected power (parallel wire grid beam-splitter and mirror directional couplers) and power transmitted through the plasma (segmented calorimeter and waveguide detector). Other fast diagnostics include ECE, Thompson scattering, soft x-rays, and fast magnetic probes. 8 refs., 2 figs

  17. ECH on the MTX

    International Nuclear Information System (INIS)

    The Microwave Tokamak Experiment (MTX) at LLNL is investigating the heating of high density Tokamak plasmas using an intense pulse FEL. Our first experiments, now beginning, will study the absorption and plasma heating of single FEL pulses (20 ns pulse length and peak power up to 2 GW) at a frequency of 140 GHz. A later phase of experiments also at 140 GHz (FY 90) will study FEL heating at 5 kHz rate for a pulse train up to 50 pulses (35 ns pulse length and peak power up to 4 GW). Future operations are planned at 250 GHz with an average power of 2 MW for a pulse train of 0.5 s. The microwave output of the FEL is transported quasi-optically to the tokamak through a window-less, evacuated pipe of 20 in diameter, using a six mirror system. Computational modelling of the non-linear absorption for the MTX geometry predicts single-pass absorption of 40% at a density and temperature of 1.8x1020 m-3 and 1 keV, respectively. To measure plasma microwave absorption and backscatter, diagnostics are available to measure forward and reflected power (parallel wire grid beam-splitter and mirror directional couplers) and power transmitted through the plasma (segmented calorimeter and waveguide detector). Other fast diagnostics include ECE, Thompson scattering, soft x-rays, and fast magnetic probes

  18. Floating data acquisition system for microwave calorimeter measurements on MTX

    International Nuclear Information System (INIS)

    A microwave calorimeter has been designed for making 140-GHz absorption measurements on the MTX. Measurement of the intensity and spatial distribution of the FEL-generated microwave beam on the inner wall will indicate the absorption characteristics of the plasma when heated with a 140 GHz FEL pulse. The calorimeter works by monitoring changes of temperature in silicon carbide tiles located on the inner wall of the tokamak. Thermistors are used to measure the temperature of each tile. The tiles are located inside the tokamak about 1 cm outside of the limiter radius at machine potential. The success of this measurement depends on our ability to float the data acquisition system near machine potential and isolate it from the rest of the vault ground system. Our data acquisition system has 48 channels of thermistor signal conditioning, a multiplexer and digitizer section, a serial data formatter, and a fiber-optic transmitter to send the data out. Additionally, we bring timing signals to the interface through optical fibers to tell it when to begin measurement, while maintaining isolation. The receiver is an HP 200 series computer with a serial data interface; the computer provides storage and local display for the shot temperature profile. Additionally, the computer provides temporary storage of the data until it can be passed to a shared resource management system for archiving. 2 refs., 6 figs

  19. Stellarator News, Issue 38, March 1995

    CERN Document Server

    Rome, J A

    1995-01-01

    Stellarator News, an international journal of the stellarator community, is Published by Fusion Energy Division, Oak Ridge National Laboratory, James A. Rome, Editor In the March 1995 issue . . . **** Exerpts from the U.S. Congress Office of Technology Assment report on TPX and Alternate Concepts. **** Edge transport and turbulence studies on U-3M The turbulent-driven particle flow is shown to be comparable with the equilibrium flow at the boundary of the configuration under Alfven-heating conditions in the U-3M torsatron. **** Topological aspects of island divertor studies on W7-AS The structure of the edge plasma in W7-AS, observed with probes, television camera, and H-alpha light agrees at low beta with vacuum field calculations: the low-valued resonances at iotabar=5/m are resolved for m = 8 to 11; external perturbations are not significant at the edge, even for iotabar = 5/10. **** 140-GHz second harmonic O-mode electron cyclotron heating at W7-AS First experimental results are presented of 140-GHz secon...

  20. The ECRH system for JET-EP

    International Nuclear Information System (INIS)

    An ECW (electron cyclotron wave) system is being designed for JET. The system will consist of 6 gyrotrons, 1 MW each, in order to deliver 5 MW into the plasma. An extension of 2 more gyrotrons is recently being considered. The system will especially be designed to enable the control of neo-classical tearing modes (NTM). Furthermore, heating and current drive is foreseen in a large number of different target plasma configurations and the control of the ratio of the electron and ion temperatures. The frequency, 113.3 GHz, is selected to enable a wide range of operating toroidal magnetic fields from 3 to 4 T and at second harmonic at lower fields and also to allow for a future upgrade to 170 GHz using the same systems, including the double-disk diamond windows. The main elements of the ECW system are: gyrotrons with a depressed collector, 1 MW each, 10 s pulse duration with a diamond window, with Gaussian output mode; main power supplies, up to 60 kV, with a solid-state crowbar to feed two gyrotrons. A series IGBT switch will enable independent control of each gyrotron; evacuated waveguides or quasi-optical mirror lines will be each capable of transmitting 1 MW, having a double-disk diamond window located near the torus as an additional tritium barrier. The total length is in the order of 80 to 100m; a plug-in launcher, steerable in both toroidal and poloidal angle. A trade-off will be made between a single launching mirror per transmission line or two beams per launching mirror in order to have the highest flexibility, but also the narrowest beam size in the plasma. The gyrotron power supplies. The configuration of the collector power supply is based on the connection of two gyrotrons to one existing (former lower hybrid) 60 kV power supply. To limit the energy deposit into an internal arc, IGBT switches are connected in series with the gyrotrons, to disconnect the gyrotron from the power supply within 2 μs. An LR snubber is connected in series with the gyrotrons to

  1. Progress report 1998/1999; Rapport d'activite 1998/1999

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    Among the significant technological achievements of 1998-99, we will note in particular the manufacture of a lower hybrid antenna. This has large size and is shielded from the plasma by side protection incorporating the same technology that is used in the limiter of the CIEL project. This antenna was tested successfully in the autumn 1999; its capacity is 4 MW steady state. Substantial progress was achieved in testing the 118 GHz gyrotrons that are intended to deliver 400 kW with a pulse length of 210 seconds. Pulses lasting some 15.5 seconds were obtained on load during the summer 1999 and were limited only by the performance of the load and by out-gassing. At these pulse lengths, the parameters of the tube are already quasi-stationary. The tests will begin again in the Spring of 2000 with a more suitable load. The very first tests on plasma took place in the Autumn of 1999 showing a strong absorption of the waves by the plasma. Work in the field of the high frequency heating systems focused on problems of local power deposition close to the antenna. This problem is exacerbated, both at the lower hybrid and at the ion cyclotron frequencies, by the need to carry out long pulse discharges. Modelling the localised effects that have been observed contributes to the evolution of the design of both types of antenna and holds out the prospect of fully-validated solutions for the 'next step'. Using the technology developed for the CIEL project in the field of the high heat flux components also made it possible to implement side protections for the antennas that can withstand the temperature rise related to these local effects. Studies in various modes of heating or current drive were continued, in order to explore the corresponding scenarios but also to make progress in modelling the phenomena of wave propagation and absorption. In the field of ion cyclotron waves, the implementation of {sup 3}He minority heating made it possible to identify the conversion of

  2. Progress report 1998/1999

    International Nuclear Information System (INIS)

