Observation of dynamic interactions between fundamental and second-harmonic modes in a high-power sub-terahertz gyrotron operating in regimes of soft and hard self-excitation.

Science.gov (United States)

Saito, Teruo; Tatematsu, Yoshinori; Yamaguchi, Yuusuke; Ikeuchi, Shinji; Ogasawara, Shinya; Yamada, Naoki; Ikeda, Ryosuke; Ogawa, Isamu; Idehara, Toshitaka

2012-10-12

Dynamic mode interaction between fundamental and second-harmonic modes has been observed in high-power sub-terahertz gyrotrons [T. Notake et al., Phys. Rev. Lett. 103, 225002 (2009); T. Saito et al. Phys. Plasmas 19, 063106 (2012)]. Interaction takes place between a parasitic fundamental or first-harmonic (FH) mode and an operating second-harmonic (SH) mode, as well as among SH modes. In particular, nonlinear excitation of the parasitic FH mode in the hard self-excitation regime with assistance of a SH mode in the soft self-excitation regime was clearly observed. Moreover, both cases of stable two-mode oscillation and oscillation of the FH mode only were observed. These observations and theoretical analyses of the dynamic behavior of the mode interaction verify the nonlinear hard self-excitation of the FH mode.

Gyrotron development at KIT: FULGOR test facility and gyrotron concepts for DEMO

Energy Technology Data Exchange (ETDEWEB)

Schmid, M., E-mail: martin.schmid@kit.edu [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Franck, J.; Kalaria, P.; Avramidis, K.A.; Gantenbein, G.; Illy, S. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Jelonnek, J. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute of High Frequency Techniques and Electronics (IHE), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Pagonakis, I. Gr.; Rzesnicki, T. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Thumm, M. [Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany); Institute of High Frequency Techniques and Electronics (IHE), Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany)

2015-10-15

Highlights: • Substantial extension of the KIT gyrotron test facility FULGOR has started. • FULGOR will be able to test gyrotrons with continuous RF output power up to 4 MW. • Design of 240 GHz gyrotrons for efficient electron cyclotron current drive is progressing. • Output power of 240 GHz gyrotrons with conventional cavity up to 830 kW, with coaxial cavity up to 2 MW is feasible. • Multi-frequency operation with gyrotrons is also possible (170–267 GHz). - Abstract: At the Karlsruhe Institute of Technology (KIT), theoretical and experimental foundations for the development of future gyrotrons for fusion applications are being laid down. This includes the construction of the new Fusion Long Pulse Gyrotron Laboratory (FULGOR) test facility as well as physical design studies towards DEMO-compatible gyrotrons. Initially FULGOR will comprise of a 10 MW CW power supply, a 5 MW water cooling system (upgradeable to 10 MW), a superconducting 10 T magnet, one or two 2 MW ECRH test loads and a new control and data acquisition system for all these elements. The test facility will then be equipped to test the conventional 1 MW or coaxial 2 MW gyrotrons for DEMO, currently under design, as well as possible upgraded gyrotrons for W7-X and ITER. The design of the new high voltage DC power supply (HVDCPS) is flexible enough to handle gyrotrons with 4 MW CW output power (conceivably up to 170 GHz), but also test gyrotrons with higher frequencies (>250 GHz) which, due to physical limitations in the gyrotron design, will require less power but have more stringent demands on voltage stability.

Subterahertz gyrotron developments for collective Thomson scattering in LHDa)

Science.gov (United States)

Notake, T.; Saito, T.; Tatematsu, Y.; Kubo, S.; Shimozuma, T.; Tanaka, K.; Nishiura, M.; Fujii, A.; Agusu, La; Ogawa, I.; Idehara, T.

2008-10-01

Collective Thomson scattering (CTS) is expected to provide the spatially resolved velocity distribution functions of not only thermal and tail ions but also alpha particles resulting from fusion reactions. CTS using gyrotrons with frequency higher than the conventional ones used for plasma heating would have advantages to alleviate refraction, cutoff effects, and background electron cyclotron emission noise. Therefore, a high-power pulse gyrotron operating at approximately 400 GHz is being developed for CTS in Large Helical Device (LHD). A single-mode oscillation with a frequency greater than 400 GHz, applying the second-harmonic resonance, was successfully demonstrated in the first stage. At the same time, concrete feasibility study based on ray tracing, scattering spectra, and electron cyclotron emission calculations has been conducted.

High-frequency gyrotrons and their application to tokamak plasma heating

International Nuclear Information System (INIS)

Kreischer, K.E.

1981-01-01

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

Time-dependent spectrum analysis of high power gyrotrons

Energy Technology Data Exchange (ETDEWEB)

Schlaich, Andreas

2015-07-01

In this work, an investigation of vacuum electronic oscillators capable of generating multi-megawatt continuous wave output power in the millimeter-wave range (so-called gyrotrons) through spectral measurements is presented. The centerpiece is the development of a measurement system with a high dynamic range (50-60 dB) for time-dependent spectrum analysis, covering the frequency range 100-170 GHz with instantaneous bandwidths of 6-12 GHz. Despite relying on heterodyne reception through harmonic mixers, the Pulse Spectrum Analysis (PSA) system maintains RF unambiguity in the spectrogram output through the application of a novel RF reconstruction technique. Using the new possibilities, a wide range of spectral phenomena in gyrotrons has been investigated, such as cavity mode jumps, lowfrequency modulation, frequency tuning in long pulses and the spectral behavior during the presence of an RF window arc. A dedicated investigation on parasitic RF oscillations in W7-X gyrotrons combining several analysis techniques led to the conclusion that after-cavity oscillations can be physical reality in high power gyrotrons, and are the probable cause for the undesired signals observed. Apart from systematic parameter sweeps using the PSA system, an analytical dispersion analysis in the Brillouin diagram was applied, and numerical gyrotron interaction simulations of unprecedented extent were conducted. Furthermore, the improved frequency measurement capabilities were employed to analyze the frequency tuning through thermal expansion and electrostatic neutralization caused by ionization inside the tube in long-pulse operation. By macroscopically modeling the gas dynamics and ionization processes in combination with a fitting process, the time dependences of the two processes could be investigated. In doing so, indication was found that the neutralization in W7-X gyrotrons amounts to only 60% of the electrostatic depression voltage, instead of 100% as widely believed for

Time-dependent spectrum analysis of high power gyrotrons

International Nuclear Information System (INIS)

Schlaich, Andreas

2015-01-01

In this work, an investigation of vacuum electronic oscillators capable of generating multi-megawatt continuous wave output power in the millimeter-wave range (so-called gyrotrons) through spectral measurements is presented. The centerpiece is the development of a measurement system with a high dynamic range (50-60 dB) for time-dependent spectrum analysis, covering the frequency range 100-170 GHz with instantaneous bandwidths of 6-12 GHz. Despite relying on heterodyne reception through harmonic mixers, the Pulse Spectrum Analysis (PSA) system maintains RF unambiguity in the spectrogram output through the application of a novel RF reconstruction technique. Using the new possibilities, a wide range of spectral phenomena in gyrotrons has been investigated, such as cavity mode jumps, lowfrequency modulation, frequency tuning in long pulses and the spectral behavior during the presence of an RF window arc. A dedicated investigation on parasitic RF oscillations in W7-X gyrotrons combining several analysis techniques led to the conclusion that after-cavity oscillations can be physical reality in high power gyrotrons, and are the probable cause for the undesired signals observed. Apart from systematic parameter sweeps using the PSA system, an analytical dispersion analysis in the Brillouin diagram was applied, and numerical gyrotron interaction simulations of unprecedented extent were conducted. Furthermore, the improved frequency measurement capabilities were employed to analyze the frequency tuning through thermal expansion and electrostatic neutralization caused by ionization inside the tube in long-pulse operation. By macroscopically modeling the gas dynamics and ionization processes in combination with a fitting process, the time dependences of the two processes could be investigated. In doing so, indication was found that the neutralization in W7-X gyrotrons amounts to only 60% of the electrostatic depression voltage, instead of 100% as widely believed for

Status of gyrotron development

International Nuclear Information System (INIS)

Craig, L.J.

1987-01-01

This discussion briefly reviews the usual scaling law for predicting higher-power gyrotron performance from existing data, proposes another way of charting improvement progress, perhaps more applicable than the scaling laws, and shows the number of actual experimental vehicles that were required to achieve various high-power CW gyrotron goals. It also briefly touches on some of the key elements and design factors considered for CW gyrotron design. Ongoing megawatt-gyrotron experiments at Varian Associates are presented and gyrotron applications in accelerators, weapons, ceramic sintering, and fusion are assessed

Advanced configuration of hybrid passive filter for reactive power and harmonic compensation.

Science.gov (United States)

Kececioglu, O Fatih; Acikgoz, Hakan; Sekkeli, Mustafa

2016-01-01

Harmonics is one of the major power quality problems for power systems. The harmonics can be eliminated by power filters such as passive, active, and hybrid. In this study, a new passive filter configuration has been improved in addition to the existing passive filter configurations. Conventional hybrid passive filters are not successful to compensate rapidly changing reactive power demand. The proposed configure are capable of compensating both harmonics and reactive power at the same time. Simulation results show that performance of reactive power and harmonic compensation with advanced hybrid passive filter is better than conventional hybrid passive filters.

Harmonic analysis and suppression in hybrid wind & PV solar system

Science.gov (United States)

Gupta, Tripti; Namekar, Swapnil

2018-04-01

The growing demand of electricity has led to produce power through non-conventional source of energy such as solar energy, wind energy, hydro power, energy through biogas and biomass etc. Hybrid system is taken to complement the shortcoming of either sources of energy. The proposed system is grid connected hybrid wind and solar system. A 2.1 MW Doubly fed Induction Generator (DFIG) has been taken for analysis of wind farm whose rotor part is connected to two back-to-back converters. A 250 KW Photovoltaic (PV) array taken to analyze solar farm where inverter is required to convert power from DC to AC since electricity generated through solar PV is in the form of DC. Stability and reliability of the system is very important when the system is grid connected. Harmonics is the major Power quality issue which degrades the quality of power at load side. Harmonics in hybrid system arise through the use of power conversion unit. The other causes of harmonics are fluctuation in wind speed and solar irradiance. The power delivered to grid must be free from harmonics and within the limits specified by Indian grid codes. In proposed work, harmonic analysis of the hybrid system is performed in Electrical Transient Analysis program (ETAP) and single tuned harmonic filter is designed to maintain the utility grid harmonics within limits.

Feasibility of a dual regime gyrotron

International Nuclear Information System (INIS)

Sawant, Ashwini; Jain, Prerit; Kartikeyan, M.V.

2012-01-01

The design concept of a 42/84 GHz, 500 kW, CW, dual-regime gyrotron for ECRH of plasma in an experimental Tokamak will be presented in this paper. Operation at 42 GHz is fundamental where as that in 84 GHz will be second harmonic so that a similar guidance system will be retained for dual regime operation. In this paper, the mode competition and mode selection procedures are presented for such a dual regime operation. Cold cavity design and self-consistent calculations will be carried out for power and efficiencies. (author)

High power, 140 GHz gyrotron

International Nuclear Information System (INIS)

Kreischer, K.E.; Temkin, R.J.; Mulligan, W.J.; MacCabe, S.; Chaplya, R.

1982-01-01

The design and construction of a pulsed 100 kW, 140 GHz gyrotron is described. Initial gyrotron operation is expected in early 1982. Advances in gyrotron theory have also been carried out in support of this experimental research. The application of gyrotrons to plasma diagnostics is also under investigation. (author)

Development of collective Thomson scattering system using the gyrotrons of sub-tera Hz region

International Nuclear Information System (INIS)

Tatematsu, Y.; Kubo, S.; Nishiura, M.

2010-11-01

Collective Thomson scattering (CTS) system is being developed for fusion plasma and CTS measurement on the large helical device (LHD) plasma is discussed. Sub-terahertz frequencies are suitable to the probe beam for CTS on LHD. According to the feasibility study, frequency around 0.4 THz is best for the CTS measurement on LHD high density plasma, and power of 100 kW is required. Thus, only gyrotrons in the sub-terahertz range can meet these parameters. At the first stage of development, second harmonic gyrotrons have been developed. A sealed-off type of gyrotrons has been manufactured to improve a demountable one. Measured output power has increased to about 60 kW. In parallel with the development of gyrotrons, an actual CTS system using a 77 GHz gyrotron originally installed for heating is being developed as a benchmark of LHD CTS. A heterodyne receiver system of a fundamental mixer with a fixed frequency local oscillator was installed on the upstream of the transmission line. The probe beam is 100% power modulated at 50 Hz to separate the scattering component from background ECE. Signals that can be attributed to the CTS were obtained and the analysis method of these data is developed. (author)

Gyrotrons

International Nuclear Information System (INIS)

Ebrahim, N.A.

1987-05-01

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

Startup and mode competition in a 420 GHz gyrotron

Science.gov (United States)

Qixiang Zhao, A.; Sheng Yu, B.; Tianzhong Zhang, C.

2017-09-01

In the experiments of a 420 GHz second-harmonic gyrotron, it is found that the electron beam voltage and current ranges for single mode operation of TE17.4 are slightly narrower than those in the simulation. To explain this phenomenon, the startup scenario has been investigated with special emphasis on mode competition. The calculations indicate that the decreases of the operating ranges are caused by the voltage overshoot in the startup scenario.

High power gyrotrons: a close perspective

International Nuclear Information System (INIS)

Kartikeyan, M.V.

2012-01-01

Gyrotrons and their variants, popularly known as gyrodevices are millimetric wave sources provide very high powers ranging from long pulse to continuous wave (CW) for various technological, scientific and industrial applications. From their conception (monotron-version) in the late fifties until their successful development for various applications, these devices have come a long way technologically and made an irreversible impact on both users and developers. The possible applications of high power millimeter and sub-millimeter waves from gyrotrons and their variants (gyro-devices) span a wide range of technologies. The plasma physics community has already taken advantage of the recent advances of gyrotrons 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 lower hybrid current drive (LHCD) (8 GHz), electron cyclotron resonance heating (ECRH) (28-170-220 GHz), electron cyclotron current drive (ECCD), collective Thomson scattering (CTS), heat-wave propagation experiments, and space-power grid (SPG) applications. Other important applications of gyrotrons are electron cyclotron resonance (ECR) discharges for the generation of multi- charged ions and soft X-rays, as well as industrial materials processing and plasma chemistry. Submillimeter wave gyrotrons are employed in high frequency, broadband electron paramagnetic resonance (EPR) spectroscopy. Additional future applications await the development of novel high power gyro-amplifiers and devices for high resolution radar ranging and imaging in atmospheric and planetary science as well as deep space and specialized satellite communications, RF drivers for next generation high gradient linear accelerators (supercolliders), high resolution Doppler radar, radar ranging and imaging in atmospheric and planetary science, drivers for next-generation high-gradient linear accelerators

Voltage harmonics mitigation through hybrid active power filer

International Nuclear Information System (INIS)

Sahito, A.A.; Tunio, S.M.; Khizer, A.N.

2016-01-01

Fast dynamic response, high efficiency, low cost and small size of power electronic converters have exponentially increased their use in modern power system which resulted in harmonically distorted voltage and currents. Voltage harmonics mainly caused by current harmonics are more dangerous as performance and expected operating life of other power system equipment are affected by harmonically distorted supply voltage. Electronic filter circuits are used to improve system power quality by mitigating adverse effects of harmonics. Hybrid filters having advantages of both passive and active filters are preferred to resolve the problem of harmonics efficiently and avoiding any chance of resonance. In this paper, a three phase three wire network is considered to supply an adjustable speed drive represented by a resistive load connected across a three phase bridge rectifier. Simulation of the considered system shows THD (Total Harmonic Distortion) of 18.91 and 7.61 percentage in supply current and voltage respectively. A HAPF (Hybrid Active Power Filter) is proposed to reduce these THD values below 5 percentage as recommended by IEEE Standard-519. P-Q theorem is used to calculate required parameters for proposed filter, which is implemented through hysteresis control. Simulation results confirm the effectiveness of the designed filter as THD for both current and voltage have reduced below allowable limit of 5 percentage. (author)

Voltage Harmonics Mitigation through Hybrid Active Power Filter

Directory of Open Access Journals (Sweden)

Anwer Ali Sahito

2016-01-01

Full Text Available Fast dynamic response, high efficiency, low cost and small size of power electronic converters have exponentially increased their use in modern power system which resulted in harmonically distorted voltage and currents. Voltage harmonics mainly caused by current harmonics are more dangerous as performance and expected operating life of other power system equipment are affected by harmonically distorted supply voltage. Electronic filter circuits are used to improve system power quality by mitigating adverse effects of harmonics. Hybrid filters having advantages of both passive and active filters are preferred to resolve the problem of harmonics efficiently and avoiding any chance of resonance. In this paper, a three phase three wire network is considered to supply an adjustable speed drive represented by a resistive load connected across a three phase bridge rectifier. Simulation of the considered system shows THD (Total Harmonic Distortion of 18.91 and 7.61% in supply current and voltage respectively. A HAPF (Hybrid Active Power Filter is proposed to reduce these THD values below 5% as recommended by IEEE Standard-519. P-Q theorem is used to calculate required parameters for proposed filter, which is implemented through hysteresis control. Simulation results confirm the effectiveness of the designed filter as THD for both current and voltage have reduced below allowable limit of 5%.

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

International Nuclear Information System (INIS)

Lohr, J.; Calahan, P.; Callis, R.W.

1999-01-01

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

Transmission Line for 258 GHz Gyrotron DNP Spectrometry

Science.gov (United States)

Bogdashov, Alexandr A.; Belousov, Vladimir I.; Chirkov, Alexey V.; Denisov, Gregory G.; Korchagin, Vyacheslav V.; Kornishin, Sergey Yu.; Tai, Evgeny M.

2011-06-01

We describe the design and test results of the transmission line for liquid-state (LS) and solid-state (SS) DNP spectrometers with the second-harmonic 258.6 GHz gyrotron at the Institute of the Biophysical Chemistry Center of Goethe University (Frankfurt). The 13-meter line includes a mode converter, HE11 waveguides, 4 mitre bends, a variable polarizer-attenuator, directional couplers, a water-flow calorimeter and a mechanical switch. A microwave power of about 15 W was obtained in the pure HE11 mode at the spectrometer inputs.

Advanced configuration of hybrid passive filter for reactive power and harmonic compensation

OpenAIRE

Kececioglu, O. Fatih; Acikgoz, Hakan; Sekkeli, Mustafa

2016-01-01

Harmonics is one of the major power quality problems for power systems. The harmonics can be eliminated by power filters such as passive, active, and hybrid. In this study, a new passive filter configuration has been improved in addition to the existing passive filter configurations. Conventional hybrid passive filters are not successful to compensate rapidly changing reactive power demand. The proposed configure are capable of compensating both harmonics and reactive power at the same time. ...

Operation and control of high power Gyrotrons for ECRH systems in SST-1 and Aditya

Energy Technology Data Exchange (ETDEWEB)

Shukla, B.K., E-mail: shukla@ipr.res.in; Bora, D.; Jha, R.; Patel, Jatin; Patel, Harshida; Babu, Rajan; Dhorajiya, Pragnesh; Dalakoti, Shefali; Purohit, Dharmesh

2016-11-15

Highlights: • Operation and control of high power Gyrotrons. • Data acquisition and control (DAQ) for Gyrotron system. • Ignitron based crowbar protection. • VME and PXI based systems. - Abstract: The Electron Cyclotron Resonance Heating (ECRH) system is an important heating system for the reliable start-up of tokamak. The 42 GHz and 82.6 GHz ECRH systems are used in tokamaks SST-1 and Aditya to carry out ECRH related experiments. The Gyrotrons are high power microwave tubes used as a source for ECRH systems. The Gyrotron is a delicate microwave tube, which deliver megawatt level power at very high voltage ∼40–50 kV with the current requirement ∼10 A–50 A. The Gyrotrons are associated with the subsystems like: High voltage power supplies (Beam voltage and anode voltage), dedicated crowbar system, magnet, filament and ion pump power supplies, cooling, interlocks and a dedicated data acquisition & control (DAC) system. There are two levels of interlocks used for the protection of Gyrotron: fast interlocks (arcing, beam over current, dI/dt, anode voltage and anode over current etc.) operate within 10 μs and slow interlocks (cooling, filament, silence of Gyrotron, ion pump and magnet currents) operate within 100 ms. Two Gyrotrons (42 GHz/500 kW/500 ms and 82.6 GHz/200 kW/1000 s) have been commissioned on dummy load for full parameters. The 42 GHz ECRH system has been integrated with SST-1 & Aditya tokamak and various experiments have been carried out related to ECRH assisted breakdown and start-up of tokamak at fundamental and second harmonic. These Gyrotrons are operated with VME based data acquisition and control (DAC) system. The DAC system is capable to acquire 64 digital and 32 analog signals. The system is used to monitor & acquire the data and also used for slow interlocks for the protection of Gyrotron. The data acquired from the system are stored online on VME system and after the shot stored in a file in binary format. The MDSPlus, a set of

Development of field simulator to test and qualify the gyrotron local control unit for ITER-India Gyrotron Test Facility

International Nuclear Information System (INIS)

Shah, Ronak; Mandge, Deepak; Rathod, Vipal; Parmar, Rajvi; Dilip, E. Sharan; Yadav, Amit; Sharma, Anjali; Rao, S.L.

2017-01-01

High power RF sources such as a Gyrotron system are operated at required output parameter by using various auxiliary power supplies, High voltage power supplies, auxiliary services and a dedicated Local Control Unit (LCU). These sub-systems must be operated in synchronous and safe way to control the gyrotron output parameters. The LCU performs remote, synchronous and safe operation of the all the gyrotron sub-systems. Broadly the LCU functions are operational control, data acquisition, protection and safety of the gyrotron system. At ITER-India gyrotron Test Facility (IIGTF) a local control unit (LCU) is being developed to operate the complete gyrotron system. This paper presents the design, development and various features of the field simulator. It also discuss LCU functionality test cases and results obtained using field simulator

Innovation on high-power long-pulse gyrotrons

International Nuclear Information System (INIS)

Litvak, Alexander; Sakamoto, Keishi; Thumm, Manfred

2011-01-01

Progress in the worldwide development of high-power gyrotrons for magnetic confinement fusion plasma applications is described. After technology breakthroughs in research on gyrotron components in the 1990s, significant progress has been achieved in the last decade, in particular, in the field of long-pulse and continuous wave (CW) gyrotrons for a wide range of frequencies. At present, the development of 1 MW-class CW gyrotrons has been very successful; these are applicable for self-ignition experiments on fusion plasmas and their confinement in the tokamak ITER, for long-pulse confinement experiments in the stellarator Wendelstein 7-X (W7-X) and for EC H and CD in the future tokamak JT-60SA. For this progress in the field of high-power long-pulse gyrotrons, innovations such as the realization of high-efficiency stable oscillation in very high order cavity modes, the use of single-stage depressed collectors for energy recovery, highly efficient internal quasi-optical mode converters and synthetic diamond windows have essentially contributed. The total tube efficiencies are around 50% and the purity of the fundamental Gaussian output mode is 97% and higher. In addition, activities for advanced gyrotrons, e.g. a 2 MW gyrotron using a coaxial cavity, multi-frequency 1 MW gyrotrons and power modulation technology, have made progress.

Gyrotron: an ECH system component

International Nuclear Information System (INIS)

Loring, C.M.; Eason, H.O.; Kimrey, H.D.; White, T.L.; Jory, H.R.; Evans, S.J.

1981-01-01

The gyrotron, or electron-cyclotron maser, in the form of a gyromonotron, is being developed as a source of millimeter wave energy for fusion plasma heating. The characteristics of this high power, high efficiency electron tube are described in terms of the requirements for the beam power supply system, the mechanical support system, the cooling system, the focusing and tuning magnets, and the waveguide system. Requirements of power level and transmission efficiency dictate the use of oversize waveguide. The implications, both to the user and to the interaction mechanisms in the gyrotron, of the use of oversize waveguide are treated. The effects of variations of various operating parameters upon the gyrotron's power output and stability are also discussed. Data from gyrotron development and system operation are used where appropriate

Development of frequency tunable gyrotrons for plasma diagnostics

International Nuclear Information System (INIS)

Idehara, T.; Mitsudo, S.; Sabchevski, S.; Glyavin, M.; Ogawa, I.; Sato, M.; Kawahata, K.; Brand, G.F.

2000-01-01

Development of two types of frequency tunable gyrotrons are described. One is frequency step-tunable gyrotrons (Gyrotron FU Series) which cover wide range from millimeter to submillimeter wavelength region. The other is a quasi-optical gyrotron operating in 90 and 180 GHz bands. Both are applicable for plasma diagnostics as power sources. (author)

Lower-hybrid absorption at the ion cyclotron harmonics

International Nuclear Information System (INIS)

Puri, S.

1975-01-01

In the presence of magnetic field gradients, the lower-hybrid wave can be absorbed through linear collisionless damping at the location of cyclotron or cyclotron harmonic resonances acting as singular turning points in the path of the advancing wave-front. (Auth.)

Harmonic Resonance Damping with a Hybrid Compensation System in Power Systems with Dispersed Generation

DEFF Research Database (Denmark)

Chen, Zhe; Pedersen, John Kim; Blaabjerg, Frede

2004-01-01

A hybrid compensation system consisting of an active filter and a group of distributed passive filters has been studied previously. The passive filters are used for each distorting load or Dispersed Generation (DG) unit to remove major harmonics and provide reactive power compensation. The active...... filter is connected in parallel with the distributed passive filters and loads/DGs to correct the system unbalance and remove the remaining harmonic components. The effectiveness of the presented compensation system has also been demonstrated. This paper studies the performance of the hybrid compensation...... demonstrated that the harmonic resonance can be damped effectively. The hybrid filter system is an effective compensation system for dispersed generation systems. In the compensation system, the passive filters are mainly responsible for main harmonic and reactive power compensation of each individual load/ DG...

Gyrotrons for fusion. Status and prospects

International Nuclear Information System (INIS)

Litvak, A.G.; Alikaev, V.V.; Denisov, G.G.; Kurbatov, V.I.; Myasnikov, V.E.; Tai, E.M.; Zapevalov, V.E.

2001-01-01

Gyrotrons are the most advanced high-power sources of millimeter wavelength radiation. They have been used for many years in electron-cyclotron-wave (ECW) systems of many existing fusion installations. Typically modern gyrotrons produce power of 0.5...0.8 MW in pulses of 2-3 seconds, or lower power in longer pulses (e.g. 300-400 kW in pulses up to 10-15 seconds). For the next generation of fusion installations, such as ITER or W7-X the ECW systems based on gyrotrons capable to produce 1MW/CW radiation are considered. Definitely, such gyrotrons with enhanced performance are very interesting also for the use also at existing installations

Hybrid Active Filter with Variable Conductance for Harmonic Resonance Suppression in Industrial Power Systems

DEFF Research Database (Denmark)

Lee, Tzung-Lin; Wang, Yen-Ching; Li, Jian-Cheng

2015-01-01

Unintentional series and/or parallel resonances, due to the tuned passive filter and the line inductance, may result in severe harmonic distortion in the industrial power system. This paper presents a hybrid active filter to suppress harmonic resonance and reduce harmonic distortion as well...... expensive. A reasonable trade-off between filtering performances and cost is to use the hybrid active filter. Design consideration are presented and experimental results are provided to validate effectiveness of the proposed method. Furthermore, this paper discusses filtering performances on line impedance...

Study of a high-order-mode gyrotron traveling-wave amplifier

International Nuclear Information System (INIS)

Chiu, C. C.; Tsai, C. Y.; Kao, S. H.; Chu, K. R.; Barnett, L. R.; Luhmann, N. C. Jr.

2010-01-01

Physics and performance issues of a TE 01 -mode gyrotron traveling-wave amplifier are studied in theory. For a high order mode, absolute instabilities on neighboring modes at the fundamental and higher cyclotron harmonic frequencies impose severe constraints to the device capability. Methods for their stabilization are outlined, on the basis of which the performance characteristics are examined in a multidimensional parameter space under the marginal stability criterion. The results demonstrate the viability of a high-order-mode traveling-wave amplifier and provide a roadmap for design tradeoffs among power, bandwidth, and efficiency. General trends are observed and illustrated with specific examples.

Research on megawatt gyrotrons, January 1983-December 1984

International Nuclear Information System (INIS)

Read, M.E.

1984-01-01

During the last several years, NRL has performed research on concepts for high power gyrotrons. The work funded by the Department of Energy has been in support of industrial development of high frequency (60 to 140 GHz) CW gyrotrons, with NRL research being on the origination, development, and testing of advanced concepts. The research performed under this agreement has included experimental work on quasi-optical and complex cavity gyrotrons and theoretical efforts on these concepts as well as whispering gallery gyrotrons

New results in development of MW output power gyrotrons for fusion systems

International Nuclear Information System (INIS)

Litvak, A.G.; Denisov, G.G.; Ilin, V.I.; Kurbatov, V.I.; Myasnikov, V.E.; Soluyanova, E.A.; Tai, E.M.; Usachev, S.V.; Zapevalov, V.E.

2005-01-01

The paper presents the latest achievements of the Russian gyrotron team in development of MW power gyrotrons for fusion installations. During two last years four new gyrotrons were designed and tested: a new version of 170 GHz gyrotron for ITER; multi-frequency (105-140 GHz) gyrotron for Asdex-Up, 84GHz gyrotron for LHD and 82.7 GHz gyrotron for SST-1. All these gyrotrons are equipped with diamond CVD windows and depressed collectors

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.

Three-wave interaction during electron cyclotron resonance heating and current drive

DEFF Research Database (Denmark)

Nielsen, Stefan Kragh; Jacobsen, Asger Schou; Hansen, Søren Kjer

2016-01-01

Non-linear wave-wave interactions in fusion plasmas, such as the parametric decay instability (PDI) of gyrotron radiation, can potentially hamper the use of microwave diagnostics. Here we report on anomalous scattering in the ASDEX Upgrade tokamak during electron cyclotron resonance heating...... experiments. The observations can be linked to parametric decay of the gyrotron radiation at the second harmonic upper hybrid resonance layer....

Chaos in high-power high-frequency gyrotrons

International Nuclear Information System (INIS)

Airila, M.

2004-01-01

Gyrotron interaction is a complex nonlinear dynamical process, which may turn chaotic in certain circumstances. The emergence of chaos renders dynamical systems unpredictable and causes bandwidth broadening of signals. Such effects would jeopardize the prospect of advanced gyrotrons in fusion. Therefore, it is important to be aware of the possibility of chaos in gyrotrons. There are three different chaos scenarios closely related to the development of high-power gyrotrons: First, the onset of chaos in electron trajectories would lead to difficulties in the design and efficient operation of depressed potential collectors, which are used for efficiency enhancement. Second, the radio-frequency signal could turn chaotic, decreasing the output power and the spectral purity of the output signal. As a result, mode conversion, transmission, and absorption efficiencies would be reduced. Third, spatio-temporal chaos in the resonator field structure can set a limit for the use of large-diameter interaction cavities and high-order TE modes (large azimuthal index) allowing higher generated power. In this thesis, the issues above are addressed with numerical modeling. It is found that chaos in electron residual energies is practically absent in the parameter region corresponding to high efficiency. Accordingly, depressed collectors are a feasible solution also in advanced high-power gyrotrons. A new method is presented for straightforward numerical solution of the one-dimensional self-consistent time-dependent gyrotron equations, and the method is generalized to two dimensions. In 1D, a chart of gyrotron oscillations is calculated. It is shown that the regions of stationary oscillations, automodulation, and chaos have a complicated topology in the plane of generalized gyrotron variables. The threshold current for chaotic oscillations exceeds typical operating currents by a factor of ten. However, reflection of the output signal may significantly lower the threshold. 2D

Design of 84 Ghz, 500 kW gyrotron for ECRH application

International Nuclear Information System (INIS)

Singh, Udaybir; Nitin Kumar; Anil Kumar; Rao, R.R.; Sinha, A.K.

2013-01-01

The design and numerical simulation of the 84 GHz gyrotron, are performed for first harmonic operation. TE 10,4 is selected as the operating mode after the rigorous analysis of several TE modes. Then the interaction cavity geometrical parameters are optimized on the basis of cold cavity simulations and Q factor calculation. The electron beam parameters are optimized in the beam-wave interaction simulations using Particle-in-Cell (PIC) code MAGIC. The triode-type magnetron injection gun with the accelerating voltage 70 kV, the beam current 10 A and the maximum transverse velocity spread less than 5% is designed. (author)

A hybrid active filter for damping of harmonic resonance in industrial power systems

OpenAIRE

Fujita, Hideaki; Yamasaki, Takahiro; Akagi, Hirofumi

1998-01-01

This paper proposes a hybrid active filter for damping of harmonic resonance in industrial power systems. The hybrid filter consists of a small-rated active filter and a 5th tuned passive filter. The active filter is characterized by detecting the 5th harmonic current flowing into the passive filter. It is controlled in such a way as to behave as a negative or positive resistor by adjusting a feedback gain from a negative to positive value, and vice versa. The negative resistor presented by t...

Mode conversion of lower hybrid waves at high ion cyclotron harmonics. Appendix F

International Nuclear Information System (INIS)

Swanson, D.G.; Cho, S.

1985-05-01

The problem of ion cyclotron harmonic absorption for a lower hybrid wave is shown to be a mode conversion problem. A new form of the dispersion relation is developed and then expanded to get a differential equation identical to that for the second harmonic problem. The validity of this model is restricted to the region far from the lower hybrid resonance layer. It is shown that mode couplings occur among the incident cold wave and two other waves, and the tunneling factor becomes singular there

Depressed collectors for millimeter wave gyrotrons

International Nuclear Information System (INIS)

Singh, A.; Granatstein, V.L.

1992-01-01

The main issues relating to design of depressed collectors for millimeter wave gyrotrons are discussed. A flow diagram is presented and the interlinking steps are outlined. Design studies are given for two kinds of gyrotrons on which severe constraints on the maximum radii of the collectors had been imposed; namely, for a cavity type and a quasi-optical gyrotron. A collector efficiency of the order of 70 percent is shown to be feasible for either case using careful tailoring of magnetic field profiles. A code has been developed to assist in doing this. A general approach toward initial placement of collectors has been indicated

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

International Nuclear Information System (INIS)

Harris, T.E.

1991-10-01

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

Nonstationary oscillations in gyrotrons revisited

International Nuclear Information System (INIS)

Dumbrajs, O.; Kalis, H.

2015-01-01

Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. It is known that in the planes of the generalized gyrotron variables: cyclotron resonance mismatch and dimensionless current or cyclotron resonance mismatch and dimensionless interaction length complicated alternating sequences of regions of stationary, periodic, automodulation, and chaotic oscillations exist. In the past, these regions were investigated on the supposition that the transit time of electrons through the interaction space is much shorter than the cavity decay time. This assumption is valid for short and/or high diffraction quality resonators. However, in the case of long and/or low diffraction quality resonators, which are often utilized, this assumption is no longer valid. In such a case, a different mathematical formalism has to be used for studying nonstationary oscillations. One example of such a formalism is described in the present paper

Numerical Simulation of a Double-anode Magnetron Injection Gun for 110 GHz, 1 MW Gyrotron

Science.gov (United States)

Singh, Udaybir; Kumar, Nitin; Purohit, L. P.; Sinha, Ashok K.

2010-07-01

A 40 A double-anode magnetron injection gun for a 1 MW, 110 GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-off equations. The electron beam analysis has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating mode of the gyrotron is TE22,6 and it is operated in the fundamental harmonic. The electron beam with a low transverse velocity spread ( δ {β_{ bot max }} = 2.26% ) and the transverse-to-axial velocity ratio of the electron beam (α) = 1.37 is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by both the codes are in good agreement. The sensitivity analysis has been carried out by changing the different gun parameters to decide the fabrication tolerance.

Operations Studies of the Gyrotrons on DIII-D

Science.gov (United States)

Storment, Stephen; Lohr, John; Cengher, Mirela; Gorelov, Yuri; Ponce, Dan; Torrezan, Antonio

2017-10-01

The gyrotrons are high power vacuum tubes used in fusion research to provide high power density heating and current drive in precisely localized areas of the plasma. Despite the increasing experience with both the manufacture and operation of these devices, individual gyrotrons with similar design and manufacturing processes can exhibit important operational differences in terms of generated rf power, efficiency and lifetime. This report discusses differences in the performance of several gyrotrons in operation at DIII-D and presents the results of a series of measurements that could lead to improved the performance of single units based on a better understanding of the causes of these differences. The rf power generation efficiency can be different from gyrotron to gyrotron. In addition, the power loading of the collector can feature localized hot spots, where the collector can locally be close to the power deposition limits. Measurements of collector power loading provide maps of the power deposition and can provide understanding of the effect of modulation of the output rf beam on the total loading, leading to improved operational rules increasing the safety margins for the gyrotrons under different operational scenarios. Work supported by US DOE under DE-FC02-04ER54698.

Quasi-optical mode converter for a coaxial cavity gyrotron

International Nuclear Information System (INIS)

Jin, J.

2007-03-01

This work concentrates on the synthesis of the quasioptical mode converter for the 170 GHz, TE 34,19 -mode, 2MW, CW coaxial-cavity gyrotron at Forschungszentrum Karlsruhe (FZK). The improvement of the general method for the design of so-call dimpled-wall launcher to provide a good Gaussian mode content is described. This method is verified through the design of a launcher operating in the TE 22,6 mode at 118 GHz. A phase rule is proposed as a quality criterion for monitoring the optimization and the choices of parameters of the quasi-optical mode converter. High-order harmonics introduced to the launcher wall deformations are proposed for this gyrotron. The launcher is numerically optimized, the fields on the cut edges are suppressed. The fields in the launcher are well approximated by the waveguide modes, the radiated fields are calculated using the scalar diffraction integral. The procedure for the numerical optimization of the mirror system is improved, the tolerance conditions of the phase correcting mirrors are investigated. A conversion efficiency of 95.8% to the circular fundamental Gaussian distribution with 20mm beam waist and power transmission of 90% are achieved in the window plane using the optimized quasi-optical mode converter. The methods to ameliorate the initial conditions of the phase correcting mirrors are explored. (orig.)

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.

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.

Electron beam instabilities in gyrotron beam tunnels

International Nuclear Information System (INIS)

Pedrozzi, M.; Alberti, S.; Hogge, J.P.; Tran, M.Q.; Tran, T.M.