    Among the significant technological achievements of 1998-99, we will note in particular the manufacture of a lower hybrid antenna. This has large size and is shielded from the plasma by side protection incorporating the same technology that is used in the limiter of the CIEL project. This antenna was tested successfully in the autumn 1999; its capacity is 4 MW steady state. Substantial progress was achieved in testing the 118 GHz gyrotrons that are intended to deliver 400 kW with a pulse length of 210 seconds. Pulses lasting some 15.5 seconds were obtained on load during the summer 1999 and were limited only by the performance of the load and by out-gassing. At these pulse lengths, the parameters of the tube are already quasi-stationary. The tests will begin again in the Spring of 2000 with a more suitable load. The very first tests on plasma took place in the Autumn of 1999 showing a strong absorption of the waves by the plasma. Work in the field of the high frequency heating systems focused on problems of local power deposition close to the antenna. This problem is exacerbated, both at the lower hybrid and at the ion cyclotron frequencies, by the need to carry out long pulse discharges. Modelling the localised effects that have been observed contributes to the evolution of the design of both types of antenna and holds out the prospect of fully-validated solutions for the 'next step'. Using the technology developed for the CIEL project in the field of the high heat flux components also made it possible to implement side protections for the antennas that can withstand the temperature rise related to these local effects. Studies in various modes of heating or current drive were continued, in order to explore the corresponding scenarios but also to make progress in modelling the phenomena of wave propagation and absorption. In the field of ion cyclotron waves, the implementation of 3He minority heating made it possible to identify the conversion of the fast wave into

  3. Annual report of Naka Fusion Research Establishment from April 1, 2004 to March 31, 2005

    International Nuclear Information System (INIS)

    This annual report provides an overview of research and development (R and D) activities at Naka Fusion Research Establishment during the period from 1 April, 2004 to 31 March, 2005, including those performed in collaboration with other research establishments of JAERI, research institutes, and universities. In the JT-60 research program, the pulse length of the tokamak discharge was extended successfully up to 65 s in FY 2003. In FY 2004, following the successful results, optimization of long pulse discharges was continued. The pulse length of the negative-ion based neutral beam injection system has reached up to 25 s with an injection power of 1 MW. In the electron cyclotron wave system, the pulse length has also extended up to 45 s with an RF power of 0.35 MW by using four gyrotrons in a series operation. Sustainment of higher normalized β of βN>2.3 for 22.3 s, or βN>2.5 for 15.5 s has been achieved by exploiting available plasma heating systems. This discharge exhibits not only the high βN, but also high confinement improvement with the H factor of H89P=1.9-2.3 and high normalized fusion performance of G≡H89PβN/q952=0.4-0.5 during the sustainment, where q95 is a safety factor at the edge. G-0.4 corresponds to the fusion energy gain of Q=10 for the ITER standard scenario. The H-mode plasma with H89P-1.4 has been maintained for about 30 s, although degradation of the performance was observed at the later half of the discharge. In the reversed shear plasmas, the operation regime was successfully extended. Demonstration of neoclassical tearing mode stabilization and improvement of plasma performance in the high beta region (βN - 3) has been performed using local current drive by the second harmonic electron cyclotron waves. In addition, a real-time control system of safety factor profile has been developed. The design of National Centralized Tokamak (NCT), which is the superconducting modification of JT-60, progressed both in physics and engineering

  4. Determination of electromagnetic modes in oversized corrugated waveguides on the electron cyclotron resonance heating installation at the tokamak Tore Supra; Determination de modes electromagnetiques de guides d'ondes corrugues surdimensionnes sur l'installation de chauffage des electrons de tokamak Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Courtois, L

    2001-03-09

    Electron cyclotron resonance heating (ECRH) in the Tore Supra tokamak constitutes an important step in the research aimed at obtaining thermonuclear fusion reactions. Electron heating is achieved by transmitting an electromagnetic wave from the oscillators (gyrotrons) to the plasma via the fundamental mode, propagating in oversized corrugated waveguides. Maximizing the proportion of the gyrotron power coupled to the fundamental waveguide mode is essential for the good functioning of the transmission line and for maximizing the effect on the plasma. This thesis gives all necessary tools for finding the proportion of the fundamental mode and all other modes present in passive components and at the output of the gyrotron as installed in the Tore Supra ECRH plant. This characterisation is based on obtaining amplitude and phase diagrams of the electric field on a plane transverse to the propagation axis. The most difficult part of obtaining these diagrams is measuring the phase which, despite the very short wavelength, is measured directly at low power levels. At high power levels the phase is numerically reconstructed from amplitude measurements for gyrotron characterisation. A complete theoretical study of the phase reconstruction code is given including its validation with theoretical diagrams. This study allows the realisation of a modal characterisation unit electromagnetic for measurement of radiated beams and usable in each part of the ECRH installation. At the end, the complete modal characterisation is given at low level for a mode converter and also at high level for the first series gyrotron installed at TORE SUPRA. (author)

  5. Upgrades for the ECH System on DIII-D

    Science.gov (United States)

    Lohr, J.; Cengher, M.; Doane, J. L.; Gorelov, Y. A.; Moeller, C. P.; Ponce, D.; Noraky, S.; Penaflor, B. G.; Kolemen, E.

    2012-10-01

    The gyrotron system for electron cyclotron heating on the DIII-D tokamak is being upgraded with the addition of higher efficiency gyrotrons having collector potential depression. Two new gyrotrons, operating at the present frequency of 110 GHz and generating 1.2 MW per unit, have been manufactured and are being installed and tested. The subsequent group of gyrotrons have been designed to generate 1.5 MW for 10 s pulses at 117.5 GHz. The first of these tubes is presently being manufactured at Communications and Power Industries. By the end of 2013, the system will comprise eight high power gyrotrons and, pending the successful performance of the 1.5 MW tube, an upgrade to a 15 MW system will begin. High voltage power supplies, transmission lines, launchers and associated control and data acquisition systems are included in the upgrades as is enhanced ability to steer the rf beams under a variety of pre-programed and reactive scenarios.

  6. Initial results for a 170 GHz high power ITER waveguide component test stand

    Science.gov (United States)

    Bigelow, Timothy; Barker, Alan; Dukes, Carl; Killough, Stephen; Kaufman, Michael; White, John; Bell, Gary; Hanson, Greg; Rasmussen, Dave

    2014-10-01

    A high power microwave test stand is being setup at ORNL to enable prototype testing of 170 GHz cw waveguide components being developed for the ITER ECH system. The ITER ECH system will utilize 63.5 mm diameter evacuated corrugated waveguide and will have 24 >150 m long runs. A 170 GHz 1 MW class gyrotron is being developed by Communications and Power Industries and is nearing completion. A HVDC power supply, water-cooling and control system has been partially tested in preparation for arrival of the gyrotron. The power supply and water-cooling system are being designed to operate for >3600 second pulses to simulate the operating conditions planned for the ITER ECH system. The gyrotron Gaussian beam output has a single mirror for focusing into a 63.5 mm corrugated waveguide in the vertical plane. The output beam and mirror are enclosed in an evacuated duct with absorber for stray radiation. Beam alignment with the waveguide is a critical task so a combination of mirror tilt adjustments and a bellows for offsets will be provided. Analysis of thermal patterns on thin witness plates will provide gyrotron mode purity and waveguide coupling efficiency data. Pre-prototype waveguide components and two dummy loads are available for initial operational testing of the gyrotron. ORNL is managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under Contract DE-AC-05-00OR22725.

  7. Remote Control System of the TJ-II Microwave Transmission Lines Mirrors

    International Nuclear Information System (INIS)

    The ECRH system of the TJ-II stellarator has two gyrotrons, which deliver a maximum power of 300 kW each at a frequency of 53.2 GHz. Another 28 GHz gyrotron will be used to heat the plasma by electron Bernstein waves (EBWH). The microwave power is transmitted from the gyrotrons to the vacuum chamber by two quasi-optical transmission lines for ECRH and a corrugated waveguide for EBWH. All transmission lines have an internal movable mirror inside the vacuum chamber to focus the beam and to be able to change the launching angle. The control of the beam polarization is very important and the lines have two corrugated mirrors, which actuate as polarizers. In this report the control system of the position of these three internal mirrors and the polarizers of the EBWH transmission line is described. (Author) 20 refs

  8. Fundamental mode rectangular waveguide system for electron-cyclotron resonant heating (ECRH) for tandem mirror experiment-upgrade (TMX-U)

    International Nuclear Information System (INIS)

    We present a brief history of TMX-U's electron cyclotron resonant heating (ECRH) progress. We emphasize the 2-year performance of the system, which is composed of four 200-kW pulsed gyrotrons operated at 28 GHz. This system uses WR42 waveguide inside the vacuum vessel, and includes barrier windows, twists, elbows, and antennas, as well as custom-formed waveguides. Outside the TMX-U vessel are directional couplers, detectors, elbows, and waveguide bends in WR42 rectangular waveguide. An arc detector, mode filter, eight-arm mode converter, and water load in the 2.5-in. circular waveguide are attached directly to the gyrotron. Other specific areas discussed include the operational performance of the TMX-U pulsed gyrotrons, windows and component arcing, alignment, mode generation, and extreme temperature variations. Solutions for a number of these problems are described

  9. Remote Control System of the TJ-II Microwave Transmission Lines Mirrors; Sistema de Control Remoto de los Espejos de las Lineas de Transmision de Microondas del TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Sanchez, A.; Fernandez, A.; Cappa, A.; Gama, J. de la; Olivares, J.; Garcia, R.; Chamorro, M.

    2007-09-27

    The ECRH system of the TJ-II stellarator has two gyrotrons, which deliver a maximum power of 300 kW each at a frequency of 53.2 GHz. Another 28 GHz gyrotron will be used to heat the plasma by electron Bernstein waves (EBWH). The microwave power is transmitted from the gyrotrons to the vacuum chamber by two quasi-optical transmission lines for ECRH and a corrugated waveguide for EBWH. All transmission lines have an internal movable mirror inside the vacuum chamber to focus the beam and to be able to change the launching angle. The control of the beam polarization is very important and the lines have two corrugated mirrors, which actuate as polarizers. In this report the control system of the position of these three internal mirrors and the polarizers of the EBWH transmission line is described. (Author) 20 refs.

  10. 3.6MW Power Supply System of the 170GHz ECH&CD System in KSTAR

    Science.gov (United States)

    Shim, Eun-yong; Ahn, Il-kun; Seo, Tae-won; Lee, Seung-kyo; Bae, Young-soon; Joung, Jin-Hyun; Joung, Mi

    2012-09-01

    A 3.6 MW (-66 kV/55 A) Gyrotron power supply system was developed for the 170 GHz ECH&CD gyrotron system in KSTAR. This power supply system consists of Cathode Power Supply(CPS), Anode Power Supply(APS) and Body Power Supply(BPS). The CPS is using the Pulse Step Modulation by the 32set of IGBT choppers. The respons time of Chopper is very fast. So the cathode voltaget is able to be controlled rapidly. The APS is a sort of voltage devider using zener and switch component. It was achieved 3kHz modulation operation. The BPS is combined the commercial power supply and special high voltage switches. It is very simple topology but 5kHz modulation was accomplished easily. Theses power supply system were installed and commissioned successfully in 2011. This paper presents the topology of the each power supply and test result for 170 GHz gyrotron in KSTAR.

  11. Design of plasmonic photodetector with high absorptance and nano-scale active regions.

    Science.gov (United States)

    Guo, Jingshu; Wu, Zhiwei; Li, Yuan; Zhao, Yanli

    2016-08-01

    We propose a novel plasmonic photodetector with high responsivity, utilizing nano-scale active regions. This design can be applied to diverse materials (group III-V or IV materials) and different operation wavelengths covering the O-U bands. The periodic structure utilizing Surface Plasmon Polariton Bloch Waves (SPP-BWs) has low optical power loss. FDTD simulation shows an absorptance of 74.4% which means a responsivity of about 0.74 A/W at 1550 nm. The low capacitance brings low noise, reduced power consumption, and a high electrical bandwidth which is estimated to be 140 GHz. Among the plasmonic PDs with inherent high speeds but low responsivities, our design makes the obvious progress on improving the absorptance. PMID:27505787

  12. Antenna system analysis and design for automatic detection and real-time tracking of electron Bernstein waves in FTU

    Science.gov (United States)

    Bin, W.; Alessi, E.; Bruschi, A.; D'Arcangelo, O.; Figini, L.; Galperti, C.; Garavaglia, S.; Granucci, G.; Moro, A.

    2014-05-01

    The algorithm for the automatic control of the new front steering antenna of the Frascati Tokamak Upgrade device has been improved, in view of forthcoming experiments aimed at testing the mode conversion of electron cyclotron waves at a frequency of 140 GHz. The existing antenna system has been prepared to provide two-point real-time measurements of electron Bernstein waves and to allow real-time tracking of the optimal conversion region. This required an accurate analysis of the antenna to minimize the risk of a mechanical damage of the movable launching mirrors, when accessing the high toroidal launching angles needed for this kind of experiment. A detailed description is presented of the work carried out to safely reach and validate the desired range of steering angles, which include the region of interest, and a technique is proposed to track and chase the correct line of sight for electron Bernstein waves detection during the shot.

  13. Evaluation of cross-connected waveguides as transfer standards of transmission at high millimetre-wave frequencies

    Science.gov (United States)

    Ridler, Nick; Clarke, Roland; Huang, Hui; Zinal, Sherko

    2016-08-01

    At the present time, transfer and verification standards of transmission coefficient (or, equivalently, transmission loss) are not readily available at high millimetre-wave frequencies (i.e. at frequencies ranging typically from 100 GHz to 300 GHz). In recent years, cross-connected waveguide devices have been proposed to provide calculable standards of transmission loss at these frequencies. This paper investigates the viability of these cross-connected waveguides as transfer standards of transmission for inter-laboratory measurement comparison exercises. This relates to their potential use in activities such as international key comparison exercises and measurement audit programmes. A trial inter-laboratory comparison involving four laboratories using two cross-connected waveguides in the WR-05 waveguide size (covering frequencies from 140 GHz to 220 GHz) is described and includes an analysis of the measurement results obtained during the comparison exercise.

  14. High-frequency resonant tunnelling diode oscillator with high-output power

    Science.gov (United States)

    Wang, Jue; Alharbi, Khalid; Ofiare, Afesomeh; Khalid, Ata; Cumming, David; Wasige, Edward

    2015-10-01

    In this paper, a prototype G-band (140 GHz-220 GHz) monolithic microwave integrated circuit (MMIC) resonant tunneling diode (RTD) oscillator is reported. The oscillator employs two In0.53Ga0.47As/AlAs RTD devices in the circuit to increase the output power. The measured output power was about 0.34 mW (-4.7 dBm) at 165.7 GHz, which is the highest power reported for RTD oscillator in G-band frequency range. This result demonstrates the validity of the high frequency/high power RTD oscillator design. It indicates that RTD devices, as one of the terahertz (THz) source candidates, have promising future for room-temperature THz applications in such as imaging, wireless communication and spectroscopy analysis, etc. By optimizing RTD oscillator design, it is expected that considerably higher power (>1 mW) at THz frequencies (>300 GHz) will be obtained.

  15. Microwave interferometer using 94-GHz solid-state sources

    International Nuclear Information System (INIS)

    A 94-GHz microwave interferometer has been designed for the Tandem Mirror Experiment Upgrade and the Mirror Fusion Test Facility to replace the 140-GHz system. The new system is smaller and has modular single-channel units designed for high reliability. It is magnetically shielded and can be mounted close to the machine, which allows the use of lower power solid-state sources. Test results of the 94-GHz prototype indicate that the phase resolution is better than 10, the Impatt FM noise is 5 MHz wide, and the Gunn FM noise is 6 kHz wide. This paper presents the antenna designs along with the test results and discusses the unique problems associated with diagnosing a high electron temperature plasma in the presence of electron cyclotron resonant heating

  16. Dual-Array Electron Cyclotron Emission Imaging (ECEI): a New Millimeter Wave Imaging System for Electron Temperature Fluctuation on the DIII-D Tokamak

    Science.gov (United States)

    Luhmann, N. C., Jr.; Tobias, B. J.; Domier, C. W.; Kong, X.; Liang, T.; Jaspers, R.; Donne, A. J. H.; Smith, M.; Nazikian, R.; Park, H. K.