1997-10-01

Electron beam instabilities occurring in a gyrotron electron beam can induce an energy spread which might significantly deteriorate the gyrotron efficiency. Three types of instabilities are considered to explain the important discrepancy found between the theoretical and experimental efficiency in the case of quasi-optical gyrotrons (QOG): the electron cyclotron maser instability, the Bernstein instability and the Langmuir instability. The low magnetic field gradient in drift tubes of QOG makes that the electron cyclotron maser instability can develop in the drift tube at very low electron beam currents. Experimental measurements show that with a proper choice of absorbing structures in the beam tunnel, this instability can be suppressed. At high beam currents, the electrostatic Bernstein instability can induce a significant energy spread at the entrance of the interaction region. The induced energy spread scales approximately linearly with the electron beam density and for QOG one observes that the beam density is significantly higher than the beam density of an equivalent cylindrical cavity gyrotron. (author) figs., tabs., refs

Development of ITER CODAC compatible gyrotron local control system and its operation

International Nuclear Information System (INIS)

Ohshima, Katsumi; Oda, Yasuhisa; Takahashi, Koji; Terakado, Masayuki; Ikeda, Ryosuke; Moriyama, Shinichi; Kajiwara, Ken; Sakamoto, Keishi; Hayashi, Kazuo

2016-03-01

In Japan Atomic Energy Agency, an ITER relevant control system for ITER gyrotron was developed according to Plant Control Design Handbook. This control system was developed based on ITER CODAC Core System and implemented state machine control of gyrotron operation system, sequential timing control of gyrotron oscillation startup, and data acquisition. The operation of ITER 170 GHz gyrotron was demonstrated with ITER relevant power supply configuration. This system is utilized for gyrotron operation test for ITER procurement. This report describes the architecture of gyrotron local control system, its basic and detailed design, and recent operation results. (author)

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

International Nuclear Information System (INIS)

Felch, K.; Bier, R.; Caplan, M.; Jory, H.

1983-09-01

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

Frequency pulling in a low-voltage medium-power gyrotron

Science.gov (United States)

Luo, Li; Du, Chao-Hai; Huang, Ming-Guang; Liu, Pu-Kun

2018-04-01

Many recent biomedical applications use medium-power frequency-tunable terahertz (THz) sources, such as sensitivity-enhanced nuclear magnetic resonance, THz imaging, and biomedical treatment. As a promising candidate, a low-voltage gyrotron can generate watt-level, continuous THz-wave radiation. In particular, the frequency-pulling effect in a gyrotron, namely, the effect of the electron beam parameters on the oscillation frequency, can be used to tune the operating frequency. Most previous investigations used complicated and time-consuming gyrotron nonlinear theory to study the influence of many beam parameters on the interaction performance. While gyrotron linear theory investigation demonstrates the advantages of rapidly and clearly revealing the physical influence of individual key beam parameters on the overall system performance, this paper demonstrates systematically the use of gyrotron linear theory to study the frequency-pulling effect in a low-voltage gyrotron with either a Gaussian or a sinusoidal axial-field profile. Furthermore, simulations of a gyrotron operating in the first axial mode are carried out in the framework of nonlinear theory as a contrast. Close agreement is achieved between the two theories. Besides, some interesting results are obtained. In a low-current sinusoidal-profile cavity, the ranges of frequency variation for different axial modes are isolated from each other, and the frequency tuning bandwidth for each axial mode increases by increasing either the beam voltage or pitch factor. Lowering the voltage, the total tuning ranges are squeezed and become concentrated. However, the isolated frequency regions of each axial mode cannot be linked up unless the beam current is increased, meaning that higher current operation is the key to achieving a wider and continuous tuning frequency range. The results presented in this paper can provide a reference for designing a broadband low-voltage gyrotron.

30 kV/10 mA solid state anode modulator for gyrotron plasma heating: design issues and results

International Nuclear Information System (INIS)

Fasel, D.; Lucia, C.; Ganuza, D.; Doyharzabal, I.

2001-01-01

Three 30 kV/10 mA solid state pulsed modulators have been delivered to the CRPP in Lausanne, by the company JEMA. Each modulator supplies the anode grid of a triode type gyrotron, used for heating purpose at the third harmonic in the TCV Tokamak. The main parameters of the final design are: the use of solid state technology, a floating output referred to the -80 kV of the gyrotron cathode potential, an output voltage range of -5 to 30 kV, 1 kHz square and sinusoidal modulation, fast switching off to -5 kV (10 μs) and pulsed operation (duty cycle of 1%). After studying and testing a solution based on regulated Mosfet transistors in series, a more stable alternative has been adopted. The final topology consists of a rectifier fed from an insulated 230 V input, a chopper, two inverter steps (for +30 and -5 kV) supplying two diode rectifiers bridges through HV transformers with two switches which commute the load to the positive or negative voltage, connected in series. This article presents the most significant aspects of the design, with special emphasis on the control principle. The final results will be presented in the context of normal operation, supplying a triode gyrotron

Recent progress in fusion gyrotron development

International Nuclear Information System (INIS)

Shively, J.F.; Stone, D.S.

1981-01-01

The gyrotron, a microwave tube capable of producing high power output at millimeter wavelengths, has recently found applications for electron cyclotron resonance heating of plasmas in controlled thermonuclear fusion reactor experiments. This paper describes work in progress to develop a gyrotron oscillator to deliver 200 kW CW at 60 GHz (/lambda/sub //. 5 mm). A pulsed oscillator is described which produced over 200 kw peak power. A CW oscillator is under construction. The latest experimental results are presented

Development of gyrotrons for plasma diagnostics (invited)

International Nuclear Information System (INIS)

Woskoboinikow, P.

1986-01-01

Recent advances in high-frequency (>100 GHz) gyrotron technology are reviewed and application to millimeter/submillimeter wave plasma diagnostics is discussed. Gyrotrons have useful capabilities of high-power (>1 kW), long pulse/cw operation, narrow linewidth (<100 kHz), and good spatial mode quality with efficient (--90%) mode converters. These capabilities could be used to significantly improve collective Thomson scattering diagnostics for the study of instabilities, plasma waves, turbulence, and thermal ion fluctuations. Imaging applications with many detector arrays of plasma density, field direction, and microinstabilities may be possible with gyrotons. In a high-field compact ignition tokamak experiment a possible millimeter wave diagnostics window could be exploited by a gyrotron to measure a number of parameters, including alpha particle density and velocity distribution

A 2 MW, CW, 170 GHz gyrotron for ITER

International Nuclear Information System (INIS)

Piosczyk, B.; Arnold, A.; Alberti, S.

2003-01-01

A 140 GHz gyrotron for CW operation is under development for the stellarator W7-X. With a prototype tube a microwave output power of about 0.9 MW has been obtained in pulses up to 180 s, limited by the capability of the high voltage power supply. The development work on coaxial cavity gyrotrons has demonstrated the feasibility of manufacturing of a 2 MW, CW 170 GHz tube that could be used for ITER. The problems specific to the coaxial arrangement have been investigated and all relevant information needed for an industrial realization of a coaxial gyrotron have been obtained in short pulse experiments (up to 17 ms). The suitability of critical components for a 2 MW, CW coaxial gyrotron has been studied and a first integrated design has been done. (author)

Velocity diagnostics of electron beams within a 140 GHz gyrotron

International Nuclear Information System (INIS)

Polevoy, J.T.

1989-06-01

Experimental measurements of the average axial velocity v parallel 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 V p and the beam current I b . V p is measured through the use of a capacitive probe installed near or within the gyrotron cavity, while I b 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 v parallel and calculations of the corresponding transverse to longitudinal beam velocity ratio α = v perpendicular /v parallel 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 v parallel 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

Velocity diagnostics of electron beams within a 140 GHz gyrotron

Science.gov (United States)

Polevoy, Jeffrey Todd

1989-06-01

Experimental measurements of the average axial velocity v(sub parallel) 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 V(sub p) and the beam current I(sub b). The V(sub p) is measured through the use of a capacitive probe installed near or within the gyrotron cavity, while I(sub b) 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 v(sub parallel) and calculations of the corresponding transverse to longitudinal beam velocity ratio (alpha) = v(sub perpendicular)/v(sub parallel) 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 v(sub parallel) and (alpha) are determined through the use of a computer code (EGUN) which is used to model the cathode and anode regions of the gyrotron. It also computes the trajectories and velocities of the electrons within the gyrotron. There is good correlation between the expected and measured values of (alpha) at low (alpha), with the expected values from EGUN often falling within the standard errors of the measured values.

Perspective gyrotron with mode converter for co- and counter-rotation operating modes

Energy Technology Data Exchange (ETDEWEB)

Chirkov, A. V.; Kuftin, A. N. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ul' yanov Street, 603950 Nizhny Novgorod (Russian Federation); Denisov, G. G. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ul' yanov Street, 603950 Nizhny Novgorod (Russian Federation); University of Nizhny Novgorod, 23 Prospekt Gagarina, 603950 Nizhny Novgorod (Russian Federation)

2015-06-29

A gyrotron oscillator operating efficiently at modes of both rotations was developed and tested. The gyrotron operation can be switched between two modes: co- and counter rotating ones with respect to electron rotation in a resonance magnetic field. A synthesized mode converter provides output of both waves in the form of two different paraxial wave beams corresponding to direction of the mode rotation. Measured gyrotron power (up to 2 MW), interaction efficiency (34%), and diffraction losses in the mode converter (≈2%) agree well with the design values. The proposed gyrotron scheme alloys principal enhancement in the device parameters—possibility of electronic switching of output wave beam direction and possibility to arrange an effective scheme to provide frequency/phase locking of a gyrotron-oscillator.

Perspective gyrotron with mode converter for co- and counter-rotation operating modes

International Nuclear Information System (INIS)

Chirkov, A. V.; Kuftin, A. N.; Denisov, G. G.

2015-01-01

A gyrotron oscillator operating efficiently at modes of both rotations was developed and tested. The gyrotron operation can be switched between two modes: co- and counter rotating ones with respect to electron rotation in a resonance magnetic field. A synthesized mode converter provides output of both waves in the form of two different paraxial wave beams corresponding to direction of the mode rotation. Measured gyrotron power (up to 2 MW), interaction efficiency (34%), and diffraction losses in the mode converter (≈2%) agree well with the design values. The proposed gyrotron scheme alloys principal enhancement in the device parameters—possibility of electronic switching of output wave beam direction and possibility to arrange an effective scheme to provide frequency/phase locking of a gyrotron-oscillator

The 140 GHZ, 1 MW Gyrotron - Status and Recent Results

Science.gov (United States)

Gantenbein, G.; Dammertz, G.; Illy, S.; Kern, S.; Leonhardt, W.; Piosczyk, B.; Schmid, M.; Thumm, M.; Braune, H.; Erckmann, V.; Laqua, H. P.; Michel, G.; Kasparek, W.; Lechte, C.; Legrand, F.; Lievin, C.; Prinz, O.

2009-04-01

A 10 MW ECRH system is currently under construction for the stellarator W7-X which will be built up and operated by IPP in Greifswald, Germany. The present status of the complete system is reported in [1]. The RF power will be provided by 10 gyrotrons. A European collaboration has been established to develop and build the 10 gyrotrons each with an output power of 1 MW for continuous wave (CW) operation [2]. Nine gyrotrons are being manufactured by Thales Electron Devices (TED), Vélizy, France, one gyrotron was produced by CPI, Palo Alto, CA and passed the acceptance tests at IPP. The acceptance tests of the TED gyrotrons are performed at the test stand at FZK and on site at IPP. The first series tube yielded a total output power of 0.98 MW, with an efficiency of 31 % (without a single stage depressed collector) in short pulse operation and of 0.92 MW in pulses of 1800 s (efficiency of almost 45 % at a depression voltage of 29 kV) [3], The Gaussian mode output power was 0.91 MW. The RF power, measured in a calorimetric load at the end of a 25 m long quasi-optical transmission line with seven mirrors, was 0.87 MW. In this contribution typical results of the next series gyrotrons will be reported.

Improved Collectors for High Power Gyrotrons

International Nuclear Information System (INIS)

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

2009-01-01

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.

Thermal analysis of gyrotron traveling-wave tube collector

International Nuclear Information System (INIS)

Zheng Zhiqing; Luo Yong; Jiang Wei; Tang Yong

2013-01-01

In order to solve cooling problem of the gyrotron traveling-wave tube(TWT) collector and guarantee the gyrotron TWT's reliability and stability, the electron trajectories in the gyrotron TWT are simulated using CST electron simulation software. Thermal analysis of the collector with finite element software ANSYS is performed. The ways of applying boundary that affects the distribution of collector temperature are compared. The influence of the water temperature and flow rate on collector temperature distribution under actual heat fluxes (boundary condition) is researched. The size and number of collector fins are optimized, and a relatively perfect structure is obtained finally. The result estimated by simulation is consistent with the experiment and proves that the model and method employed in this work are suitable. (authors)

Study of the parasitic oscillations in a gyrotron; Etudes des oscillations parasites dans un gyrotron

Energy Technology Data Exchange (ETDEWEB)

Pedrozzi, M. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

1997-01-01

This work is dedicated to the study of parasitic instabilities in a gyrotron, and to the influence of such instabilities on the interaction efficiency. The gyrotron is a high-power millimeter wave radiation source, based on the resonant interaction between a weakly relativistic electron beam immersed in a guiding magnetic field, and an electromagnetic wave. The gyrotron investigated here operates at a frequency close to 100 GHz: its main feature is that it is quasi optical. In this configuration, the electron beam interacts with a high order TEM eigenmode of a Fabry-Perot resonator, the axis of which is perpendicular to the electron beam path. During the development of this source, the highest efficiency that was achieved is approximately 30% lower than the theoretical predictions. At the same time, parasitic oscillations at frequencies close to the maximum relativistic cyclotronic frequency are detected. The power associated with these oscillations ranges from a few watts to a few kilowatts, with threshold currents of the order of 100 mA. It is suspected that the excitation of parasitic oscillations in the beam duct section before the interaction region might have a dramatic effect on the electron beam distribution function inducing, in particular, an energy spread. The cyclotron maser instability responsible for the energy exchange between particles and fields in a gyrotron, is very sensitive to energy spreads. It is thus necessary to identify the origin of the parasitic radiation. A few physical mechanisms suspected to lead to a degradation of the electron beam properties were investigated: the cyclotron maser process itself, the Bernstein electrostatic instability and the Langmuir instability. The experimental work concentrated on the study of the beam ducts between the electron gun and the resonant cavity. (author) figs., tabs., 90 refs.

Cancellation of neutral current harmonics by using a four-branch star hybrid filter

DEFF Research Database (Denmark)

Blaabjerg, Frede; Rodriguez, Pedro; Candela, I.

2008-01-01

filtering topology to a three-phase four-wire system. An extensive evaluation using simulation and experimental results are conducted in this work to validate the good performance of the proposed solution for canceling current harmonics flowing through the neutral conductor.......This paper presents a new technique for filtering current harmonics in three-phase four-wire networks based on the usage of a four-branch star (FBS) filter topology. Based on single-phase inductors and capacitors, the specific layout of the FBS filter topology allows achieving a power filter...... is improved by integrating a power converter into its structure. This paper analyzes the FBS topology and presents fundamental concepts regarding the control of a generic FBS hybrid power filter. A neutral current hybrid power filter and var compensator is presented as an illustrative example applying the FBS...

ITER ECFR Coaxial gyrotron and window development (EU-T360). Pt. 1: Coaxial gyrotron development. Final report

International Nuclear Information System (INIS)

Piosczyk, B.; Braz, O.; Dammertz, G.; Kuntze, G.; Michel, G.; Moebius, A.; Thumm, M.

1999-02-01

Based on the experience gained with the inverse magnetron injection gun (IMIG) for coaxial cavity gyrotrons, a new 4.5 MW electron gun for operation at a cathode voltage of 90 kV and a beam current of 50 A has been designed and is currently under fabrication at Thomson Tubes Electroniques (TTE). The gun is of the diode type. Different from the LaB 6 IMIG currently used, the emission of the electrons will not be directed towards the coaxial insert but towards the anode similar like in conventional MIG gyrotron electron guns. The inner conductor is supported from the gun inner conductor side and can be aligned in a reproducible way in the fully assembled tube. The insert is cooled as required for operation at long pulses up to cw. The cathode will be equipped with an impregnated tungsten matrix emitter as used in industrial tubes. A 160/170 GHz, 1.5 MW, 100 ms pulse length coaxial gyrotron employing the new electron gun and a single-stage depressed collector has been designed. The advanced quasi-optical converter for transforming the TE -31,17 cavity mode at 165 GHz into a single RF-output wave beam (only one output window) consists of a simple launcher and two mirrors. The first mirror is quasi-elliptical and the second mirror has a non-quadratic phase-correcting surface to generate an approximately homogeneous RF-field distribution with a high fundamental Gaussian content in the window plane. First test experiments with the new gyrotron have been performed employing the available LaB 6 -IMIG. (orig.)

Review of gyrotron development at the Centre de Recherche en Physique des Plasmas

International Nuclear Information System (INIS)

Tran, M.Q.

1990-01-01

Gyrotron development activities at the Centre de Recherche en Physique des Plasmas in Lausanne are directed along two directions, quasi optical gyrotrons and, with less emphasis, cylindrical cavity gyrotrons. This paper will review the recent work performed in these two fields. (author) 9 refs., 5 figs

Experimental investigation of plasma-neutralized operation of a gyrotron

International Nuclear Information System (INIS)

Kirkpatrick, D.A.; Sullivan, C.; Gold, S.H.; Manheimer, W.M.; Levush, B.; Antonsen, T.M.

1989-01-01

The authors present plans and preliminary results of an experiment to investigate the effects of a neutralizing background plasma on the operation of a gyrotron oscillator. Previous experiments operating without a neutralizing background plasma achieved output powers P = 100 - 250MW at a frequency f = 35 GHz, with beam voltages in the range V = 0.60 - 1.35MV, and beam currents I = 1 -3kA. A completely ionized plasma is injected into a gyrotron interaction region from an upstream array of plasma guns. The peak plasma density available from the plasma guns exceeds n p > 10 13 cm -3 . The plasma density is measured by 70 GHz microwave interferometry and Langmuir probes. A high current electron beam from a field emission electron gun enters the plasma-filled gyrotron cavity from the upstream side. The density of the neutralizing plasma is varied by changing the delay between the firing of plasma guns and the VEBA accelerator. The authors present measurements of the transmitted electron beam current. Subsequent design of a gyrotron oscillator which utilizes the enhanced capabilities are presented

Gravity Search Algorithm hybridized Recursive Least Square method for power system harmonic estimation

Directory of Open Access Journals (Sweden)

Santosh Kumar Singh

2017-06-01

Full Text Available This paper presents a new hybrid method based on Gravity Search Algorithm (GSA and Recursive Least Square (RLS, known as GSA-RLS, to solve the harmonic estimation problems in the case of time varying power signals in presence of different noises. GSA is based on the Newton’s law of gravity and mass interactions. In the proposed method, the searcher agents are a collection of masses that interact with each other using Newton’s laws of gravity and motion. The basic GSA algorithm strategy is combined with RLS algorithm sequentially in an adaptive way to update the unknown parameters (weights of the harmonic signal. Simulation and practical validation are made with the experimentation of the proposed algorithm with real time data obtained from a heavy paper industry. A comparative performance of the proposed algorithm is evaluated with other recently reported algorithms like, Differential Evolution (DE, Particle Swarm Optimization (PSO, Bacteria Foraging Optimization (BFO, Fuzzy-BFO (F-BFO hybridized with Least Square (LS and BFO hybridized with RLS algorithm, which reveals that the proposed GSA-RLS algorithm is the best in terms of accuracy, convergence and computational time.

Asymmetric modes in gyrotron tubes and their experimental study

International Nuclear Information System (INIS)

Garin, P.; Jedar, E.; Jendrzejczak, G.; mourier, G.; Payen, F.; Teyssier, L.

1989-01-01

High power gyrotron tubes suffer from the competition between oscillations on different modes of the resonant cavity. Different techniques for mode selection are outlined and the advantages of non symmetric modes are indicated. Their experimental study is described on a 100 GHz-200 kW - 100 ms - TE34 gyrotron. Some possible extrapolations are briefly presented. (author). 6 refs.; 4 figs

Accurate frequency measurements on gyrotrons using a ''gyro-radiometer''

International Nuclear Information System (INIS)

Rebuffi, L.

1986-08-01

Using an heterodyne system, called ''Gyro-radiometer'', accurated frequency measurements have been carried out on VARIAN 60 GHz gyrotrons. Changing the principal tuning parameters of a gyrotron, we have detected frequency variations up to 100 MHz, ∼ 40 MHz frequency jumps and smaller jumps (∼ 10 MHz) when mismatches in the transmission line were present. FWHM bandwidth of 300 KHz, parasitic frequencies and frequency drift during 100 msec pulses have also been observed. An efficient method to find a stable-, high power-, long pulse-working point of a gyrotron loaded by a transmission line, has been derived. In general, for any power value it is possible to find stable working conditions tuning the principal parameters of the tube in correspondance of a maximum of the emitted frequency

Theory of enhanced second-harmonic generation by the quadrupole-dipole hybrid exciton

International Nuclear Information System (INIS)

Roslyak, Oleksiy; Birman, Joseph L

2008-01-01

We report calculated substantial enhancement of the second-harmonic generation (SHG) in cuprous oxide crystals, resonantly hybridized with an appropriate organic material (DCM2:CA:PS 'solid state solvent'). The quadrupole origin of the inorganic part of the quadrupole-dipole hybrid provides inversion symmetry breaking and the organic part contributes to the oscillator strength of the hybrid. We show that the enhancement of the SHG, compared to the bulk cuprous oxide crystal, is proportional to the ratio of the DCM2 dipole moment and the effective dipole moment of the quadrupole transitions in the cuprous oxide. It is also inversely proportional to the line-width of the hybrid and bulk excitons. The enhancement may be regulated by adjusting the organic blend (mutual concentration of the DCM2 and CA part of the solvent) and pumping conditions (varying the angle of incidence in the case of optical pumping or populating the minimum of the lower branch of the hybrid in the case of electrical pumping)

Development of MW gyrotrons for fusion devices by University of Tsukuba

International Nuclear Information System (INIS)

Minami, R.; Kariya, T.; Imai, T.; Numakura, T.; Endo, Y.; Nakabayashi, H.; Eguchi, T.; Shimozuma, T.; Kubo, S.; Yoshimura, Y.; Igami, H.; Takahashi, H.; Mutoh, T.; Ito, S.; Idei, H.; Zushi, H.; Yamaguchi, Y.; Sakamoto, Keishi; Mitsunaka, Y.

2012-11-01

Over-1 MW power gyrotrons for electron cyclotron heating (ECH) have been developed in the joint program of NIFS and University of Tsukuba. The obtained maximum outputs are 1.9 MW for 0.1 s on the 77 GHz Large Helical Device (LHD) tube and 1.0 MW for 1 ms on the 28 GHz GAMMA 10 one, which are new records in these frequency ranges. In long pulse operation, 300 kW for 40 min at 77 GHz and 540 kW for 2 s at 28 GHz were achieved. A new program of 154 GHz 1 MW development has started for high density plasma heating in LHD and the first tube has been fabricated. These lower frequency tubes like 77 GHz or 28 GHz one are also important for advanced magnetic fusion devices, which use Electron Bernstein Wave (EBW) heating / current drive. As a next activity of 28 GHz gyrotron, we have already started the development of over-1.5 MW gyrotron and a new design study of 28 GHz / 35 GHz dual frequency gyrotron, which indicates the practicability of the multi-purpose gyrotron. (author)

Fast power measurement on a 30 GHz/15 kW gyrotron

International Nuclear Information System (INIS)

Saala, G.

2004-09-01

This work has been developed in the scope of a study-thesis at the Universitaet Karlsruhe (TH). The realization took place at the Institut fuer Hochleistungsimpuls- und Mikrowellentechnik (IHM) at the Forschungszentrum Karlsruhe (FZK). The aim was to investigate the possibilities of a fast power measurement at a compact, industrial gyrotron-system. To measure the output-power a small fraction of the gyrotron microwave radiation is coupled out and analyzed using a diode-detector. At the beginning of the work a mirror of the quasi-optical transmission line with a built in λ/4-coupler was available. This built-in coupler and other coupling structures which have been set up during this work have been characterized. To be able to perform reproduceable measurements several computer programs have been developed. Using these programs the gyrotron-system can be remote-controlled from a PC. The diode-detector signal has been analyzed under different conditions of gyrotron operation with respect to its short-term- and long-term-stability. After that the dependency of the calorimetrically measured output-power of the gyrotron has been used to calibrate the diode-voltage. (orig.)

Diamond window and its application to ITER gyrotron

International Nuclear Information System (INIS)

Sakamoto, K.

1999-01-01

On the background of having to reduce the overall cost for ITER to 50% it is proposed to replace conventional glass windows on gyrotrons by diamonds. The successful production and testing of such diamond windows is reported. A diamond window can transmit 5 times more power than usual double disk transmission windows while only costing 3 times as much. As a tradeoff, the gyrotrons could be replaced by more powerful ones and one would need fewer of them

First 200 kW CW operation of a 60 GHz gyrotron

International Nuclear Information System (INIS)

Jory, H.; Bier, R.; Evans, S.; Felch, K.; Fox, L.; Huey, H.; Shively, J.; Spang, S.

1983-01-01

The gyrotron is a microwave tube which employs the electron cyclotron maser interaction to produce high power output at millimeter wavelengths. It has important and growing applications for heating of plasmas in controlled thermonuclear fusion experiments. The Varian 60 GHz gyrotron has recently generated microwave power in excess of 200 kW during CW operation, wth excellent dynamic range and operating stability. This is the highest average power ever produced by a microwave tube in the millimeter wave region. A description of the gyrotron design and test results are presented

Hybrid code simulation on mode conversion in the second harmonic ICRF heating

International Nuclear Information System (INIS)

Sakai, K.; Takeuchi, S.; Matsumoto, M.; Sugihara, R.

1985-01-01

ICRF second harmonic heating of a single-species plasma is studied by using a 1-1/2 dimensional quasi-neutral hybrid code. Mode conversion, transmission and reflection of the magnetosonic waves are confirmed, both for the high- and low-field-side excitations. The ion heating by waves propagating perpendicularly to the static magnetic field is also observed

Quasi-optical internal mode converters for 110 GHz gyrotrons

International Nuclear Information System (INIS)

Harper, B.M.; Lorbeck, J.A.; Vernon, R.J.

1995-01-01

Many early gyrotrons had a microwave output in the same mode that was produced in the microwave cavity, e.g. the TE 02 mode. These modes were often converted outside of the tube to a more desirable mode for plasma heating using a system of perturbed-wall waveguide mode converters. The current generation of gyrotrons commonly have cavity modes with a high azimuthal index, such as the rotating TE 22,6 mode. Mode conversion by means of waveguide mode converters is not usually practical for such cases. However, an output of a Gaussian beam or other desirable field pattern can be obtained by using a Vlasov-type launcher feeding a series of two or more reflectors. This system may be placed outside or inside of the gyrotron but there are advantages to placing it within the tube, e.g. allowing for a larger collector and smaller reflectors. When such a converter system is placed inside the gyrotron, it is usually preferable to use a modification to the simple Vlasov launcher such as the Denisov-type launcher, which incorporates a series of perturbations within it. The authors have designed both internal and external versions of such quasi-optical converters. They discuss an internal converter which was designed for use inside of a Varian 110 GHz gyrotron producing the TE 22,6 cavity mode. This design consists of four reflectors which are fed by a Denisov-type launcher. Design techniques for the reflector system are discussed and experimental results are presented

Modeling of mode purity in high power gyrotrons

International Nuclear Information System (INIS)

Cai, S.Y.; Antonsen, T.M. Jr.; Saraph, G.P.

1993-01-01

Spurious mode generation at the same frequency of the operational mode in a high power gyrotron can significantly reduce the power handling capability and the stability of a gyrotron oscillator because these modes are usually not matched at the output window and thus have high absorption and reflection rates. To study the generation of this kind of mode, the authors developed a numerical model based on an existing multimode self-consistent time-dependent computer code. This model includes both TE and TM modes and accounts for mode transformations due to the waveguide inhomogeneity. With this new tool, they study the mode transformation in the gyrotron and the possibility of excitation of parasitic TE and TM modes in the up taper section due to the gyroklystron mechanism. Their preliminary results show moderate excitation of both TE and TM modes at the same frequency as the main operating mode at locations near their cutoff. Details of the model and further simulation results will be presented

Megawatt Power Level 120 GHz Gyrotrons for ITER Start-Up

Energy Technology Data Exchange (ETDEWEB)

Choi, E M; Marchewka, C; Mastovsky, I; Shapiro, M A; Sirigiri, J R; Temkin, R J [MIT - Plasma Science and Fusion Center, NW16-186, 167 Albany Street, Cambridge, MA 02139 (United States)

2005-01-01

We report operation of a 110 GHz gyrotron with 1.67 MW of output power measured in short pulses (3{mu}s) at an efficiency of 42% in the TE{sub 22,6} mode. We also present a preliminary design of a 1 MW, 120 GHz gyrotron for ITER start-up with an efficiency greater than 50%.

Megawatt Power Level 120 GHz Gyrotrons for ITER Start-Up

International Nuclear Information System (INIS)

Choi, E M; Marchewka, C; Mastovsky, I; Shapiro, M A; Sirigiri, J R; Temkin, R J

2005-01-01

We report operation of a 110 GHz gyrotron with 1.67 MW of output power measured in short pulses (3μs) at an efficiency of 42% in the TE 22,6 mode. We also present a preliminary design of a 1 MW, 120 GHz gyrotron for ITER start-up with an efficiency greater than 50%

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.

Electron beam emission and interaction of double-beam gyrotron

International Nuclear Information System (INIS)

Singh, Udaybir; Kumar, Anil; Kumar, Nitin; Kumar, Narendra; Pratap, Bhanu; Purohit, L.P.; Sinha, A.K.

2012-01-01

Highlights: ► The complete electrical design of electron gun and interaction structure of double-beam gyrotron. ► EGUN code is used for the simulation of electron gun of double-beam gyrotron. ► MAGIC code is used for the simulation of interaction structure of double-beam gyrotron. ► Design validations with other codes. - Abstract: This paper presents the numerical simulation of a double-beam magnetron injection gun (DB-MIG) and beam-wave interaction for 60 GHz, 500 kW gyrotron. The beam-wave interaction calculations, power and frequency growth estimation are performed by using PIC code MAGIC. The maximum output power of 510 kW at 41.5% efficiency, beam currents of 6 A and 12 A, electron beam velocity ratios of 1.41 and 1.25 and beam voltage of 69 kV are estimated. To obtain the design parameters, the DB-MIG with maximum transverse velocity spread less than 5% is designed. The computer simulations are performed by using the commercially available code EGUN and the in-house developed code MIGANS. The simulated results of DB-MIG design obtained by using the EGUN code are also validated with another trajectory code TRAK, which are in good agreement.

Electron beam emission and interaction of double-beam gyrotron

Energy Technology Data Exchange (ETDEWEB)

Singh, Udaybir, E-mail: uday.ceeri@gmail.com [Gyrotron Laboratory, Microwave Tube Area, Central Electronics Engineering Research Institute (CEERI), Council of Scientific and Industrial Research (CSIR), Pilani, Rajasthan 333031 (India); Department of Physics, Gurukul Kangri University, Haridwar 249404 (India); Kumar, Anil [Gyrotron Laboratory, Microwave Tube Area, Central Electronics Engineering Research Institute (CEERI), Council of Scientific and Industrial Research (CSIR), Pilani, Rajasthan 333031 (India); Kumar, Nitin, E-mail: nitin_physika@rediffmail.com [Gyrotron Laboratory, Microwave Tube Area, Central Electronics Engineering Research Institute (CEERI), Council of Scientific and Industrial Research (CSIR), Pilani, Rajasthan 333031 (India); Kumar, Narendra; Pratap, Bhanu [Gyrotron Laboratory, Microwave Tube Area, Central Electronics Engineering Research Institute (CEERI), Council of Scientific and Industrial Research (CSIR), Pilani, Rajasthan 333031 (India); Purohit, L.P. [Department of Physics, Gurukul Kangri University, Haridwar 249404 (India); Sinha, A.K., E-mail: aksinha@ceeri.ernet.in [Gyrotron Laboratory, Microwave Tube Area, Central Electronics Engineering Research Institute (CEERI), Council of Scientific and Industrial Research (CSIR), Pilani, Rajasthan 333031 (India)

2012-09-15

Highlights: Black-Right-Pointing-Pointer The complete electrical design of electron gun and interaction structure of double-beam gyrotron. Black-Right-Pointing-Pointer EGUN code is used for the simulation of electron gun of double-beam gyrotron. Black-Right-Pointing-Pointer MAGIC code is used for the simulation of interaction structure of double-beam gyrotron. Black-Right-Pointing-Pointer Design validations with other codes. - Abstract: This paper presents the numerical simulation of a double-beam magnetron injection gun (DB-MIG) and beam-wave interaction for 60 GHz, 500 kW gyrotron. The beam-wave interaction calculations, power and frequency growth estimation are performed by using PIC code MAGIC. The maximum output power of 510 kW at 41.5% efficiency, beam currents of 6 A and 12 A, electron beam velocity ratios of 1.41 and 1.25 and beam voltage of 69 kV are estimated. To obtain the design parameters, the DB-MIG with maximum transverse velocity spread less than 5% is designed. The computer simulations are performed by using the commercially available code EGUN and the in-house developed code MIGANS. The simulated results of DB-MIG design obtained by using the EGUN code are also validated with another trajectory code TRAK, which are in good agreement.

A Transformerless Hybrid Active Filter Capable of Complying with Harmonic Guidelines for Medium-Voltage Motor Drives

Science.gov (United States)

Kondo, Ryota; Akagi, Hirofumi

This paper presents a transformerless hybrid active filter that is integrated into medium-voltage adjustable-speed motor drives for fans, pumps, and compressors without regenerative braking. The authors have designed and constructed a three-phase experimental system rated at 400V and 15kW, which is a downscaled model from a feasible 6.6-kV 1-MW motor drive system. This system consists of the hybrid filter connecting a passive filter tuned to the 7th harmonic filter in series with an active filter that is based on a three-level diode-clamped PWM converter, as well as an adjustable-speed motor drive in which a diode rectifier is used as the front end. The hybrid filter is installed on the ac side of the diode rectifier with no line-frequency transformer. The downscaled system has been exclusively tested so as to confirm the overall compensating performance of the hybrid filter and the filtering performance of a switching-ripple filter for mitigating switching-ripple voltages produced by the active filter. Experimental results verify that the hybrid filter achieves harmonic compensation of the source current in all the operating regions from no-load to the rated-load conditions, and that the switching-ripple filter reduces the switching-ripple voltages as expected.

Plasma scattering measurement using a submillimeter wave gyrotron as a radiation source

International Nuclear Information System (INIS)

Ogawa, I.; Idehara, T.; Itakura, Y.; Myodo, M.; Hori, T.; Hatae, T.

2004-01-01

Plasma scattering measurement is an effective technique to observe low frequency density fluctuations excited in plasma. The spatial and wave number resolutions and the S/N ratio of measurement depend on the wavelength range, the size and the intensity of a probe beam. A well-collimated, submillimeter wave beam is suitable for improving the spatial and wave number resolutions. Application of high frequency gyrotron is effective in improving the S/N ratio of the measurement because of its capacity to deliver high power. Unlike the molecular vapor lasers, the gyrotrons generate diverging beam of radiation with TE mn mode structure. It is therefore necessary to convert the output radiation into a Gaussian beam. A quasi-optical antenna is a suitable element for the conversion system under consideration since it is applicable to several TE 0n and TE 1n modes. In order to apply the gyrotron to plasma scattering measurement, we have stabilized the output (P = 110 W, f = 354 GHz) of gyrotron up to the level (ΔP/P < 1 %, Δf< 10 kHz). The gyrotron output can be stabilized by decreasing the fluctuation of the cathode potential. (authors)

Photonic-band-gap gyrotron amplifier with picosecond pulses

Science.gov (United States)

Nanni, Emilio A.; Jawla, Sudheer; Lewis, Samantha M.; Shapiro, Michael A.; Temkin, Richard J.

2017-12-01

We report the amplification of 250 GHz pulses as short as 260 ps without observation of pulse broadening using a photonic-band-gap circuit gyrotron traveling-wave-amplifier. The gyrotron amplifier operates with a device gain of 38 dB and an instantaneous bandwidth of 8 GHz. The operational bandwidth of the amplifier can be tuned over 16 GHz by adjusting the operating voltage of the electron beam and the magnetic field. The amplifier uses a 30 cm long photonic-band-gap interaction circuit to confine the desired TE03-like operating mode while suppressing lower order modes which can result in undesired oscillations. The circuit gain is >55 dB for a beam voltage of 23 kV and a current of 700 mA. These results demonstrate the wide bandwidths and a high gain achievable with gyrotron amplifiers. The amplification of picosecond pulses of variable lengths, 260-800 ps, shows good agreement with the theory using the coupled dispersion relation and the gain-spectrum of the amplifier as measured with quasi-CW input pulses.

The MTX computer control system for the 400 kilowatt 140 GHz gyrotron

International Nuclear Information System (INIS)

Jackson, M.C.; Ferguson, S.W.; Petersen, D.E.

1991-09-01

A 400 kilowatt, 140 Ghz gyrotron is employed on MTX as a source of direct plasma heating and, additionally, as a driver for a free electron laser, which is used for plasma heating. The control system that operates this gyrotron uses a new graphics oriented software system called TACL (Thaumaturgic Automated Control Logic) developed by the Continuous Electron Beam Accelerator Facility (CEBAF) and owned by DOE. This control language does not require a software specialist, but is easily handled by the engineer or technician working on the system. All control logic and custom displays are entered via graphics oriented editors and no actual lines of code need to be written. The graphics displays make the gyrotron operation quite simple and allow individual users to define displays to meet their own needs or develop one for a specific set of tests to be run. The system, additionally, can be used for logging functions, which have been found quite useful in tracking long term trends in vacion current and calorimetry of gyrotron cooling circuits. The system is composed of one computer (HP 9000 series 300) controlling multiple CAMAC crates located at the various components used in the system. A second series 300 computer is used as a supervisor and is located in the main tokamak control room. This supervisory computer provides remote operation of the gyrotron, and also provides a link to the microwave transport vacuum control (also TACL). The supervisory computer, additionally, is used as a subsystem status summary point for permissives to the gyrotron control system

Development of steady-state 2 MW, 170 GHz gyrotrons for ITER

International Nuclear Information System (INIS)

Piosczyk, B.; Arnold, A.; Thumm, M.; Dammertz, G.; Heidinger, R.; Illy, S.; Jin, J.; Koppenburg, K.; Leonhardt, W.; Neffe, G.; Rzesnicki, T.; Schmid, M.; Yang, X.; Alberti, S.; Chavan, R.; Fasel, D.; Goodman, T.; Henderson, M.; Hogge, J.P.; Tran, M.Q.; Yovchev, I.; Erckmann, V.; Laqua, H.P.; Michel, G.; Gantenbein, G.; Kasparek, W.; Mueller, G.; Schwoerer, K.; Bariou, D.; Beunas, A.; Giguet, E.; LeCloarec, G.; Legrand, F.; Lievin, C.; Dumbrajs, O.