    2009-11-01

    A new diagnostic tool has been developed for simultaneous real-time imaging of electron temperature fluctuations at both the high and low field sides. Separate imaging arrays spanning 75 to 110 and 90 to 140 GHz, respectively consist of 160 channels (20 vertical by 8 radial) with ˜1 cm^2 resolution, providing up to 55 cm of vertical plasma coverage. Fluctuations of 1% are measurable on μs time-scales. The technical capabilities of this diagnostic, as well as potential physics issues to be investigated, are discussed. The details of the constituent technologies, including advanced antennas and substrate lenses, quasi-optical planar filter components, and double down-conversion heterodyne signal detection will be addressed.

  17. Qualification Testing of Laser Diode Pump Arrays for a Space-Based 2-micron Coherent Doppler Lidar

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    The 2-micron thulium and holmium-based lasers being considered as the transmitter source for space-based coherent Doppler lidar require high power laser diode pump arrays operating in a long pulse regime of about 1 msec. Operating laser diode arrays over such long pulses drastically impact their useful lifetime due to the excessive localized heating and substantial pulse-to-pulse thermal cycling of their active regions. This paper describes the long pulse performance of laser diode arrays and their critical thermal characteristics. A viable approach is then offered that allows for determining the optimum operational parameters leading to the maximum attainable lifetime.

  18. Conceptual design of an electron cyclotron wave system for NET/ITER

    International Nuclear Information System (INIS)

    Electron Cyclotron waves (ECWs) provide a scheme for electron heating, which, owing to the strong localization of the resonant interaction with the plasma, allows an efficient tailoring of the power deposition profile. In the proposed ITER reference scenario for current drive and heating, ECWs are considered to assist plasma formation, pre-heating, local current profile control near the q=2 surface and possibly for baking the first wall tiles. For these functions, a total power of 20 MW, CW, at a frequency around 120 GHz is needed. A higher frequency system (140 GHz, 20 MW, CW), is also considered to heat the plasma centre and provide burn control. The same system at increased power could be used for plasma heating to ignition. For NET, due to the higher magnetic field, the frequencies needed for the tasks mentioned above are approximately 140 GHz and 160 GHz, respectively. ECWs are also envisaged for bulk heating of the NET plasma. Here, frequencies of about 160 GHz are necessary. A detailed study for the 120 GHz/20 MW ITER reference system has been performed. Scaling rules as well as additional antenna designs for higher frequency systems have been developed. The design principle was to offer a high degree of flexibility for the wide range of envisaged uses of the ECWs. The ECW system should satisfy the physics requirements, advanced requirements of reliability and availability, and must be compatible with the nuclear environment (which requires radiation resistance as well as remote maintenance of at least the antenna part). Therefore, it has been tried to place the most critical components as far away from the machine as possible. To improve the availability, the installation of 15% spare tubes and transmission systems is proposed. (orig.)

  19. 300 GHz ジャイロトロンを用いた材料処理装置の開発

    OpenAIRE

    佐古, 勝英; 谷, 晋仁; 橋本, 秀一; 尾関, 隆則; 光藤, 誠太郎; 立松, 芳典; 斉藤, 輝雄; 出原, 敏孝; SAKO, Katsuhide; TANI, Shinji; HASHIMOTO, Syuiti; Ozeki, Takanori; MITSUDO, Seitaro; TATEMATSU, Yoshinori; SAITO, Teruo

    2010-01-01

    The effective characteristics of high frequency and strong electric field processing wereobserved. One of the interesting effects is the so-called non-thermal effect or microwave effect. In order to widely study the non-thermal effect of ceramics sintering and application of material processing, we developed a material processing system by using the 300 GHz gyrotron FU CW I. This system consists of a 300GHz, 2.3 kW, CW gyrotron with a cryogen free 12 T superconducting magnet, a corrugated cir...

  20. Recent progresses in the 110 GHz ECRF system on JT-60U tokamak

    International Nuclear Information System (INIS)

    The 110 GHz ECRF system on the JT-60U started its operation with a 1 MW gyrotron in 1999. Two additional units were completed in 2000. The forth unit was available to generate the total power of 4 MW in 2001. The 1 MW gyrotron is featured by a collector potential depression structure and a diamond output window. The system has four evacuated waveguide lines in 50-60 m length with nine miter bends, each of which has a diamond window near the antenna. One of the recent progresses in this system is to up-grade the gyrotron, whose previous performance was limited to less than 1 MW x 2 sec by a parasitic oscillation in it. Three of four gyrotrons were improved for suppression of the parasitic oscillation by installing a RF absorber in the beam tunnel. The second progress is to reduce the fluctuation in the acceleration voltage for the high power gyrotron operation. The main DC voltage power supply for the gyrotron is not regulated in the system. Before this progress, a large fluctuation in the DC voltage disturbed the stable gyrotron oscillation when four gyrotrons were simultaneously in operation. The third progress is to improve the transmission efficiency from 60-75% to 70-80% by re-adjusting the alignment of the waveguide lines. By these progresses, a generated power on the best unit has reached up to ∼ 1.2 MW x 4.1 s (∼ 1 MW x 5 s) corresponding to ∼ 1 MW (∼ 0.8 MW) for the injected power into plasmas. The total injected power has been 3 MW x 2 sec (∼ 2.8 MW x 3.6 s) using four units. A local profile control has been performed using two steerable antennas at this power level during a plasma discharge. The test of the feedback control of the steerable antenna linked with the perturbation of electron temperature has been successfully done for stabilization the MHD instability such as NTM. (authors)

  1. High power test of a wideband diplexer with short-slotted metal half mirrors for electron cyclotron current drive system

    International Nuclear Information System (INIS)

    The wideband high power diplexer has been developed for combining and fast switching of high power millimeter waves generated by a dual frequency gyrotron. The actual diplexer was tested at the frequency band of 170 GHz in low power. After adjusting a resonant frequency of diplexer for the gyrotron frequency, the evacuated wideband diplexer with short-slotted metal half mirrors was tested at an incident power of about 150 kW, a pulse duration of 30 ms and a frequency band of 170.2–170.3 GHz. Any discharge damage was not observed in the diplexer

  2. Commissioning activities and first results from the collective Thomson scattering diagnostic on ASDEX Upgrade (invited)

    DEFF Research Database (Denmark)

    Meo, Fernando; Bindslev, Henrik; Korsholm, Søren Bang;

    2008-01-01

    The collective Thomson scattering (CTS) diagnostic installed on ASDEX Upgrade uses millimeter waves generated by the newly installed 1 MW dual frequency gyrotron as probing radiation at 105 GHz. It measures backscattered radiation with a heterodyne receiver having 50 channels (between 100 and 110...... of the diagnostic. It then describes the commissioning activities carried out to date. These activities include gyrotron studies, transmission line alignment, and beam pattern measurements in the vacuum vessel. Overlap experiments in near perpendicular and near parallel have confirmed the successful alignment...

  3. Web data display system based on data segment technology of MDSplus

    International Nuclear Information System (INIS)

    Long pulse operation is the main character of advanced Tokamak, so the technology of data storage and human-data interaction are vital for dealing with the large data generated in long pulse experiment. The Web data display system was designed. The system is based on the ASP. NET architecture, and it reads segmented-record data from MDSplus database by segmented-record technology and displays the data on Web page by using NI Measurement Studio control library. With the segmented-record technology, long pulse data could be divided into many small units, data segments. Users can read the certain data segments from the long pulse data according to their special needs. Also, the system develops an efficient strategy for reading segmented record data, showing the waveforms required by users accurately and quickly. The data display Web system was tested on J-TEXT Tokamak, and was proved to be reliable and efficient to achieve the initial design goal. (authors)

  4. Cascaded Soliton Compression of Energetic Femtosecond Pulses at 1030 nm

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin

    2012-01-01

    We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved.......We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved....