2005-01-01

A prototype of a 1 MW, CW, 140 GHz conventional gyrotron for the W7-X stellarator in Greifswald/Germany has been tested successfully and the fabrication of series tubes started. In extended studies the feasibility for manufacturing a continuously operated high power coaxial cavity gyrotron has been demonstrated and all needed data for an industrial design has been obtained. Based on this results the fabrication of a first prototype of a 2 MW, CW, 170 GHz coaxial cavity gyrotron started recently in cooperation between European research institutions and European tube industry. The prototype tube is foreseen to be tested in 2006 at CRPP Lausanne where a suitable test facility is under construction. (author)

Performance, diagnostics, controls and plans for the gyrotron system on the DIII-D tokamak

Directory of Open Access Journals (Sweden)

Ponce D.M.

2012-09-01

Full Text Available The DIII-D ECH complex is being upgraded with three new depressed collector gyrotrons. The performance of the existing system has been very good. As more gyrotrons having higher power are added to the system, diagnostics of gyrotron operation, optimization of the performance and qualification of components for higher power become more important. A new FPGA-based gyrotron control system is being installed, additional capabilities for rapid real time variation of the rf injection angles by the DIII-D Plasma Control System are being tested and infrastructure enhancements are being completed. Longer term plans continue to include ECH as a major component in the DIII-D heating and current drive capabilities.

Integrated Design of Undepressed Collector for Low Power Gyrotron

Science.gov (United States)

Kumar, Anil; Goswami, Uttam K.; Poonia, Sunita; Singh, Udaybir; Kumar, Nitin; Alaria, M. K.; Bera, A.; Khatun, Hasina; Sinha, A. K.

2011-06-01

A 42 GHz, 200 kW continuous wave (CW) gyrotron, operating at TE03 mode is under development for the electron cyclotron resonance plasma heating of the Indian TOKAMAK system. The gyrotron is made up of an undepressed collector. The undepressed collector is simple to design and cost effective. In this paper, a detailed design study of the undepressed collector for the 42 GHz gyrotron is presented. The EGUN code is used to analyze the spent electron beam trajectory for the maximum spread to reduce the power loading on the collector surface. To achieve wall loading ≤1 kW/cm2, a collector with a length of 800 mm and a radius of 42.5 mm is designed. The design also includes the three magnet systems around the collector for maximum and uniform beam spread. The thermal and the structural analyses are done using the ANSYS code to optimize the collector structure and dimensions with tolerance.

Analysis of a prototype of a novel 1.5 MW, 170 GHz coaxial cavity gyrotron

International Nuclear Information System (INIS)

Rzesnicki, T.

2007-06-01

A 170 GHz, 2 MW coaxial cavity gyrotron is under development at the Institut fuer Hochleistungsimpuls- und Mikrowellentechnik (IHM) at Forschungszentrum Karlsruhe (FZK) which will be used as a high power microwave source for heating, current drive and stability control of plasmas in the International Thermonuclear Experimental Reactor (ITER). At frequencies above about 100 GHz the output power of conventional gyrotrons with cylindrical hollow waveguide cavities is limited to 1 MW in CW operation mainly due to the high Ohmic losses and the space charge voltage depression of the electron beam. The coaxial geometry enables a reduction of the mode competition in the gyrotron resonator and decreases also the influence of the beam voltage depression. As result a very high order operating mode (for example TE34,19 at 170 GHz) can be chosen which ultimately allows to increase the output power of the gyrotron in CW operation to a value as high as 2 MW. A first prototype of the 170 GHz, 2 MW coaxial cavity gyrotron has been designed, built and experimentally tested in short pulse operation at FZK. The main goal of this work was to investigate experimentally the design of the critical gyrotron components such as electron gun, resonator and a quasi-optical RF system. Those components are same as used in the first industrial coaxial prototype gyrotron for ITER. During the experiments a strong instability was observed inside the gyrotron tube due to the excitation of parasitic low frequency oscillations. The mechanism of the oscillations has been studied and possibilities for their suppression of these oscillations are proposed and experimentally verified. The RF output system is one of the most critical components. It is responsible for the coupling of the gyrotron power out of the gyrotron by converting the microwave power generated in the TE 34,19 -mode into a fundamental free space TEM 0,0 ''Gaussian'' mode. The performance of the RF output system has been tested in low

Local control unit for ITER-India gyrotron test facility (IIGTF)

Energy Technology Data Exchange (ETDEWEB)

Rathod, Vipal, E-mail: vipal.rathod@iter-india.org; Shah, Ronak; Mandge, Deepak; Parmar, Rajvi; Rao, S.L.

2016-11-15

Highlights: • A dedicated full scale ITER prototype Local Control Unit for ITER-India Gyrotron test facility. • National Instruments® make PXIe system for real time control & data acquisition and Siemens® PLC for sequence control function. • Hardwired FPGA based fast protection interlock system. • High speed analog fiber optical transmission link using V/F and F/V technique. • Software framework based on LabVIEW™ platform and ITER CODAC Core System. - Abstract: Electron Cyclotron system on ITER, is one of the important RF ancillary systems based on high power Gyrotron RF sources, that is used for plasma heating and current drive applications. To operate a Gyrotron source, various auxiliary systems and services such as Super Conducting Magnet set, High Voltage Power Supplies, Auxiliary Power Supplies, Waveguide components, Cooling water system and a Local Control Unit (LCU) are required. The LCU plays a very crucial role for the safe and reliable operation of Gyrotron system. A dedicated full scale ITER prototype LCU is being developed for testing and commissioning of an ITER like Test Gyrotron at ITER-India Gyrotron Test facility (IIGTF). The main functions of LCU include Sequence Control, Local Interlock Protection and Real Time Data Acquisition. PLC based slow controller is used for implementing the Sequence Control & Slow Interlock functions. Critical Protection Interlocks are required to have a response time of <10 μs and are implemented using custom built hardware and PXIe based fast controller. Also PXIe system is used for implementing Real Time Data Acquisition function that is required to have slow and fast acquisition with online visualization and off line analysis facility. A Signal Conditioning Unit (SCU) is used to interface and faithfully transmit the field signals to the remote control systems. Necessary controller hardware is procured and several pre-prototype developments have been taken up to establish the critical subsystems such as

Local control unit for ITER-India gyrotron test facility (IIGTF)

International Nuclear Information System (INIS)

Rathod, Vipal; Shah, Ronak; Mandge, Deepak; Parmar, Rajvi; Rao, S.L.

2016-01-01

Highlights: • A dedicated full scale ITER prototype Local Control Unit for ITER-India Gyrotron test facility. • National Instruments® make PXIe system for real time control & data acquisition and Siemens® PLC for sequence control function. • Hardwired FPGA based fast protection interlock system. • High speed analog fiber optical transmission link using V/F and F/V technique. • Software framework based on LabVIEW™ platform and ITER CODAC Core System. - Abstract: Electron Cyclotron system on ITER, is one of the important RF ancillary systems based on high power Gyrotron RF sources, that is used for plasma heating and current drive applications. To operate a Gyrotron source, various auxiliary systems and services such as Super Conducting Magnet set, High Voltage Power Supplies, Auxiliary Power Supplies, Waveguide components, Cooling water system and a Local Control Unit (LCU) are required. The LCU plays a very crucial role for the safe and reliable operation of Gyrotron system. A dedicated full scale ITER prototype LCU is being developed for testing and commissioning of an ITER like Test Gyrotron at ITER-India Gyrotron Test facility (IIGTF). The main functions of LCU include Sequence Control, Local Interlock Protection and Real Time Data Acquisition. PLC based slow controller is used for implementing the Sequence Control & Slow Interlock functions. Critical Protection Interlocks are required to have a response time of <10 μs and are implemented using custom built hardware and PXIe based fast controller. Also PXIe system is used for implementing Real Time Data Acquisition function that is required to have slow and fast acquisition with online visualization and off line analysis facility. A Signal Conditioning Unit (SCU) is used to interface and faithfully transmit the field signals to the remote control systems. Necessary controller hardware is procured and several pre-prototype developments have been taken up to establish the critical subsystems such as

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)

Castro, J.J.B. de.

1988-12-01

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 (η perpendicular MAX =0.86) have been calculated for interaction at the fundamental 1 cyclotron harmonic and for uniform external magnetic field. A maximum efficiency scaling parameter S has been introduced, by which scaling relations η perpendicular MAX = η perpendicular MAX (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 TE 021 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) [pt

Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz.

Science.gov (United States)

Hornstein, Melissa K; Bajaj, Vikram S; Griffin, Robert G; Temkin, Richard J

2007-02-01

The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE(2) (,) (3) (,) (1) mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents.

The MTX computer control system for the 400 kilowatt 140 Ghz gyrotron

International Nuclear Information System (INIS)

Jackson, M.C.; Ferguson, S.W.; Petersen, D.E.

1992-01-01

This paper reports on a 400 kilowatt, 140 Ghz gyrotron employed on MTX as a source of direct plasma heating and, additionally, as a driver for a free electron laser, which is used for plasma heating. The control system that operates this gyrotron uses a new graphics oriented software system called TACL (Thaumaturgic Automated Control Logic) developed by the Continuous Electron Beam Accelerator Facility (CEBAF) and owned by DOE. This control language does not require a software specialist, but is easily handled by the engineer or technician working on the system. All control logic and custom displays are entered via graphics oriented editors and no actual lines of code need to be written. The graphics displays make the gyrotron operation quite simple and allow individual users to define displays to meet their own needs or develop one for a specific set of tests to be run. The system, additionally, can be used for data logging functions, which have been found quite useful in tracking long term trends in vacion current and calorimetry of gyrotron cooling circuits

High voltage K/sub a/-band gyrotron oscillator experiment

International Nuclear Information System (INIS)

Gold, S.H.; Fliflet, A.W.; Manheimer, W.M.; Black, W.M.; Granatstein, V.L.; Kinkead, A.K.; Hardesty, D.L.; Sucy, M.

1986-01-01

Future applications of millimeter-waves may require significantly higher powers (>100 MW) than are available from the long-pulse thermionic gyrotrons that are presently available or under development. Scaling studies suggest that these power levels should be accessible to gyrotrons employing relativistic (0.5-1 MeV), multi-kA electron beams, such as can be generated for short pulse lengths (≤100 nsec) using pulseline accelerators with plasma-induced field-emission cathodes. To explore this potential, the authors have assembled a new gyrotron experiment based on a compact Febetron pulser. Initial experiments using a 350keV, 700A electron beam with a ratio of transverse to longitudinal velocity of ≅0.75 have produced ≅20MW at 35GHz at 8.5% efficiency in a TE/sub 62/ mode, in good agreement with the predictions of theory for the experimental parameters. Substantially higher powers and efficiencies are predicted for a new experimental configuration, which will operate at a higher voltage with improved beam parameters. In this new experiment, a 600 keV, multi-kA electron beam will be produced with low initial transverse energy. Transverse kinetic energy will then be added to the beam either by resonant pumping, via a magnetic wiggler, or by transit through a nonadiabatic magnetic ''bump.'' Finally, the beam will be adiabatically compressed to the desired radius in the gyrotron cavity with a final α≅1. The authors plan to report on the latest results from this new experimental configuration

Soviet Development of Gyrotrons

Science.gov (United States)

1986-05-01

Relationship Type of Device Remarks V, - Vc, anomalous Doppler Capable of 100 percent efficiency, CRM but more cumbersome than Cheren- kov devices V...authors; and discusses inlividual Soviet reseaLc- groups, the basic organizational units responAiLle for the CRM and gyrotron research and development. The...maintained a cCnEistEnt iecord of significant achievements; it has managed to overcome the systenic yeaxness of the Soviet R&C systeg in teimg atle to

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

International Nuclear Information System (INIS)

Caplan, M.

1986-01-01

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

Design of an electronically tunable millimeter wave Gyrotron Backward Wave Oscillator

International Nuclear Information System (INIS)

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

Analytic theory of the gyrotron

International Nuclear Information System (INIS)

Lentini, P.J.

1989-06-01

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

Development of over 1 MW and multi-frequency gyrotrons for fusion

International Nuclear Information System (INIS)

Imai, T.; Kariya, T.; Minami, R.; Numakura, T.; Kato, T.; Endo, Y.; Ichimura, M.; Eguchi, T.; Mitsunaka, Y.; Shimozuma, T.; Kubo, S.; Takahashi, H.; Yoshimura, Y.; Igami, H.; Ito, S.; Mutoh, T.; Sakamoto, Keishi; Idei, H.; Zushi, H.; Nagasaki, K.; Sano, F.; Ono, M.

2014-10-01

The development of wide frequency range from 14 to 300 GHz of high power mega-watt gyrotron for fusion is in progress in University of Tsukuba. The strong development activity was carried out in collaboration with JAEA, NIFS, TETD and universities. Over-1 MW dual frequency gyrotron of new frequency range (14 – 35 GHz), where the reduction of diffraction loss and cathode optimization are quite important, has been developed for EC/EBW H and CD for GAMMA 10/PDX, QUEST, Heliotron J and NSTX-U. Output power of 1.25 MW at 28 GHz and estimated oscillation power of 1.2 MW at 35.45 GHz from the same tube have been achieved with the cathode angle improvement and two frequency window. This is the first demonstration of the over 1 MW dual-frequency operations in lower frequency, which contributes to the technology of wide band multi-frequency/multi-MW tube. The output power of 600 kW for 2 s at 28 GHz is also demonstrated. It is applied to the QUEST and has resulted higher EC-driven current than ever. As for higher frequency range, in the joint program of NIFS and Tsukuba for LHD ECH gyrotrons, a new frequency of 154 GHz has been successfully developed with a TE 28,8 cavity, which delivered 1.16 MW for 1 s and the total power of 4.4 MW to LHD plasma with other three 77 GHz tubes, which extended the LHD plasma to high T e region. All these gyrotron performances are new records in each frequency range. The sub-THz gyrotron development is also just begun in collaboration with JAEA for Demo-Reactor ECH system. (author)

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

International Nuclear Information System (INIS)

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

2006-01-01

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

Nanostructure induced changes in lifetime and enhanced second-harmonic response of organic-plasmonic hybrids

Energy Technology Data Exchange (ETDEWEB)

Leißner, Till [NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg (Denmark); Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense (Denmark); Kostiučenko, Oksana; Rubahn, Horst-Günter; Fiutowski, Jacek, E-mail: fiutowski@mci.sdu.dk [NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, 6400 Sønderborg (Denmark); Brewer, Jonathan R. [Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense (Denmark)

2015-12-21

In this letter we show that the optical response of organic nanofibers, grown from functionalized para-quaterphenylene molecules, can be controlled by forming organic-plasmonic hybrid systems. The interaction between nanofibers and supporting regular arrays of nanostructures leads to a strongly enhanced second harmonic response. At the same time, the fluorescence lifetime of the nanofibers is reduced from 0.32 ns for unstructured gold films to 0.22 ns for gold nanosquare arrays, demonstrating efficient organic–plasmonic interaction. To study the origin of these effects, we applied two-photon laser scanning microscopy and fluorescence lifetime imaging microscopy. These findings provide an effective approach for plasmon-enhanced second-harmonic generation at the nanoscale, which is attractive for nanophotonic circuitry.

A hybrid filter to mitigate harmonics caused by nonlinear load and resonance caused by power factor correction capacitor

Science.gov (United States)

Adan, N. F.; Soomro, D. M.

2017-01-01

Power factor correction capacitor (PFCC) is commonly installed in industrial applications for power factor correction (PFC). With the expanding use of non-linear equipment such as ASDs, power converters, etc., power factor (PF) improvement has become difficult due to the presence of harmonics. The resulting capacitive impedance of the PFCC may form a resonant circuit with the source inductive reactance at a certain frequency, which is likely to coincide with one of the harmonic frequency of the load. This condition will trigger large oscillatory currents and voltages that may stress the insulation and cause subsequent damage to the PFCC and equipment connected to the power system (PS). Besides, high PF cannot be achieved due to power distortion. This paper presents the design of a three-phase hybrid filter consisting of a single tuned passive filter (STPF) and shunt active power filter (SAPF) to mitigate harmonics and resonance in the PS through simulation using PSCAD/EMTDC software. SAPF was developed using p-q theory. The hybrid filter has resulted in significant improvement on both total harmonic distortion for voltage (THDV) and total demand distortion for current (TDDI) with maximum values of 2.93% and 9.84% respectively which were within the recommended IEEE 519-2014 standard limits. Regarding PF improvement, the combined filters have achieved PF close to desired PF at 0.95 for firing angle, α values up to 40°.

High Power Microwave Emission of Large and Small Orbit Gyrotron Devices in Rectangular Interaction Structures

Science.gov (United States)

Hochman, J. M.; Gilgenbach, R. M.; Jaynes, R. L.; Rintamaki, J. I.; Luginsland, J. W.; Lau, Y. Y.; Spencer, T. A.

1996-11-01

Experiments utilize large and small orbit e-beam gyrotron devices in a rectangular-cross-section (RCS) gyrotron. This device is being explored to examine polarization control. Other research issues include pulse shortening, and mode competition. MELBA generates electron beams with parameters of: -800kV, 1-10kA diode current, and 0.5-1.0 μ sec pulselengths. The small orbit gyrotron device is converted to a large orbit experiment by running MELBA's annular electron beam through a magnetic cusp. Initial experiments showed an increase in beam alpha (V_perp/V_par) of a factor of ~ 4 between small and large orbit devices. Experimental results from the RCS gyrotron will be compared for large-orbit and small-orbit electron beams. Beam transport data and frequency measurements will be presented. Computer modeling utilizing the MAGIC and E-gun codes will be shown.

Startup methods for single-mode gyrotron operation

International Nuclear Information System (INIS)

Whaley, D.R.; Tran, M.Q.; Alberti, S.; Tran, T.M.; Antonsen, T.M. Jr.; Dubrovin, A.; Tran, C.

1995-01-01

Experimental results of startup studies on a 118 GHz TE 22,6 gyrotron are presented and compared with theory. The startup paths through the energy-velocity-pitch-angle plane are determined by the time evolution of the beam parameters during the startup phase. These startup paths are modified by changing the anode and cathode voltage rise from zero to their nominal values and are seen to determine the cavity oscillating mode. Experimental results show specifically that competition between the TE 22,6 and TE -19,7 mode can be completely eliminated by use of the proper startup method in a case where a typical triode startup results in oscillation in the competing TE -19,7 mode. These new results are shown to be in excellent agreement with the theory whose approach is general and therefore applicable to gyrotrons operating in any arbitrary cavity mode. (author) 3 figs., 4 refs

Single-stage depressed collectors for gyrotrons

International Nuclear Information System (INIS)

Piosczyk, B.; Iatrou, C.T.; Dammertz, G.; Thumm, M.; Univ. Karlsruhe

1996-01-01

Two 140 GHz gyrotrons with a single-step depressed collector have been operated. The different position of the isolating collector gap in the stray magnetic field causes the electron motion in the retarding region to be in one case adiabatic and in the other case nonadiabatic. The kind of motion within the retarding field influences strongly the behavior of the gyrotron with a depressed collector. In the case of nonadiabatic motion a significant amount of transverse momentum is given to the electrons reflected at the collector potential. This causes the reflected electrons to be trapped between the magnetic mirror and the collector. The electrons escape from the trap by diffusion across the magnetic field to the body of the tube thus contributing to the body current. Despite the high body current there is no observable influence of the collector voltage on the RF output power. In the case of adiabatic motion the reflected electrons do not gain a sufficient amount of transverse momentum to be trapped by the magnetic mirror. They pass the cavity toward the gun and they are trapped between the negative gun potential and the collector. The interaction with the RF field by electrons traveling through the cavity enhances the diffusion in the velocity space thus enabling the trapped electrons to overcome the potential barrier and escape toward the collector. Therefore the body current stays at low values since in this case the reflected electrons do not contribute to it. However, at higher collector voltages a reduction of RF power occurred and some noise in the electron beam was observed. The main motivation for the development of gyrotrons in the frequency range above 100 GHz with power levels in excess of several hundreds kW per tube, is the application in magnetic fusion devices for plasma heating and for electron current drive

Quasi-optical gyrotron: present status and future prospect

International Nuclear Information System (INIS)

Tran, M.Q.

1989-01-01

A review of the main experiments on quasi-optical gyrotron is presented. Methods to improve the efficiency (pencil beam electron gun and depressed collector) will be discussed. (author) 5 figs., 1 tab., 10 refs

Upgrade of a 30 kV/10 mA anode power supply for triode type gyrotron

Energy Technology Data Exchange (ETDEWEB)

Siravo, Ugo, E-mail: ugo.siravo@epfl.ch; Alberti, Stefano; Dubray, Jérémie; Fasel, Damien; Hogge, Jean-Philippe; Marlétaz, Blaise; Marmillod, Philippe; Perez, Albert; Silva, Miguel

2015-10-15

Highlights: • Triode type gyrotron is fed by 3 power supplies: the main, an anode PS(APS) and a heater. • This paper presents the upgrade of 3APS, supplied in 1999, that never fulfilled the specs. • The new working principle is very efficient, easy to implement, for a minimal cost. • Upgraded APS provides extended modulation capabilities, no overshoot and lowerripple. • This upgrade will allow exploring new operation regimes for the 3 TCV X3 gyrotrons. - The RF power of a gyrotron with a triode type magnetron-injection-gun (MIG) can be directly controlled via the voltage applied between its anode and its cathode. Hence, the performance of this type of gyrotron relies directly on the possibilities offered by the power supply controlling the anode to cathode voltage. For a system of gyrotrons connected to the same main high-voltage power supply, with a triode MIG one has the additional advantage of independently controlling each individual gyrotron. This paper presents the modifications brought to the three existing 30 kV/10 mA anode power supplies connected to the 500 kW/118 GHz/2s X3 gyrotrons operated on the TCV Tokamak. The new working principle based on phase-shift modulation (PSM) is described in detail. Experimental results obtained on dummy load are compared to simulations performed during the design phase. With respect to the initial working principle, the modulation frequency capability has been increased by a factor 10 reaching more than 5 kHz, whereas the output voltage ripple as well as the overshoot/undershoot have been significantly reduced.

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

Energy Technology Data Exchange (ETDEWEB)

Piosczyk, B [Forschungszentrum Karlsruhe, Association EURATOM-FZK, Institut fuer Hochleistungsimpuls- und Mikrowellentechnik (IHM), Postfach 3640, D-76021 Karlsruhe (Germany); Dammertz, G [Forschungszentrum Karlsruhe, Association EURATOM-FZK, Institut fuer Hochleistungsimpuls- und Mikrowellentechnik (IHM), Postfach 3640, D-76021 Karlsruhe (Germany); Dumbrajs, O [Department of Engineering Physics and Mathematics, Helsinki University of Technology, Association EURATOM-TEKES, FIN-02150 Espoo (Finland)] (and others)

2005-01-01

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 ({approx} 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.

A Modular Cascaded Multilevel Inverter Based Shunt Hybrid Active Power Filter for Selective Harmonic and Reactive Power Compensation Under Distorted/Unbalanced Grid Voltage Conditions

Directory of Open Access Journals (Sweden)

T. Demirdelen

2016-10-01

Full Text Available In recent years, shunt hybrid active power filters are being increasingly considered as a viable alternative to both passive filters and active power filters for compensating harmonics. In literature, their applications are restricted to balanced systems and low voltage applications and therefore not for industrial applications. This paper investigates the performance of a modular cascaded multilevel inverter based Shunt Hybrid Active Power Filter (SHAPF for reactive power compensation and selective harmonics elimination under distorted/unbalanced grid voltage conditions in medium voltage levels. In the proposed control method, reactive power compensation is achieved successfully with a perceptible amount and the performance results of harmonic compensation are satisfactory. Theoretical analysis and simulation results are obtained from an actual industrial network model in PSCAD. The simulation results are presented for a proposed system in order to demonstrate that the harmonic compensation performance meets the IEEE-519 standard.

Startup methods for single-mode gyrotron operation

International Nuclear Information System (INIS)

Whaley, D.R.; Tran, M.Q.; Alberti, S.; Tran, T.M.; Antonsen, T.M.; Tran, C.

1995-03-01

Experimental results of startup studies on a 118 GHz TE 22,6 gyrotron are presented and compared with theory. The theoretical excitation regimes of competing modes are computed in the energy-velocity-pitch-angle plane near the operation point. The startup paths through the plane are determined by the time evolution of the beam parameters during the startup phase. These startup paths are modified by changing the anode and cathode voltage rise from zero to their nominal values and are seen to determine the cavity oscillating mode. Experimental results show specifically that competition between the TE 22,6 and TE -19,7 mode can be completely eliminated by using the proper startup method in a case where a typical triode startup results in oscillation in the competing TE -19,7 mode. These new results are shown to be in excellent agreement with theory whose approach is general and therefore applicable to gyrotrons operating in any arbitrary cavity mode. (author) 5 figs., 1 tab., 13 refs

Simulation of Non-Uniform Electron Beams in the Gyrotron Electron-Optical System

Science.gov (United States)

Louksha, O. I.; Trofimov, P. A.

2018-04-01

New calculated data on the effect of emission inhomogeneities on the quality of the electron beam, which is formed in an electron-optical system of a gyrotron, have been obtained. The calculations were based on emission current density distributions, which were measured for the different cathodes in the gyrotron of Peter the Great St. Petersburg Polytechnic University. A satisfactory agreement between the experimental and calculated data on the influence of emission nonuniformities on the velocity spread of electrons has been shown. The necessity of considering the real distribution of the emission current density over the cathode surface to determine the main parameters of the electron beam—the velocity and energy spreads of the electrons, spatial structure of the beam, and coefficient of reflection of electrons from the magnetic mirror—has been demonstrated. The maximum level of emission inhomogeneities, which are permissible for effective work of gyrotrons, has been discussed.

Design of 95 GHz gyrotron based on continuous operation copper solenoid with water cooling

International Nuclear Information System (INIS)

Borodin, Dmitri; Ben-Moshe, Roey; Einat, Moshe

2014-01-01

The design work for 2nd harmonic 95 GHz, 50 kW gyrotron based on continuous operation copper solenoid is presented. Thermionic magnetron injection gun specifications were calculated according to the linear trade off equation, and simulated with CST program. Numerical code is used for cavity design using the non-uniform string equation as well as particle motion in the “cold” cavity field. The mode TE02 with low Ohmic losses in the cavity walls was chosen as the operating mode. The Solenoid is designed to induce magnetic field of 1.8 T over a length of 40 mm in the interaction region with homogeneity of ±0.34%. The solenoid has six concentric cylindrical segments (and two correction segments) of copper foil windings separated by water channels for cooling. The predicted temperature in continuous operation is below 93 °C. The parameters of the design together with simulation results of the electromagnetic cavity field, magnetic field, electron trajectories, and thermal analyses are presented

Design of 95 GHz gyrotron based on continuous operation copper solenoid with water cooling

Energy Technology Data Exchange (ETDEWEB)

Borodin, Dmitri; Ben-Moshe, Roey; Einat, Moshe [Department of Electrical and Electronic Engineering, Ariel University, Ariel 40700 (Israel)

2014-07-15

The design work for 2nd harmonic 95 GHz, 50 kW gyrotron based on continuous operation copper solenoid is presented. Thermionic magnetron injection gun specifications were calculated according to the linear trade off equation, and simulated with CST program. Numerical code is used for cavity design using the non-uniform string equation as well as particle motion in the “cold” cavity field. The mode TE02 with low Ohmic losses in the cavity walls was chosen as the operating mode. The Solenoid is designed to induce magnetic field of 1.8 T over a length of 40 mm in the interaction region with homogeneity of ±0.34%. The solenoid has six concentric cylindrical segments (and two correction segments) of copper foil windings separated by water channels for cooling. The predicted temperature in continuous operation is below 93 °C. The parameters of the design together with simulation results of the electromagnetic cavity field, magnetic field, electron trajectories, and thermal analyses are presented.

110GHz-500kW long-pulse gyrotron with built-in quasi-optical mode converter

International Nuclear Information System (INIS)

Sakamoto, Keishi; Kariya, Tsuyoshi; Hayashi, Ken-ichi.

1994-01-01

We have designed, fabricated, and tested a 110 GHz-500 kW long-pulse gyrotron. The gyrotron incorporates a quasi-optical mode converter which transforms the oscillation mode, TE 22,2 , into a Gaussian radiation beam. The adoption of a built-in mode converter enabled us to design the electron beam collector so as to be capable of tolerating a 2 MW heat load. Attention was also paid to designing the gyrotron cavity and output window so as to permit long-pulse operations. In an experiment, we observed a maximum output power of 550 kW and achieved 1.3 s operation at a power level of 410 kW. (author)

A Repetitive Control Scheme Aimed at Compensating the 6k + 1 Harmonics for a Three-Phase Hybrid Active Filter

DEFF Research Database (Denmark)

Luo, Zhaoxu; Su, Mei; Yang, Jian

2016-01-01

these disadvantages, many repetitive controllers with reduced delay time have been proposed, which can selectively compensate the odd harmonics or 6k±1 harmonics with delay time reduced to T0/2 and T0/3,repectively. To further study in this area, this paper proposes an improved repetitive scheme implemented...... in stationary reference frame, which only compensates the 6k+1 harmonics (e.g. -5, +7, -11, +13) in three-phase systems and reduces the time delay to T0/6 . So compared with the earlier reduced delay time repetitive controllers, the robustness and transient performance is further improved, the waste of control...... effort is reduced, and the possibility of amplifying and even injecting any harmonic noises into system is avoided to the greatest extent. Moreover, the proposed repetitive scheme is used in the control of a three-phase hybrid active power filter. The experimental results validate the effectiveness...

Development of frequency step tunable 1 MW gyrotron at 131 to 146.5 GHz

Energy Technology Data Exchange (ETDEWEB)

Samartsev, A.; Gantenbein, G.; Dammertz, G.; Illy, S.; Kern, S.; Leonhardt, W.; Schlaich, A.; Schmid, M.; Thumm, M., E-mail: andrey.samartsev@kit.edu [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany)

2011-07-01

Effective control of power absorption in tokamaks and stellarators could be achieved by the frequency tuning of ECH and CD power delivered by high-power gyrotrons. In this report some results of the development of a frequency tunable gyrotron with fused-silica Brewster window are presented. Excitation of several modes at 1 MW power level in the range of frequencies from 131 to 146.5 GHz is achieved. (author)

MAGY: An innovative high voltage-low current power supply for gyrotron

International Nuclear Information System (INIS)

Siravo, Ugo; Alex, Juergen; Bader, Michael; Carpita, Mauro; Fasel, Damien; Gavin, Serge; Perez, Albert

2011-01-01

From the electrical point of view, the body and the anode of high power gyrotrons behave as capacitive loads. A highly dynamic power supply is, therefore, hard to achieve. The MAGY concept (Modulator for the Anode of a triode type GYrotron) embodies an innovative solution to manage the capacitive current ensuring a very low ripple on the output voltage. It consists of a series of independent, bi-directional and regulated DC sources. Compared to existing topologies, this solution requires a smaller number of power modules. It avoids internal high frequency modulation and simultaneously offers high resolution of the output voltage and a wide range of operating scenarios.

Hybrid simplified spherical harmonics with diffusion equation for light propagation in tissues

International Nuclear Information System (INIS)

Chen, Xueli; Sun, Fangfang; Yang, Defu; Ren, Shenghan; Liang, Jimin; Zhang, Qian

2015-01-01

Aiming at the limitations of the simplified spherical harmonics approximation (SP N ) and diffusion equation (DE) in describing the light propagation in tissues, a hybrid simplified spherical harmonics with diffusion equation (HSDE) based diffuse light transport model is proposed. In the HSDE model, the living body is first segmented into several major organs, and then the organs are divided into high scattering tissues and other tissues. DE and SP N are employed to describe the light propagation in these two kinds of tissues respectively, which are finally coupled using the established boundary coupling condition. The HSDE model makes full use of the advantages of SP N and DE, and abandons their disadvantages, so that it can provide a perfect balance between accuracy and computation time. Using the finite element method, the HSDE is solved for light flux density map on body surface. The accuracy and efficiency of the HSDE are validated with both regular geometries and digital mouse model based simulations. Corresponding results reveal that a comparable accuracy and much less computation time are achieved compared with the SP N model as well as a much better accuracy compared with the DE one. (paper)

Hybrid simplified spherical harmonics with diffusion equation for light propagation in tissues.

Science.gov (United States)

Chen, Xueli; Sun, Fangfang; Yang, Defu; Ren, Shenghan; Zhang, Qian; Liang, Jimin

2015-08-21

Aiming at the limitations of the simplified spherical harmonics approximation (SPN) and diffusion equation (DE) in describing the light propagation in tissues, a hybrid simplified spherical harmonics with diffusion equation (HSDE) based diffuse light transport model is proposed. In the HSDE model, the living body is first segmented into several major organs, and then the organs are divided into high scattering tissues and other tissues. DE and SPN are employed to describe the light propagation in these two kinds of tissues respectively, which are finally coupled using the established boundary coupling condition. The HSDE model makes full use of the advantages of SPN and DE, and abandons their disadvantages, so that it can provide a perfect balance between accuracy and computation time. Using the finite element method, the HSDE is solved for light flux density map on body surface. The accuracy and efficiency of the HSDE are validated with both regular geometries and digital mouse model based simulations. Corresponding results reveal that a comparable accuracy and much less computation time are achieved compared with the SPN model as well as a much better accuracy compared with the DE one.

Development of new generation software tools for simulation of electron beam formation in novel high power gyrotrons

Science.gov (United States)

Sabchevski, S.; Zhelyazkov, I.; Benova, E.; Atanassov, V.; Dankov, P.; Thumm, M.; Dammertz, G.; Piosczyk, B.; Illy, S.; Tran, M. Q.; Alberti, S.; Hogge, J.-Ph

2006-07-01

Computer aided design (CAD) based on numerical experiments performed by using adequate physical models and efficient simulation codes is an indispensable tool for development, investigation, and optimization of gyrotrons used as radiation sources for electron cyclotron resonance heating (ECRH) of fusion plasmas. In this paper, we review briefly the state-of-the-art in the field of modelling and simulation of intense, relativistic, helical electron beams formed in the electron-optical systems (EOS) of powerful gyrotrons. We discuss both the limitations of the known computer codes and the requirements for increasing their capabilities for solution of various design problems that are being envisaged in the development of the next generation gyrotrons for ECRH. Moreover, we present the concept followed by us in an attempt to unite the advantages of the modern programming techniques with self-consistent, first-principles 3D physical models in the creation of a new highly efficient and versatile software package for simulation of powerful gyrotrons.

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

International Nuclear Information System (INIS)

Ferguson, S.W.; Felker, B.; Jackson, M.C.; Petersen, D.E.; Sewall, N.R.; Stever, R.D.

1991-09-01

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

Suppression criteria of parasitic mode oscillations in a gyrotron beam tunnel

Science.gov (United States)

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

2011-02-01

This paper presents the design criteria of the parasitic mode oscillations suppression for a periodic, ceramic, and copper loaded gyrotron beam tunnel. In such a type of beam tunnel, the suppression of parasitic mode oscillations is an important design problem. A method of beam-wave coupling coefficient and its mathematical formulation are presented. The developed design criteria are used in the beam tunnel design of a 42 GHz gyrotron to be developed for the Indian TOKAMAK system. The role of the thickness and the radius of the beam tunnel copper rings to obtain the developed design criteria are also discussed. The commercially available electromagnetic code CST and the electron trajectory code EGUN are used for the simulations.

Suppression criteria of parasitic mode oscillations in a gyrotron beam tunnel

International Nuclear Information System (INIS)

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

2011-01-01

This paper presents the design criteria of the parasitic mode oscillations suppression for a periodic, ceramic, and copper loaded gyrotron beam tunnel. In such a type of beam tunnel, the suppression of parasitic mode oscillations is an important design problem. A method of beam-wave coupling coefficient and its mathematical formulation are presented. The developed design criteria are used in the beam tunnel design of a 42 GHz gyrotron to be developed for the Indian TOKAMAK system. The role of the thickness and the radius of the beam tunnel copper rings to obtain the developed design criteria are also discussed. The commercially available electromagnetic code CST and the electron trajectory code EGUN are used for the simulations.

Optimal Selective Harmonic Control for Power Harmonics Mitigation

DEFF Research Database (Denmark)

Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede

2015-01-01

of power harmonics. The proposed optimal SHC is of hybrid structure: all recursive SHC modules with weighted gains are connected in parallel. It bridges the real “nk+-m order RC” and the complex “parallel structure RC”. Compared to other IMP based control solutions, it offers an optimal trade-off among...

The first preliminary experiments on an 84 GHz gyrotron with a single-stage depressed collector

International Nuclear Information System (INIS)

Shimozuma, T.; Sato, M.; Takita, Y.

1997-10-01

We fabricated and tested an 84GHz gyrotron with a single-stage depressed collector. The gyrotron has a high-voltage insulating section made of a low loss silicon nitride composite. In this preliminary experiment in the depressed collector configuration, we obtained 591kW, 41% operation with a depression voltage of 22.5kV. Access to the higher efficiency region was inhibited by an increase in anode current. (author)

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.

Self-consistent theory of a harmonic gyroklystron with a minimum Q cavity

International Nuclear Information System (INIS)

Tran, T.M.; Kreischer, K.E.; Temkin, R.J.

1986-01-01

In this paper, the energy extraction stage of the gyroklystron [in Advances in Electronics and Electron Physics, edited by C. Marton (Academic, New York, 1979), Vol. 1, pp. 1--54], with a minimum Q cavity is investigated by using a self-consistent radio-frequency (rf) field model. In the low-field, low-current limit, expressions for the self-consistent field and the resulting energy extraction efficiency are derived analytically for an arbitrary cyclotron harmonic number. To our knowledge, these are the first analytic results for the self-consistent field structure and efficiency of a gyrotron device. The large signal regime analysis is carried out by numerically integrating the coupled self-consistent equations. Several examples in this regime are presented

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.

Towards a 1 MW, 170 GHz gyrotron design for fusion application

Science.gov (United States)

Kumar, Anil; Kumar, Nitin; Singh, Udaybir; Bhattacharya, Ranajoy; Yadav, Vivek; Sinha, A. K.

2013-03-01

The electrical design of different components of 1 MW, 170 GHz gyrotron such as, magnetron injection gun, cylindrical interaction cavity and collector and RF window is presented in this article. Recently, a new project related to the development of 170 GHz, 1 MW gyrotron has been started for the Indian Tokamak. TE34,10 mode is selected as the operating mode after studied the problem of mode competition. The triode type geometry is selected for the design of magnetron injection gun (MIG) to achieve the required beam parameters. The maximum transverse velocity spread of 3.28% at the velocity ratio of 1.34 is obtained in simulations for a 40 A, 80 kV electron beam. The RF output power of more than 1 MW with 36.5% interaction efficiency without depressed collector is predicted by simulation in single-mode operation at 170 GHz frequency. The simulated single-stage depressed collector of the gyrotron predicted the overall device efficiencies >55%. Due to the very good thermal conductivity and very weak dependency of the dielectric parameters on temperature, PACVD diamond is selected for window design for the transmission of RF power. The in-house developed code MIGSYN and GCOMS are used for initial geometry design of MIG and mode selection respectively. Commercially available simulation tools MAGIC and ANSYS are used for beam-wave interaction and mechanical analysis respectively.