  5. Fusion development and technology

    International Nuclear Information System (INIS)

    This report discusses the following topics: superconducting magnet technology high field superconductors; advanced magnetic system and divertor development; poloidal field coils; gyrotron development; commercial reactor studies -- Aries; ITER physics; ITER superconducting PF scenario and magnet analysis; and safety, environmental and economic factors in fusion development

  6. Investigation of first mirror heating for the collective Thomson scattering diagnostic in ITER

    DEFF Research Database (Denmark)

    Salewski, Mirko; Meo, Fernando; Bindslev, Henrik;

    2008-01-01

    Collective Thomson scattering (CTS) has the capabilities to measure phase space densities of fast ion populations in ITER resolved in configuration space, in velocity space, and in time. In the CTS system proposed for ITER, probing radiation at 60 GHz generated by two 1 MW gyrotrons is scattered...

  7. 1990's annual report of INPE's Plasma Associated Laboratory

    International Nuclear Information System (INIS)

    This is the 1990's annual report of INPE's Plasma Associated Laboratory it contains information on current research developed at the laboratory including quiescent plasma, magnetized plasma, plasma centrifuge, plasma and radiation (gyrotron), ionic propulsion, and toroidal plasma. (A.C.A.S.)

  8. System using a megawatt class millimeter wave source and a high-power rectenna to beam power to a suspended platform

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, Malcolm; Friedman, Herbert W.

    2005-07-19

    A system for beaming power to a high altitude platform is based upon a high power millimeter gyrotron source, optical transmission components, and a high-power receiving antenna (i.e., a rectenna) capable of rectifying received millimeter energy and converting such energy into useable electrical power.

  9. EC power sources: European technological developments towards ITER

    International Nuclear Information System (INIS)

    The activities in Europe towards the development of the EC power sources for ITER are centered on the development of a 170 GHz, 2 MW, CW coaxial cavity gyrotron of collector potential depressed (CPD) type. A gyrotron with a higher unit power than the ITER reference (1 MW) would yield a reduction of the installation costs, a more compact launcher design and, if required, an increase of the power delivered through one port. Tests proving the principle were successfully performed on a short-pulse experimental gyrotron delivering up to 2.2 MW in single mode. Following this success, a coordinated and fully consistent programme of development has been launched. The first industrial 2 MW prototype is now at an advanced stage of construction. The associated superconductive magnet producing 6.86 T on the cavity axis is also being procured. Dummy loads suitable for short and CW operation are also part of the development effort. Finally, a new EC test facility, with the features necessary for the testing of the gyrotron up to full power in CW, has been established and includes a fully solid-state power supply system

  10. PERFORMANCE OF THE DIII-D SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    CALLIS,RW; KAJIWARA,K; LOHR,J; GORELOV,YA; PONCE,D

    2003-08-01

    A271 PERFORMANCE OF THE DIII-D SYSTEM. Three 110 GHz gyrotrons with nominal output power of 1 MW each have been installed and are operational on the DIII-D tokamak. All three gyrotrons were built by Communications and Power Industries (CPI). The CPI gyrotrons utilize a single disc CVD (chemical-vapor-deposition) diamond window that employs water cooling around the edge of the disc. Calculations predict that the CVD diamond window should be capable of full 1 MW cw operation, which is supported by IR camera measurements that show the window reaching equilibrium after 2.5 s. All gyrotrons are connected to the tokamak by low-loss-windowless evacuated transmission line using circular corrugated waveguide for propagation in the HE{sub 11} mode. Each waveguide system incorporates a two-mirror launcher, which can steer the rf beam poloidally from the center to the outer edge of the plasma. Results obtained using the DIII-D ECH systems will be reported.

  11. Spectrum response and analysis of 77 GHz band collective Thomson scattering diagnostic for bulk and fast ions in LHD plasmas

    DEFF Research Database (Denmark)

    Nishiura, M.; Kubo, S.; Tanaka, K.;

    2014-01-01

    cyclotron heating beam. To clarify the diagnostic applicability of the gyrotron in the 77 GHz frequency band, we investigated the dependence of the probe and receiver beam trajectories in plasmas with high electron densities of (4–5) × 1019 m−3 and low electron densities of (1–2) × 1019 m−3. At high density...

  12. Elmo Bumpy Torus proof of principle, Phase II: Title 1 report. Volume IV. Microwave system. Preliminary design report

    International Nuclear Information System (INIS)

    The EBT-P Microwave System provides microwaves for electron cyclotron resonance heating (ECRH) to both stabilize and heat the EBT-P plasma. A 28 gigahertz (GHz) system is required to form the hot electron annulus plasma that provides MHD stabilization to the core plasma. A 60 GHz system is required to heat the core plasma and will provide some second harmonic heating of the hot electron annulus. The principal microwave system elements and their design characteristics are summarized. The microwave system includes 200 kilowatt (kW) gyrotrons at 60 GHz for core heating and 200 kW gyrotrons at 28 GHz for annulus heating. The basic operating complement will be six (6) 60 GHz tubes and two (2) 28 GHz tubes. PACE (Plant and Capital Equipment) procurement will include four (4) 60 GHz gyrotrons with two (2) GHz tubes procured under operations and the two (2) 28 GHz tubes will be provided, with mounts, from the EBT-S program. Each tube is rigidly mounted on an oil filled tank assembly which provides electrical isolation and cooling. All tubes and mounts will be located in the lower level of the torus enclosure. An extensive demineralized water flow system is required to provide gyrotron cooling

  13. Fast ion millimeter wave collective Thomson scattering diagnostics on TEXTOR and ASDEX upgrades

    DEFF Research Database (Denmark)

    Michelsen, S.; Korsholm, Søren Bang; Bindslev, H.;

    2004-01-01

    Collective Thomson scattering (CTS) diagnostic systems for measuring fast ions in TEXTOR and ASDEX Upgrade are described in this article. Both systems use millimeter waves generated by gyrotrons as probing radiation and the scattered radiation is detected with heterodyne receivers having 40...

  14. Contributions to resolving issues impeding the operation of high power microwave devices

    Science.gov (United States)

    Kashyn, Dmytro

    This thesis reports an experimental study aimed at extending high power, high efficiency gyrotron operation to submillimeter wavelengths. A series of experiments carried out both at the University of Maryland and the Institute of Applied Physics of the Russian Academy of Science, succeeded in demonstrating output power at 670 GHz of 180 kilowatts with 20% efficiency (gyrotron voltage was 57 kV and beam current was 16 amperes). The maximum output power achieved in the experiments was 210kW at somewhat higher voltage and current (viz. 58kV and 22A). The achieved output power and efficiency are twice as large as achieved in previous experiments in this frequency range with pulse duration in the range of tens of microseconds. These performance parameters are relevant to a previously proposed application of detecting concealed radioactive materials by air breakdown in a focused beam of sub-millimeter radiation. The 670 GHz gyrotron combined features of two lines of previous experiments: (a) to operate at the required frequency, pulsed solenoids producing 28T magnetic were employed and (b) to obtain high efficiency a very high order mode was used in the gyrotron cavity, as in the experiments with gyrotrons for plasma heating. Evidence of multimode beating was observed in submillimeter output envelope. The excitation of spurious modes, especially during the rise of the gyrotron voltage pulse, was analyzed and the method of avoiding this was proposed which also allows to reduce collector loading in gyrotrons operating in modulated regimes. The present study also includes theoretical analysis of the processes that deepens the understanding of microwave breakdown (arcing) in high power microwave devices. The effect of the dust particles microprotrusions on the device operation was analyzed. These microprotrusions were observed and their negative effects were remedied by careful polishing and machining of the resonator surface. Finally, the generated 670 GHz radiation was

  15. A Multifrequency Notch Filter for Millimeter Wave Plasma Diagnostics based on Photonic Bandgaps in Corrugated Circular Waveguides

    Directory of Open Access Journals (Sweden)

    Wagner D.