Frequency-agile gyrotron for electron decoupling and pulsed dynamic nuclear polarization

Science.gov (United States)

Scott, Faith J.; Saliba, Edward P.; Albert, Brice J.; Alaniva, Nicholas; Sesti, Erika L.; Gao, Chukun; Golota, Natalie C.; Choi, Eric J.; Jagtap, Anil P.; Wittmann, Johannes J.; Eckardt, Michael; Harneit, Wolfgang; Corzilius, Björn; Th. Sigurdsson, Snorri; Barnes, Alexander B.

2018-04-01

We describe a frequency-agile gyrotron which can generate frequency-chirped microwave pulses. An arbitrary waveform generator (AWG) within the NMR spectrometer controls the microwave frequency, enabling synchronized pulsed control of both electron and nuclear spins. We demonstrate that the acceleration of emitted electrons, and thus the microwave frequency, can be quickly changed by varying the anode voltage. This strategy results in much faster frequency response than can be achieved by changing the potential of the electron emitter, and does not require a custom triode electron gun. The gyrotron frequency can be swept with a rate of 20 MHz/μs over a 670 MHz bandwidth in a static magnetic field. We have already implemented time-domain electron decoupling with dynamic nuclear polarization (DNP) magic angle spinning (MAS) with this device. In this contribution, we show frequency-swept DNP enhancement profiles recorded without changing the NMR magnet or probe. The profile of endofullerenes exhibits a DNP profile with a <10 MHz linewidth, indicating that the device also has sufficient frequency stability, and therefore phase stability, to implement pulsed DNP mechanisms such as the frequency-swept solid effect. We describe schematics of the mechanical and vacuum construction of the device which includes a novel flanged sapphire window assembly. Finally, we discuss how commercially available continuous-wave gyrotrons can potentially be converted into similar frequency-agile high-power microwave sources.

Numerical design and analysis of parasitic mode oscillations for 95 GHz gyrotron beam tunnel

Science.gov (United States)

Kumar, Nitin; Singh, Udaybir; Yadav, Vivek; Kumar, Anil; Sinha, A. K.

2013-05-01

The beam tunnel, equipped with the high lossy ceramics, is designed for 95 GHz gyrotron. The geometry of the beam tunnel is optimized considering the maximum RF absorption (ideally 100%) and the suppression of parasitic oscillations. The excitation of parasitic modes is a concerning problem for high frequency, high power gyrotrons. Considering the problem of parasitic mode excitation in beam tunnel, a detail analysis is performed for the suppression of these kinds of modes. Trajectory code EGUN and CST Microwave Studio are used for the simulations of electron beam trajectory and electromagnetic analysis, respectively.

Interpretation of the nonlinear mode excitation in the ITER gyrotron

International Nuclear Information System (INIS)

Nusinovich, G. S.; Sinitsyn, O. V.

2007-01-01

This study was motivated by an interesting physical effect observed in experiments with a 1 MW, 170 GHz, continuous-wave gyrotron developed at the Japan Atomic Energy Agency for plasma heating and current drive in ITER [see, e.g., Fusion Eng. Des. 55, issues 2-3 (2001)]. In these experiments, the gyrotron switching from a parasitic mode to the operating one was observed with the increase in external magnetic field in the region of hard self-excitation of the operating mode where it cannot be excited from the noise level in the absence of other modes. Below, the theory describing this effect is developed. The switching mechanism caused by merging and disappearance of two (one stable and another unstable) equilibrium states with nonzero amplitudes of both modes is proposed. It is found that the present theory can correctly interpret experimental results qualitatively, but the lack of experimental data does not let the authors carry out some simulations more adequate to experimental conditions

Stability analysis of a coaxial-waveguide gyrotron traveling-wave amplifier

International Nuclear Information System (INIS)

Hung, C.L.; Yeh, Y.S.

2005-01-01

The gyrotron traveling-wave tube (gyro-TWT) amplifier is known to be highly susceptible to spurious oscillations. This study develops a simulation approach to analyze the stability of a coaxial-waveguide gyro-TWT with distributed wall losses. The interplay among the absolute instabilities, the gyrotron backward-wave oscillations, and the circuit parameters is analyzed. Simulation results reveal that the distributed wall losses effectively stabilize spurious oscillations in the coaxial gyro-TWT. Furthermore, the wall resistivity of the center conductor is shown to be an additional effective mechanism for suppressing oscillations. Under stable operation conditions, the coaxial gyro-TWT with distributed losses is predicted to generate 435 kW in the Ka band with 31% efficiency, a saturated gain of 45 dB, and a bandwidth of 1.86 GHz (≅5.8%) for a 70 kV, 20 A electron beam with an α(=ν perpendicular )/ν z )=1.0 and an axial velocity spread of Δν z /ν z =5%

High-power and long-pulse operation of TE{sub 31,11} mode gyrotron

Energy Technology Data Exchange (ETDEWEB)

Ikeda, Ryosuke, E-mail: ikeda.ryosuke@jaea.go.jp; Kajiwara, Ken; Oda, Yasuhisa; Takahashi, Koji; Sakamoto, Keishi

2015-10-15

Highlights: • We are under development of TE{sub 31,11} mode gyrotron to aim ITER specification. • HE{sub 11} mode purity reached 96% of ITER specification. • Mode competition was suppressed in initial phase of oscillation by anode voltage control. • Maximum output power of 1.2 MW was achieved. • Steady state operation of 500 MJ was achieved. - Abstract: The ITER electron cyclotron system is designed to inject a 20 MW RF beam by using twenty-four 170 GHz/1 MW gyrotrons. JAEA is currently developing a gyrotron having a high-order mode (TE{sub 31,11}) to reduce the heat load in the cavity resonator and achieve an output power greater than 1 MW. The measured radiation profile at the front of the diamond window agreed with the results of the calculation. In order to suppress RF loss in the equatorial and upper port launchers, a high-quality HE{sub 11} mode is required at the exit of the matching optics unit (MOU). An HE{sub 11} mode purity of 96% was achieved by finely adjusting the two mirrors in the MOU. During the oscillation start-up phase, mode competition with counter-rotating TE{sub 29,12} mode was observed on the higher magnetic field side which caused arcing and pressure increase in the gyrotron. To avoid the counter-rotating TE{sub 29,12} mode from being excited, a start-up scenario that controls the voltage between the anode and cathode electrodes at the initial phase of operation was introduced, which was able to achieve a stable start-up of TE{sub 31,11} mode. A 1.2 MW output power having a total electric efficiency of 43% was obtained in high-power experiments. In steady-state operation, a 1000 s oscillation length and output power of 0.51 MW was achieved.

Final Report for 'Gyrotron Design and Evaluation using New Particle-in-Cell Capability'

International Nuclear Information System (INIS)

Smithe, David N.

2008-01-01

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 and 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.

Design, Development & Functional Validation of Magnets system in support of 42 GHz Gyrotron in India

Directory of Open Access Journals (Sweden)

Pradhan S.

2017-01-01

Full Text Available A multi institutional initiative is underway towards the development of 42 GHz, 200 kW gyrotron system in India under the frame work of Department of Science and Technology, Government of India. Indigenous realization comprising of design, fabrication, prototypes and functional validations of an appropriate Magnet System is one of the primary technological objective of these initiatives. The 42 GHz gyrotron magnet system comprises of a warm gun magnet, a NbTi/Cu based high homogenous superconducting cavity magnet and three warm collector magnets. The superconducting cavity magnet has been housed inside a low loss cryostat. The magnet system has been designed in accordance with gyrotron physics and engineering considerations respecting highly homogenous spatial field profile as well as maintaining steep gradient as per the compression and velocity ratios between the emission and resonator regions. The designed magnet system further ensures the co-linearity of the magnetic axis with that of the beam axis with custom winding techniques apart from a smooth collection of beam with the collector magnet profiles. The designed magnets have been wound after several R & D validations. The superconducting magnet has been housed inside a low loss designed cryostat with in-built radial and axial alignment flexibilities to certain extent. The cryostat further houses liquid helium port, liquid nitrogen ports, current communication ports, ports for monitoring helium level and other instrumentations apart from over-pressure safety intensive burst disks etc. The entire magnet system comprising of warm and superconducting magnets has been installed and integrated in the Gyrotron test set-up. The magnet system has been aligned in both warm and when the superconducting cavity magnet is cold. The integrated geometric axes have been experimentally ensured as well as the field profiles have been measured with the magnets being charged. Under experimental conditions

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

International Nuclear Information System (INIS)

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

2016-01-01

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. (paper)

Update on the DIII-D ECH system: experiments, gyrotrons, advanced diagnostics, and controls

Directory of Open Access Journals (Sweden)

Lohr John

2017-01-01

Full Text Available The ECH system on DIII-D is continuing to be upgraded, while simultaneously being operated nearly daily for plasma experiments. The latest major hardware addition is a new 117.5 GHz gyrotron, which generated 1.7 MW for short pulses during factory testing. A new gyrotron control system based on Field Programmable Gate Array (FPGA technology with very high speed system data acquisition has significantly increased the flexibility and reliability of individual gyrotron operation. We have improved the performance of the fast mirror scanning, both by increasing the scan speeds and by adding new algorithms for controlling the aiming using commands generated by the Plasma Control System (PCS. The system is used for transport studies, ELM control, current profile control, non-inductive current generation, suppression of MHD modes, startup assist, plasma density control, and other applications. A program of protective measures, which has been in place for more than two years, has eliminated damage to hardware and diagnostics caused by overdense operation. Other activities not directly related to fusion research have used the ECH system to test components, study methods for improving production of semiconductor junctions and materials, and test the feasibility of using ground based microwave systems to power satellites into orbit.

Update on the DIII-D ECH system: experiments, gyrotrons, advanced diagnostics, and controls

Science.gov (United States)

Lohr, John; Brambila, Rigoberto; Cengher, Mirela; Gorelov, Yuri; Grosnickle, William; Moeller, Charles; Ponce, Dan; Torrezan, Antonio; Ives, Lawrence; Reed, Michael; Blank, Monica; Felch, Kevin; Parisuaña, Claudia; LeViness, Alexandra

2017-08-01

The ECH system on DIII-D is continuing to be upgraded, while simultaneously being operated nearly daily for plasma experiments. The latest major hardware addition is a new 117.5 GHz gyrotron, which generated 1.7 MW for short pulses during factory testing. A new gyrotron control system based on Field Programmable Gate Array (FPGA) technology with very high speed system data acquisition has significantly increased the flexibility and reliability of individual gyrotron operation. We have improved the performance of the fast mirror scanning, both by increasing the scan speeds and by adding new algorithms for controlling the aiming using commands generated by the Plasma Control System (PCS). The system is used for transport studies, ELM control, current profile control, non-inductive current generation, suppression of MHD modes, startup assist, plasma density control, and other applications. A program of protective measures, which has been in place for more than two years, has eliminated damage to hardware and diagnostics caused by overdense operation. Other activities not directly related to fusion research have used the ECH system to test components, study methods for improving production of semiconductor junctions and materials, and test the feasibility of using ground based microwave systems to power satellites into orbit.

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

Energy Technology Data Exchange (ETDEWEB)

Pereyaslavets, M.; Sato, M.; Shimozuma, T.; Takita, Y.; Idei, H.; Kubo, S.; Ohkubo, K.; Hayashi, K.

1996-11-01

To test gyrotron RF components, efficient low-power generators for rotating high-order modes of high purity are necessary. Designs of generators for the TE{sub 15,3} mode at 84 GHz and for the TE{sub 31,8} 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 TE{sub 15,3} 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)

Feasibility study of the EU home team on a 170 GHz 1 MW CW gyrotron for ECH on ITER

International Nuclear Information System (INIS)

Iatrou, C.T.; Kern, S.; Thumm, M.; Moebius, A.; Nickel, H.U.; Horajitra, P.; Wien, A.; Tran, T.M.; Bon Mardion, G.; Pain, M.; Tonon, G.

1995-03-01

The gyrotron system for ECH and burn control on ITER requires at least 50 MW of RF power at frequencies near 170 GHz operating in CW. To meet these requirements, high efficiency gyrotron tubes with ≥1 MW power output capability are necessary, as well as simple coupling to either a quasi-optical or waveguide transmission line. The paper reports the feasibility study on the design of an ITER-relevant gyrotron oscillator at 170 GHz, 1 MW CW employing a diode electron gun, an advanced internal quasi-optical converter, a cryogenically cooled single disk sapphire window, and a depressed potential collector. The operating mode selection and the cavity design is a compromise between many design constraints. (author) 18 figs., 6 tabs., 21 refs

Control of generation spectrum of gyrotron with external reflection in mode of several longitudinal modes

International Nuclear Information System (INIS)

Rozental', R.M.; Ginzburg, N.S.; Zajtsev, N.I.; Ilyakov, E.V.; Kulagin, I.S.

2006-01-01

One studies possibility to control the spectrum of multiparticle generation in a gyrotron due to application of external reflections. It is shown that in self-modulation regimes of generation the radiation spectrum lines may be close to the resonance frequencies throughout electrodynamic system covering a part of output waveguide restricted by a reflector. Under the mentioned conditions variation of distance between mode frequencies and, respectively, period of self-modulation may be reached due to varying of position of the reflector. The theory deductions are supported by the results of experimental investigation into 30 GHz region relativistic gyrotron with external reflections [ru

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.

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

International Nuclear Information System (INIS)

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

Parasitic oscillation in and suppression of a gyro BW mode in a low-Q 8 GHz gyrotron

International Nuclear Information System (INIS)

Muggli, P.; Tran, M.Q.; Tran, T.M.

1991-12-01

The parasitic oscillation of the TE o 21 gyrotron Backward Wave (gyro BW) mode is observed in a low-Q, 8 GHz TE o 011 gyrotron. Although at low power (P BW o 011 mode efficiency of less than 0.25. The parasitic oscillation is suppressed by operating the gyrotron with a negative magnetic field gradient along the electron beam, which allows the maximum efficiency to reach 0.40 and the output power to be multiplied by a factor varying from 1.4 to 1.7. The optimum efficiency curve of the TE o 011 mode indicates that the low-Q cavity behaves as a much higher Q diff cavity. Too large magnetic field gradient and α values favour the TE o 012 longitudinal mode, which oscillates in place of the TE o 011 mode and limits its maximum output power. This competitive process is responsible for the high-Q like output power. (author) 14 figs., 14 refs

Frequency Adaptive Selective Harmonic Control for Grid-Connected Inverters

DEFF Research Database (Denmark)

Yang, Yongheng; Zhou, Keliang; Wang, Huai

2015-01-01

SHC scheme consists of multiple parallel recursive (nk±m)-order (k = 0, 1, 2, . . ., and m ≤ n/2) harmonic control modules with independent control gains, which can be optimally weighted in accordance with the harmonic distribution. The hybrid SHC thus offers an optimal trade-off among cost...

TFTR 60 GHz alpha particle collective Thomson Scattering diagnostic

International Nuclear Information System (INIS)

Machuzak, J.S.; Woskov, P.P.; Gilmore, J.; Bretz, N.L.; Park, H.K.; Bindslev, H.

1995-03-01

A 60 GHz gyrotron collective Thomson Scattering alpha particle diagnostic has been implemented for the D-T period on TFM. Gyrotron power of 0.1-1 kW in pulses of up to 1 second can be launched in X-mode. Efficient corrugated waveguides are used with antennaes and vacuum windows of the TFTR Microwave Scattering system. A multichannel synchronous detector receiver system and spectrum analyzer acquire the scattered signals. A 200 Megasample/sec digitizer is used to resolve fine structure in the frequency spectrum. By scattering nearly perpendicular to the magnetic field, this experiment will take advantage of an enhancement of the scattered signal which results from the interaction of the alpha particles with plasma resonances in the lower hybrid frequency range. Significant enhancements are expected, which will make these measurements possible with gyrotron power less than 1 kW, while maintaining an acceptable signal to noise ratio. We hope to extract alpha particle density and velocity distribution functions from the data. The D and T fuel densities and temperatures may also be obtainable by measurement of the respective ion cyclotron harmonic frequencies

Synthesis of mig-type electron guns for gyrotrons

International Nuclear Information System (INIS)

Castro, J.J.B. de; Montes, A.; Silva, C.A.B.

1984-01-01

A synthesis method is used in the design of axially symmetrical guns in the moderate to high space charge regime. Self-consistent equations for the temperature limited emission case are used to represent the beam and solve the internal problem, under the requirement of laminar flow. The external problem is solved by integrating the equations with boundary conditions defined by the analytically extended solutions of the internal problem. This technique will be used in the development of INPE's gyrotron. (Author) [pt

Third harmonic X-mode electron cyclotron resonance heating on TCV using top launch

International Nuclear Information System (INIS)

Porte, L.; Alberti, S.; Arnoux, G.; Martin, Y.; Hogge, J.P.; Goodman, T.P.; Henderson, M.A.; Nelson-Melby, E.; Pochelon, A.; Tran, M.Q.

2003-01-01

A third harmonic electron cyclotron resonance heating system (X3) has been installed, commissioned and brought into service on the Tokamak a Configuration Variable (TCV). It comprises three 118 GHz, 0.5 MW gyrotrons designed to produce pulses up to 2 seconds long. In the present configuration, 1.0MW is launched vertically from the top of the vessel into the plasma and the remaining 0.5MW is launched horizontally from the low field side. X3 has been used to heat plasmas at density exceeding the 2 nd harmonic cut-off significantly extending the operational space of additionally heated TCV plasmas. Studies have been performed to determine the optimal plasma/launcher configuration for X3 absorption for various plasma conditions and to find methods for real time feedback control of the X3 launcher. First experiments have been performed aimed at heating H-mode plasmas on TCV. First results show that the ELMs in TCV ohmic H-mode plasmas exhibit all characteristics of Type III ELMs. If, at moderate X3 power ( 0.45MW) the Type III ELMs disappear and the H-mode discharge exhibits different MHD phenomena eventually disrupting. (author)

New window materials for high power gyrotron

International Nuclear Information System (INIS)

Afsar, M.N.; Hua Chi

1993-01-01

A single free standing synthetic diamond window seems to have higher absorption coefficient value at millimeter wavelength region at this time although it is claimed that it possesses good mechanical strength and higher thermal conductivity characteristics. It certainly does not rule out the use of diamond film on single crystal high resistivity silicon to improve its mechanical strength and thermal conductivity. One may have to use an appropriate film thickness for a particular wavelength in gyrotron window application. It is also necessary to use an appropriate thickness for the silicon perhaps equivalent to a quaterwavelength in order to avoid the reflection mismatch

The Use of a 28 GHz Gyrotron for EBW Startup Experiments on MAST

Science.gov (United States)

Caughman, J. B.; Bigelow, T. S.; Diem, S. J.; Peng, Y. K. M.; Rasmussen, D. A.; Shevchenko, V.; Hawes, J.; Lloyd, B.

2009-11-01

The use of electron Bernstein waves for non-inductive plasma current startup in MAST has recently been demonstrated [1]. The injection of 100 kW at 28 GHz generated plasma currents of up to 33 kA without the use of solenoid flux, and limited solenoid assist resulted in up to 55 kA of plasma current. A higher power 28 GHz gyrotron, with power levels of up to 300 kW for 0.5 seconds, is currently being commissioned. It is being used to investigate the scaling of startup current with microwave power and power profile as a function of time. Power modulation experiments are also being explored. Gyrotron performance and experimental results will be presented. [4pt] [1] V. Shevchenko, et al., Proceedings of the 15^th Joint Workshop on ECE and ECRH, Yosimite, USA, p. 68 (2009)

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.

Experimental considerations concerning the velocity measurement of the relativistic electron beam in a gyrotron by means of Thomson scattering

International Nuclear Information System (INIS)

Siegrist, M.R.; Soumagne, G.; Tran, M.Q.

1992-11-01

The feasibility of Thomson scattering to determine the beam velocity in a gyrotron has been analyzed and preliminary experiments to implement such a system on our 100 GHz quasi-optical gyrotron are reported. Although the project had to be abandoned due to technical problems, the conclusions are that for the 90 o scattering arrangement discussed it should be possible to determine at least one velocity component with an acceptable signal-to-noise ratio. (author) 11 figs., 10 refs

Upgrade Of The TH1506B 118 GHz Gyrotron Using Modeing Tools

International Nuclear Information System (INIS)

Darbos, C.; Bouquey, F.; Lambert, R.; Magne, R.; Traisnel, E.; Arnold, A.; Prinz, H. O.; Thumm, M.; Hogge, J. P.; Lievin, C.

2007-01-01

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

Hybridized centroid technique for 3D Molodensky-Badekas ...

African Journals Online (AJOL)

In view of this, the present study developed and tested two new hybrid centroid techniques known as the harmonic-quadratic mean and arithmetic-quadratic mean centroids. The proposed hybrid approaches were compared with the geometric mean, harmonic mean, median, quadratic mean and arithmetic mean. In addition ...

Development of Gyrotron and JT-60U EC heating system for fusion reactor

International Nuclear Information System (INIS)

Sakamoto, K.; Kasugai, A.; Ikeda, Yo.

2003-01-01

The progress of ECH technology, for ITER and JT-60U tokamak, are presented. In the development of gyrotron, 0.9MW/9.2sec, 0.5MW/30sec, 0.3MW/60sec, etc. have been demonstrated at 170GHz. At 110GHz, 1.3MW/1.2sec, 1.2MW/4.1sec, 1MW/5sec were obtained. It is found that the reduction of the stray radiation and the enhancement of cooling capability are keys for CW operation. Four 110GHz gyrotrons are under operation in the ECH system of JT-60U. The power up to approximately 3MW/2.7sec was injected into the plasma through the poloidally movable mirrors, and contributed to the electron heating up to 26keV(n e ∼0.5x10 13 cm -3 ), and the suppression of the neo-classical tearing mode. (author)

Development of gyrotron and JT-60U EC heating system for fusion reactor

International Nuclear Information System (INIS)

Sakamoto, K.; Kasugai, A.; Ikeda, Yo.

2003-01-01

The progress of ECH technology, for ITER and JT-60U tokamak, are presented. In the development of gyrotron, 0.9MW/9.2sec, 0.5MW/30sec, 0.3MW/60sec, etc. have been demonstrated at 170GHz. At 110GHz, 1.3MW/1.2sec, 1.2MW/4. 1sec. 1MW/5sec were obtained. It is found that the reduction of the stray radiation and the enhancement of cooling capability are keys for CW operation. Four 110GHz gyrotrons are under operation in the ECH system of JT-60U. The power up to approximately 3MW/2.7sec was injected into the plasma through the poloidally movable mirrors, and contributed to the electron heating up to 26keV(n e ∼0.5x10 13 cm -3 ), and the suppression of the neo-classical tearing mode. (author)

Particle-in-cell analysis of beam-wave interaction in gyrotron cavity with tapered magnetic field

Energy Technology Data Exchange (ETDEWEB)

Kumar, A., E-mail: anil.gyrotron@gmail.com [Gyrotron Lab., Microwave Tube Area, Central Electronics Engineering Research Inst. (CEERI, CSIR), Pilani, Rajasthan (India); Banasthali Univ., Dept. of Physics, Banasthali, Rajasthan (India); Khatun, H.; Kumar, N.; Singh, U.; Sinha, A.K. [Gyrotron Lab., Microwave Tube Area, Central Electronics Engineering Research Inst. (CEERI, CSIR), Pilani, Rajasthan (India); Vyas, V. [Banasthali Univ., Dept. of Physics, Banasthali, Rajasthan (India)

2010-11-15

A commercially available electromagnetic simulator -- MAGIC, a particle-in-cell (PIC) code -- has been used to carry out a comparative study of the beam-wave interaction under uniform and tapered magnetic field profiles of a 42 GHz, 200kW gyrotron. The magnetic field profile across the resonant cavity varies by ±6.5% with a peak value of 1.615 T. The MAGIC simulation shows the desire performance of the gyrotron under both magnetic field conditions with an operating mode TE{sub 03} and a pitch factor of 1.26. The analysis of the simulated results show that stability in the power growth was reached more quickly and achieved higher output power in the case of a tapered magnetic field. (author)

A high-voltage equipment (high voltage supply, high voltage pulse generators, resonant charging inductance, synchro-instruments for gyrotron frequency measurements) for plasma applications

International Nuclear Information System (INIS)

Spassov, Velin

1996-01-01

This document reports my activities as visitor-professor at the Gyrotron Project - INPE Plasma Laboratory. The main objective of my activities was designing, construction and testing a suitable high-voltage pulse generator for plasma applications, and efforts were concentrated on the following points: Design of high-voltage resonant power supply with tunable output (0 - 50 kV) for line-type high voltage pulse generator; design of line-type pulse generator (4 microseconds pulse duration, 0 - 25 kV tunable voltage) for non linear loads such as a gyrotron and P III reactor; design of resonant charging inductance for resonant line-type pulse generator, and design of high resolution synchro instrument for gyrotron frequency measurement. (author)

Design of the all solid high-voltage power supply for a gyrotron body

Energy Technology Data Exchange (ETDEWEB)

Rao, Yihua [School of Mathematics and Physics, University of South China, Hengyang, 421001 (China); Chen, Wenguang, E-mail: 430000485393@usc.edu.cn [School of Electrical Engineering, University of South China, Hengyang, 421001 (China); Hu, Bo [School of Electrical Engineering, University of South China, Hengyang, 421001 (China); Rao, Jun; Huang, Mei; Kang, Zihua; Feng, Kun [Southwestern Institute of Physics, Chengdu, 610041 (China); Huang, Jiaqi [School of Electrical Engineering, University of South China, Hengyang, 421001 (China)

2017-04-15

Highlights: • Completed design of all solid-state high-voltage power supply for gyrotron body on HL-2M ECRH. • Consist of 58 PSM modules and one BUCK module, controlled by DSP system. • Fabricated full voltage 35 kV, 200 mA BPS and tested in dummy load. • The BPS can operate in three modes: single pulse mode, multi-pulse modulation mode and the six-level preset mode. - Abstract: Gyrotron plays an important role in the research of electron cyclotron resonance heating (ECRH) on Tokomak. The high-frequency switched power supply technology and pulse step modulation (PSM) technology are used in the development of the all solid high-voltage body power supply (BPS) for 1 MW/105 GHz Gyrotron on ECRH system. Firstly, the basic structure of the BPS and its control system are introduced. Secondly, the software control algorithm of voltage stabilization and modulate method are developed. Finally, the design is verified by the experiments. The experimental results of the single pulse mode, the multi-pulse modulation mode and the six-level preset mode, are shown. The output voltage of the power supply can reach 35 kV and the current at about 200 mA, which are adjustable in the full range. The maximum modulation frequency can reach 1 kHz and the front edge of the pulse can be adjust from 0 to 3 ms and the accuracy of the output voltage is less than 100 V. The results show that the control method is feasible and can be applied to other high power microwave sources.

Experimental results and recent developments on the EU 2 MW 170 GHz coaxial cavity gyrotron for ITER

Directory of Open Access Journals (Sweden)

Thumm M. K.

2012-09-01

Full Text Available The European Gyrotron Consortium (EGYC is responsible for developing one set of 170 GHz mm-wave sources, in support of Europe’s contribution to ITER. The original plan of targeting a 2 MW coaxial gyrotron is currently under discussion, in view of essential delays and damages. This paper reports on the latest results and plans with regard to the two 2 MW gyrotron prototypes, the industrial prototype at CRPP’s CW test stand and a modular pre-prototype at KIT. The industrial prototype was delivered to CRPP end of September 2011 and reached an output power of 2 MW at an efficiency of 45 % and with good RF beam pattern, in only four days of short pulse RF test. These results validated all design changes made in reaction to the results of the experiments in 2008. On the fifth experimental day, an internal absorber broke, terminating any further experiment with this tube. In parallel, design and experimental activities at KIT went on, in particular featuring reduced stray radiation down to 4% of the RF power. Next years’ plans for the 2 MW modular pre-prototype foresee a stepwise increase of pulse length.

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

International Nuclear Information System (INIS)

Muggli, P.

1991-11-01

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 TE o 011 mode of the cavity. (author) figs., tabs., 102 refs

Status of the development of the EU 170 GHz/1 MW/CW gyrotron

Energy Technology Data Exchange (ETDEWEB)

Pagonakis, Ioannis Gr., E-mail: ioannis.pagonakis@kit.edu [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Albajar, Ferran [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Alberti, Stefano [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Avramidis, Konstantinos [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Bonicelli, Tullio [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Braunmueller, Falk [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Bruschi, Alex [Plasma Physics Institute, National Research Council of Italy, Milano (Italy); Chelis, Ioannis [School of Electrical and Computer Engineering, National Technical University of Athens (Greece); Cismondi, Fabio [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Gantenbein, Gerd [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Hermann, Virgile [Thales Electron Devices (TED), Vélizy-Villacoublay (France); Hesch, Klaus [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Hogge, Jean-Philippe [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Jelonnek, John; Jin, Jianbo; Illy, Stefan [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Ioannidis, Zisis C. [Faculty of Physics, National and Kapodistrian University of Athens (Greece); Kobarg, Thorsten [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); and others

2015-10-15

The progress in the development of the European 170 GHz, 1 MW/CW gyrotron for electron cyclotron heating & current drive (ECH&CD) on ITER is reported. A continuous wave (CW) prototype is being manufactured by Thales Electron Devices (TED), France, while a short-pulse (SP) prototype gyrotron is in parallel under manufacture at Karlsruhe Institute of Technology (KIT), with the purpose of validating the design of the CW industrial prototype components. The fabrication of most of the sub-assemblies of the SP prototype has been completed. In a first step, an existing magnetron injection gun (MIG) available at KIT was used. Despite this non-ideal configuration, the experiments provided a validation of the design, substantiated by an excellent agreement with numerical simulations. The tube, operated without a depressed collector, is able to produce more than 1 MW of output power with efficiency in excess of 30%, as expected, and compatible with the ITER requirements.

Novel dielectric photonic-band-gap resonant cavity loaded in a gyrotron

International Nuclear Information System (INIS)

Chen Xiaoan; Liu Gaofeng; Tang Changjian

2010-01-01

A novel resonant cavity composed of a periodic, multilayer, dielectric photonic crystal is proposed. Using the transfer matrix method and the Bloch theorem for periodic systems, an analysis on the band-gap property of such a structure is made, and the basic electromagnetic property of the photonic-band-gap resonant cavity (PBGC) is preliminarily exhibited. The theoretical studies and the cold cavity simulation results obtained from a high-frequency structure simulator are presented. On the basis of the present research, such a PBGC is quite similar to the two-dimensional PBGC made of triangular lattices of metal rods with a defect at its centre, in which a frequency selectivity is similarly demonstrated. Because of its unique electromagnetic property, the cavity has many promising applications in active and passive devices operating in the millimetre, sub-millimetre, and even THz wave range. As a specific application, the feasibility of substituting the traditional cylindrical resonant cavity loaded in a gyrotron for a dielectric PBGC to achieve a transverse high-order operation is discussed under the consideration of the electromagnetic features of the cavity. The study shows the great potential value of such a cavity for gyrotron devices.

Second harmonic generation in a bounded magnetoplasma

International Nuclear Information System (INIS)

Thomas, D.G.

1975-01-01

An experimental study of second harmonic generation in a magnetized plasma contained in a cylindrical cavity resonator shows how the harmonic power varies with fundamental power, background gas pressure, and magnetization. Two cavities were designed. For each the TM010 resonance was in the S-band and the TM011 resonance in the C-band. Both frequencies were harmonically related when the d.c. discharge sustaining the plasma was adjusted to give plasma frequencies of approximately 0.7 GHz and 1.53 GHz. The experimental results show the harmonic power approximately proportional to the square of the fundamental power from 5 to 100 mw, and a decreasing function of pressure from 10 to 150 millitorr. Experiments at constant plasma frequency and varying magnetic field from 0 to 3000 Gauss show a sharp drop in harmonic power to undetectable levels when the electron cyclotron frequency approximates either the fundamental or second harmonic frequencies. These effects are attributed, respectively, to the coupling of fundamental power to other modes and to cavity detuning away from the harmonic. With the plasma frequency adjusted to maintain simultaneous resonance of fundamental and harmonic, a harmonic signal maximum occurred when the upper hybrid frequency approximated the harmonic frequency. Several anomalies, apparently related to the magnetization, background gas, and electron density distribution were observed. Otherwise, the results are qualitatively consistent with the first order theory for a cold, collisional plasma

Improved Design of Beam Tunnel for 42 GHz Gyrotron

Science.gov (United States)

Singh, Udaybir; Kumar, Nitin; Purohit, L. P.; Sinha, A. K.

2011-04-01

In gyrotron, there is the chance of generation and excitation of unwanted RF modes (parasite oscillations). These modes may interact with electron beam and consequently degrade the beam quality. This paper presents the improved design of the beam tunnel to reduce the parasite oscillations and the effect of beam tunnel geometry on the electron beam parameters. The design optimization of the beam tunnel has been done with the help of 3-D simulation software CST-Microwave Studio and the effect of beam tunnel geometry on the electron beam parameters has been analyzed by EGUN code.

Nonlinearly driven oscillations in the gyrotron traveling-wave amplifier

International Nuclear Information System (INIS)

Chiu, C. C.; Pao, K. F.; Yan, Y. C.; Chu, K. R.; Barnett, L. R.; Luhmann, N. C. Jr.

2008-01-01

By delivering unprecedented power and gain, the gyrotron traveling-wave amplifier (gyro-TWT) offers great promise for advanced millimeter wave radars. However, the underlying physics of this complex nonlinear system is yet to be fully elucidated. Here, we report a new phenomenon in the form of nonlinearly driven oscillations. A zero-drive stable gyro-TWT is shown to be susceptible to a considerably reduced dynamic range at the band edge, followed by a sudden transition into driven oscillations and then a hysteresis effect. An analysis of this unexpected behavior and its physical interpretation are presented.

Simultaneous Stabilization of Gyrotron Frequency and Power by PID Double Feedback Control on the Acceleration and Anode Voltages

Science.gov (United States)

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

2017-07-01

In this paper, we present the results of simultaneous stabilization of both the frequency and the output power by a double PID feedback control on the acceleration and anode voltages in the 460-GHz gyrotron FU CW GVI, also known as "Gyrotron FU CW GO-1" (according to the nomenclature adopted at Osaka University). The approach used in the experiments is based on the modulation of the cyclotron frequency and the pitch factor (velocity ratio) of the electron beam by varying the acceleration and the anode voltages, respectively. In a long-term experiment, the frequency and power stabilities were made to be better than ±10-6 and ±1%, respectively.

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

International Nuclear Information System (INIS)

Stock, Andreas

2013-01-01

Within this thesis a parallelized, transient, three-dimensional, high-order discontinuous Galerkin Particle-in-Cell solver is developed and used to simulate the resonant cavity of a gyrotron. The high-order discontinuous Galerkin approach - a Finite-Element type method - provides a fast and efficient algorithm to numerically solve Maxwell's equations used within this thesis. Besides its outstanding dissipation and dispersion properties, the discontinuous Galerkin approach easily allows for using unstructured grids, as required to simulate complex-shaped engineering devices. The discontinuous Galerkin approach approximates a wavelength with significantly less degrees of freedom compared to other methods, e.g. Finite Difference methods. Furthermore, the parallelization capabilities of the discontinuous Galerkin framework are excellent due to the very local dependencies between the elements. These properties are essential for the efficient numerical treatment of the Vlasov-Maxwell system with the Particle-in-Cell method. This system describes the self-consistent interaction of charged particles and the electromagnetic field. As central application within this thesis gyrotron resonators are simulated with the discontinuous Galerkin Particle-in-Cell method on high-performance-computers. The gyrotron is a high-power millimeter wave source, used for the electron cyclotron resonance heating of magnetically confined fusion plasma, e.g. in the Wendelstein 7-X experimental fusion-reactor. Compared to state-of-the-art simulation tools used for the design of gyrotron resonators the Particle-in-Cell method does not use any significant physically simplifications w.r.t. the modelling of the particle-field-interaction, the geometry and the wave-spectrum. Hence, it is the method of choice for validation of current simulation tools being restricted by these simplifications. So far, the Particle-in-Cell method was restricted to be used for demonstration calculations only, because

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

Within this thesis a parallelized, transient, three-dimensional, high-order discontinuous Galerkin Particle-in-Cell solver is developed and used to simulate the resonant cavity of a gyrotron. The high-order discontinuous Galerkin approach - a Finite-Element type method - provides a fast and efficient algorithm to numerically solve Maxwell's equations used within this thesis. Besides its outstanding dissipation and dispersion properties, the discontinuous Galerkin approach easily allows for using unstructured grids, as required to simulate complex-shaped engineering devices. The discontinuous Galerkin approach approximates a wavelength with significantly less degrees of freedom compared to other methods, e.g. Finite Difference methods. Furthermore, the parallelization capabilities of the discontinuous Galerkin framework are excellent due to the very local dependencies between the elements. These properties are essential for the efficient numerical treatment of the Vlasov-Maxwell system with the Particle-in-Cell method. This system describes the self-consistent interaction of charged particles and the electromagnetic field. As central application within this thesis gyrotron resonators are simulated with the discontinuous Galerkin Particle-in-Cell method on high-performance-computers. The gyrotron is a high-power millimeter wave source, used for the electron cyclotron resonance heating of magnetically confined fusion plasma, e.g. in the Wendelstein 7-X experimental fusion-reactor. Compared to state-of-the-art simulation tools used for the design of gyrotron resonators the Particle-in-Cell method does not use any significant physically simplifications w.r.t. the modelling of the particle-field-interaction, the geometry and the wave-spectrum. Hence, it is the method of choice for validation of current simulation tools being restricted by these simplifications. So far, the Particle-in-Cell method was restricted to be used for demonstration calculations only, because

Plasma heating and hot ion sustaining in mirror based hybrids

International Nuclear Information System (INIS)

Moiseenko, V. E.; Ågren, O.

2012-01-01

Possibilities of plasma heating and sloshing ion sustaining in mirror based hybrids are briefly reviewed. Sloshing ions, i.e. energetic ions with a velocity distribution concentrated to a certain pitch-angle, play an important role in plasma confinement and generation of fusion neutrons in mirror machines. Neutral beam injection (NBI) is first discussed as a method to generate sloshing ions. Numerical results of NBI modeling for a stellarator-mirror hybrid are analyzed. The sloshing ions could alternatively be sustained by RF heating. Fast wave heating schemes, i.e. magnetic beach, minority and second harmonic heating, are addressed and their similarities and differences are described. Characteristic features of wave propagation in mirror hybrid devices including both fundamental harmonic minority and second harmonic heating are examined. Minority heating is efficient for a wide range of minority concentration and plasma densities; it allows one to place the antenna aside from the hot ion location. A simple-design strap antenna suitable for this has good performance. However, this scenario is appropriate only for light minority ions. The second harmonic heating can be applied for the heavy ion component. Arrangements are similar for minority and second harmonic heating. The efficiency of second harmonic heating is influenced by a weaker wave damping than for minority heating. Numerical calculations show that in a hybrid reactor scaled mirror machine the deuterium sloshing ions could be heated within the minority heating scheme, while the tritium ions could be sustained by second harmonic heating.

Velocity-space tomography of fusion plasmas by collective Thomson scattering of gyrotron radiation

DEFF Research Database (Denmark)

Salewski, Mirko; Jacobsen, A.S.; Jensen, Thomas

2016-01-01

-tonoise ratio becomes fairly low for MeV-range ions. Ions at any energy can be detected well by collective Thomson scattering of mm-wave radiation from a high-power gyrotron. We demonstrate how collective Thomson scattering can be used to measure 푓2퐷푣 in the MeV-range in reactor relevant plasmas...

Circuit design and simulation of a HV-supply controlling the power of 140 GHz 1 MW gyrotrons for ECRH on W7-X

International Nuclear Information System (INIS)

Brand, P.; Mueller, G.A.

2003-01-01

For plasma heating by ECR in the Stellarator W7-X under construction, 140 GHz gyrotrons with 1 MW cw output power are under development. These tubes have a voltage depressed collector for electron energy recovery. Each gyrotron is fed by two high-voltage sources: a high-power supply for driving the electron beam and a precision low-power supply for beam acceleration. In addition, a protection system with a thyratron crowbar for fast power removal in case of gyrotron arcing is installed. The low-power high-voltage source for beam acceleration is realized by a high-voltage servo-amplifier driving the depression voltage such that the influence of the voltage noise of the main high-power supply on the acceleration voltage is suppressed by feed-back control of the amplifier. Design and simulation of the servo-amplifier by PSpice is presented

RF Behavior of Cylindrical Cavity Based 240 GHz, 1 MW Gyrotron for Future Tokamak System

Science.gov (United States)

Kumar, Nitin; Singh, Udaybir; Bera, Anirban; Sinha, A. K.

2017-11-01

In this paper, we present the RF behavior of conventional cylindrical interaction cavity for 240 GHz, 1 MW gyrotron for futuristic plasma fusion reactors. Very high-order TE mode is searched for this gyrotron to minimize the Ohmic wall loading at the interaction cavity. The mode selection process is carried out rigorously to analyze the mode competition and design feasibility. The cold cavity analysis and beam-wave interaction computation are carried out to finalize the cavity design. The detail parametric analyses for interaction cavity are performed in terms of mode stability, interaction efficiency and frequency. In addition, the design of triode type magnetron injection gun is also discussed. The electron beam parameters such as velocity ratio and velocity spread are optimized as per the requirement at interaction cavity. The design studies presented here confirm the realization of CW, 1 MW power at 240 GHz frequency at TE46,17 mode.

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...

Experimental results for a 1.5 MW, 110 GHz gyrotron oscillator with reduced mode competition

Science.gov (United States)

Choi, E. M.; Marchewka, C. D.; Mastovsky, I.; Sirigiri, J. R.; Shapiro, M. A.; Temkin, R. J.

2006-02-01

A new result from a 110GHz gyrotron at MIT is reported with an output power of 1.67MW and an efficiency of 42% when operated at 97kV and 41A for 3μs pulses in the TE22,6 mode. These results are a major improvement over results obtained with an earlier cavity design, which produced 1.43MW of power at 37% efficiency. These new results were obtained using a cavity with a reduced output taper angle and a lower ohmic loss when compared with the earlier cavity. The improved operation is shown experimentally to be the result of reduced mode competition from the nearby TE19,7 mode. The reduced mode competition agrees well with an analysis of the startup scenario based on starting current simulations. The present results should prove useful in planning long pulse and CW versions of the 110GHz gyrotron.

Experimental results for a 1.5 MW, 110 GHz gyrotron oscillator with reduced mode competition

International Nuclear Information System (INIS)

Choi, E.M.; Marchewka, C.D.; Mastovsky, I.; Sirigiri, J.R.; Shapiro, M.A.; Temkin, R.J.

2006-01-01

A new result from a 110 GHz gyrotron at MIT is reported with an output power of 1.67 MW and an efficiency of 42% when operated at 97 kV and 41 A for 3 μs pulses in the TE 22,6 mode. These results are a major improvement over results obtained with an earlier cavity design, which produced 1.43 MW of power at 37% efficiency. These new results were obtained using a cavity with a reduced output taper angle and a lower ohmic loss when compared with the earlier cavity. The improved operation is shown experimentally to be the result of reduced mode competition from the nearby TE 19,7 mode. The reduced mode competition agrees well with an analysis of the startup scenario based on starting current simulations. The present results should prove useful in planning long pulse and CW versions of the 110 GHz gyrotron

Third harmonic generation of high power far infrared radiation in semiconductors

Energy Technology Data Exchange (ETDEWEB)

Urban, M [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

1996-04-01

We investigated the third harmonic generation of high power infrared radiation in doped semiconductors with emphasis on the conversion efficiency. The third harmonic generation effect is based on the nonlinear response of the conduction band electrons in the semiconductor with respect to the electric field of the incident electromagnetic wave. Because this work is directed towards a proposed application in fusion plasma diagnostics, the experimental requirements for the radiation source at the fundamental frequency are roughly given as follows: a wavelength of the radiation at the fundamental frequency in the order of 1 mm and an incident power greater than 1 MW. The most important experiments of this work were performed using the high power far infrared laser of the CRPP. With this laser a new laser line was discovered, which fits exactly the source specifications given above: the wavelength is 676 {mu}m and the maximum power is up to 2 MW. Additional experiments were carried out using a 496 {mu}m laser and a 140 GHz (2.1 mm) gyrotron. The main experimental progress with respect to previous work in this field is, in addition to the use of a very high power laser, the possibility of an absolute calibration of the detectors for the far infrared radiation and the availability of a new type of detector with a very fast response. This detector made it possible to measure the power at the fundamental as well as the third harmonic frequency with full temporal resolution of the fluctuations during the laser pulse. Therefore the power dependence of the third harmonic generation efficiency could be measured directly. The materials investigated were InSb as an example of a narrow gap semiconductor and Si as standard material. The main results are: narrow gap semiconductors indeed have a highly nonlinear electronic response, but the narrow band gap leads at the same time to a low power threshold for internal breakdown, which is due to impact ionization. figs., tabs., refs.

Third harmonic generation of high power far infrared radiation in semiconductors

International Nuclear Information System (INIS)

Urban, M.

1996-04-01

In this work we investigated the third harmonic generation of high power infrared radiation in doped semiconductors with emphasis on the conversion efficiency. The third harmonic generation effect is based on the nonlinear response of the conduction band electrons in the semiconductor with respect to the electric field of the incident electromagnetic wave. Because this work is directed towards a proposed application in fusion plasma diagnostics, the experimental requirements for the radiation source at the fundamental frequency are roughly given as follows: a wavelength of the radiation at the fundamental frequency in the order of 1 mm and an incident power greater than 1 MW. The most important experiments of this work were performed using the high power far infrared laser of the CRPP. With this laser a new laser line was discovered, which fits exactly the source specifications given above: the wavelength is 676 μm and the maximum power is up to 2 MW. Additional experiments were carried out using a 496 μm laser and a 140 GHz (2.1 mm) gyrotron. The main experimental progress with respect to previous work in this field is, in addition to the use of a very high power laser, the possibility of an absolute calibration of the detectors for the far infrared radiation and the availability of a new type of detector with a very fast response. This detector made it possible to measure the power at the fundamental as well as the third harmonic frequency with full temporal resolution of the fluctuations during the laser pulse. Therefore the power dependence of the third harmonic generation efficiency could be measured directly. The materials investigated were InSb as an example of a narrow gap semiconductor and Si as standard material. The main results are: narrow gap semiconductors indeed have a highly nonlinear electronic response, but the narrow band gap leads at the same time to a low power threshold for internal breakdown, which is due to impact ionization. (author) figs

Development of 1 MW gyrotron and progress of ECH system for the GAMMA 10 tandem mirror in Tsukuba

International Nuclear Information System (INIS)

Imai, T.; Kariya, T.; Minami, R.; Shidara, H.; Endo, Y.; Harigae, M.; Nakamura, M.; Sakagoshi, Y.; Murofushi, N.; Ichimura, M.; Nakashima, Y.; Yoshikawa, M.; Yamaguchi, Y.; Sakamoto, Keishi; Kubo, S.; Shimozuma, T.; Mutoh, T.; Takahashi, H.; Mitsunaka, Y.

2008-10-01

High power gyrotrons with TE 4,2 cavity at 28 GHz and with TE 18,6 cavity and a diamond window at 77 GHz have been developed for GAMMA 10 and LHD in the joint program of NIFS and University of Tsukuba. The maximum outputs of 570 kW at 28 GHz and 1.1 MW at 77 GHz were obtained corresponding to each design. The operations of more than 750 kW for 5 sec. and 810 kW for 3.5 sec. were achieved in the developing tubes at 77 GHz, which is the first high power-long pulse result of the 77 GHz tube. The experimental simulation of the effect of the stray RF in the 28 GHz tube indicates the stray RF is the one of the major causes limiting gyrotron performance. The output of more than 1 MW with 40% oscillation efficiency is expected from the design of the next 28 GHz gyrotron for GAMMA 10. Installation of the polarizer in the transmission line enhanced the performance of the ECH system in GAMMA 10, that is the first result which clearly showed ∼100% X mode excitation is a key to design the efficient fundamental ECH system of strong field side injection in mirror devices. (author)

Advances in High Power Calorimetric Matched Loads for Short Pulses and CW Gyrotrons

International Nuclear Information System (INIS)

Bin, W.M.; Bruschi, A.; Cirant, S.; Gandini, F.; Granucci, G.; Mellera, V.; Muzzini, V.; Nardone, A.; Sozzi, C.; Spinicchia, N.

2006-01-01

The development of high power gyrotrons for plasma physics research needs proper matched and calorimetric loads able to absorb and measure the power, which nowadays is foreseen to be as high as 2 MW during CW operations. To this end IFP/CNR has developed a family of matched loads useful in the mm-wave frequency band for applications ranging from a few ms to CW in pulse length. The different loads in the family, made of an integrating sphere with a partially reflecting coating on the inner wall, are characterized by having the same absorbing geometry for the incoming beam and a different heat removal system for the specific application. Some important advances have been recently achieved from the point of view of the uniformity of power distribution on the absorbing wall and of the load construction. With high precision achieved in the coating thickness a better control of the heating power distribution is possible by proper shaping of the local reflectivity, in addition to the shaping of the mirror dispersing the input beam. A more sophisticated model describing the power distribution has been developed, taking into account a variable thickness of the absorbing coating, the proper shape of the spreading mirror, the frequency of the incoming radiation and the shape of the input beam. Lower coating thickness is shown to be preferable, at equal local reflectivity, from the point of view of a lower peak temperature and thermal stress. The paper describes a load with variable coating thickness along the meridian of the sphere, showing a uniform power deposition on the inner walls. The cooling pipe is completely electroformed on the spherical copper shell, ensuring the maintenance of the correct curvature of the inner surface and a fast heat conduction from the absorbing coating to the water through the thin copper body. For CW use all heated parts of the load must be cooled and this is achieved by 16 electroformed spiral channels. Both short pulse loads (0.1-1 s) and

Development program for a 200 kW, cw gyrotron. Quarterly report No. 11, January-March 1982

International Nuclear Information System (INIS)

Tancredi, J.J.; Caplan, M.; Sandoval, J.J.; Matranga, V.A.

1982-01-01

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. During this report period, the beam instability problem which plagued S/N 1 testing was evaluated in more detail. Separate tests were conducted on the gun tester and the lossy drift section, as well as both of these combined, and the results were compared to gyrotron tests on S/N 1. The instability problem now appears to be associated with RF leakage from the cavity

Experimental study of a 1 MW, 170 GHz gyrotron oscillator

Science.gov (United States)

Kimura, Takuji

A detailed experimental study is presented of a 1 MW, 170 GHz gyrotron oscillator whose design is consistent with the ECH requirements of the International Thermonuclear Experimental Reactor (ITER) for bulk heating and current drive. This work is the first to demonstrate that megawatt power level at 170 GHz can be achieved in a gyrotron with high efficiency for plasma heating applications. Maximum output power of 1.5 MW is obtained at 170.1 GHz in 85 kV, 50A operation for an efficiency of 35%. Although the experiment at MIT is conducted with short pulses (3 μs), the gyrotron is designed to be suitable for development by industry for continuous wave operation. The peak ohmic loss on the cavity wall for 1 MW of output power is calculated to be 2.3 kW/cm2, which can be handled using present cooling technology. Mode competition problems in a highly over-moded cavity are studied to maximize the efficiency. Various aspects of electron gun design are examined to obtain high quality electron beams with very low velocity spread. A triode magnetron injection gun is designed using the EGUN simulation code. A total perpendicular velocity spread of less than 8% is realized by designing a low- sensitivity, non-adiabatic gun. The RF power is generated in a short tapered cavity with an iris step. The operating mode is the TE28,8,1 mode. A mode converter is designed to convert the RF output to a Gaussian beam. Power and efficiency are measured in the design TE28,8,1 mode at 170.1 GHz as well as the TE27,8,1 mode at 166.6 GHz and TE29,8,1 mode at 173.5 GHz. Efficiencies between 34%-36% are consistently obtained over a wide range of operating parameters. These efficiencies agree with the highest values predicted by the multimode simulations. The startup scenario is investigated and observed to agree with the linear theory. The measured beam velocity ratio is consistent with EGUN simulation. Interception of reflected beam by the mod-anode is measured as a function of velocity ratio

High benefits approach for electrical energy conversion in electric vehicles from DC to PWM-AC without any generated harmonic

International Nuclear Information System (INIS)

Fathabadi, Hassan

2014-01-01

Highlights: • Novel hybrid power source including AC feature for using in electric/hybrid vehicles. • Minimizing the energy loss in electric/hybrid vehicles by using the proposed system. • Suitable AC wave form for braking/accelerating purposes in electric/hybrid vehicles. • A novelty is that the harmonic generated by the added AC feature is really zero. • Another novelty is the capability of choosing arbitrary frequency for AC feature. - Abstract: This paper presents a novel hybrid power source, including a Li-ion battery together with an interface, which generates simultaneously electrical energy with the forms of both DC and AC for electric vehicles. A novel and high benefits approach is applied to convert the electrical energy of the Li-ion battery from DC form to single-phase symmetric pulse-width modulation (PWM)-AC form. Harmonic generation is one of the important problems when electrical energy is converted from DC to AC but there are not any generated harmonic during the DC/AC conversion using the proposed technique. The proposed system will be widely used in electric/hybrid vehicles because it has many benefits. Minimizing the energy loss (saving energy), no generated harmonic (it is really zero), the capability of arbitrary/necessary frequency selection for output AC voltage and the ability of long distance energy transmission are some novelties and advantages of the proposed system. The proposed hybrid power source including DC/AC PWM inverter is simulated in Proteus 6 software environment and a laboratory-based prototype of the hybrid power source is constructed to validate the theoretical and simulation results. Simulation and experimental results are presented to prove the superiority of the proposed hybrid power supply

Operation of a quasi-optical gyrotron with a gaussian output coupler

Energy Technology Data Exchange (ETDEWEB)

Hogge, J.P.; Tran, T.M.; Paris, P.J.; Tran, M.Q. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

1996-03-01

The operation of a 92 GHz quasi-optical gyrotron (QOG) having a resonator formed by a spherical mirror and a diffraction grating placed in -1 order Littrow mount is presented. A power of 150 kW with a gaussian output pattern was measured. The gaussian content in the output was 98% with less than 1% of depolarization. By optimizing the magnetic field at fixed frequency, a maximum efficiency of 15% was reached. (author) 12 figs., 2 tabs., 22 refs.

DSP Control of Line Hybrid Active Filter

DEFF Research Database (Denmark)

Dan, Stan George; Benjamin, Doniga Daniel; Magureanu, R.

2005-01-01

Active Power Filters have been intensively explored in the past decade. Hybrid active filters inherit the efficiency of passive filters and the improved performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter...... is studied for current harmonic compensation. The hybrid filter is formed by a single tuned Le filter and a small-rated power active filter, which are directly connected in series without any matching transformer. Thus the required rating of the active filter is much smaller than a conventional standalone...... active filter. Simulation and experimental results obtained in laboratory confirmed the validity and effectiveness of the control....

First experimental results of the LAP/INPE (Plasma Associated Lab) gyrotron

International Nuclear Information System (INIS)

Barroso, J.J.; Rossi, J.O.; Castro, P.J.; Correa, R.A.; Montes, A.; Ludwig, G.O.; Idehara, T.; Ogawa, I.

1994-01-01

The design and operation of a high power pulsed gyrotron are reported. A magnetron injection gun generates a 5 A, 50 keV helical laminar electron beam with a pitch ratio of 1.5. The electron beam is then placed on the second radial maximum of the T E 02 nominal mode in the resonant cavity. The magnet system comprises three independent water-cooled solenoids located in the gun, cavity and collector regions, consisting of split pair magnets with the field direction vertical. The resonator is a weakly tapered waveguide with a straight section of 0.5 cm in length, a down taper angle of 0.8 0 and an up taper angle of 5 0 The gyrotron runs in pulsed regime with a 20μs pulse length at a frequency repetition rate of 10 Hz and during operation the pressure in the tube is ordinarily less than 4.0 X 10 -7 Torr. Several TE modes were detected over the magnetic field range 9.5 to 12.5 kG and the measured resonant frequencies (29.0 to 32.0 GHz) showed to be in close agreement with the self-consistent calculated values. Experiments are currently under way to measure the absolute output power and to identify the modes through field pattern measurement techniques. (author). 3 refs, 3 figs

Local field enhanced second-harmonic response of organic nanofibers

DEFF Research Database (Denmark)

Leißner, Till; Kostiučenko, Oksana; Fiutowski, Jacek

Organic CNHP4 nanofibers showing a strong second-harmonic (SH) response have been successfully implemented as active components in a metal-organic hybrid system. Using nondestructive roll-on transfer technique nanofibers were transferred from the growing mica substrates onto electron...

Development of over-1 MW gyrotrons for the LHD and the GAMMA 10 ECH systems

International Nuclear Information System (INIS)

Imai, T.; Kariya, T.; Minami, R.

2010-11-01

For the ECH upgrade program of LHD and GAMMA10, over-1 MW power gyrotrons have been developed in the joint program of NIFS and University of Tsukuba. The gyrotrons for LHD and GAMMA 10 have TE 18,6 cavity and a diamond window at 77 GHz, and with TE 8,3 cavity at 28 GHz, respectively. The maximum outputs obtained are 1.9 MW for 0.1 s on the 77 GHz LHD tube and ∼ 1 MW on the 28 GHz one, which are the new records in these frequency ranges. The results of 1.8 MW for 1 s, 1.6 MW for 1.8s, 1 MW for 5 s, 300 kW for 40 min and 200 kW for 75 min were achieved at 77 GHz. In the long pulse operation, it is found that the stray RF is the major cause limiting the pulse length. Design improvements of the diffraction loss, the cavity and pitch factor α (=v sub(perpendicular)/v sub(parallel)) dispersion of the MIG have made the 77 GHz tube performance better, which have enabled to demonstrate 1.9 MW output and long pulse operation for more than 1 hour with 200 kW. The three 77 GHz gyrotrons have already been installed in the LHD ECH system and more than 3 MW has been injected into LHD plasma. In the 28 GHz long pulse operation, 400 kW for 1 sec has been obtained and it is found the higher and longer pulse operation would be possible with the operation optimization and conditioning. (author)

The gyrotron - a natural source of high-power orbital angular momentum millimeter-wave beams

Science.gov (United States)

Thumm, M.; Sawant, A.; Choe, M. S.; Choi, E. M.

2017-08-01

Orbital angular momentum (OAM) of electromagnetic-wave beams provides further diversity to multiplexing in wireless communication. The present report shows that higher-order mode gyrotrons are natural sources of high-power OAM millimeter (mm) wave beams. The well-defined OAM of their rotating cavity modes operating at near cutoff frequency has been derived by photonic and electromagnetic wave approaches.

Gyrotron development at the Instituto de Pesquisas Espaciais

International Nuclear Information System (INIS)

Barroso, J.J.; Castro, P.J. de; Correa, R.A.; Galvao, G.P.; Ludwig, G.O.; Montes, A.; Nono, M.C.A.

1987-07-01

The conceptual design of a 35GHz gyrotron operating in the TE 01 mode, intended for plasma heating experiments, is presented. The electrooptical system is sinthesized from 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 de action of an RF field with fixed spatial distribution. The experimental activities are concentrated on the construction of a system of magnetic coils, able to generate a 15 KG magnetic induction with a fluctuation of 0.1% over an extension of 13 cm; the manufacture of caerties by using electroforming techniques; and the development of techiques for the construction of electron guns. (author) [pt

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.

Modelling, simulation and computer-aided design (CAD) of gyrotrons for novel applications in the high-power terahertz science and technologies

Science.gov (United States)

Sabchevski, S.; Idehara, T.; Damyanova, M.; Zhelyazkov, I.; Balabanova, E.; Vasileva, E.

2018-03-01

Gyrotrons are the most powerful sources of CW coherent radiation in the sub-THz and THz frequency bands. In recent years, they have demonstrated a remarkable potential for bridging the so-called THz-gap in the electromagnetic spectrum and opened the road to many novel applications of the terahertz waves. Among them are various advanced spectroscopic techniques (e.g., ESR and DNP-NMR), plasma physics and fusion research, materials processing and characterization, imaging and inspection, new medical technologies and biological studies. In this paper, we review briefly the current status of the research in this broad field and present our problem-oriented software packages developed recently for numerical analysis, computer-aided design (CAD) and optimization of gyrotrons.

Design of 28 GHz, 200 kW Gyrotron for ECRH Applications

Science.gov (United States)

Yadav, Vivek; Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Deorani, S. C.; Sinha, A. K.

2013-01-01

This paper presents the design of 28 GHz, 200 kW gyrotron for Indian TOKAMAK system. The paper reports the designs of interaction cavity, magnetron injection gun and RF window. EGUN code is used for the optimization of electron gun parameters. TE03 mode is selected as the operating mode by using the in-house developed code GCOMS. The simulation and optimization of the cavity parameters are carried out by using the Particle-in-cell, three dimensional (3-D)-electromagnetic simulation code MAGIC. The output power more than 250 kW is achieved.

Recent operating experience with Varian 70 GHz and 140 GHz gyrotrons

International Nuclear Information System (INIS)

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

1985-01-01

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 TE 031 0 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

Advantages of using gyrotron scattering for alpha particle diagnostics

International Nuclear Information System (INIS)

Woskoboinikow, P.P.; Cohn, D.R.; Machuzak, J.S.; Myer, R.C.; Rhee, R.Y.

1987-07-01

Millimeter-wave gyrotron collective Thomson scattering can be an effective diagnostic technique for the study of alpha particle behavior in ignited plasmas. The measurement of alpha particle density, velocity distribution, and alpha particle induced plasma instabilities can be accomplished with both spatial and temporal resolution. Advantages include long pulse operation which can make possible very high signal to noise ratios and use of millimeter waves which maximizes the Doppler shifted scattered signal in WHz -1 and makes possible scattering angles up to 180 0 . Extraordinary mode scattering at approximately 60 and 200 GHz would be used in TFTR and CIT respectively, and 140 GHz ordinary mode scattering in JET. 8 refs., 1 fig

Advanced Output Coupling for High Power Gyrotrons

Energy Technology Data Exchange (ETDEWEB)

Read, Michael [Calabazas Creek Research, Inc., San Mateo, CA (United States); Ives, Robert Lawrence [Calabazas Creek Research, Inc., San Mateo, CA (United States); Marsden, David [Calabazas Creek Research, Inc., San Mateo, CA (United States); Collins, George [Calabazas Creek Research, Inc., San Mateo, CA (United States); Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Guss, William [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Lohr, John [General Atomics, La Jolla, CA (United States); Neilson, Jeffrey [Lexam Research, Redwood City, CA (United States); Bui, Thuc [Calabazas Creek Research, Inc., San Mateo, CA (United States)

2016-11-28

The Phase II program developed an internal RF coupler that transforms the whispering gallery RF mode produced in gyrotron cavities to an HE11 waveguide mode propagating in corrugated waveguide. This power is extracted from the vacuum using a broadband, chemical vapor deposited (CVD) diamond, Brewster angle window capable of transmitting more than 1.5 MW CW of RF power over a broad range of frequencies. This coupling system eliminates the Mirror Optical Units now required to externally couple Gaussian output power into corrugated waveguide, significantly reducing system cost and increasing efficiency. The program simulated the performance using a broad range of advanced computer codes to optimize the design. Both a direct coupler and Brewster angle window were built and tested at low and high power. Test results confirmed the performance of both devices and demonstrated they are capable of achieving the required performance for scientific, defense, industrial, and medical applications.

Hybrid undulator numerical optimization

Energy Technology Data Exchange (ETDEWEB)

Hairetdinov, A.H. [Kurchatov Institute, Moscow (Russian Federation); Zukov, A.A. [Solid State Physics Institute, Chernogolovka (Russian Federation)

1995-12-31

3D properties of the hybrid undulator scheme arc studied numerically using PANDIRA code. It is shown that there exist two well defined sets of undulator parameters which provide either maximum on-axis field amplitude or minimal higher harmonics amplitude of the basic undulator field. Thus the alternative between higher field amplitude or pure sinusoidal field exists. The behavior of the undulator field amplitude and harmonics structure for a large set of (undulator gap)/(undulator wavelength) values is demonstrated.

Development program for a 200-kW, c-w gyrotron. Quarterly report No. 7, January-March 1981

International Nuclear Information System (INIS)

Tancredi, J.J.; Caplan, M.; Sandoval, J.J.; Jordan, E.; Matranga, V.A.

1981-01-01

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, which will be 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 rf load mismatch. An interim program goal is to demonstrate operation at 100 ms pulse widths by 31 December 1981. During this quarter, progress was made in the areas of tube, solenoid, and facility construction. Two magnetron injection gun assemblies were completed, and one was partially evaluated as a gun tester. The superconducting solenoid was assembled, but a vacuum leak prevented early delivery in March. Construction began on the gyrotron test facility by enclosing the area and providing bake-out and vacuum processing utilities

Demonstration of a High-Order Mode Input Coupler for a 220-GHz Confocal Gyrotron Traveling Wave Tube

Science.gov (United States)

Guan, Xiaotong; Fu, Wenjie; Yan, Yang

2018-02-01

A design of high-order mode input coupler for 220-GHz confocal gyrotron travelling wave tube is proposed, simulated, and demonstrated by experimental tests. This input coupler is designed to excite confocal TE 06 mode from rectangle waveguide TE 10 mode over a broadband frequency range. Simulation results predict that the optimized conversion loss is about 2.72 dB with a mode purity excess of 99%. Considering of the gyrotron interaction theory, an effective bandwidth of 5 GHz is obtained, in which the beam-wave coupling efficiency is higher than half of maximum. The field pattern under low power demonstrates that TE 06 mode is successfully excited in confocal waveguide at 220 GHz. Cold test results from the vector network analyzer perform good agreements with simulation results. Both simulation and experimental results illustrate that the reflection at input port S11 is sensitive to the perpendicular separation of two mirrors. It provides an engineering possibility for estimating the assembly precision.

Quasi-optical converters for high-power gyrotrons: a brief review of physical models, numerical methods and computer codes

International Nuclear Information System (INIS)

Sabchevski, S; Zhelyazkov, I; Benova, E; Atanassov, V; Dankov, P; Thumm, M; Arnold, A; Jin, J; Rzesnicki, T

2006-01-01

Quasi-optical (QO) mode converters are used to transform electromagnetic waves of complex structure and polarization generated in gyrotron cavities into a linearly polarized, Gaussian-like beam suitable for transmission. The efficiency of this conversion as well as the maintenance of low level of diffraction losses are crucial for the implementation of powerful gyrotrons as radiation sources for electron-cyclotron-resonance heating of fusion plasmas. The use of adequate physical models, efficient numerical schemes and up-to-date computer codes may provide the high accuracy necessary for the design and analysis of these devices. In this review, we briefly sketch the most commonly used QO converters, the mathematical base they have been treated on and the basic features of the numerical schemes used. Further on, we discuss the applicability of several commercially available and free software packages, their advantages and drawbacks, for solving QO related problems

DC space-charge induced frequency up-shift in a quasi-optical gyrotron

International Nuclear Information System (INIS)

Alberti, S.; Tran, M.Q.; Tran, T.M.

1990-10-01

Recent experiments on a 100GHz quasi-optical gyrotron have shown that for a large resonator set-up the observed frequency up-shift between the starting current and a current of 10A corresponds to a shift of 4-5 longitudinal modes. In this Letter it is shown that the interpretation of this frequency up-shift should involve the current dependent electron beam voltage depression in the beam tunnel and the interaction region for both the single-mode and multi-mode time evolution codes. (author) 7 refs., 5 figs., 1 tab

Recent results of studies of plasma fluctuations in stellarators by microwave scattering technique

International Nuclear Information System (INIS)

Skvortsova, N.N.; Batanov, G.M.; Kolik, L.V.; Petrov, A.E.; Pshenichnikov, A.A.; Sarksyan, K.A.; Kharchev, N.K.; Khol'nov, Yu.V.; Kubo, S.; Sanchez, J.

2005-01-01

Microwave scattering diagnostics are described that allow direct measurements of the turbulent processes in a high-temperature plasma of magnetic confinement systems. Plasma density fluctuations in the heating region of the L-2M stellarator were measured from microwave scattering at the fundamental and the second harmonics of the heating gyrotron radiation. In the TJ-II stellarator, a separate 2-mm microwave source was used to produce a probing beam; the measurements were performed at the middle of the plasma radius. Plasma density fluctuations in the axial (heating) region of the LHD stellarator were measured from microwave scattering at the fundamental harmonic of the heating gyrotron radiation. Characteristic features of fluctuations, common for all three devices, are revealed with the methods of statistical and spectral analysis. These features are the wide frequency Fourier and wavelet spectra, autocorrelation functions with slowly decreasing tails, and non-Gaussian probability distributions of the magnitudes and the increments of the magnitude of fluctuations. The drift-dissipative instability and the instability driven by trapped electrons are examined as possible sources of turbulence in a high-temperature plasma. Observations showed the high level of coherence between turbulent fluctuations in the central region and at the edge of the plasma in L-2M. It is shown in L-2M that the relative intensity of the second harmonic of gyrotron radiation on the axis of a microwave beam after quasi-optical filtering in a four-mirror quasi-optical transmission line is about -50 dB of the total radiation intensity. Spatiotemporal structures in plasma density fluctuations were observed in the central region of the plasma column. The correlation time between the structures was found to be on the order of 1 ms. It is shown that, the spectrum of the signal from the second-harmonic scattering extends to higher frequencies in comparison with that from the fundamental-harmonic

Gyrotron development at the Instituto de Pesquisas Espaciais

International Nuclear Information System (INIS)

Barroso, J.J.; Castro, P.J. de; Correa, R.A.; Galvao, G.P.

1987-01-01

The conceptual design of a 35GHz gyrotron operating in the TE 021 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) [pt

Development program for a 200-kW, cw gyrotron. Quarterly report No. 9, July-September 1981

International Nuclear Information System (INIS)

Tancredi, J.J.; Caplan, M.; Matranga, V.A.; Sandoval, J.J.

1981-01-01

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, which will be 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 rf load mismatch. The superconducting solenoid which had been sent back to the manufacturer because of an open coil, was repaired and returned to Hughes. The gyrotron S/N 1 was successfully operated at a frequency of 59.7 GHz with a power level of 160 kW peak. Diagnostic x-ray measurements of the collector area revealed a reasonable beam power density of 600 W/cm 2 , under worst case conditions of no rf output, and with no auxilary means of spreading the beam. The latter portion of this report period was spent characterizing S/N 1's rf and dc performance and evaluating an anomolous oscillation emitted from the electron gun

Spherical harmonic expansion of short-range screened Coulomb interactions

Energy Technology Data Exchange (ETDEWEB)

Angyan, Janos G [Laboratoire de Cristallographie et de Modelisation des Materiaux Mineraux et Biologiques, UMR 7036, CNRS-Universite Henri Poincare, BP 239, F-54506 Vandoeuvre-les-Nancy (France); Gerber, Iann [Laboratoire de Cristallographie et de Modelisation des Materiaux Mineraux et Biologiques, UMR 7036, CNRS-Universite Henri Poincare, BP 239, F-54506 Vandoeuvre-les-Nancy (France); Marsman, Martijn [Institut fuer Materialphysik and Center for Computational Materials Science, Universitaet Wien, Sensengasse 8, A-1090, Vienna (Austria)

2006-07-07

Spherical harmonic expansions of the screened Coulomb interaction kernel involving the complementary error function are required in various problems in atomic, molecular and solid state physics, like for the evaluation of Ewald-type lattice sums or for range-separated hybrid density functionals. A general analytical expression is derived for the kernel, which is non-separable in the radial variables. With the help of series expansions a separable approximate form is proposed, which is in close analogy with the conventional multipole expansion of the Coulomb kernel in spherical harmonics. The convergence behaviour of these expansions is studied and illustrated by the electrostatic potential of an elementary charge distribution formed by products of Slater-type atomic orbitals.

Second harmonic inversion for ultrasound contrast harmonic imaging

Energy Technology Data Exchange (ETDEWEB)

Pasovic, Mirza; Danilouchkine, Mike; Faez, Telli; Van Neer, Paul L M J; Van der Steen, Antonius F W; De Jong, Nico [THORAXCENTER, Department of Biomedical Engineering Ee2302, Erasmus MC, Rotterdam (Netherlands); Cachard, Christian; Basset, Olivier, E-mail: mirza.pasovic@creatis.insa-lyon.fr [CREATIS-LRMN, Universite de Lyon, INSA-Lyon, Universite Lyon 1, Inserm U630, CNRS UMR 5220 (France)

2011-06-07

Ultrasound contrast agents (UCAs) are small micro-bubbles that behave nonlinearly when exposed to an ultrasound wave. This nonlinear behavior can be observed through the generated higher harmonics in a back-scattered echo. In past years several techniques have been proposed to detect or image harmonics produced by UCAs. In these proposed works, the harmonics generated in the medium during the propagation of the ultrasound wave played an important role, since these harmonics compete with the harmonics generated by the micro-bubbles. We present a method for the reduction of the second harmonic generated during nonlinear-propagation-dubbed second harmonic inversion (SHI). A general expression for the suppression signals is also derived. The SHI technique uses two pulses, p' and p'', of the same frequency f{sub 0} and the same amplitude P{sub 0} to cancel out the second harmonic generated by nonlinearities of the medium. Simulations show that the second harmonic is reduced by 40 dB on a large axial range. Experimental SHI B-mode images, from a tissue-mimicking phantom and UCAs, show an improvement in the agent-to-tissue ratio (ATR) of 20 dB compared to standard second harmonic imaging and 13 dB of improvement in harmonic power Doppler.

Second harmonic inversion for ultrasound contrast harmonic imaging

International Nuclear Information System (INIS)

Pasovic, Mirza; Danilouchkine, Mike; Faez, Telli; Van Neer, Paul L M J; Van der Steen, Antonius F W; De Jong, Nico; Cachard, Christian; Basset, Olivier

2011-01-01

Ultrasound contrast agents (UCAs) are small micro-bubbles that behave nonlinearly when exposed to an ultrasound wave. This nonlinear behavior can be observed through the generated higher harmonics in a back-scattered echo. In past years several techniques have been proposed to detect or image harmonics produced by UCAs. In these proposed works, the harmonics generated in the medium during the propagation of the ultrasound wave played an important role, since these harmonics compete with the harmonics generated by the micro-bubbles. We present a method for the reduction of the second harmonic generated during nonlinear-propagation-dubbed second harmonic inversion (SHI). A general expression for the suppression signals is also derived. The SHI technique uses two pulses, p' and p'', of the same frequency f 0 and the same amplitude P 0 to cancel out the second harmonic generated by nonlinearities of the medium. Simulations show that the second harmonic is reduced by 40 dB on a large axial range. Experimental SHI B-mode images, from a tissue-mimicking phantom and UCAs, show an improvement in the agent-to-tissue ratio (ATR) of 20 dB compared to standard second harmonic imaging and 13 dB of improvement in harmonic power Doppler.

Hybrid VAR compensator with improved efficiency

Directory of Open Access Journals (Sweden)

V. V. Burlaka

2015-03-01

Full Text Available In modern electrical networks thyristor-switched capacitors (TSC are most used devices for VAR compensation. These devices don’t contain rotating parts and mechanical contacts, provide a stepwise control of reactive power and no generation of harmonics to the network. However, with the help of TSC it’s not possible to ensure smooth control of reactive power and capacitor banks (CB are exposed to the negative impact of higher harmonic components of the network voltage. Hybrid VAR compensator don’t have such drawbacks. It consists of active filter (AF and capacitor bank with discrete regulation. The main drawback of such systems is the necessity of accessing all six terminals of CB, while most of them are manufactured with three terminals, internally delta-connected. In the article, the topology and control system of hybrid VAR compensator free from beforementioned drawback, is proposed. The control system provides operating modes of overcompensation or undercompensation reactive power. VAR distribution regulator performs redistribution of reactive power between active filter and capacitor banks with the condition to minimize active filter’s power. Scheme of the hybrid VAR compensator, which includes a three-phase three-terminal delta-connected capacitor banks, is shown. Proposed approach allows to provide smooth control of reactive power, isolate the capacitor bank from harmonic currents and use a more effective low-voltage power components

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

International Nuclear Information System (INIS)

Maebara, Sunao; Kasugai, Atsushi; Sakamoto, Keishi; Tsuneoka, Masaki; Imai, Tsuyoshi

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)

Analysis of parasitic oscillations in 42 GHz gyrotron beam tunnel

Science.gov (United States)

Kumar, N.; Singh, U.; Singh, T. P.; Sinha, A. K.

2011-02-01

Parasitic oscillation excitation analysis has been carried out for the 42 GHz gyrotron beam tunnel. This article presents a systematic approach for the analysis of parasitic oscillation excitation. The electron trajectory code EGUN has been used for the estimation of the electron beam parameters in the beam tunnel. The electromagnetic simulation code CST-MS has been used for the eigenmode and Q value analysis. The analysis of the parasitic oscillations has been performed for the symmetric TE modes and the first three cavity side copper rings. Four different approaches- the Q value study, the mode maxima-electron beam radius mismatching, the electron cyclotron frequency-mode excitation frequency mismatching and the backward wave interaction analysis- have been used for the parasitic oscillation analysis.

The upgrade of the DIII-D EC system using 120 GHz ITER gyrotrons

International Nuclear Information System (INIS)

Callis, R.W.; Lohr, J.; Gorelov, I.A.; Ponce, D.; Kajiwara, K.; Tooker, J.F.