    2015-01-01

    Full Text Available Sensitive millimeter wave diagnostics need often to be protected against unwanted radiation like, for example, stray radiation from high power Electron Cyclotron Heating applied in nuclear fusion plasmas. A notch filter based on a waveguide Bragg reflector (photonic band-gap may provide several stop bands of defined width within up to two standard waveguide frequency bands. A Bragg reflector that reflects an incident fundamental TE11 into a TM1n mode close to cutoff is combined with two waveguide tapers to fundamental waveguide diameter. Here the fundamental TE11 mode is the only propagating mode at both ends of the reflector. The incident TE11 mode couples through the taper and is converted to the high order TM1n mode by the Bragg structure at the specific Bragg resonances. The TM1n mode is trapped in the oversized waveguide section by the tapers. Once reflected at the input taper it will be converted back into the TE11 mode which then can pass through the taper. Therefore at higher order Bragg resonances, the filter acts as a reflector for the incoming TE11 mode. Outside of the Bragg resonances the TE11 mode can propagate through the oversized waveguide structure with only very small Ohmic attenuation compared to propagating in a fundamental waveguide. Coupling to other modes is negligible in the non-resonant case due to the small corrugation amplitude (typically 0.05·λ0, where λ0 is the free space wavelength. A Bragg reflector for 105 and 140 GHz was optimized by mode matching (scattering matrix simulations and manufactured by SWISSto12 SA, where the required mechanical accuracy of ± 5 μm could be achieved by stacking stainless steel rings, manufactured by micro-machining, in a high precision guiding pipe. The two smooth-wall tapers were fabricated by electroforming. Several measurements were performed using vector network analyzers from Agilent (E8362B, ABmm (MVNA 8-350 and Rohde&Schwarz (ZVA24 together with frequency multipliers. The

  16. A Multifrequency Notch Filter for Millimeter Wave Plasma Diagnostics based on Photonic Bandgaps in Corrugated Circular Waveguides

    Science.gov (United States)

    Wagner, D.; Bongers, W.; Kasparek, W.; Leuterer, F.; Monaco, F.; Münich, M.; Schütz, H.; Stober, J.; Thumm, M.; Brand, H. v. d.

    2015-03-01

    Sensitive millimeter wave diagnostics need often to be protected against unwanted radiation like, for example, stray radiation from high power Electron Cyclotron Heating applied in nuclear fusion plasmas. A notch filter based on a waveguide Bragg reflector (photonic band-gap) may provide several stop bands of defined width within up to two standard waveguide frequency bands. A Bragg reflector that reflects an incident fundamental TE11 into a TM1n mode close to cutoff is combined with two waveguide tapers to fundamental waveguide diameter. Here the fundamental TE11 mode is the only propagating mode at both ends of the reflector. The incident TE11 mode couples through the taper and is converted to the high order TM1n mode by the Bragg structure at the specific Bragg resonances. The TM1n mode is trapped in the oversized waveguide section by the tapers. Once reflected at the input taper it will be converted back into the TE11 mode which then can pass through the taper. Therefore at higher order Bragg resonances, the filter acts as a reflector for the incoming TE11 mode. Outside of the Bragg resonances the TE11 mode can propagate through the oversized waveguide structure with only very small Ohmic attenuation compared to propagating in a fundamental waveguide. Coupling to other modes is negligible in the non-resonant case due to the small corrugation amplitude (typically 0.05·λ0, where λ0 is the free space wavelength). A Bragg reflector for 105 and 140 GHz was optimized by mode matching (scattering matrix) simulations and manufactured by SWISSto12 SA, where the required mechanical accuracy of ± 5 μm could be achieved by stacking stainless steel rings, manufactured by micro-machining, in a high precision guiding pipe. The two smooth-wall tapers were fabricated by electroforming. Several measurements were performed using vector network analyzers from Agilent (E8362B), ABmm (MVNA 8-350) and Rohde&Schwarz (ZVA24) together with frequency multipliers. The stop bands

  17. Concepts of magnetic filter fields in powerful negative ion sources for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, W., E-mail: kraus@ipp.mpg.de; Fantz, U.; Heinemann, B.; Wünderlich, D. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany)

    2016-02-15

    The performance of large negative ion sources used in neutral beam injection systems is in long pulses mainly determined by the increase of the currents of co-extracted electrons. This is in particular a problem in deuterium and limits the ion currents which are for long pulses below the requirements for the ITER source. In the source of the ELISE test facility, the magnetic field in front of the first grid, which is essential to reduce the electron current, is generated by a current of several kA flowing through the plasma facing grid. Weakening of this field by the addition of permanent magnets placed close to the lateral walls has led to a reduction of the electron current by a factor three without loss of ion current when source was operated in volume production. If this effect can be validated for the cesiated source, it would be a large step towards achieving the ITER parameter in long pulses.

  18. Combining gigawatt level X-band high power microwave beams with an overmoded circular waveguide diplexer

    International Nuclear Information System (INIS)

    The high power microwave (HPM) beam combining results at X-band with an overmoded waveguide diplexer are presented. As the key device for the beam combining experiments, the diplexer is designed, fabricated, and tested. Then the beam combining experiments under short and long pulses are performed at HPM source, respectively. The experiment results reveal that short and long pulse HPM beams have been successfully operated without microwave breakdown at 3-GW with pulse duration of 25 ns and 1.3-GW with pulse duration of 96 ns. According to the experiments, conservative breakdown thresholds for the diplexer are concluded to be 800 kV/cm and 550 kV/cm, respectively, under the short and long pulse HPM conditions

  19. Final report for the tunable driver for the LLNL FEL experiment

    International Nuclear Information System (INIS)

    This section of the report covers the recent operation of the prototype backward-wave oscillator (BWO) gyrotron. The tube was mounted in its fixture on the superconducting magnet, the beam aligned, and microwaves generated. Initial alignment and operation was performed at low wiggler magnet strength (Bw = 9 G) and thus low α = υ perpendicular/υ parallel. The microwaves observed under these conditions were at a frequency just above the electron cyclotron frequency of the interaction region. Identification of these waves is tentatively that of forward waves generated in what is a very long gyrotron cavity. By increasing the wiggler field to ∼ 18 G, the backward wave could then be observed. Voltage tunability of the backward wave was demonstrated and frequencies from 13 GHz to 143 GHz were observed

  20. Initial operation of ECRH heating experiments on the Versator II tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Luckhardt, S.C.; Chen, K.I.; Kirkwood, R.; Porkolab, M.; Singleton, D.; Squire, J.; Villasenor, J.; Lu, Z.

    1987-09-01

    Operation of a 35GHz electron cyclotron heating experiment has begun on Versator II with gyrotron power of 100kW. The EC antenna is located on the high magnetic field side of the plasma and launches linearly polarized radiation in the HE11 hybrid mode with externally controllable polarization and parallel index of refraction. The transmission system provides mode conversion from the TE01 output mode of the gyrotron to the HE11 mode and polarization control. The mode transformation characteristics of the transmission system were measured by means of a computer controlled two dimensional scanning system, and contour plots of the far field radiation pattern of each transmission system element were made and compared with theory. Overall the transmission system is found to be approximately 95% efficient with mode patterns in generally excellent agreement with theory.

  1. Experimental study on resonance relativistic SHF generators on the base of linear induction electron accelerator

    International Nuclear Information System (INIS)

    The results of studies on relativistic SHF-generators - orotron and gyrotron for obtaining data on the quality of a high-current electron beam shaped in the section of a linear induction accelerator are given. Axisymmetric resonators as sections of weak-irregular waveguides were used in both generators. Stable generation of short-wave radiation of 15-20 MW at the efficiency of 5-7% SHF pulse duration of 50 ns was obtained in the orotron at the wave length of 8.5 mm and current of 600 A. Stable generation of 7-10 MW SHF-radiation at the efficiency of 3-5% and pulse duration of 150 ns was observed in the gyrotron at the wave length of 12 mm. Under further acceleration in the following sections of the accelerator the electron beam may be used for obtaining radiation of shorter waves

  2. Infrared and millimeter waves. Volume 13 - Millimeter components and techniques. Part 4

    Science.gov (United States)

    Button, K. J.