2005-01-01

The planned growth in the EC system on DIII-D over the next few years requires the installation of two depressed collector gyrotrons, a high voltage power supply, two low loss transmission lines, and the required support equipment. This new DIII-D EC equipment could be made identical to the ITER EC system requirements. By building the DIII-D hardware to the ITER specifications, it will allow ITER to gain beneficial prototyping experience on a working tokamak, prior to committing to building the hardware for delivery to ITER

Towers of hybrid mesons

International Nuclear Information System (INIS)

Semay, Claude; Buisseret, Fabien; Silvestre-Brac, Bernard

2009-01-01

A hybrid meson is a quark-antiquark pair in which, contrary to ordinary mesons, the gluon field is in an excited state. In the framework of constituent models, the interaction potential is assumed to be the energy of an excited string. An approximate, but accurate, analytical solution of the Schroedinger equation with such a potential is presented. When applied to hybrid charmonia and bottomonia, towers of states are predicted in which the masses are a linear function of a harmonic oscillator band number for the quark-antiquark pair. Such a formula could be a reliable guide for the experimental detection of heavy hybrid mesons.

Fuel cell/back-up battery hybrid energy conversion systems: Dynamic modeling and harmonic considerations

International Nuclear Information System (INIS)

Fathabadi, Hassan

2015-01-01

Highlights: • Novel technique to completely eliminate the harmful harmonics of fuel cell system. • Presenting a novel high accurate detailed electrochemical dynamic model of fuel cells. • Back-up battery system to compensate the slow dynamic response of fuel cell system. • Exact analysis of real electrochemical reactions occurring inside fuel cells. - Abstract: In this study, a novel dynamic model of fuel cells is presented. High accurate static and dynamic responses of the proposed model are experimentally validated by comparing simulated results with real experimental data. The obtained model together with theoretical results shows that a fuel cell or a fuel cell stack has very slow dynamic response, so that, it cannot adapt itself to the fast variations in load demand. It is shown that for adapting well a fuel cell stack to the load demand, the stack should be equipped with a proposed back-up battery system which compensates the slow dynamic response of the stack by providing a bidirectional path to transmit/absorb the extra instant power. It is proved that the conventional switching waveforms used in the converters of the stacks and back-up systems produce an enormous amount of harmful harmonics. Then, a novel technique is proposed to completely eliminate main harmful harmonics. It is worthwhile to note that all the other techniques only reduce the harmful harmonics. Simulated results verify that the back-up battery system together with applying the proposed technique provide a fast dynamic response for the fuel cell/back-up battery system, and also completely eliminate the main harmful harmonics

Analysis of Mig-type electron guns for a 35GHz gyrotron

International Nuclear Information System (INIS)

Barroso, J.J.; Galvao, G.P.

1988-05-01

A 35GHz gyrotron is currently under construction at the Associated Plasma Laboratory of the Institute for Space Research to be used in plasma heating and noninductive current drive experiments. A critical component of the device is the electrooptical system, which must generate a beam with low velocity spread and high transverse energy. One way to decrease the velocity spread is to use laminar beams. For laminar flow, where the trajectories do not cross, the axial component of the space-charge forces changes sign each half cycle models of magnetron injection guns that produce laminar beams are analyzed and procedures for controlling the pitch angle parameter, which defines the transverse-to-axial electron velocity ratio are investigated. (author)

Magnetron injection gun for a broadband gyrotron backward-wave oscillator

International Nuclear Information System (INIS)

Yuan, C. P.; Chang, T. H.; Chen, N. C.; Yeh, Y. S.

2009-01-01

The magnetron injection gun is capable of generating relativistic electron beam with high velocity ratio and low velocity spread for a gyrotron backward-wave oscillator (gyro-BWO). However, the velocity ratio (α) varies drastically against both the magnetic field and the beam voltage, which significantly limits the tuning bandwidth of a gyro-BWO. This study remedies this drawback by adding a variable trim field to adjust the magnetic compression ratio when changing the operating conditions. Theoretical results obtained by employing a two-dimensional electron gun code (EGUN) demonstrate a constant velocity ratio of 1.5 with a low axial velocity spread of 6% from 3.4-4.8 Tesla. These results are compared with a three-dimensional particle-tracing code (computer simulation technology, CST). The underlying physics for constant α will be discussed in depth.

Magnetron injection gun for a broadband gyrotron backward-wave oscillator

Science.gov (United States)

Yuan, C. P.; Chang, T. H.; Chen, N. C.; Yeh, Y. S.

2009-07-01

The magnetron injection gun is capable of generating relativistic electron beam with high velocity ratio and low velocity spread for a gyrotron backward-wave oscillator (gyro-BWO). However, the velocity ratio (α) varies drastically against both the magnetic field and the beam voltage, which significantly limits the tuning bandwidth of a gyro-BWO. This study remedies this drawback by adding a variable trim field to adjust the magnetic compression ratio when changing the operating conditions. Theoretical results obtained by employing a two-dimensional electron gun code (EGUN) demonstrate a constant velocity ratio of 1.5 with a low axial velocity spread of 6% from 3.4-4.8 Tesla. These results are compared with a three-dimensional particle-tracing code (computer simulation technology, CST). The underlying physics for constant α will be discussed in depth.

Development program for a 200 kW, CW gyrotron. Quarterly report No. 4, April-June 1980

International Nuclear Information System (INIS)

Tancredi, J.J.; Caplan, M.; Sandoval, J.J.; Weiss, W.

1980-01-01

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, which will be 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-varyinng rf load mismatch

Studies of self-consistent field structure in a quasi-optical gyrotron

International Nuclear Information System (INIS)

Antonsen, T.M. Jr.

1993-04-01

The presence of an electron beam in a quasi-optical gyrotron cavity alters the structure of the fields from that of the empty cavity. A computer code has been written which calculates this alteration for either an electron beam or a thin dielectric tube placed in the cavity. Experiments measuring the quality factor of such a cavity performed for the case of a dielectric tube and the results agree with the predictions of the code. Simulations of the case of an electron beam indicate that self-consistent effects can be made small in that almost all the power leaves the cavity in a symmetric gaussian-like mode provided the resonator parameters are chosen carefully. (author) 6 figs., 1 tab., 13 refs

New design for the anode power supply of a gyrotron

International Nuclear Information System (INIS)

Fasel, D.; Alberti, S.; Favre, A.; Perez, A.; Acero, J.; Ganuza, D.; Garcia, I.; Lucia, C.

1998-01-01

The introduction will remind the main supply structure installed in the CRPP, related to the ECRH (Electron Cyclotron Resonance Heating) project on the TCV (Tokamak Configuration Variable) tokamak. Then this paper concentrates on the description of the power source designed to supply the anode of the triode type gyrotron. First the requirements asked for this power supply will be presented, taking into account the possible feeding structures in relation with the existing HV DC cathode power supply. The following section will focus on the selected design, describing in details the power structure based on MOSFET, referred to the cathode potential. Afterwards the control electronics is presented, including the feedback control implemented, the HV measurements, the internal reference generator and the interface to the TCV control. Finally, the last section will give information on the project status. (author)

Initial operation of a high-power quasi-optical gyrotron

International Nuclear Information System (INIS)

Fliflet, A.W.; Hargreaves, T.A.; Manheimer, W.M.; Fischer, R.P.; Barsanti, M.L.

1990-01-01

Results from the initial operating of a high-power quasi-optical gyrotron based on the 90-kV 50-A Varian VUW-8144 electron gun are reported. The output power and efficiency have been measured for a resonator mirror separation of 19.4 cm with a magnetic field of 4.95 T, corresponding to resonator output coupling of 1.9%, and for a resonator mirror separation of 21.4 cm with a magnetic field of 4.7 T, corresponding to a resonator output coupling of 3.1%. Operation was multimoded with 3--6 modes excited in the range of 125--130 GHz for the 4.95-T magnetic field. A peak efficiency of 15% at an output power of 161 kW was obtained for a gun voltage of 93 kV and a current of 12 A. A peak-output power of 364 kW at an efficiency of 10% was obtained at a voltage of 95.6 kV and 37.5 A

Cross-border Intra-group Hybrid Finance and International Taxation

OpenAIRE

Eberhartinger, Eva; Pummerer, Erich; Göritzer, Andreas

2010-01-01

In intra-group finance hybrid instruments allow for tailor-made form of finance. Hence hybrid finance is often used for international tax planning in multinational groups. Due to a lack of international tax harmonization or tax coordination qualification conflict can arise. A specific hybrid instrument is classified as debt in one country, and as equity in the other country. This may lead to double taxation. In the reverse case, double non-taxation can arise. Against this legal background one...

Towards the optimization of the thermal–hydraulic performance of gyrotron collectors

Energy Technology Data Exchange (ETDEWEB)

Savoldi, Laura; Bertani, Cristina [Dipartimento Energia, Politecnico di Torino, 10129 Torino (Italy); Cau, Francesca; Cismondi, Fabio [F4E, Barcelona (Spain); Gantenbein, Gerd; Illy, Stefan [Karlsruhe Institute of Technology (KIT), Institute for Pulsed Power and Microwave Technology (IHM), Kaiserstr. 12, 76131 Karlsruhe (Germany); Monni, Grazia [Dipartimento Energia, Politecnico di Torino, 10129 Torino (Italy); Rozier, Yoann [Thales Electron Devices, 78141 Vélizy-Villacoublay (France); Zanino, Roberto, E-mail: roberto.zanino@polito.it [Dipartimento Energia, Politecnico di Torino, 10129 Torino (Italy)

2015-11-15

Different configurations of water-cooled Cu collector for gyrotrons are investigated using the StarCCM + CFD code, aimed at optimizing its thermal–hydraulic (TH) performance. Although the current collectors show a good performance, the collector can be subjected to transient heat loads, due to the spent electron beam, of up to several tens of MW/m{sup 2}, and there is an interest to increase the gyrotron output power in the future. Furthermore, an optimized cooling will lead to improved reliability and lifetime of the collector. Starting from a hypervapotron (HV)-like collector, characterized by 100+ deep rectangular cavities with aspect ratio (AR) = 3, we present in the first part of the paper a single-cavity steady-state parametric analysis of the effect of AR on the heat exhaust capabilities. The investigation is then extended to other collector designs, including circumferential ribs and dimples, in order to assess the options for further improvements of the TH performance. The peak Cu temperature is computed by the code and its minimization is the target of the present optimization exercise. A self-consistent estimate of the heat transfer coefficient between collector and coolant is also obtained, which could be useful for fatigue and lifetime assessments. In the second part of the paper the most promising collector geometries identified in the first part are analyzed in the case of a transient heat load (vertical sweeping), first at the level of a single spatial period of the collector structure, then at the full-collector level. The results of the TH transient analysis are compared with both the results of the first part and with the transient purely thermal analysis of the full collector, showing for all geometries considered in this study a room for cooling efficiency improvement with respect to the HV-like design with AR = 3, at least in the operating conditions considered for this study (V ∼ 4 m/s, almost 100 °C sub-cooling).

Parametric decay below the upper hybrid frequency

Energy Technology Data Exchange (ETDEWEB)

Albers, E; Krause, K; Schlueter, H [Bochum Univ. (Germany, F.R.). Inst. fuer Experimentalphysik 2

1977-03-21

Parametric decay of the upper hybrid mode is observed between the electron cyclotron frequency and its first two harmonics. The decay products are identified as electron Bernstein and ion acoustic mode. The diagnostic results confirm the relevant dispersion relations.

Harmonic statistics

International Nuclear Information System (INIS)

Eliazar, Iddo

2017-01-01

The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their ‘public relations’ for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford’s law, and 1/f noise. - Highlights: • Harmonic statistics are described and reviewed in detail. • Connections to various statistical laws are established. • Connections to perturbation, renormalization and dynamics are established.

Harmonic statistics

Energy Technology Data Exchange (ETDEWEB)

Eliazar, Iddo, E-mail: eliazar@post.tau.ac.il

2017-05-15

The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their ‘public relations’ for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford’s law, and 1/f noise. - Highlights: • Harmonic statistics are described and reviewed in detail. • Connections to various statistical laws are established. • Connections to perturbation, renormalization and dynamics are established.

A Method for Harmonic Sources Detection based on Harmonic Distortion Power Rate

Science.gov (United States)

Lin, Ruixing; Xu, Lin; Zheng, Xian

2018-03-01

Harmonic sources detection at the point of common coupling is an essential step for harmonic contribution determination and harmonic mitigation. The harmonic distortion power rate index is proposed for harmonic source location based on IEEE Std 1459-2010 in the paper. The method only based on harmonic distortion power is not suitable when the background harmonic is large. To solve this problem, a threshold is determined by the prior information, when the harmonic distortion power is larger than the threshold, the customer side is considered as the main harmonic source, otherwise, the utility side is. A simple model of public power system was built in MATLAB/Simulink and field test results of typical harmonic loads verified the effectiveness of proposed method.

Development of a dummy load and waveguide components for 1 MW CW gyrotron

Energy Technology Data Exchange (ETDEWEB)

Ioki, Kimihiro, E-mail: ioki@toyama-jp.com [Toyama Company Limited, 3816-1 Kishi, Ymakita-machi, Ashigarakami-gun, Kanagawa 258-0112 (Japan); Hiranai, Shinichi; Moriyama, Shinichi [Naka Fusion Institute, JAEA, 801-1, Mukoyama, Naka-shi, Ibaraki 311-0193 (Japan); Tanaka, Suguru [Toyama Company Limited, 3816-1 Kishi, Ymakita-machi, Ashigarakami-gun, Kanagawa 258-0112 (Japan)

2016-11-01

Highlights: • A dummy load is a required component for the electron cyclotron heating system to test and adjust a gyrotron or a transmission line in ITER and JT60SA. • A new design concept was developed considering reliable durability and long lifetime. • Linear movement is used as a main mechanism for the reflector to mitigate the heat deposition concentration instead of rotating reflector, and the vacuum boundary for the linear movement is simply made with bellows. • The distribution of the ceramic coating thickness is carefully optimized considering the heat deposition rate. • A prototypical dummy load will be manufactured and tested, following the design phase. - Abstract: A dummy load dissipates the radiofrequency power and is required for the electron cyclotron heating system to test and adjust a gyrotron or a transmission line in ITER and JT60SA. The dummy load is comprised of a water-cooled vacuum chamber and a reflector. The vacuum chamber has intensive cooling and the inside surface has a ceramic coating layer. It is important that the dummy load has reliable durability and long lifetime. Linear movement is used as a main mechanism for the reflector to mitigate the heat deposition concentration instead of rotating reflector. The vacuum boundary for the linear movement is simply made with bellows and the bellows is accessible from the outside. The distribution of the ceramic coating thickness is carefully optimized considering the heat deposition rate. Another critical issue is to minimize the back reflection of the RF power from the dummy load. However, it is desired to design the dummy load without the pre-dummy-load. A prototypical dummy load will be manufactured and tested, following the design phase.

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

International Nuclear Information System (INIS)

Dionne, N.J.; Mallavarpu, R.; Palevsky, A.

1983-01-01

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

Fast evaluation of solid harmonic Gaussian integrals for local resolution-of-the-identity methods and range-separated hybrid functionals

Science.gov (United States)

Golze, Dorothea; Benedikter, Niels; Iannuzzi, Marcella; Wilhelm, Jan; Hutter, Jürg

2017-01-01

An integral scheme for the efficient evaluation of two-center integrals over contracted solid harmonic Gaussian functions is presented. Integral expressions are derived for local operators that depend on the position vector of one of the two Gaussian centers. These expressions are then used to derive the formula for three-index overlap integrals where two of the three Gaussians are located at the same center. The efficient evaluation of the latter is essential for local resolution-of-the-identity techniques that employ an overlap metric. We compare the performance of our integral scheme to the widely used Cartesian Gaussian-based method of Obara and Saika (OS). Non-local interaction potentials such as standard Coulomb, modified Coulomb, and Gaussian-type operators, which occur in range-separated hybrid functionals, are also included in the performance tests. The speed-up with respect to the OS scheme is up to three orders of magnitude for both integrals and their derivatives. In particular, our method is increasingly efficient for large angular momenta and highly contracted basis sets.

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

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 and the operat...

One dimension harmonic oscillator

International Nuclear Information System (INIS)

Cohen-Tannoudji, Claude; Diu, Bernard; Laloe, Franck.

1977-01-01

The importance of harmonic oscillator in classical and quantum physics, eigenvalues and eigenstates of hamiltonian operator are discussed. In complement are presented: study of some physical examples of harmonic oscillators; study of stationnary states in the /x> representation; Hermite polynomials; resolution of eigenvalue equation of harmonic oscillator by polynomial method; isotope harmonic oscillator with three dimensions; charged harmonic oscillator in uniform electric field; quasi classical coherent states of harmonic oscillator; eigenmodes of vibration of two coupled harmonic oscillators; vibration modus of a continuous physical system (application to radiation: photons); vibration modus of indefinite linear chain of coupled harmonic oscillators (phonons); one-dimensional harmonic oscillator in thermodynamic equilibrium at temperature T [fr

Large power electron tubes for high frequency heating

International Nuclear Information System (INIS)

Okamoto, Tadashi; Sato, Hisaaki.

1988-01-01

On the large power electron tubes used for electron cyclotron heating, lower hybrid resonance frequency heating, and ion cyclotron range of frequency heating, namely gyrotron, klystron and quadrupole tube, the features, the present status of development, the construction, the principle and so on are explained. The research and development of gyrotrons are most advanced in USSR, the inventor. The course of the development of gyrotrons in foreign countries and in Japan is described. There are many variants of gyrotrons, for example whispering gallery mode, klystron type, backward wave oscillator type, gyro-peniotron and others. The principle of gyrotrons is explained, and about the examples of the developed gyrotrons, the design parameters are shown. For the purpose of using for the LHRF heating in JT-60, a superlarge power klystron of 1 MW output at 2 GHz frequency, which is the largest class in the world, has been developed. Its total length is 2.7 m, and weight is 1.5 t. It features, construction, function and performance are reported. The trend of large power quadrupole tubes is toward stable action with large power in VHF zone, and the typical products in USA and Europe are shown. (Kako, I.)

HARMONIC DRIVE SELECTION

Directory of Open Access Journals (Sweden)

Piotr FOLĘGA

2014-03-01

Full Text Available The variety of types and sizes currently in production harmonic drive is a problem in their rational choice. Properly selected harmonic drive must meet certain requirements during operation, and achieve the anticipated service life. The paper discusses the problems associated with the selection of the harmonic drive. It also presents the algorithm correct choice of harmonic drive. The main objective of this study was to develop a computer program that allows the correct choice of harmonic drive by developed algorithm.

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

International Nuclear Information System (INIS)

Felch, K.; Feinstein, J.; Hess, C.; Huey, H.; Jongewaard, E.; Jory, H.; Neilson, J.; Pendleton, R.; Pirkle, D.; Zitelli, L.

1989-09-01

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 TE 15,2,1 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

Numerical optimization of quasi-optical mode converter for frequency step-tunable gyrotron

International Nuclear Information System (INIS)

Drumm, O.

2002-08-01

This work concentrates on the design of a quasi-optical mode converter for a frequency step-tunable gyrotron. Special attention is paid to the optimization of the conversion and forming of the exited wave of different frequencies inside the resonator. The investigations were part of the HGF-strategy-fonds-project ''Optimization of Tokamak Operation with controlled ECRH-Deposition''. In the resonator of the gyrotron modes can be exited at frequencies between 105 and 140 GHz. With the designed converter the desired field distribution at the output window for all frequencies will be approximately obtained. The newly gained knowledge and invented synthesis methods are applied to this practical example and verified. In this work, the waveguide antenna and the mirror system of the quasi-optical mode converter are presented separately from each other. At the beginning the synthesis of the aperture antenna for a frequency step-tunable design of the Vlasov-type as well as the Denisov-type is considered. As a conclusion of the investigation, the important parameters for the design of all antennas are summarized and the frequency behavior is compared. In the second part of this work new broadband design methods for the synthesis of the mirror surface are presented. These mirrors make an optimal wave forming for all frequencies equally possible. Therefore new quality criteria are introduced for the broadband evaluation of the mirror. Afterwards the surface is varied until the criteria reach an optimum. For the numerical optimization, in this work the gradient method and the extended Katsenelenbaum-Semenov algorithm are invented and applied. The efficient realization of the described algorithms on a computer is the significant point. The theoretical background of the presented methods for the synthesis of a mirror system is based on the general solution of the Helmholtz equation. Due to this, these methods can be utilized in other fields outside the microwave applications in

Design of test JIG for centralized interlock and protection module of ITER-India Gyrotron Test Facility

International Nuclear Information System (INIS)

Rathod, Vipal; Rao, S.L.; Edappala, Praveenlal; Rajpal, Rachana

2017-01-01

Fast Interlock and protection system plays very crucial role in ensuring the safe and reliable operation of high power RF sources such as a Gyrotron system. Critical Protection Interlocks are generally implemented using hardwired components and are required to have a response time as fast as < 10 μs. In this context, an Industrial grade prototype Centralized Interlock and Protection Module (CIM) based on ITER-India design has been developed successfully with the help of local industry. This paper presents the complete requirements, approach, detailed design concept and current status of Test JIG in detail

Static harmonization of dynamically harmonized Fourier transform ion cyclotron resonance cell.

Science.gov (United States)

Zhdanova, Ekaterina; Kostyukevich, Yury; Nikolaev, Eugene

2017-08-01

Static harmonization in the Fourier transform ion cyclotron resonance cell improves the resolving power of the cell and prevents dephasing of the ion cloud in the case of any trajectory of the charged particle, not necessarily axisymmetric cyclotron (as opposed to dynamic harmonization). We reveal that the Fourier transform ion cyclotron resonance cell with dynamic harmonization (paracell) is proved to be statically harmonized. The volume of the statically harmonized potential distribution increases with an increase in the number of trap segments.

Design of Passive Power Filter for Hybrid Series Active Power Filter using Estimation, Detection and Classification Method

Science.gov (United States)

Swain, Sushree Diptimayee; Ray, Pravat Kumar; Mohanty, K. B.

2016-06-01

This research paper discover the design of a shunt Passive Power Filter (PPF) in Hybrid Series Active Power Filter (HSAPF) that employs a novel analytic methodology which is superior than FFT analysis. This novel approach consists of the estimation, detection and classification of the signals. The proposed method is applied to estimate, detect and classify the power quality (PQ) disturbance such as harmonics. This proposed work deals with three methods: the harmonic detection through wavelet transform method, the harmonic estimation by Kalman Filter algorithm and harmonic classification by decision tree method. From different type of mother wavelets in wavelet transform method, the db8 is selected as suitable mother wavelet because of its potency on transient response and crouched oscillation at frequency domain. In harmonic compensation process, the detected harmonic is compensated through Hybrid Series Active Power Filter (HSAPF) based on Instantaneous Reactive Power Theory (IRPT). The efficacy of the proposed method is verified in MATLAB/SIMULINK domain and as well as with an experimental set up. The obtained results confirm the superiority of the proposed methodology than FFT analysis. This newly proposed PPF is used to make the conventional HSAPF more robust and stable.

Nonstationary oscillation of gyrotron backward wave oscillators with cylindrical interaction structure

International Nuclear Information System (INIS)

Chen, Shih-Hung; Chen, Liu

2013-01-01

The nonstationary oscillation of the gyrotron backward wave oscillator (gyro-BWO) with cylindrical interaction structure was studied utilizing both steady-state analyses and time-dependent simulations. Comparisons of the numerical results reveal that the gyro-BWO becomes nonstationary when the trailing field structure completely forms due to the dephasing energetic electrons. The backward propagation of radiated waves with a lower resonant frequency from the trailing field structure interferes with the main internal feedback loop, thereby inducing the nonstationary oscillation of the gyro-BWO. The nonstationary gyro-BWO exhibits the same spectral pattern of modulated oscillations with a constant frequency separation between the central frequency and sidebands throughout the whole system. The frequency separation is found to be scaled with the square root of the maximum field amplitude, thus further demonstrating that the nonstationary oscillation of the gyro-BWO is associated with the beam-wave resonance detuning

Hybrid compensation arrangement in dispersed generation systems

DEFF Research Database (Denmark)

Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim

2005-01-01

This paper presents a hybrid compensation system consisting of an active filter and distributed passive filters. In the system, each individual passive filter is connected to a distortion source and designed to eliminate main harmonics and supply reactive power for the distortion source, while...... filter system consisting of distributed passive filters and an active filter....... the active filter is responsible for the correction of the system unbalance and the cancellation of the remaining harmonics. The paper also analyzes the effects of the circuit configuration on the system impedance characteristics and consequently the effectiveness of the filter system. Simulation studies...

Third-harmonic generation for photoionization studies

International Nuclear Information System (INIS)

Compton, R.N.; Miller, J.C.

1982-01-01

Our group at Oak Ridge National Laboratory (ORNL) has studied resonantly enhanced multiphoton ionization (MPI) of alkali atoms, rare gases, and small molecules using tightly focused dye laser beams (power densities of 10 9 to 10 11 W/cm 2 ). In the case of alkali atoms, some ionization signals appear as a result of gas density effects (dimers or quasi-collisions) as previously discovered by Collins and his collaborators. These have been termed hybrid-resonances. By contrast, in the case of the rare gases, certain resonance ionization signals disappear with increasing gas density. The disappearance of the ionization signals in the rare gases is due to the interference of excitation of the third-harmonic and fundamental laser beam. At low pressure (10 -7 to 10 -5 torr) we have studied (1) mass spectra, (2) kinetic energy released in ionic fragmentation, and (3) photoelectron kinetic energy spectra using time-of-flight mass analysis and a 160 0 spherical sector electrostatic energy analyzer. These experiments, combined with two-color dye laser experiments, can often offer an unambiguous and detailed description of the MPI and subsequent fragmentation events. The major part of this talk will be devoted to the production and the use of vacuum ultraviolet (VUV) light from third-harmonic generation (THG) in the rare gases

Dielectric properties during electron irradiation of alternative materials for gyrotron windows

International Nuclear Information System (INIS)

Vila, R.; Ibarra, A.; Hodgson, E.R.

1996-01-01

Recent work on high power gyrotron windows has focused interest on some homopolar insulators as alternatives to sapphire due to their combined low dielectric loss and high thermal conductivity. The two main candidates at this moment, CVD diamond and high resistivity silicon, have been studied. As an indicator of their radiation behaviour, loss tangent and permittivity at about 15 GHz have been measured under 1.8 MeV electron irradiation at RT. In the case of silicon the previously observed radiation-induced decrease of loss tangent has been confirmed reaching a lower saturation level of 3.5 x 10 -5 at higher doses, and falling with increasing frequency. An even more important observation is that the sensitivity to ionizing radiation dropped by 4 orders of magnitude due to the radiation dose. First results for diamond are also promising, only a small degradation at relatively short times being seen with no further changes up to the maximum dose used. (orig.)

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.

Design of a double-anode magnetron-injection gun for the W-band gyrotron

Science.gov (United States)

Jang, Kwang Ho; Choi, Jin Joo; So, Joon Ho

2015-07-01

A double-anode magnetron-injection gun (MIG) was designed. The MIG is for a W-band 10-kW gyrotron. Analytic equations based on adiabatic theory and angular momentum conservation were used to examine the initial design parameters such as the cathode angle, and the radius of the beam emitting surface. The MIG's performances were predicted by using an electron trajectory code, the EGUN code. The beam spread of the axial velocity, Δvz/vz, obtained from the EGUN code was observed to be 1.34% at α = 1.3. The cathode edge emission and the thermal effect were modeled. The cathode edge emission was found to have a major effect on the velocity spread. The electron beam's quality was significantly improved by affixing non-emissive cylinders to the cathode.

Harmonics and energy management

International Nuclear Information System (INIS)

Andresen, M.

1993-01-01

To summarize what this paper has presented: Voltage and current non-sinusoidal wave shapes exist in our power system. These harmonics result from the prolific use of non-linear loads. The use of these types of loads is increasing dramatically, partly due to the push to implement energy management techniques involving harmonic generating equipment. Harmonic analysis can identify specific harmonics, their frequency, magnitude, and phase shift referenced to the fundamental. Harmonic distortion forces the use of true RMS multimeters for measurement accuracy. High levels of neutral current and N-G voltages are now possible. Transformers may overheat and fail even though they are below rated capacity. Low power factors due to harmonics cannot be corrected by the installation of capacitors, and knowledge of the fundamental VARs or the displacement power factor is needed to use capacitors alone for power factor correction. The harmonic related problems presented are by no means an exhaustive list. Many other concerns arise when harmonics are involved in the power system. The critical issue behind these problems is that many of the devices being recommended from an energy management point of view are contributing to the harmonic levels, and thus to the potential for harmonic problems. We can no longer live in the sinusoidal mentality if we are to be effective in saving energy and reducing costs

154 GHz collective Thomson scattering in LHD

Science.gov (United States)

Tanaka, K.; Nishiura, M.; Kubo, S.; Shimozuma, T.; Saito, T.; Moseev, D.; Abramovic, I.

2018-01-01

Collective Thomson scattering (CTS) was developed by using a 154 GHz gyrotron, and the first data has been obtained. Already, 77 GHz CTS has worked successfully. However, in order to access higher density region, 154 GHz option enhances the usability that reduces the refraction effect, which deteriorates in the local measurements. The system in the down converted frequency was almost identical to the system for 77 GHz. Probing beam, a notch filter, a mixer, and a local oscillator in the receiver system for 77 GHz option were replaced to those for the 154 GHz option. 154 GHz gyrotron was originally prepared for the second harmonic electron cyclotron heating (ECRH) at 2.75 T. However, scattering signal was masked by the second harmonic electron cyclotron emission (ECE) at 2.75 T. Therefore, 154 GHz CTS was operated at 1.375 T with fourth harmonic ECE, and an acceptable signal to noise ratio was obtained. There is a signature of fast ion components with neutral beam (NB) injection. In addition, the CTS spectrum became broader in hydrogen discharge than in deuterium discharge, as the theoretical CTS spectrum expects. This observation indicates a possibility to identify ion species ratio by the 154 GHz CTS diagnostic.

Shunt hybrid active power filter for harmonic mitigation: A practical ...

Indian Academy of Sciences (India)

The increasing importance of Power Quality problems has been responsible for several improvements in Active Power Filter (APF) typologies in the last decade. The increased cost and switching losses make a pure shunt APF economically impractical for high power applications. In higher power levels shunt Hybrid Active ...

Digital Simulation of a Hybrid Active Filter - An Active Filter in Series with a Shunt Passive Filter

OpenAIRE

Sitaram, Mahesh I; Padiyar, KR; Ramanarayanan, V

1998-01-01

Active filters have long been in use for the filtering of power system load harmonics. In this paper, the digital simulation results of a hybrid active power filter system for a rectifier load are presented. The active filter is used for filtering higher order harmonics as the dominant harmonics are filtered by the passive filter. This reduces the rating of the active filter significantly. The DC capacitor voltage of the active filter is controlled using a PI controller.

Atto second high harmonic sources

International Nuclear Information System (INIS)

Nam, Chang Hee

2008-01-01

High harmonic generation is a powerful method to produce attosecond pulses. The high harmonics, emitted from atoms driven by intense femtosecond laser pulses, can from an attosecond pulse train with equally spaced harmonic spectrum or an isolated single attosecond pulse with broad continuum spectrum. Using high power femtosecond laser technology developed at CXRC, we have investigated the spectral and temporal characteristics of high harmonics obtained from gaseous atoms. The spectral structure of harmonics could be manipulated by controlling laser chirp, and continuous tuning of harmonic wavelengths was achieved. For rigorous temporal characterization of attosecond harmonic pulses a cross correlation technique was applied to the photoionization process by harmonic and IR femtosecond pulses and achieved the complete temporal reconstruction of attosecond pulse trains, revealing the detailed temporal structure of the attosecond chirp by material dispersion. The duration of attosecond high harmonic pulses is usually much longer than that of transform limited pulses due to the inherent chirp originating from the harmonic generation process. The attosecond chirp compensation in the harmonic generation medium itself was demonstrated, thereby realizing the generation of near transform limited attosecond pulses. The interference of attosecond electron wave packets, generated from an atom by attosecond harmonic pulses, will be also presented

The three-dimensional particle-in-cell simulation analysis of cavity of high power subterahertz pulsed gyrotron

International Nuclear Information System (INIS)

Ito, Koyu; Jiang, Weihua

2013-01-01

High power sub-terahertz pulsed gyrotrons for Collective Thomson Scattering (CTS) diagnostics of fusion plasmas are being developed. The typical target parameters are: output power of 100-200 kW, operation frequency of 300 GHz, and pulsed length > 10 us. In order to support experimental development, numerical simulations were carried out by using Particle-In-Cell (PIC) code MAGIC. The oscillation mode of the electromagnetic radiation was selected as TE_1_5_,_2, for which the beam parameters and cavity dimensions were determined accordingly. The simulation results have showed maximum power of 144 kW at oscillation frequency of 292.80 GHz, with oscillation efficiency of 22.15%. (author)

High-harmonic spectroscopy of oriented OCS molecules: emission of even and odd harmonics.

Science.gov (United States)

Kraus, P M; Rupenyan, A; Wörner, H J

2012-12-07

We study the emission of even and odd high-harmonic orders from oriented OCS molecules. We use an intense, nonresonant femtosecond laser pulse superimposed with its phase-controlled second harmonic field to impulsively align and orient a dense sample of molecules from which we subsequently generate high-order harmonics. The even harmonics appear around the full revivals of the rotational dynamics. We demonstrate perfect coherent control over their intensity through the subcycle delay of the two-color fields. The odd harmonics are insensitive to the degree of orientation, but modulate with the degree of axis alignment, in agreement with calculated photorecombination dipole moments. We further compare the shape of the even and odd harmonic spectra with our calculations and determine the degree of orientation.

FPGA Techniques Based New Hybrid Modulation Strategies for Voltage Source Inverters

Science.gov (United States)

Sudha, L. U.; Baskaran, J.; Elankurisil, S. A.

2015-01-01

This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results. PMID:25821852

Harmonic supergraphs

International Nuclear Information System (INIS)

Galperin, A.; Ivanov, E.; Ogievetsky, V.; Sokatchev, E.

1985-01-01

This paper completes a descrption of the quantization procedure in the harmonic superspace approach. The Feynman rules for N=2 matter and Yang-Mills theories are derived and the various examples of harmonic supergraph calculations are given. Calculations appear to be not more difficult than those in the N=1 case. The integration over harmonic variables does not lead to any troubles, a non-locality in these disappears on-shell. The important property is that the quantum corrections are always writen as integrals over the full harmonic superspace even though the initial action is an integral over the analytic subspace. As a by-product our results imply a very simple proof of finiteness of a wide class of the N=4, d=2 non-linear Σ-models. The most general self-couplings of hypermultiplets including those with broken SU(2) are considered.The duality relations among the N=2 linear multiplet and both kinds of hypermultiplet are established

Dynamic nuclear polarization by frequency modulation of a tunable gyrotron of 260GHz.

Science.gov (United States)

Yoon, Dongyoung; Soundararajan, Murari; Cuanillon, Philippe; Braunmueller, Falk; Alberti, Stefano; Ansermet, Jean-Philippe

2016-01-01

An increase in Dynamic Nuclear Polarization (DNP) signal intensity is obtained with a tunable gyrotron producing frequency modulation around 260GHz at power levels less than 1W. The sweep rate of frequency modulation can reach 14kHz, and its amplitude is fixed at 50MHz. In water/glycerol glassy ice doped with 40mM TEMPOL, the relative increase in the DNP enhancement was obtained as a function of frequency-sweep rate for several temperatures. A 68 % increase was obtained at 15K, thus giving a DNP enhancement of about 80. By employing λ/4 and λ/8 polarizer mirrors, we transformed the polarization of the microwave beam from linear to circular, and achieved an increase in the enhancement by a factor of about 66% for a given power. Copyright © 2015 Elsevier Inc. All rights reserved.

On how differently the quasi-harmonic approximation works for two isostructural crystals: Thermal properties of periclase and lime

International Nuclear Information System (INIS)

Erba, A.; Dovesi, R.; Shahrokhi, M.; Moradian, R.

2015-01-01

Harmonic and quasi-harmonic thermal properties of two isostructural simple oxides (periclase, MgO, and lime, CaO) are computed with ab initio periodic simulations based on the density-functional-theory (DFT). The more polarizable character of calcium with respect to magnesium cations is found to dramatically affect the validity domain of the quasi-harmonic approximation that, for thermal structural properties (such as temperature dependence of volume, V(T), bulk modulus, K(T), and thermal expansion coefficient, α(T)), reduces from [0 K-1000 K] for MgO to just [0 K-100 K] for CaO. On the contrary, thermodynamic properties (such as entropy, S(T), and constant-volume specific heat, C V (T)) are described reliably at least up to 2000 K and quasi-harmonic constant-pressure specific heat, C P (T), up to about 1000 K in both cases. The effect of the adopted approximation to the exchange-correlation functional of the DFT is here explicitly investigated by considering five different expressions of three different classes (local-density approximation, generalized-gradient approximation, and hybrids). Computed harmonic thermodynamic properties are found to be almost independent of the adopted functional, whereas quasi-harmonic structural properties are more affected by the choice of the functional, with differences that increase as the system becomes softer

Elmo Bumpy Torus proof of principle, Phase II: Title 1 report. Volume IV. Microwave system. Preliminary design report

International Nuclear Information System (INIS)

Adams, R.N.

1982-01-01

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

Cold test measurements on components of the 1 MW, 140 GHz, CW gyrotron for the stellarator Wendelstein 7-X

International Nuclear Information System (INIS)

Dammertz, G.; Alberti, S.; Arnold, A.; Giguet, E.; LeGoff, Y.; Thumm, M.

2001-01-01

For the development of a 1 MW, 140 GHz gyrotron for CW operation which will be installed at the stellarator facility Wendelstein 7-X at IPP Greifswald, a collaboration between different European research institutes and an industrial company has been established. In order to prove the proper functioning of the millimeter wave components installed in the gyrotron -- such as the cavity, the waveguide taper and the quasioptical mode converter -- these components should be cold tested, preferably before installation. However, due to lack of time as well as long delivery times, this was not possible. Therefore, two units of the quasioptical mode converter and the cavity were fabricated with identical geometry, one of those being used for measurements on the low power test device. To perform these cold tests for tapers and mode converters, the gyrotron cavity output mode has to be simulated. This means that a high order rotating mode (TE 28,8 mode) must be generated at low power. This can be achieved by means of a mode generator consisting of two mirrors and a coaxial cavity with a perforated outer wall. Before applying the mode generator to the components, its proper behavior and the accurate alignment of the system must be verified either by radiation pattern measurements or k-spectrometer measurements. As the coupling through the holes of the k-spectrometer is extremely low, a special vector network analyzer with a dynamic range of at least 100 dB had to be developed. This has been achieved by integration of a phase locked backward-wave oscillator with a line width of 100 Hz and an output power of 10 mW. A non-destructive measurement of the resonance frequency and the quality factor of the cavity does not seem possible. The second cavity will be prepared for the cold measurement by drilling a small radial hole into its wall in the plane of the field maximum. This hole is then used for the input coupling. The accuracy required for this hole is rather critical. The

Harmonic operation of high gain harmonic generation free electron laser

International Nuclear Information System (INIS)

Deng Haixiao; Chinese Academy of Sciences, Beijing; Dai Zhimin

2008-01-01

In high gain harmonic generation (HGHG) free electron laser (FEL), with the right choice of parameters of the modulator undulator, the dispersive section and the seed laser, one may make the spatial bunching of the electron beam density distribution correspond to one of the harmonic frequencies of the radiator radiation, instead of the fundamental frequency of the radiator radiation in conventional HGHG, thus the radiator undulator is in harmonic operation (HO) mode. In this paper, we investigate HO of HGHG FEL. Theoretical analyses with universal method are derived and numerical simulations in ultraviolet and deep ultraviolet spectral regions are given. It shows that the power of the 3rd harmonic radiation in the HO of HGHG may be as high as 18.5% of the fundamental power level. Thus HO of HGHG FEL may obtain short wavelength by using lower beam energy. (authors)

General Lp-harmonic Blaschke bodies

Indian Academy of Sciences (India)

Lutwak introduced the harmonic Blaschke combination and the harmonic Blaschke body of a star body. Further, Feng and Wang introduced the concept of the -harmonic Blaschke body of a star body. In this paper, we define the notion of general -harmonic Blaschke bodies and establish some of its properties.

Removal of Direct Current Link Harmonic Ripple in Single Phase Voltage Source Inverter Systems Using Supercapacitors

Science.gov (United States)

2016-09-01

Khaligh, “Optimization of sizing and battery cycle life in battery/ultracapacitor hybrid energy storage systems for electric vehicle applications...depth cycling operation in photovoltaic system ,” in 22nd International Conference “Mixed Design of Integrated Circuits and Systems ,” Toruń, Poland...CURRENT LINK HARMONIC RIPPLE IN SINGLE-PHASE VOLTAGE SOURCE INVERTER SYSTEMS USING SUPERCAPACITORS by Gabriel D. Hernandez September 2016

Numerical Simulation of Single-anode and Double-anode Magnetron Injection Guns for 127.5 GHz 1 MW Gyrotron

Science.gov (United States)

Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Purohit, Laxmi Prasad; Sinha, Ashok Kumar

2011-07-01

This paper presents the design of two types of magnetron injection guns (MIG's) for 1 MW, 127.5 GHz gyrotron. TE24,8 mode has been chosen as the operating mode. In-house developed code MIGSYN has been used to estimate the initial gun parameters. The electron trajectory tracing program EGUN and in-house developed code MIGANS have been used to optimize the single-anode and the double-anode design for 80 kV, 40 A MIG. The parametric analysis of MIG has also been presented. The advantages and the disadvantages of each kind of configuration have been critically examined.

High Power Factor Hybrid Rectifier | Odeh | Nigerian Journal of ...

African Journals Online (AJOL)

This paper presents the analysis of a new single-phase hybrid rectifier with high power factor (PF) and low harmonic distortion current. The proposed rectifier structure is composed of an ordinary single-phase diode rectifier with parallel connection of a switched converter. It is outlined that the switched converter is capable of ...

General Lp-harmonic Blaschke bodies

Indian Academy of Sciences (India)

Abstract. Lutwak introduced the harmonic Blaschke combination and the harmonic. Blaschke body of a star body. Further, Feng and Wang introduced the concept of the L p- harmonic Blaschke body of a star body. In this paper, we define the notion of general. L p-harmonic Blaschke bodies and establish some of its ...

Second-harmonic generation in second-harmonic fiber Bragg gratings.

Science.gov (United States)

Steel, M J; de Sterke, C M

1996-06-20

We consider the production of second-harmonic light in gratings resonant with the generated field, through a Green's function approach. We recover some standard results and obtain new limits for the uniform grating case. With the extension to nonuniform gratings, we find the Green's function for the second harmonic in a grating with an arbitrary phase shift at some point. We then obtain closed form approximate expressions for the generated light for phase shifts close to π/2 and at the center of the grating. Finally, comparing the uniform and phase-shifted gratings with homogeneous materials, we discuss the enhancement in generated light and the bandwidth over which it occurs, and the consequences for second-harmonic generation in optical fiber Bragg gratings.

Harmonic Interaction Analysis in Grid Connected Converter using Harmonic State Space (HSS) Modeling

DEFF Research Database (Denmark)

Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

2015-01-01

-model, are introduced to analyze these problems. However, it is found that Linear Time Invariant (LTI) base model analysis makes it difficult to analyze these phenomenon because of time varying system operation trajectories, varying output impedance seen by grid connected systems and neglected switching component......An increasing number of power electronics based Distributed Generation (DG) systems and loads generate coupled harmonic as well as non-characteristic harmonic with each other. Several methods like impedance based analysis, which is derived from conventional small signal- and average...... during the modeling process. This paper investigates grid connected converter by means of Harmonic State Space (HSS) small signal model, which is modeled from Linear Time varying Periodically (LTP) system. Further, a grid connected converter harmonic matrix is investigated to analyze the harmonic...

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.

Enhancement of oscillation characteristics of a gyrotron by a built-in quasi-optical mode converter

International Nuclear Information System (INIS)

Hayashi, Kenichi; Mitsunaka, Yoshika; Komuro, Mitsuo

1994-01-01

Oscillation characteristics are analyzed experimentally and numerically by using two gyrotrons with a power level of 500 kW, a conventional tube and a tube with a built-in quasi-optical mode converter. Both tubes have a 120 GHz, TE 12,2 cavity of the same geometry and a single disk alumina window. The quasi-optical mode converter consists of an α-cut launcher and five mirrors. In the conventional tube, reflection of the competing mode at the output window prevents the main mode from oscillating stably in the operation region predicted by the design. Mode selectivity of the quasi-optical mode converter removes the influence of the reflection on the oscillation. Consequently, the experimental results in the tube with the quasi-optical mode converter are in good agreement with the design values. (author)

Input Harmonic Analysis on the Slim DC-Link Drive Using Harmonic State Space Model

DEFF Research Database (Denmark)

Yang, Feng; Kwon, Jun Bum; Wang, Xiongfei

2017-01-01

The harmonic performance of the slim dc-link adjustable speed drives has shown good performance in some studies but poor in some others. The contradiction indicates that a feasible theoretical analysis is still lacking to characterize the harmonic distortion for the slim dc-link drive. Considerin...... results of the slim dc-link drive, loaded up to 2.0 kW, are presented to validate the theoretical analysis....... variation according to the switching instant, the harmonics at the steady-state condition, as well as the coupling between the multiple harmonic impedances. By using this model, the impaction on the harmonics performance by the film capacitor and the grid inductance is derived. Simulation and experimental...

Comparison study among conventional, tissue harmonic and pulse inversion harmonic images to evaluate pleural effusion and ascites

International Nuclear Information System (INIS)

Chung, Hwan Hoon; Kim, Yun Hwan; Kang, Chang Ho; Park, Bum Jin; Chung, Kyoo Byung; Suh, Won Hyuck

2000-01-01

To determine the most useful sonographic technique to evaluate pleural effusion and ascites by comparing conventional, tissue harmonic and pulse inversion harmonic images. 12 patients having pleural effusion and 14 patients having ascites were included in this study. 18 patients were male and 8 patients were female. Average age was 54.8 yrs (25-77). We compared images which had been taken at the same section with 3 above mentioned sonographic techniques. Evaluation was done by 3 radiologists in consensus and grades were given to 3 techniques from 1 to 3. Evaluating points were 1) normal structures that border the fluid such as liver, peritoneal lining, pleura, 2) septation in fluid, 3) debris floating in fluid, and 4) artifacts. Pulse inversion harmonic image was the best in image quality for normal structures, followed by tissue harmonic and conventional image (p<0.05). Pulse inversion harmonic image was better than conventional image to evaluate septation in fluid (p<0.05), but there were no statistically significant difference between pulse inversion and tissue harmonic images, and tissue harmonic and conventional images. Tissue harmonic image was better than pulse inversion harmonic and conventional images to evaluate debris floating in fluid (p<0.05) but there was no statistically significant difference between these two latter techniques. Artifacts were most prominent on conventional image followed by tissue harmonic and pulse inversion harmonic image (p<0.05). Pulse inversion harmonic image was the best sonographic technique to evaluate pleural effusion or ascites, However, Tissue harmonic image was the best for evaluation of debris.

Comparison study among conventional, tissue harmonic and pulse inversion harmonic images to evaluate pleural effusion and ascites

Energy Technology Data Exchange (ETDEWEB)

Chung, Hwan Hoon; Kim, Yun Hwan; Kang, Chang Ho; Park, Bum Jin; Chung, Kyoo Byung; Suh, Won Hyuck [Korea University College of Medicine, Seoul (Korea, Republic of)

2000-12-15

To determine the most useful sonographic technique to evaluate pleural effusion and ascites by comparing conventional, tissue harmonic and pulse inversion harmonic images. 12 patients having pleural effusion and 14 patients having ascites were included in this study. 18 patients were male and 8 patients were female. Average age was 54.8 yrs (25-77). We compared images which had been taken at the same section with 3 above mentioned sonographic techniques. Evaluation was done by 3 radiologists in consensus and grades were given to 3 techniques from 1 to 3. Evaluating points were 1) normal structures that border the fluid such as liver, peritoneal lining, pleura, 2) septation in fluid, 3) debris floating in fluid, and 4) artifacts. Pulse inversion harmonic image was the best in image quality for normal structures, followed by tissue harmonic and conventional image (p<0.05). Pulse inversion harmonic image was better than conventional image to evaluate septation in fluid (p<0.05), but there were no statistically significant difference between pulse inversion and tissue harmonic images, and tissue harmonic and conventional images. Tissue harmonic image was better than pulse inversion harmonic and conventional images to evaluate debris floating in fluid (p<0.05) but there was no statistically significant difference between these two latter techniques. Artifacts were most prominent on conventional image followed by tissue harmonic and pulse inversion harmonic image (p<0.05). Pulse inversion harmonic image was the best sonographic technique to evaluate pleural effusion or ascites, However, Tissue harmonic image was the best for evaluation of debris.

Polyfunctional inorganic-organic hybrid materials: an unusual kind of NLO active layered mixed metal oxalates with tunable magnetic properties and very large second harmonic generation.

Science.gov (United States)

Cariati, Elena; Macchi, Roberto; Roberto, Dominique; Ugo, Renato; Galli, Simona; Casati, Nicola; Macchi, Piero; Sironi, Angelo; Bogani, Lapo; Caneschi, Andrea; Gatteschi, Dante

2007-08-01

Mixed M(II)/M(III) metal oxalates, as "stripes" connected through strong hydrogen bonding by para-dimethylaminobenzaldeide (DAMBA) and water, form an organic-inorganic 2D network that enables segregation in layers of the cationic organic NLO-phore trans-4-(4-dimethylaminostyryl)-1-methylpyridinium, [DAMS+]. The crystalline hybrid materials obtained have the general formula [DAMS]4[M2M'(C2O4)6].2DAMBA.2H2O (M = Rh, Fe, Cr; M' = Mn, Zn), and their overall three-dimensional packing is non-centrosymmetric and polar, therefore suitable for second harmonic generation (SHG). All the compounds investigated are characterized by an exceptional SHG activity, due both to the large molecular quadratic hyperpolarizability of [DAMS+] and to the efficiency of the crystalline network which organizes [DAMS+] into head-to-tail arranged J-type aggregates. The tunability of the pairs of metal ions allows exploiting also the magnetic functionality of the materials. Examples containing antiferro-, ferro-, and ferri-magnetic interactions (mediated by oxalato bridges) are obtained by coupling proper M(III) ions (Fe, Cr, Rh) with M(II) (Mn, Zn). This shed light on the role of weak next-nearest-neighbor interactions and main nearest-neighbor couplings along "stripes" of mixed M(II)/M(III) metal oxalates of the organic-inorganic 2D network, thus suggesting that these hybrid materials may display isotropic 1D magnetic properties along the mixed M(II)/M(III) metal oxalates "stripes".

Modelling of combined ICRF and NBI heating in JET hybrid plasmas

Directory of Open Access Journals (Sweden)

Gallart Dani

2017-01-01

Full Text Available During the 2015-2016 JET campaigns many efforts have been devoted to the exploration of high performance plasma scenarios envisaged for ITER operation. In this paper we model the combined ICRF+NBI heating in selected key hybrid discharges using PION. The antenna frequency was tuned to match the cyclotron frequency of minority hydrogen (H at the center of the tokamak coinciding with the second harmonic cyclotron resonance of deuterium. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of deuterium beam ions which allows us to assess its impact on the neutron rate RNT. We evaluate the influence of H concentration which was varied in different discharges in order to test their role in the heating performance. According to our modelling, the ICRF enhancement of RNT increases by decreasing the H concentration which increases the ICRF power absorbed by deuterons. We find that in the recent hybrid discharges this ICRF enhancement was in the range of 10-25%. Finally, we extrapolate the results to D-T and find that the best performing hybrid discharges correspond to an equivalent fusion power of ∼7.0 MW in D-T.

Mechanical reliability of current alumina and beryllia ceramics used in microwave windows for gyrotrons

International Nuclear Information System (INIS)

Becher, P.F.; Ferber, M.K.

1983-02-01

The mechanical reliability was evaluated for the alumina and beryllia ceramics now used as microwave windows in the high-power (greater than or equal to 200 kW) high-frequency (greater than or equal to 60 GHz) gyrotron tubes being developed for plasma heating in fusion systems. Analysis of the stresses generated in the various window configurations and tube operating conditions indicated that significant tensile stresses are generated in the ceramic window by dielectric heating. As a result, we characterized the static and dynamic fatigue behavior and the inert strength distributions for these two ceramics (i.e., fatigue studies included the behavior in the fluorocarbon fluid used for window cooling at 22 and 48 0 C and in both air (65% relative humidity) and distilled water at 22 0 C. These data were then analyzed in order to construct reliability diagrams for these materials

Experimental study of parametric decay close to the upper hybrid frequency

Energy Technology Data Exchange (ETDEWEB)

Albers, E; Krause, K; Schlueter, H [Ruhr-Univ., Bochum (Germany, F.R.)

1978-04-01

In He, Ne, and Ar plasmas the parametric decay of the electromagnetic upper hybrid mode is studied in the range between the electron cyclotron frequency and its first two harmonics. The pump wave is excited by outside antennae. The decay products are identified as electron Bernstein and ion acoustic modes.

Harmonic Patterns in Forex Trading

OpenAIRE

Nemček, Sebastian

2013-01-01

This diploma thesis is committed to examination of validity of Harmonic Patterns in Forex trading. Scott Carney described existing and introduced new Harmonic Patterns in 1999 in his book Harmonic Trader. These patterns use the Fibonacci principle to analyze price action and to provide both bullish and bearish trading signals. The goal of this thesis is to find out whether harmonic trading strategy on selected pairs is profitable in FX market, which patterns are the most profitable and what i...

Current Harmonics Cancellation in Three-Phase Four-Wire Systems by Using a Four-Branch Star Filtering Topology

DEFF Research Database (Denmark)

Rodriguez, Pedro; Candela, J. I.; Luna, A.

2009-01-01

This paper presents a new solution for filtering current harmonics in three-phase four-wire networks. The original four-branch star (FBS) filter topology presented in this paper is characterized by a particular layout of single-phase inductances and capacitors, without using any transformer......, a specific implementation of a three-phase four-wire hybrid power filter is presented as an illustrative application of the filtering topology. An extensive evaluation using simulation and experimental results from a DSP-based laboratory prototype is conducted in order to verify and validate the good...... only passive components are employed, or as a hybrid filter, when its behavior is improved by integrating a power converter into the filter structure. The paper analyzes the proposed topology, and derives fundamental concepts about the control of the resulting hybrid power filter. From this analysis...

Synthesis of Variable Harmonic Impedance in Inverter-Interfaced Distributed Generation Unit for Harmonic Damping Throughout a Distribution Network

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

2012-01-01

This paper proposes a harmonic impedance synthesis technique for voltage-controlled distributed generation inverters in order to damp harmonic voltage distortion on a distribution network. The approach employs a multiloop control scheme, where a selective harmonic load current feedforward loop...... at the dominant harmonic frequencies. Thus, the harmonic voltage drop on the grid-side inductance and the harmonic resonances throughout a distribution feeder with multiple shunt-connected capacitors can be effectively attenuated. Simulation and laboratory test results validate the performance of the proposed...

Tuvan throat singing and harmonics

Science.gov (United States)

Ruiz, Michael J.; Wilken, David

2018-05-01

Tuvan throat singing, also called overtone singing, provides for an exotic demonstration of the physics of harmonics as well as introducing an Asian musical aesthetic. A low fundamental is sung and the singer skillfully alters the resonances of the vocal system to enhance an overtone (harmonic above the fundamental). The result is that the listener hears two pitches simultaneously. Harmonics such as H8, H9, H10, and H12 form part of a pentatonic scale and are commonly selected for melody tones by Tuvan singers. A real-time spectrogram is provided in a video (Ruiz M J 2018 Video: Tuvan Throat Singing and Harmonics http://mjtruiz.com/ped/tuva/) so that Tuvan harmonics can be visualized as they are heard.

Tissue Harmonic Synthetic Aperture Imaging

DEFF Research Database (Denmark)

Rasmussen, Joachim

The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB...

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

International Nuclear Information System (INIS)

Hogge, J.P.

1993-12-01

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

Superstrings and harmonic superspace

International Nuclear Information System (INIS)

Kallosh, R.E.; AN SSSR, Moscow. Fizicheskij Inst.)

1987-01-01

The paper on superstrings and harmonic superspace is a contribution to the book dedicated to E.S. Fradkin on his sixtieth birthday. The purpose of the paper is to propose a description of N = 2,3 superspace which could be used for the investigation of the effective d = 10 harmonic superspace corresponding to the heterotic superstring. A description is given of the structure of semi-simple Lie algebras in the Cartan-Weyl basis, as well as the general properties of the even, compact part of harmonic superspace. The main properties of the four-dimensional N = 2 SYM theory are discussed, along with the N = 3, d = 4 super Yang-Mills theory. Finally the relation between the harmonic superspace and the heterotic E 8 x E 8 superstring is examined. (U.K.)

On the conformal equivalence of harmonic maps and exponentially harmonic maps

International Nuclear Information System (INIS)

Hong Minchun.

1991-06-01

Suppose that (M,g) and (N,h) are compact smooth Riemannian manifolds without boundaries. For m = dim M ≥3, and Φ: (M,g) → (N,h) is exponentially harmonic, there exists a smooth metric g-tilde conformally equivalent to g such that Φ: (M,g-tilde) → (N,h) is harmonic. (author). 7 refs

Waveguide harmonic damper for klystron amplifier

International Nuclear Information System (INIS)

Kang, Y.

1998-01-01

A waveguide harmonic damper was designed for removing the harmonic frequency power from the klystron amplifiers of the APS linac. Straight coaxial probe antennas are used in a rectangular waveguide to form a damper. A linear array of the probe antennas is used on a narrow wall of the rectangular waveguide for damping klystron harmonics while decoupling the fundamental frequency in dominent TE 01 mode. The klystron harmonics can exist in the waveguide as waveguide higher-order modes above cutoff. Computer simulations are made to investigate the waveguide harmonic damping characteristics of the damper

Strong toroidal effects on tokamak tearing mode stability in the hybrid and conventional scenarios

International Nuclear Information System (INIS)

Ham, C J; Connor, J W; Cowley, S C; Gimblett, C G; Hastie, R J; Hender, T C; Martin, T J

2012-01-01

The hybrid scenario is thought to be an important mode of operation for the ITER tokamak. Analytic and numerical calculations demonstrate that toroidal effects at finite β have a strong influence on tearing mode stability of hybrid modes. Indeed, they persist in the large aspect ratio limit, R/a → ∞. A similar strong coupling effect is found between the m = 1, n = 1 harmonic and the m = 2, n = 1 harmonic if the minimum safety factor is less than unity. In both cases the tearing stability index, Δ′ increases rapidly as β approaches ideal marginal stability, providing a potential explanation for the onset of linearly unstable tearing modes. The numerical calculations have used an improved version of the T7 code (Fitzpatrick et al 1993 Nucl. Fusion 33 1533), and complete agreement is obtained with the analytic theory for this demanding test of the code. (paper)

Harmonic Damping in DG-Penetrated Distribution Network

DEFF Research Database (Denmark)

Lu, Jinghang; Savaghebi, Mehdi; Guerrero, Josep M.

2016-01-01

Grid background harmonics may be amplified, propagate through a long distribution feeder and even lead to power system instability. In this paper, harmonic propagation issue is investigated and mitigation of the harmonics is analyzed by using transmission line theory which has already been applied...... in power systems. It is demonstrated that a specific harmonic will not be amplified if the feeder’s length is less than one quarter of the harmonic wavelength meanwhile the terminal impedance is less than characteristic impedance. Besides, three scenarios will be considered in accordance...... with the relationship between the feeder’s length and harmonic wavelength. Harmonic suppression control strategies will be respectively designed considering 5th and 7th harmonics coexisting in the distribution line. Finally, a simulation study has been performed to verify the theoretical analysis and demonstrate...

Design, analysis and modeling of a novel hybrid powertrain system based on hybridized automated manual transmission

Science.gov (United States)

Wu, Guang; Dong, Zuomin

2017-09-01

Hybrid electric vehicles are widely accepted as a promising short to mid-term technical solution due to noticeably improved efficiency and lower emissions at competitive costs. In recent years, various hybrid powertrain systems were proposed and implemented based on different types of conventional transmission. Power-split system, including Toyota Hybrid System and Ford Hybrid System, are well-known examples. However, their relatively low torque capacity, and the drive of alternative and more advanced designs encouraged other innovative hybrid system designs. In this work, a new type of hybrid powertrain system based hybridized automated manual transmission (HAMT) is proposed. By using the concept of torque gap filler (TGF), this new hybrid powertrain type has the potential to overcome issue of torque gap during gearshift. The HAMT design (patent pending) is described in details, from gear layout and design of gear ratios (EV mode and HEV mode) to torque paths at different gears. As an analytical tool, mutli-body model of vehicle equipped with this HAMT was built to analyze powertrain dynamics at various steady and transient modes. A gearshift was decomposed and analyzed based basic modes. Furthermore, a Simulink-SimDriveline hybrid vehicle model was built for the new transmission, driveline and vehicle modular. Control strategy has also been built to harmonically coordinate different powertrain components to realize TGF function. A vehicle launch simulation test has been completed under 30% of accelerator pedal position to reveal details during gearshift. Simulation results showed that this HAMT can eliminate most torque gap that has been persistent issue of traditional AMT, improving both drivability and performance. This work demonstrated a new type of transmission that features high torque capacity, high efficiency and improved drivability.

Harmonic supergraphs. Green functions

International Nuclear Information System (INIS)

Galperin, A.; Ivanov, E.; Gievetsky, V.; Sokatchev, E.

1985-01-01

The quantization procedure in the harmonic superspace approach is worked out. Harmonic distributions are introduced and are used to construct the analytic superspace delta-functions and the Green functions for the hypermultiplet and the N=2 Yang-Mills superfields. The gauge fixing is described and the relevant Faddeev-Popov ghosts are defined. The corresponding BRST transformations are found. The harmonic superspace quantization of the N=2 gauge theory turns out to be rather simple and has many parallels with that for the standard (N=0) Yang-Mills theory. In particular, no ghosts-forghosts are needed

A pretandem harmonic buncher

International Nuclear Information System (INIS)

Lin, Qui-xun; Van Wechel, T.D.

1987-01-01

A single gap harmonic buncher has been constructed as a pretandem buncher. Over 85% of a proton dc beam has been bunched into pulses. The width (fwhm) of the pulses is 0.7 ns. The buncher is based on that built at Argonne. Changes were made to the buncher's configuration so that the buncher could be tuned to the desired four harmonic frequencies. A method of calibrating and setting the relative phases and amplitudes of the four harmonic frequencies has been used to obtain an optimum sawtooth-like bunching waveform

Harmonic Interaction Analysis in Grid-connected Converter using Harmonic State Space (HSS) Modeling

DEFF Research Database (Denmark)

Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede

2017-01-01

research about the harmonic interaction. However, it is found that the Linear Time Invariant (LTI) based model analysis makes it difficult to analyze these phenomena because of the time-varying properties of the power electronic based systems. This paper investigates grid-connected converter by using......An increasing number of power electronic based Distributed Generation (DG) systems and loads generate not only characteristic harmonics but also unexpected harmonics. Several methods like impedance based analysis, which are derived from the conventional average model, are introduced to perform...

Design and control of hybrid actuation lower limb exoskeleton

Directory of Open Access Journals (Sweden)

Hipolito Aguilar-Sierra

2015-06-01

Full Text Available In this article, two types of actuators are applied for a lower limb exoskeleton. They are DC motors with the harmonic drive and the pneumatic artificial muscles. This combination takes advantages of both the harmonic drive and the pneumatic artificial muscle. It provides both high accuracy position control and high ratio of strength and weight. The shortcomings of the two actuators are overcome by the hybrid actuation, for example, low control accuracy and modeling difficult of pneumatic artificial muscle, compactness, and structural flexibility of DC motors. The design and modeling processes are discussed to show the proposed exoskeleton can increase the strength of human lower limbs. Experiments and analysis of the exoskeleton are given to evaluate the effectiveness of the design and modeling.

Four-branch Star Hybrid Power Filter for Three-phase Four-wire Systems

DEFF Research Database (Denmark)

Blaabjerg, Frede; Teodorescu, Remus; Rodriguez, Pedro

2008-01-01

and derives fundamental concepts about the control of the resulting hybrid power filter. From this analysis, a specifc implementation of a three-phase four-wire hybrid power filter is presented as an illustrative application of the filtering topology. An extensive evaluation using simulation and experimental......This paper presents a new concept for filtering current harmonics in three-phase four-wire networks. The four-branch star (FBS) filtering topology presented in this work is characterized by a particular layout consisting of single-phase inductances and capacitors. Via this layout, a power filter...

Numerical investigation of collector cooling for a 1 MW ITER gyrotron operated with vertical sweeping

Energy Technology Data Exchange (ETDEWEB)

Savoldi, Laura; Bertani, Cristina [Dipartimento Energia, Politecnico di Torino (Italy); Cau, Francesca; Cismondi, Fabio [Fusion for Energy, Barcelona (Spain); Gantenbein, Gerd; Illy, Stefan [KIT, Karlsruhe (Germany); Monni, Grazia [Dipartimento Energia, Politecnico di Torino (Italy); Zanino, Roberto, E-mail: roberto.zanino@polito.it [Dipartimento Energia, Politecnico di Torino (Italy)

2015-11-15

The present gyrotron designs for EC plasma heating in nuclear fusion reactors require the safe exhaust of a power comparable to that injected into the plasma, in order to keep the maximum temperature below the acceptable value of 300 °C. In this paper, the commercial computational fluid dynamics (CFD) software STAR-CCM+{sup ®} is used to analyze the thermal performance of the annular copper collector of a 1 MW ITER gyrotron, equipped with a hypervapotron structure made of annular fins with rectangular cavities of aspect ratio (depth/width) = 3, cooled by highly subcooled (90–100 °C) pressurized water flowing at ∼4 m/s. It is assumed that the simple vertical sweeping strategy is used to reduce the very high peak heat flux on the collector (up to 30 MW/m{sup 2} transient, 5 MW/m{sup 2} time average), due to the spent electron beam. The 2D steady-state conjugate heat transfer problem is solved assuming azimuthal symmetry and accounting for 2-phase flow. The single-cavity flow and heat transfer problem is considered first, to optimize the mesh and the selection of the turbulence model. For the operating conditions considered in this paper, the full collector (100+ cavities) solution shows that boiling occurs only in a limited number of cavities close to the peaks of the heat flux, with the vapor remaining trapped in the bottom of the cavities, i.e. no full hypervapotron regime should be achieved in these operating conditions. The steady-state analysis allows the numerical evaluation of the heat transfer coefficients between Cu and water; these are then used as input for the simplified, purely thermal (solid only) analysis of the actual transient problem for the full collector. The results of the simplified model, which allows a huge reduction of the computational effort, are successfully benchmarked against those of a comprehensive thermal–hydraulic simulation. The computed peak Cu temperature is below the acceptable limit under the steady-state (time averaged

Terahertz electron cyclotron maser interactions with an axis-encircling electron beam

Science.gov (United States)

Li, G. D.; Kao, S. H.; Chang, P. C.; Chu, K. R.

2015-04-01

To generate terahertz radiation via the electron cyclotron maser instability, harmonic interactions are essential in order to reduce the required magnetic field to a practical value. Also, high-order mode operation is required to avoid excessive Ohmic losses. The weaker harmonic interaction and mode competition associated with an over-moded structure present challenging problems to overcome. The axis-encircling electron beam is a well-known recipe for both problems. It strengthens the harmonic interaction, as well as minimizing the competing modes. Here, we examine these advantages through a broad data base obtained for a low-power, step-tunable, gyrotron oscillator. Linear results indicate far more higher-harmonic modes can be excited with an axis-encircling electron beam than with an off-axis electron beam. However, multi-mode, time-dependent simulations reveal an intrinsic tendency for a higher-harmonic mode to switch over to a lower-harmonic mode at a high beam current or upon a rapid current rise. Methods are presented to identify the narrow windows in the parameter space for stable harmonic interactions.

Terahertz electron cyclotron maser interactions with an axis-encircling electron beam

International Nuclear Information System (INIS)

Li, G. D.; Kao, S. H.; Chang, P. C.; Chu, K. R.

2015-01-01

To generate terahertz radiation via the electron cyclotron maser instability, harmonic interactions are essential in order to reduce the required magnetic field to a practical value. Also, high-order mode operation is required to avoid excessive Ohmic losses. The weaker harmonic interaction and mode competition associated with an over-moded structure present challenging problems to overcome. The axis-encircling electron beam is a well-known recipe for both problems. It strengthens the harmonic interaction, as well as minimizing the competing modes. Here, we examine these advantages through a broad data base obtained for a low-power, step-tunable, gyrotron oscillator. Linear results indicate far more higher-harmonic modes can be excited with an axis-encircling electron beam than with an off-axis electron beam. However, multi-mode, time-dependent simulations reveal an intrinsic tendency for a higher-harmonic mode to switch over to a lower-harmonic mode at a high beam current or upon a rapid current rise. Methods are presented to identify the narrow windows in the parameter space for stable harmonic interactions

Harmonics in transmission power systems

DEFF Research Database (Denmark)

Wiechowski, Wojciech Tomasz

. The comparison shows that results obtained used both types of the cores are the same, so it is concluded that both cores can be used for harmonic measurements. Low-inductance resistors are introduced in the secondary circuits, in series with the metering and protective relaying. On those resistors, the harmonic......Some time ago, Energinet.dk, the Transmission System Operator of the 150 kV and 400 kV transmission network in Denmark, had experienced operational malfunctions of some of the measuring and protection equipment. Also an overloading of a harmonic filter has been reported, and therefore, a need...... end only so the ground is not used as a return path. A way to reduce the capacitive coupling is to provide shielding. Harmonic currents are measured using the conventional inductive voltage transformers. Both protective and metering cores were compared if they could be used for harmonic measurements...

Research study on harmonized molecular materials (HMM); Bunshi kyocho zairyo ni kansuru chosa kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

As functional material to satisfy various needs for environmental harmonization and efficient conversion for information-oriented and aging societies, HMM were surveyed. Living bodies effectively carry out transmission/processing of information, and transport/conversion of substances, and these functions are based on harmonization between organic molecules, and between those and metal or inorganic ones. HMM is a key substance to artificially realize these bio-related functions. Its R & D aims at (1) Making a breakthrough in production process based on innovation of material separation/conversion technology, (2) Contribution to an information-oriented society by high-efficiency devices, and (3) Growth of a functional bio-material industry. HMM is classified into three categories: (1) Assembly materials such as organic ultra-thin films (LB film, self-organizing film), and organic/inorganic hybrid materials for optoelectronics, sensors and devices, (2) Mesophase materials such as functional separation membrane and photo-conductive material, and (3) Microporous materials such as synthetic catalyst using guest/host materials. 571 refs., 88 figs., 21 tabs.

Multidimensional high harmonic spectroscopy

International Nuclear Information System (INIS)

Bruner, Barry D; Soifer, Hadas; Shafir, Dror; Dudovich, Nirit; Serbinenko, Valeria; Smirnova, Olga

2015-01-01

High harmonic generation (HHG) has opened up a new frontier in ultrafast science where attosecond time resolution and Angstrom spatial resolution are accessible in a single measurement. However, reconstructing the dynamics under study is limited by the multiple degrees of freedom involved in strong field interactions. In this paper we describe a new class of measurement schemes for resolving attosecond dynamics, integrating perturbative nonlinear optics with strong-field physics. These approaches serve as a basis for multidimensional high harmonic spectroscopy. Specifically, we show that multidimensional high harmonic spectroscopy can measure tunnel ionization dynamics with high precision, and resolves the interference between multiple ionization channels. In addition, we show how multidimensional HHG can function as a type of lock-in amplifier measurement. Similar to multi-dimensional approaches in nonlinear optical spectroscopy that have resolved correlated femtosecond dynamics, multi-dimensional high harmonic spectroscopy reveals the underlying complex dynamics behind attosecond scale phenomena. (paper)

On the connection between the hydrogen atom and the harmonic oscillator: the zero-energy case

International Nuclear Information System (INIS)

Kibler, M.; Negali, T.

1983-09-01

The connection between the three-dimensional hydrogen atom and a four-dimensional harmonic oscillator obtained in previous works, from an hybridization of the infinitesimal Pauli approach to the hydrogen system with the Schwinger approach to spherical and hyperbolical angular momenta, is worked out in the case of the zero-energy point of the hydrogen atom. This leads to the equivalence of the three-dimensional hydrogen problem with a four-dimensional free-particle problem involving a constraint condition. For completeness, the latter results is also derived by using the Kustaanheimo-Stiefel transformation introduced in celestial mechanics. Finally, it is shown how the Lie algebra of SO(4,2) quite naturally arises for the whole spectrum (discrete + continuum + zero-energy point) of the three-dimensional hydrogen atom from the introduction of the constraint condition into the Lie algebra of Sp(8,R) associated to the four-dimensional harmonic oscillator

Audibility of harmonics in 'periodic white noise'

NARCIS (Netherlands)

Duifhuis, H.; Tomesen, H.H.

1970-01-01

In a previous article (Duifhuis, 1970) results' concerning the audibility of harmonics in a periodic pulse have been presented. Each of the lower harmonics could be perceived separately, whereas the high harmonics were heard together as one complex signal. High harmonics, however, appeared to be

Probabilistic Harmonic Modeling of Wind Power Plants

DEFF Research Database (Denmark)

Guest, Emerson; Jensen, Kim H.; Rasmussen, Tonny Wederberg

2017-01-01

A probabilistic sequence domain (SD) harmonic model of a grid-connected voltage-source converter is used to estimate harmonic emissions in a wind power plant (WPP) comprised of Type-IV wind turbines. The SD representation naturally partitioned converter generated voltage harmonics into those...... with deterministic phase and those with probabilistic phase. A case study performed on a string of ten 3MW, Type-IV wind turbines implemented in PSCAD was used to verify the probabilistic SD harmonic model. The probabilistic SD harmonic model can be employed in the planning phase of WPP projects to assess harmonic...

A possible upgrade of FLASH for harmonic lasing down to 1.3 nm

International Nuclear Information System (INIS)

Schneidmiller, E.A.; Yurkov, M.V.

2012-10-01

We propose the 3rd harmonic lasing in a new FLASH undulator as a way to produce intense, narrow-band, and stable SASE radiation down to 1.3 nm with the present accelerator energy of 1.25 GeV. To provide optimal conditions for harmonic lasing, we suggest to suppress the fundamental with the help of a special set of phase shifters. We rely on the standard technology of gap-tunable planar hybrid undulators, and choose the period of 2.3 cm and the minimum gap of 0.9 cm; total length of the undulator system is 34.5 m. With the help of numerical simulations we demonstrate that the 3rd harmonic lasing at 1.3 nm provides peak power at a gigawatt level and the narrow intrinsic bandwidth, 0.1% (FWHM). Pulse duration can be controlled in the range of a few tens of femtoseconds, and the peak brilliance reaches the value of 10 31 photons/(s mrad 2 mm 2 0.1% BW). With the given undulator design, a standard option of lasing at the fundamental wavelength to saturation is possible through the entire water window and at longer wavelengths. In this paper we briefly consider additional options such as polarization control, bandwidth reduction, self-seeding, X-ray pulse compression, and two-color operation. We also discuss possible technical issues and backup solutions.

A possible upgrade of FLASH for harmonic lasing down to 1.3 nm

Energy Technology Data Exchange (ETDEWEB)

Schneidmiller, E.A.; Yurkov, M.V.

2012-10-15

We propose the 3rd harmonic lasing in a new FLASH undulator as a way to produce intense, narrow-band, and stable SASE radiation down to 1.3 nm with the present accelerator energy of 1.25 GeV. To provide optimal conditions for harmonic lasing, we suggest to suppress the fundamental with the help of a special set of phase shifters. We rely on the standard technology of gap-tunable planar hybrid undulators, and choose the period of 2.3 cm and the minimum gap of 0.9 cm; total length of the undulator system is 34.5 m. With the help of numerical simulations we demonstrate that the 3rd harmonic lasing at 1.3 nm provides peak power at a gigawatt level and the narrow intrinsic bandwidth, 0.1% (FWHM). Pulse duration can be controlled in the range of a few tens of femtoseconds, and the peak brilliance reaches the value of 10{sup 31} photons/(s mrad{sup 2} mm{sup 2} 0.1% BW). With the given undulator design, a standard option of lasing at the fundamental wavelength to saturation is possible through the entire water window and at longer wavelengths. In this paper we briefly consider additional options such as polarization control, bandwidth reduction, self-seeding, X-ray pulse compression, and two-color operation. We also discuss possible technical issues and backup solutions.

Three-dimensional simulation of triode-type MIG for 1 MW, 120 GHz gyrotron for ECRH applications

Science.gov (United States)

Singh, Udaybir; Kumar, Nitin; Kumar, Narendra; Kumar, Anil; Sinha, A. K.

2012-01-01

In this paper, the three-dimensional simulation of triode-type magnetron injection gun (MIG) for 120 GHz, 1 MW gyrotron is presented. The operating voltages of the modulating anode and the accelerating anode are 57 kV and 80 kV respectively. The high order TE 22,6 mode is selected as the operating mode and the electron beam is launched at the first radial maxima for the fundamental beam-mode operation. The initial design is obtained by using the in-house developed code MIGSYN. The numerical simulation is performed by using the commercially available code CST-Particle Studio (PS). The simulated results of MIG obtained by using CST-PS are validated with other simulation codes EGUN and TRAK, respectively. The results on the design output parameters obtained by using these three codes are found to be in close agreement.