    Recent experimentation and theoretical modeling of IR and millimeter-wave devices for various applications are discussed in depth. Attention is given to powerful gyrotrons for thermonuclear research, new, high power coherent, millimeter radiation sources, and a kinetic theory of a harmonic gyrotron oscillator with a slotted resonant structure. Communication, radar and radiometer applications of integrated fin-line components are discussed, and investigations into propagation and mode coupling phenomena in corrugated and smooth-wall circular waveguides are reviewed. The known far-infrared (FIR) properties of inhomogeneous materials are described, including experimentation with normal-metal and insulator composites and with superconductivity. Finally, recent experimental and theoretical work on solid-state spectroscopy with FIR continuous-wave lasers is summarized in comparison with the performance bounds of Fourier spectroscopy.

  3. Injection locking of an electronic maser in the hard excitation mode

    Energy Technology Data Exchange (ETDEWEB)

    Yakunina, K. A. [Saratov State University, 83 Astrakhanskaya St., 410012 Saratov (Russian Federation); Kuznetsov, A. P.; Ryskin, N. M. [Saratov State University, 83 Astrakhanskaya St., 410012 Saratov (Russian Federation); Department of Nonlinear Physics, Saratov Branch, V.A. Kotel' nikov Institute of Radio Engineering and Electronics, 38 Zelenaya St., 410019 Saratov (Russian Federation)

    2015-11-15

    The phenomenon of hard excitation is natural for many electronic oscillators. In particular, in a gyrotron, a maximal efficiency is often attained in the hard excitation regime. In this paper, we study the injection-locking phenomena using two models of an electronic maser in the hard excitation mode. First, bifurcation analysis is performed for the quasilinear model described by ordinary differential equations for the slow amplitude and phase. Two main scenarios of transition to the injection-locked mode are described, which are generalizations of the well-known phase-locking and suppression mechanisms. The results obtained for the quasilinear model are confirmed by numerical simulations of a gyrotron with fixed Gaussian structure of the RF field.

  4. Development of a Propagating Millimeter-Wave Beam Position and Profile Monitor in the Oversize Corrugated Waveguide Used in an ECRH System

    Science.gov (United States)

    Shimozuma, Takashi; Kobayashi, Sakuji; Ito, Satoshi; Ito, Yasuhiko; Kubo, Shin; Yoshimura, Yasuo; Nishiura, Masaki; Igami, Hiroe; Takahashi, Hiromi; Mizuno, Yoshinori; Okada, Kohta; Mutoh, Takashi

    2016-01-01

    In a high-power electron cyclotron resonance heating (ECRH) system for plasma heating, a long-distance and low-loss transmission system of the millimeter wave is required. A real-time monitor of the millimeter-wave beam position and its intensity profile, which can be used in a high-power, evacuated, and cooled transmission line, is proposed, designed, manufactured, and tested. The beam-position and profile monitor (BPM) consists of a reflector, Peltier-device array, and a heat-sink, which is installed in the reflector-plate of a miterbend. The BPM was tested using both simulated electric heater power and high-power gyrotron output power. The profile obtained from the monitor using the gyrotron output was well agreed with the burn patter on a thermal sensitive paper. Methods of data analysis and mode-content analysis of a propagating millimeter-wave in the corrugated waveguide are proposed.

  5. High-Power Microwave Transmission and Mode Conversion Program

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, Ronald J. [Univ. of Wisconsin, Madison, WI (United States)

    2015-08-14

    This is a final technical report for a long term project to develop improved designs and design tools for the microwave hardware and components associated with the DOE Plasma Fusion Program. We have developed basic theory, software, fabrication techniques, and low-power measurement techniques for the design of microwave hardware associated gyrotrons, microwave mode converters and high-power microwave transmission lines. Specifically, in this report we discuss our work on designing quasi-optical mode converters for single and multiple frequencies, a new method for the analysis of perturbed-wall waveguide mode converters, perturbed-wall launcher design for TE0n mode gyrotrons, quasi-optical traveling-wave resonator design for high-power testing of microwave components, and possible improvements to the HSX microwave transmission line.

  6. Synthesis method for using in the design of an electron gun for gyrotion

    International Nuclear Information System (INIS)

    In this work a synthesis method is applied to the design of an electron gun for a 94GHz gyrotron. Using the synthesis method, it is found the shape of the electrodes compatible with the laminar flow which minimizes the action of space change on the electron velocity dispersion. A sistematic procedure is presented to fuid the parameters of the synthesis method which, in turn, are closely related to the characteristics of the aptoclechonic system. (author)

  7. Initial results of electron cyclotron range of frequency (ECRF) operation and experiments in JT-60U

    International Nuclear Information System (INIS)

    The 110 GHz 1 MW electron cyclotron range of frequency (ECRF) system was designed and constructed on JT-60U to locally heat and control the plasmas. The gyrotron has a diamond window to transmit RF power with Gaussian mode, which is easily transformed to HE11 mode for the transmission line of the corrugated waveguide. The second diamond window is installed at the inlet of the antenna for a vacuum seal between the transmission line and the JT-60U tokamak. The total length of the transmission line from the gyrotron to the antenna is about 60 m including nine meter bends, The antenna has a focusing mirror and a flat steerable one to focus and to control the RF beam angle mainly in the poloidal direction. In the initial operation, the power of PEC∼0.75 MW for 2 s was successfully injected into plasma when the gyrotron generated the power up to 1 MW. The total transmission efficiency from the gyrotron to the plasma was about 75%. A controllability of local electron heating with the deposition width of =15 cm was well demonstrated by using the steerable mirror. A large downshift in the deposition position was observed at the high Te plasma. Strong central electron heating was obtained from 2.2 to 6.6 keV for PEC∼0.75 MW, 0.3 s at the optimized polarization. An effective electron heating was also obtained up to ∼10 keV during EC injection for ∼1.6 s in the high βp H-mode plasma produced by NBI

  8. Characteristics of a Teflon rod antenna for millimeter and submillimeter wave irradiation on living bodies

    OpenAIRE

    TATSUKAWA, Toshiaki; Doi, Akitaka; TERANAKA, Masato; Takashima, Hitoshi; Goda, Fuminori; Idehara, Toshitaka; Ogawa, Isamu; KANEMAKI, Tomohiro; NISHIZAWA, Seiji; NAMBA, Tunetoyo

    2003-01-01

    The development of a millimeter and submillimeter wave catheter for irradiation on living bodies using a Teflon rod dielectric antenna is described. The power sources of electromagnetic wave are an Impatt oscillator (90 GHz, 0.3 W) and gyrotron (302 GHz, 30 W). Irradiation tests using various Teflon rod dielectric antennas were performed on beef livers. Irradiation results were considered by microwave theory and ray optics.

  9. テフロンフレキシブル導波管によるジャイロトロンFUCW-Ⅰの出力測定

    OpenAIRE

    寺中, 正人; 土井, 昭孚; 立川, 敏明; 光藤, 誠太郎; 斉藤, 輝雄; 出原, 敏孝; 難波, 経豊

    2007-01-01

    In order to develop the millimeter and sub-millimeter wave catheter irradiation apparatus for the living body, the output power by the catheter transmission using Gyrotron FUCW-Ⅰ(GYCOM, Russia) was measured at 300 GHz.The output power was measured by water loading. That was transferred by some flexible Teflon rod waveguides and that was decreased according to Teflon rod length. And we measured the power using dielectric Anti-Reflecting (AR) antennas too.

  10. Wills Plasma Physics Department annual progress report 1984

    International Nuclear Information System (INIS)

    The experimental program continued to be centred around work on the research tokamak TORTUS. Projects included the guiding of Alfven waves along helical magnetic field lines, the excitation of Alfven waves by an antenna and antenna designs for Alfven wave heating. Supporting work included studies of surface waves using the linear SUPPER IV machine, development of lasers and laser diagnostics, development of a neutral particle analyser for measuring ion temperatures, and development of a continuously tunable gyrotron

  11. Free-space power transmission

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    NASA Lewis Research Center organized a workshop on technology availability for free-space power transmission (beam power). This document contains a collection of viewgraph presentations that describes the effort by academia, industry, and the national laboratories in the area of high-frequency, high-power technology applicable to free-space power transmission systems. The areas covered were rectenna technology, high-frequency, high-power generation (gyrotrons, solar pumped lasers, and free electron lasers), and antenna technology.

  12. Preliminary conceptual design of DEMO EC system

    Energy Technology Data Exchange (ETDEWEB)

    Garavaglia, S., E-mail: garavaglia@ifp.cnr.it; Bin, W.; Bruschi, A.; Granucci, G.; Moro, A.; Rispoli, N. [Institute of Plasma Physics “P.Caldirola”, National Research Council of Italy, Milan (Italy); Grossetti, G.; Strauss, D. [IAM-AWP, Kaiserstr. 12, D-76131 Karlsruhe (Germany); Jelonnek, J. [IHM, KIT, Kaiserstr. 12, D-76131 Karlsruhe (Germany); Tran, Q. M. [CRPP, EPFL, EURATOM Association, CH-1015 Lausanne (Switzerland); Franke, T. [EUROfusion Consortium, Boltzmannstr. 2, D-85748 Garching (Germany); Max-Planck-Institut für Plasmaphysik, Garching (Germany)

    2015-12-10

    In the framework of EUROfusion Consortium the Work Package Heating and Current Drive addresses the engineering design and R&D for the electron cyclotron, ion cyclotron and neutral beam systems. This paper reports the activities performed in 2014, focusing on the work done regarding the input for the conceptual design of the EC system, particularly for the gyrotron, the transmission line and the launchers.

  13. Mode competition in fourth-harmonic magnicon amplifiers

    International Nuclear Information System (INIS)

    The magnicon is under development as an efficient high-power microwave amplifier for powering the next generation of electron accelerators for high-energy physics research. In the magnicon RF amplifier, the drive and gain cavities are cylindrical deflection cavities which operate in a rotating TM110-mode and spin up an electron beam to high transverse momentum. As a result of the rotating-mode interaction, the electron beam entry point into the output cavity rotates about the axis at the drive frequency. The gyrotron-like output cavity can be operated at m times the drive frequency by using a mode with an azimuthal index of m, as this mode rotates at m-1 times its RF frequency, thus maintaining synchronism with the electron beam. Previous frequency-multiplying magnicons have used m = 2; in this paper it is shown that magnicons with m = 4 may be practical, provided one also operates the output cavity at the m/2 harmonic of the cyclotron frequency. Operation at higher harmonics lowers the frequency of the deflection cavities allowing lower RF fields, reducing magnet cost and complexity; and a larger electron beam, relaxing beam quality constraints. On the other hand, higher order azimuthal-index magnicon modes interacting at higher order cyclotron interactions are subject to competition with nonsynchronous (gyrotron) modes and are more sensitive to electron beam scanning angle spread. A time-dependent multimode gyrotron code has been modified to examine competition in the output cavity between the phase-synchronous operating mode and other nonsynchronous modes which interact via the conventional gyrotron interaction

  14. Structure Design and Analysis of High-Voltage Power Supply for ECRH

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; HUANG Yiyun; ZHAO Yanping; ZHANG Jian; YANG Lei; GUO Wenjun

    2014-01-01

    In order to develop a high-voltage power supply (HVPS) with high quality parameters,not only its electrical circuit but also its structure should be studied in detail.In this paper,the structure design of the collector power supply for gyrotron is discussed first.Then the electrical field and potential simulations of its main devices are analyzed.Finally,relevant calculations and conclusions are given.

  15. Fusion development and technology

    International Nuclear Information System (INIS)

    This report discusses the following: superconducting magnet technology; high field superconductors; advanced magnetic system and divertor development; poloidal field coils; gyrotron development; commercial reactor studies--aries; ITER physics: alpha physics and alcator R ampersand D for ITER; lower hybrid current drive and heating in the ITER device; ITER superconducting PF scenario and magnet analysis; ITER systems studies; and safety, environmental and economic factors in fusion development

  16. High-power microwave transmission systems for electron-cyclotron-resonance plasma heating

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, R.J.

    1991-08-01

    This progress report is for the sixth year of a grant from the US Department of Energy for the design, development, and fabrication of ECRH transmission and mode conversion systems to transport microwave power from a gyrotron to a magnetically confined plasma. The design and low-power testing of new and improved components for such systems and development of underlying theory is the focus of this project. Devising and improving component testing and diagnostic techniques is also an important part of this effort. The development of possible designs for sections of gyrotrons themselves, such as tapers or Vlasov-type launchers, in support of the Varian gyrotron development program is also considered when appropriate. We also provide support to other groups working on ECR heating of magnetically confined plasmas such as the groups at General Atomics, the University of Texas at Austin, and Lawrence Livermore National Laboratory. During the last year, we designed and had fabricated a two-dimensional Vlasov antenna system for a 110 GHz TE{sub 15,2} mode gyrotron for possible use at General Atomics. The system included the launcher section, a visor, main reflector, and focusing reflector. Programs to generate the tool-path profiles to cut the General Atomics'' Vlasov components on a milling machine were developed. We have also developed state-of-the art theory and programs for three-dimensional whispering-gallery-mode Vlasov antenna systems. A design for a 110 GHz TE{sub 01}-TE{sub 15,2} mode converter system for cold testing WGM Vlasov antenna systems was developed and is currently being fabricated also.

  17. Coupled moderator neutronics

    International Nuclear Information System (INIS)

    Optimizing the neutronic performance of a coupled-moderator system for a Long-Pulse Spallation Source is a new and challenging area for the spallation target-system designer. For optimal performance of a neutron source, it is essential to have good communication with instrument scientists to obtain proper design criteria and continued interaction with mechanical, thermal-hydraulic, and materials engineers to attain a practical design. A good comprehension of the basics of coupled-moderator neutronics will aid in the proper design of a target system for a Long-Pulse Spallation Source

  18. DIII-D Advanced Tokamak Research Overview

    International Nuclear Information System (INIS)

    This paper reviews recent progress in the development of long-pulse, high performance discharges on the DIII-D tokamak. It is highlighted by a discharge achieving simultaneously βNH of 9, bootstrap current fraction of 0.5, noninductive current fraction of 0.75, and sustained for 16 energy confinement times. The physics challenge has changed in the long-pulse regime. Non-ideal MHD modes are limiting the stability, fast ion driven modes may play a role in fast ion transport which limits the stored energy and plasma edge behavior can affect the global performance. New control tools are being developed to address these issues

  19. 7. IAEA Technical Meeting on Steady State Operation of Magnetic Fusion Devices - Booklet of abstracts

    International Nuclear Information System (INIS)

    This meeting has provided an appropriate forum to discuss current issues covering a wide range of technical topics related to the steady state operation issues and also to encourage forecast of the ITER performances. The technical meeting includes invited and contributed papers. The topics that have been dealt with are: 1) Superconducting devices (ITER, KSTAR, Tore-Supra, HT-7U, EAST, LHD, Wendelstein-7-X,...); 2) Long-pulse operation and advanced tokamak physics; 3) steady state fusion technologies; 4) Long pulse heating and current drive; 5) Particle control and power exhaust, and 6) ITER-related research and development issues. This document gathers the abstracts

  20. Improving Lifetime of Quasi-CW Laser Diode Arrays for Pumping 2-Micron Solid State Lasers

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data on the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.