Flexible Microgrid Power Quality Enhancement Using Adaptive Hybrid Voltage and Current Controller

DEFF Research Database (Denmark)

He, Jinwei; Li, Yun Wei; Blaabjerg, Frede

2014-01-01

-pass/bandpass filters in the DG unit digital controller. Moreover, phase-locked loops are not necessary as the microgrid frequency deviation can be automatically identified by the power control loop. Consequently, the proposed control method provides opportunities to reduce DG control complexity, without affecting......To accomplish superior harmonic compensation performance using distributed generation (DG) unit power electronics interfaces, an adaptive hybrid voltage and current controlled method (HCM) is proposed in this paper. It shows that the proposed adaptive HCM can reduce the numbers of low...... the harmonic compensation performance. Comprehensive simulated and experimental results from a single-phase microgrid are provided to verify the feasibility of the proposed adaptive HCM approach....

Complex harmonic modal analysis of rotor systems

International Nuclear Information System (INIS)

Han, Dong Ju

2015-01-01

Complex harmonic analysis for rotor systems has been proposed from the strict complex modal analysis based upon Floquet theory. In this process the harmonic balance method is adopted, effectively associated with conventional eigenvalue analysis. Also, the harmonic coefficients equivalent to dFRFs in harmonic mode has been derived in practice. The modes are classified from identifying the modal characteristics, and the adaptation of harmonic balance method has been proven by comparing the results of the stability analyses from Floque theory and the eigen analysis. The modal features of each critical speed are depicted in quantitatively and qualitatively by showing that the strengths of each component of the harmonic coefficients are estimated from the order of magnitude analysis according to their harmonic patterns. This effectiveness has been verified by comparing with the numerical solutions

Harmonic uniflow engine

Science.gov (United States)

Bennett, Charles L.

2016-03-22

A reciprocating-piston uniflow engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. When released, the inlet valve head undergoes a single oscillation past the equilibrium position to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. In other embodiments, the harmonic oscillator arrangement of the inlet valve enables the uniflow engine to be reversibly operated as a uniflow compressor.

Analysis of Harmonic Coupling and Stability in Back-to-Back Converter Systems for Wind Turbines using Harmonic State Space (HSS)

DEFF Research Database (Denmark)

Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

2015-01-01

Understanding about harmonic propagation in wind turbine converter is fundamental to research the influence of these on a large network harmonic distortion. Therefore, the analysis of wind turbine converter harmonic spectrum as well as the influence of converter operating point into the network i...... connected into the large wind farm model to analyze the overall steady-state harmonic as well as harmonic stability. All theoretical modeling and analysis is verified by means of simulation and experimental results.......Understanding about harmonic propagation in wind turbine converter is fundamental to research the influence of these on a large network harmonic distortion. Therefore, the analysis of wind turbine converter harmonic spectrum as well as the influence of converter operating point into the network...... is urgently important issues in harmonic studies on wind farm. However, the conventional modeling procedure and simplified model for controller design are not enough to analyze such complicated systems. Besides, they have many limitations in terms of including a non-linear component, different operating...

High-frequency harmonic imaging of the eye

Science.gov (United States)

Silverman, Ronald H.; Coleman, D. Jackson; Ketterling, Jeffrey A.; Lizzi, Frederic L.

2005-04-01

Purpose: Harmonic imaging has become a well-established technique for ultrasonic imaging at fundamental frequencies of 10 MHz or less. Ophthalmology has benefited from the use of fundamentals of 20 MHz to 50 MHz. Our aim was to explore the ability to generate harmonics for this frequency range, and to generate harmonic images of the eye. Methods: The presence of harmonics was determined in both water and bovine vitreous propagation media by pulse/echo and hydrophone at a series of increasing excitation pulse intensities and frequencies. Hydrophone measurements were made at the focal point and in the near- and far-fields of 20 MHz and 40 MHz transducers. Harmonic images of the anterior segment of the rabbit eye were obtained by a combination of analog filtering and digital post-processing. Results: Harmonics were generated nearly identically in both water and vitreous. Hydrophone measurements showed the maximum second harmonic to be -5 dB relative to the 35 MHz fundamental at the focus, while in pulse/echo the maximum harmonic amplitude was -15dB relative to the fundamental. Harmonics were absent in the near-field, but present in the far-field. Harmonic images of the eye showed improved resolution. Conclusion: Harmonics can be readily generated at very high frequencies, and at power levels compliant with FDA guidelines for ophthalmology. This technique may yield further improvements to the already impressive resolutions obtainable in this frequency range. Improved imaging of the macular region, in particular, may provide significant improvements in diagnosis of retinal disease.

Harmonics Monitoring Survey on LED Lamps

Directory of Open Access Journals (Sweden)

Abdelrahman Ahmed Akila

2017-03-01

Full Text Available Light Emitting Diode (LED lamps are being increasingly used in many applications. These LED lamps operate using a driver, which is a switching device. Hence, LED lamps will be a source of harmonics in the power system. These harmonics if not well treated, may cause severe performance and operational problems. In this paper, harmonics (amplitude and phase angles generated by both LED lamps and conventional fluorescent lamps will be studied practically. Then they will be analyzed and evaluated. Compared to each other harmonics generated by both LED and conventional florescent lamps, self mitigation may occur based on the phase angle of these harmonics. All data will be measured using power analyzer and will be done on a sample of actual lamps.

Computer model for harmonic ultrasound imaging.

Science.gov (United States)

Li, Y; Zagzebski, J A

2000-01-01

Harmonic ultrasound imaging has received great attention from ultrasound scanner manufacturers and researchers. In this paper, we present a computer model that can generate realistic harmonic images. In this model, the incident ultrasound is modeled after the "KZK" equation, and the echo signal is modeled using linear propagation theory because the echo signal is much weaker than the incident pulse. Both time domain and frequency domain numerical solutions to the "KZK" equation were studied. Realistic harmonic images of spherical lesion phantoms were generated for scans by a circular transducer. This model can be a very useful tool for studying the harmonic buildup and dissipation processes in a nonlinear medium, and it can be used to investigate a wide variety of topics related to B-mode harmonic imaging.

High-order harmonics generation from overdense plasmas

International Nuclear Information System (INIS)

Quere, F.; Thaury, C.; Monot, P.; Martin, Ph.; Geindre, J.P.; Audebert, P.; Marjoribanks, R.

2006-01-01

Complete test of publication follows. When an intense laser beam reflects on an overdense plasma generated on a solid target, high-order harmonics of the incident laser frequency are observed in the reflected beam. This process provides a way to produce XUV femtosecond and attosecond pulses in the μJ range from ultrafast ultraintense lasers. Studying the mechanisms responsible for this harmonic emission is also of strong fundamental interest: just as HHG in gases has been instrumental in providing a comprehensive understanding of basic intense laser-atom interactions, HHG from solid-density plasmas is likely to become a unique tool to investigate many key features of laser-plasma interactions at high intensities. We will present both experimental and theoretical evidence that two mechanisms contribute to this harmonic emission: - Coherent Wake Emission: in this process, harmonics are emitted by plasma oscillations in te overdense plasma, triggered in the wake of jets of Brunel electrons generated by the laser field. - The relativistic oscillating mirror: in this process, the intense laser field drives a relativistic oscillation of the plasma surface, which in turn gives rise to a periodic phase modulation of the reflected beam, and hence to the generation of harmonics of the incident frequency. Left graph: experimental harmonic spectrum from a polypropylene target, obtained with 60 fs laser pulses at 10 19 W/cm 2 , with a very high temporal contrast (10 10 ). The plasma frequency of this target corresponds to harmonics 15-16, thus excluding the CWE mechanism for the generation of harmonics of higher orders. Images on the right: harmonic spectra from orders 13 et 18, for different distances z between the target and the best focus. At the highest intensity (z=0), harmonics emitted by the ROM mechanism are observed above the 15th order. These harmonics have a much smaller spectral width then those due to CWE (below the 15th order). These ROM harmonics vanish as soon

Harmonic Detection at Initialization With Kalman Filter

DEFF Research Database (Denmark)

Hussain, Dil Muhammad Akbar; Imran, Raja Muhammad; Shoro, Ghulam Mustafa

2014-01-01

Most power electronic equipment these days generate harmonic disturbances, these devices hold nonlinear voltage/current characteristic. The harmonics generated can potentially be harmful to the consumer supply. Typically, filters are integrated at the power source or utility location to filter out...... the affect of harmonics on the supply. For the detection of these harmonics various techniques are available and one of that technique is the Kalman filter. In this paper we investigate that what are the consequences when harmonic detection system based on Kalman Filtering is initialized...

Harmonic response of coupled and uncoupled granular YBCO

International Nuclear Information System (INIS)

Torralba, Maria Veronica S; Sarmago, Roland V

2004-01-01

The harmonic responses of granular YBCO were obtained via mutual inductance measurements. Two samples, one with and another without intergranular coupling, were investigated in terms of the harmonic components of magnetization at various field amplitudes and frequencies. By comparing the behaviour of the features in the harmonics to that of the peaks in the fundamental response, we explicitly identified which features in the harmonics originate from intragranular harmonic generation and which arise due to a contribution of intergranular coupling. Harmonic responses were obtained despite the absence of vortices and even harmonics were detected in a purely AC magnetic field

Electromagnetic cyclotron harmonic waves

International Nuclear Information System (INIS)

Ohnuma, T.; Watanabe, T.; Hamamatsu, K.

1981-09-01

Electromagnetic electron cyclotron harmonic waves just below the electron cyclotron harmonics are investigated numerically and experimentally. Backward waves which are observed to propagate nearly perpendicular to the magnetic field just below the electron cyclotron frequency in a high density magnetoplasma are confirmed to be in accord with the theoretical electromagnetic cyclotron waves. (author)

Intense harmonic generation from various ablation media

International Nuclear Information System (INIS)

Ozaki, T.; Elouga, L.; Suzuki, M.; Kuroda, H.; Ganeev, R.A.

2006-01-01

Complete test of publication follows. High-order harmonic generation (HHG) is a unique source of coherent extreme ultraviolet (XUV) radiation, which can produce soft x-rays within the spectral 'water-window' (between 2.3 and 4.4 nm), and ultimately short pulses with attosecond duration. However, the intensity of present-day harmonics is still low, and serious applications will need an increase of the conversion efficiency. Instead of using gas media, one can also use ablation material, produced on solid targets using a low-intensity prepulse, as the nonlinear medium to generate high-order harmonics. Recently, we have successfully demonstrated the generation of up to the 63 rd harmonic (λ = 12.6 nm) of a Ti:sapphire laser radiation using boron ablation, and a strong enhancement in the intensity of the 13 th harmonic from indium ablation. These harmonics were generated with a modest laser (10 mJ, 150 fs) and with the pre-pulse to main pulse energy ratio constant. In this paper, we perform systematic investigations of ablation harmonics, using the 200 mJ, 30 fs Ti:sapphire beam line of the Canadian Advanced Laser Light Source (ALLS) facility. ALLS allows studying ablation harmonics over wider experimental parameters, and with independent control over the pre-pulse and main pulse energies. The 10 Hz, 200 mJ Ti:sapphire beam line of ALLS is divided into two beams. Each beam has its own energy control system, which allows independent control over the energy of each beam. One of the beams is used as a pre-pulse for creating ablation, which is focused onto the solid target without pulse compression, with pulse duration of 200 ps. The second beam is used as the main pulse for harmonic generation. The main pulse is delayed in time relative to the pre-pulse by propagating through an optical delay line, and then sent through a pulse compressor. The compressed pulse duration have typical pulse duration of 30 fs FWHM, which is then focused onto the ablation medium using MgF 2

Harmonic balance approach to the periodic solutions of the (an)harmonic relativistic oscillator

International Nuclear Information System (INIS)

Belendez, Augusto; Pascual, Carolina

2007-01-01

The first-order harmonic balance method via the first Fourier coefficient is used to construct two approximate frequency-amplitude relations for the relativistic oscillator for which the nonlinearity (anharmonicity) is a relativistic effect due to the time line dilation along the world line. Making a change of variable, a new nonlinear differential equation is obtained and two procedures are used to approximately solve this differential equation. In the first the differential equation is rewritten in a form that does not contain a square-root expression, while in the second the differential equation is solved directly. The approximate frequency obtained using the second procedure is more accurate than the frequency obtained with the first due to the fact that, in the second procedure, application of the harmonic balance method produces an infinite set of harmonics, while in the first procedure only two harmonics are produced. Both approximate frequencies are valid for the complete range of oscillation amplitudes, and excellent agreement of the approximate frequencies with the exact one are demonstrated and discussed. The discrepancy between the first-order approximate frequency obtained by means of the second procedure and the exact frequency never exceeds 1.6%. We also obtained the approximate frequency by applying the second-order harmonic balance method and in this case the relative error is as low 0.31% for all the range of values of amplitude of oscillation A

Harmonically excited orbital variations

International Nuclear Information System (INIS)

Morgan, T.

1985-01-01

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs

Expansion into lattice harmonics in cubic symmetries

Science.gov (United States)

Kontrym-Sznajd, G.

2018-05-01

On the example of a few sets of sampling directions in the Brillouin zone, this work shows how important the choice of the cubic harmonics is on the quality of approximation of some quantities by a series of such harmonics. These studies led to the following questions: (1) In the case that for a given l there are several independent harmonics, can one use in the expansion only one harmonic with a given l?; (2) How should harmonics be ordered: according to l or, after writing them in terms of (x4 + y4 + z4)n (x2y2z2)m, according to their degree q = n + m? To enable practical applications of such harmonics, they are constructed in terms of the associated Legendre polynomials up to l = 26. It is shown that electron momentum densities, reconstructed from experimental data for ErGa3 and InGa3, are described much better by harmonics ordered with q.

Balancing Vibrations at Harmonic Frequencies by Injecting Harmonic Balancing Signals into the Armature of a Linear Motor/Alternator Coupled to a Stirling Machine

Science.gov (United States)

Holliday, Ezekiel S. (Inventor)

2014-01-01

Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.

Explaining the harmonic sequence paradox.

Science.gov (United States)

Schmidt, Ulrich; Zimper, Alexander

2012-05-01

According to the harmonic sequence paradox, an expected utility decision maker's willingness to pay for a gamble whose expected payoffs evolve according to the harmonic series is finite if and only if his marginal utility of additional income becomes zero for rather low payoff levels. Since the assumption of zero marginal utility is implausible for finite payoff levels, expected utility theory - as well as its standard generalizations such as cumulative prospect theory - are apparently unable to explain a finite willingness to pay. This paper presents first an experimental study of the harmonic sequence paradox. Additionally, it demonstrates that the theoretical argument of the harmonic sequence paradox only applies to time-patient decision makers, whereas the paradox is easily avoided if time-impatience is introduced. ©2011 The British Psychological Society.

Synthesis of variable harmonic impedance in inverter-interfaced distributed generation unit for harmonic damping throughout a distribution network

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

2012-01-01

This paper proposes a harmonic impedance synthesis technique for voltage-controlled distributed generation inverter in order to damp harmonic voltage distortion on a distribution network. The approach employs a multiloop control scheme, where a selective load harmonic current feedforward loop bas...

Harmonic d-tensors

Energy Technology Data Exchange (ETDEWEB)

Hohmann, Manuel [Physikalisches Institut, Universitaet Tartu (Estonia)

2016-07-01

Tensor harmonics are a useful mathematical tool for finding solutions to differential equations which transform under a particular representation of the rotation group SO(3). In order to make use of this tool also in the setting of Finsler geometry, where the objects of relevance are d-tensors instead of tensors, we construct a set of d-tensor harmonics for both SO(3) and SO(4) symmetries and show how these can be used for calculations in Finsler geometry and gravity.

Numerical Design of Megawatt Gyrotron with 120 GHz Frequency and 50% Efficiency for Plasma Fusion Application

Science.gov (United States)

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

2013-02-01

The design of 120 GHz, 1 MW gyrotron for plasma fusion application is presented in this paper. The mode selection is carried out considering the aim of minimum mode competition, minimum cavity wall heating, etc. On the basis of the selected operating mode, the interaction cavity design and beam-wave interaction computation are carried out by using the PIC code. The design of triode type Magnetron Injection Gun (MIG) is also presented. Trajectory code EGUN, synthesis code MIGSYN and data analysis code MIGANS are used in the MIG designing. Further, the design of MIG is also validated by using the another trajectory code TRAK. The design results of beam dumping system (collector) and RF window are also presented. Depressed collector is designed to enhance the overall tube efficiency. The design study confirms >1 MW output power with tube efficiency around 50% (with collector efficiency).

HARMONIZATION OF TAX POLICIES: REVIEWING MACEDONIA AND CROATIA

Directory of Open Access Journals (Sweden)

Sasho Kozuharov

2015-12-01

Full Text Available The tax harmonization is a complex issue in the process of European integration. The tax harmonization is a process of convergence of the tax system based on mutual set of rules and, in general, it means existence of identical or similar tax rates for the tax payers in European Union, i.e. Euro zone. In case there are identical tax rates, then we are talking about a, so called, total explicit tax harmonization, whereas, if there are similar tax rates, we are talking about partial explicit tax harmonization, which refers to determination of the highest and the lowest tax rates. Thus, countries can determine the tax rates of certain taxes. The total harmonization, besides tax rates harmonization, means structural harmonization or harmonization of the tax structure. The harmonization of direct taxes mainly relies on the following main objectives: avoiding tax evasion and elimination of double taxation. The harmonization of regulations and directives in the field of indirect taxes is necessary in terms of establishing a single market, or removal of barriers to the free movement of goods, people, services and capital.

Harmonic mappings into manifolds with boundary

International Nuclear Information System (INIS)

Chen Yunmei; Musina, R.

1989-08-01

In this paper we deal with harmonic maps from a compact Riemannian manifold into a manifold with boundary. In this case, a weak harmonic map is by definition a solution to a differential inclusion. In the first part of the paper we investigate the general properties of weak harmonic maps, which can be seen as solutions to a system of elliptic differential equations. In the second part we concentrate our attention on the heat flow method for harmonic maps. The result we achieve in this context extends a result by Chen and Struwe. (author). 21 refs

Power quality issues current harmonics

CERN Document Server

Mikkili, Suresh

2015-01-01

Power Quality Issues: Current Harmonics provides solutions for the mitigation of power quality problems related to harmonics. Focusing on active power filters (APFs) due to their excellent harmonic and reactive power compensation in two-wire (single phase), three-wire (three-phase without neutral), and four-wire (three-phase with neutral) AC power networks with nonlinear loads, the text:Introduces the APF technology, describing various APF configurations and offering guidelines for the selection of APFs for specific application considerationsCompares shunt active filter (SHAF) control strategi

Three-Phase Harmonic Analysis Method for Unbalanced Distribution Systems

Directory of Open Access Journals (Sweden)

Jen-Hao Teng

2014-01-01

Full Text Available Due to the unbalanced features of distribution systems, a three-phase harmonic analysis method is essential to accurately analyze the harmonic impact on distribution systems. Moreover, harmonic analysis is the basic tool for harmonic filter design and harmonic resonance mitigation; therefore, the computational performance should also be efficient. An accurate and efficient three-phase harmonic analysis method for unbalanced distribution systems is proposed in this paper. The variations of bus voltages, bus current injections and branch currents affected by harmonic current injections can be analyzed by two relationship matrices developed from the topological characteristics of distribution systems. Some useful formulas are then derived to solve the three-phase harmonic propagation problem. After the harmonic propagation for each harmonic order is calculated, the total harmonic distortion (THD for bus voltages can be calculated accordingly. The proposed method has better computational performance, since the time-consuming full admittance matrix inverse employed by the commonly-used harmonic analysis methods is not necessary in the solution procedure. In addition, the proposed method can provide novel viewpoints in calculating the branch currents and bus voltages under harmonic pollution which are vital for harmonic filter design. Test results demonstrate the effectiveness and efficiency of the proposed method.

Harmonic engine

Science.gov (United States)

Bennett, Charles L [Livermore, CA

2009-10-20

A high efficiency harmonic engine based on a resonantly reciprocating piston expander that extracts work from heat and pressurizes working fluid in a reciprocating piston compressor. The engine preferably includes harmonic oscillator valves capable of oscillating at a resonant frequency for controlling the flow of working fluid into and out of the expander, and also preferably includes a shunt line connecting an expansion chamber of the expander to a buffer chamber of the expander for minimizing pressure variations in the fluidic circuit of the engine. The engine is especially designed to operate with very high temperature input to the expander and very low temperature input to the compressor, to produce very high thermal conversion efficiency.

Coherent harmonics generated by a super-short electron pulse

International Nuclear Information System (INIS)

Ding Wu

1996-01-01

A novel mechanism generating superradiance harmonics is found. In this superradiance harmonics, the temporal width of harmonics is extremely short, the ratio of high harmonic fundamental wave is much higher than the known superradiance harmonics

Harmonic lasing in X-ray FELs

Energy Technology Data Exchange (ETDEWEB)

Schneidmiller, E.A.; Yurkov, M.V.

2012-05-15

Harmonic lasing in a free electron laser with a planar undulator (under the condition that the fundamental frequency is suppressed) might be a cheap and efficient way of extension of wavelength ranges of existing and planned X-ray FEL facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental frequency. In this paper we perform a parametrization of the solution of the eigenvalue equation for lasing at odd harmonics, and present an explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental harmonic. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam at saturation. Considering 3rd harmonic lasing as a practical example, we come to the conclusion that it is much more robust than usually thought, and can be widely used in the existing or planned X-ray FEL facilities. In particular, LCLS after a minor modification can lase to saturation at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level and narrow bandwidth. As for the European XFEL, harmonic lasing would allow to extend operating range (ultimately up to 100 keV), to reduce FEL bandwidth and to increase brilliance, to enable two-color operation for pump-probe experiments, and to provide more flexible operation at different electron energies. Similar improvements can be realized in other X-ray FEL facilities with gap-tunable undulators like FLASH II, SACLA, LCLS II, etc. Harmonic lasing can be an attractive option for compact X-ray FELs (driven by electron beams with a relatively low energy), allowing the use of the standard undulator technology instead of small-gap in-vacuum devices. Finally, in this paper we discover that in a part of the

Symmetries in physics and harmonics

International Nuclear Information System (INIS)

Kolk, D.

2006-01-01

In this book the symmetries of elementary particles are described in relation to the rules of harmonics in music. The selection rules are described in connections with harmonic intervals. Also symmetry breaking is considered in this framework. (HSI)

Precision Characterization of Gyrotron Window Materials

Energy Technology Data Exchange (ETDEWEB)

Jones, Charles R. [North Carolina Central Univ., Durham, NC (United States)

2012-12-31

utilize this material to solve the challenging problems that are encountered as devices are pushed to operate at higher frequencies and higher power levels. In particular, for the fusion energy program, it may provide an economical alternative to CVD diamond for certain gyrotron and beam line applications. In addition, the value obtained for the Debye temperature provides an important datum for modeling the crystalline structure of SiC. Clearly SiC is a unique material with few competitors and should see wider utilization.

Microwave generation for magnetic fusion energy applications: Task A -- Experimental and numerical study of microwave sources for ECRH incorporating depressed collectors and with ITER-relevant parameters, and Task B -- Theory and modeling of high frequency, high power gyrotron operation. Final report, July 15, 1994--July 14, 1995

International Nuclear Information System (INIS)

1995-01-01

A proof-of-principle short pulse (∼ 100 ns) experiment has successfully demonstrated operation of a sheet-beam FEL amplifier with output power of 250 kW at 86 Ghz and with 24 dB saturated gain and ∼ 3% efficiency. Gain in the linear region was 30 dB. Measured performance parameters were in good agreement with predictions of a multi-mode, time dependence code. Also, a code has been developed to design depressed collectors which will enhance efficiency of ECRH sources (both FELs and gyrotrons). Extensive analytical and theoretical work in support of high power gyrotron development at Varian and MIT, and in support of ITER has been carried out. Specific studies are described. The effect of beam quality on the operation of the 145 GHz gyrotrons at MIT has been characterized using experimentally measured beam velocity distribution functions. The observed performance of these devices is consistent with a 10% RMS perpendicular velocity spread. An extensive study of mode competition in the 110 GHZ experiments at Varian and MIT has been carried out. Design criteria for the suppression of parasitic modes have been given for these experiments. The issues of mode competition and beam quality in the proposed 170 GHz megawatt gyrotrons for ITER have been investigated. Designs of cavities which eliminate unwanted modes have been made, and their sensitivity to beam quality studied. The constraints of lower power density and absence of mode competition coupled with the anticipated beam quality restrict efficiency. Efficiency can be improved by increasing the power density in the wall, improving beam quality, or perhaps by using a more advanced cavity. Studies of the causes of velocity spread in MIG guns have been initiated. Further, the effect of beam cavity misalignment on mode competition has been addressed

Harmonic generation effect in high-Tc films

International Nuclear Information System (INIS)

Khare, Neeraj; Shrivastava, S.K.; Padmanabhan, V.P.N.; Khare, Sangeeta; Gupta, A.K.

1997-01-01

Harmonic generation in thick BPSCCO and thin YBCO films are reported. The application of an ac field (H ac > H c1 ) of frequency f causes the generation of odd harmonics of frequency (2n+1)f. The application of dc field in addition to the ac field causes the appearance of even harmonics also in the BPSCCO film. However, the appearance of even harmonics is not observed in YBCO film with high J c ∼ 1.6x10 6 A/cm 2 and appearance of second harmonic with small magnitude is observed in YBCO film with low J c ∼ 2x10 3 A/cm 2 . The variation of amplitudes of these harmonics are studied as a function of magnitude of ac and dc field and the results are explained in the framework of critical state model. A high-T c film magnetometer based on the measurement of the amplitude of second harmonic has been developed whose field sensitivity is ∼ 1.5x10 -8 T. (author)

High-harmonic generation in a dense medium

International Nuclear Information System (INIS)

Strelkov, V.V.; Platonenko, V.T.; Becker, A.

2005-01-01

The high-harmonic generation in a plasma or gas under conditions when the single-atom response is affected by neighboring ions or atoms of the medium is studied theoretically. We solve numerically the three-dimensional Schroedinger equation for a single-electron atom in the combined fields of the neighboring particles and the laser, and average the results over different random positions of the particles using the Monte Carlo method. Harmonic spectra are calculated for different medium densities and laser intensities. We observe a change of the harmonic properties due to a random variation of the harmonic phase induced by the field of the medium, when the medium density exceeds a certain transition density. The transition density is found to depend on the harmonic order, but it is almost independent of the fundamental intensity. It also differs for the two (shorter and longer) quantum paths. The latter effect leads for ionic densities in the transition regime to a narrowing of the harmonic lines and a shortening of the attosecond pulses generated using a group of harmonics

Harmonic sums and polylogarithms generated by cyclotomic polynomials

Energy Technology Data Exchange (ETDEWEB)

Ablinger, Jakob; Schneider, Carsten [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation; Bluemlein, Johannes [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2011-05-15

The computation of Feynman integrals in massive higher order perturbative calculations in renormalizable Quantum Field Theories requires extensions of multiply nested harmonic sums, which can be generated as real representations by Mellin transforms of Poincare-iterated integrals including denominators of higher cyclotomic polynomials. We derive the cyclotomic harmonic polylogarithms and harmonic sums and study their algebraic and structural relations. The analytic continuation of cyclotomic harmonic sums to complex values of N is performed using analytic representations. We also consider special values of the cyclotomic harmonic polylogarithms at argument x=1, resp., for the cyclotomic harmonic sums at N{yields}{infinity}, which are related to colored multiple zeta values, deriving various of their relations, based on the stuffle and shuffle algebras and three multiple argument relations. We also consider infinite generalized nested harmonic sums at roots of unity which are related to the infinite cyclotomic harmonic sums. Basis representations are derived for weight w=1,2 sums up to cyclotomy l=20. (orig.)

Harmonic currents circulation in electrical networks simulation and analysis

Energy Technology Data Exchange (ETDEWEB)

Em-Mamlouk, W.M. [MEP, Cairo (Egypt); El-Sharkawy, M.A. [Shams Univ., Cairo (Egypt). Dept. of Electrical Power and Machines; Mostafa, H.E. [Jazan Univ., Jazan (Saudi Arabia). Electrical Dept.

2009-07-01

A detailed harmonic flow analysis for a 13-bus balanced industrial distribution system was presented. The aim of the study was to determine the influence of harmonic sources in various branches of the system on voltage and current waveforms before disruptions to the utility supply system occurred. The current harmonic contents of an adjustable speed drive (ASD) were studied under various loading conditions. The test system was simulated using a standard study test system. Harmonic effects from multiple sources were investigated, and voltage distortion on the different buses was monitored. The study demonstrated that while the harmonic loads circulated harmonic currents in all system branches, no harmonic source was directly connected to the system buses. Many of the investigated cases exceeded allowable voltage total harmonic distortion and or current total harmonic distortion standards set by the Institute of Electrical and Electronic Engineers (IEEE). It was concluded that active harmonic filters should be used to prevent the effects of harmonic current circulation at different buses on neighbouring loads within a system. 8 refs., 11 tabs., 15 figs.

Exact solution of the time-dependent harmonic plus an inverse harmonic potential with a time-dependent electromagnetic field

International Nuclear Information System (INIS)

Yuece, Cem

2003-01-01

In this paper, the problem of the charged harmonic plus an inverse harmonic oscillator with time-dependent mass and frequency in a time-dependent electromagnetic field is investigated. It is reduced to the problem of the inverse harmonic oscillator with time-independent parameters and the exact wave function is obtained

Young children's harmonic perception.

Science.gov (United States)

Costa-Giomi, Eugenia

2003-11-01

Harmony and tonality are two of the most difficult elements for young children to perceive and manipulate and are seldom taught in the schools until the end of early childhood. Children's gradual harmonic and tonal development has been attributed to their cumulative exposure to Western tonal music and their increasing experiential knowledge of its rules and principles. Two questions that are relevant to this problem are: (1) Can focused and systematic teaching accelerate the learning of the harmonic/tonal principles that seem to occur in an implicit way throughout childhood? (2) Are there cognitive constraints that make it difficult for young children to perceive and/or manipulate certain harmonic and tonal principles? A series of studies specifically addressed the first question and suggested some possible answers to the second one. Results showed that harmonic instruction has limited effects on children's perception of harmony and indicated that the drastic improvement in the perception of implied harmony noted approximately at age 9 is due to development rather than instruction. I propose that young children's difficulty in perceiving implied harmony stems from their attention behaviors. Older children have less memory constraints and more strategies to direct their attention to the relevant cues of the stimulus. Younger children focus their attention on the melody, if present in the stimulus, and specifically on its concrete elements such as rhythm, pitch, and contour rather than its abstract elements such as harmony and key. The inference of the abstract harmonic organization of a melody required in the perception of implied harmony is thus an elusive task for the young child.

Classical and multilinear harmonic analysis

CERN Document Server

Muscalu, Camil

2013-01-01

This two-volume text in harmonic analysis introduces a wealth of analytical results and techniques. It is largely self-contained and useful to graduates and researchers in pure and applied analysis. Numerous exercises and problems make the text suitable for self-study and the classroom alike. The first volume starts with classical one-dimensional topics: Fourier series; harmonic functions; Hilbert transform. Then the higher-dimensional Calderón-Zygmund and Littlewood-Paley theories are developed. Probabilistic methods and their applications are discussed, as are applications of harmonic analysis to partial differential equations. The volume concludes with an introduction to the Weyl calculus. The second volume goes beyond the classical to the highly contemporary and focuses on multilinear aspects of harmonic analysis: the bilinear Hilbert transform; Coifman-Meyer theory; Carleson's resolution of the Lusin conjecture; Calderón's commutators and the Cauchy integral on Lipschitz curves. The material in this vo...

Higher order harmonics of reactor neutron equation

International Nuclear Information System (INIS)

Li Fu; Hu Yongming; Luo Zhengpei

1996-01-01

The flux mapping method using the higher order harmonics of the neutron equation is proposed. Based on the bi-orthogonality of the higher order harmonics, the process and formulas for higher order harmonics calculation are derived via the source iteration method with source correction. For the first time, not only any order harmonics for up-to-3-dimensional geometry are achieved, but also the preliminary verification to the capability for flux mapping have been carried out

Bounce-harmonic Landau Damping of Plasma Waves

Science.gov (United States)

Anderegg, Francois

2015-11-01

We present measurement of plasma wave damping, spanning the temperature regimes of direct Landau damping, bounce-harmonic Landau damping, inter-species drag damping, and viscous damping. Direct Landau damping is dominant at high temperatures, but becomes negligible as v vph / 5 . The measurements are conducted in trapped pure ion plasmas contained in Penning-Malmberg trap, with wave-coherent LIF diagnostics of particle velocities. Our focus is on bounce harmonics damping, controlled by an applied ``squeeze'' potential, which generates harmonics in the wave potential and in the particle dynamics. A particle moving in z experiences a non-sinusoidal mode potential caused by the squeeze, producing high spatial harmonics with lower phase velocity. These harmonics are Landau damped even when the mode phase velocity vph is large compared to the thermal velocity v , since the nth harmonic is resonant with a particle bouncing at velocity vb =vph / n . Here we increase the bounce harmonics through applied squeeze potential; but some harmonics are always present in finite length systems. For our centered squeeze geometry, theory shows that only odd harmonics are generated, and predicts the Landau damping rate from vph / n . Experimentally, the squeeze potential increases the wave damping and reduces its frequency. The frequency shift occurs because the squeeze potential reduces the number of particle where the mode velocity is the largest, therefore reducing the mode frequency. We observe an increase in the damping proportional to Vs2,and a frequency reduction proportional to Vs , in quantitative agreement with theory. Wave-coherent laser induced fluorescence allows direct observation of bounce resonances on the particle distribution, here predominantly at vph / 3 . A clear increase of the bounce harmonics is visible on the particle distribution when the squeeze potential is applied. Supported by NSF Grant PHY-1414570, and DOE Grants DE-SC0002451 and DE-SC0008693.

Understanding fifth-harmonic generation in CLBO

Science.gov (United States)

Patankar, S.; Yang, S. T.; Moody, J. D.; Bayramian, A. J.; Swadling, G. F.; Barker, D.; Datte, P.; Mennerat, G.; Norton, M.; Carr, C. W.; Begishev, I. A.; Bromage, J.; Ross, J. S.

2018-02-01

We report on results of fifth harmonic generation in Cesium Lithium Borate (CLBO) using a three-crystal cascaded frequency conversion scheme designed to study the energy balance of the final sum frequency generation stage. The experimental setup independently combines the first and fourth harmonic of a Nd:Glass laser in a 5mm thick CLBO crystal. Energy balance between the incoming and output energy is close to unity when the CLBO is out of phase matching and approximately 80% when the crystal is in phase matching. A detailed analysis of the residual fundamental and fourth harmonic energy indicates 5th harmonic light is being generated but only 26% is unaccounted for. We attribute the missing light to linear transmission loss in the CLBO oven. The ratio of the output to input energy is unity when the missing 5th harmonic is incorporated into the calculations. Two-dimensional plane wave mixing simulations show agreement with the results at lower intensities.

Proposal of a resonant controller for a three phase four wire grid-connected shunt hybrid filter

DEFF Research Database (Denmark)

Candela, J. I.; Rodriguez, P.; Luna, A.

2009-01-01

This paper present a three-phase four wire hybrid filter able to perform a selective cancellation of harmonic currents based on resonant controllers. As it will be shown in this work, this kind of control permits to enhance the bandwidth of the filter controller, without hindering the stability...

Third Harmonic Imaging using a Pulse Inversion

DEFF Research Database (Denmark)

Rasmussen, Joachim; Du, Yigang; Jensen, Jørgen Arendt

2011-01-01

The pulse inversion (PI) technique can be utilized to separate and enhance harmonic components of a waveform for tissue harmonic imaging. While most ultrasound systems can perform pulse inversion, only few image the 3rd harmonic component. PI pulse subtraction can isolate and enhance the 3rd...

Validation Techniques of network harmonic models based on switching of a series linear component and measuring resultant harmonic increments

DEFF Research Database (Denmark)

Wiechowski, Wojciech Tomasz; Lykkegaard, Jan; Bak, Claus Leth

2007-01-01

In this paper two methods of validation of transmission network harmonic models are introduced. The methods were developed as a result of the work presented in [1]. The first method allows calculating the transfer harmonic impedance between two nodes of a network. Switching a linear, series network......, as for example a transmission line. Both methods require that harmonic measurements performed at two ends of the disconnected element are precisely synchronized....... are used for calculation of the transfer harmonic impedance between the nodes. The determined transfer harmonic impedance can be used to validate a computer model of the network. The second method is an extension of the fist one. It allows switching a series element that contains a shunt branch...

The 8 MW lower hybrid electron mode system for the additional heating of the plasma of the FTU Tokamak

International Nuclear Information System (INIS)

Andreani, R.; De Marco, F.; Ferro, C.; Mirizzi, F.; Papitto, P.; Santini, F.; Segre, S.E.; Sassi, M.

1985-01-01

The ''Electron Mode'' regime of LH Heating, based on the same physics as the current drive, has been extensively studied and experimentally tested especially with respect to the relation between frequency and density limit. These results have largely contributed to the decision to build a CD system on TORE SUPRA. Based on the same motivations, the Lower Hybrid 'Electron Mode' Heating (frequency: 8 ''Electron Mode'' Heating (frequency: 8 GHz), has been chosen to heat the plasma of the FTU Tokamak. The RF power required (8 MW at 8 GHz) will be produced by 16 gyrotron oscillators (500 KW unit power) feeding 16 grill couplers installed on 8 equatorial ports of FTU. The dc power supplies will be ,odularly built to be compatible even with completely different sort of tubes (e.g. for IRCH). The transmission lines between the generators and the grills will be circular oversized waveguides to reduce the losses to less than 1 dB. Each grill will consist of an 8x8 matrix of rectangular waveguides pressurized and terminated by thik (one wavelength) alumina windows facing the grill mouth. Gyrotron availability has been verified through studies conducted by the two major manufacturers presently on the market. Preliminary quotations and delivery times have been obtained. The design of the grill couplers has been supplemented by a study contract with an industrial research laboratory which is producing a prototype structure and ceramic windows with very promising results. Microwave mode converters and power dividers for the transmission system have been designed and prototypes are being built and will be tested shortly. An 8 GHz, 25 KW cw test bench has been already commissioned and will be used to test all the microwave components. The power level is more than adequate also to process single channels of the coupling structures

Benefits from the BESSY FEL Higher Harmonic Radiation

CERN Document Server

Goldammer, K

2005-01-01

In the FEL process, bunching and coherent radiation is produced at the fundamental frequency as well as its higher harmonics. BESSY proposes a linac-based cascaded High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) multi-user facility. The BESSY soft X-ray FEL will be seeded by three lasers spanning the spectral range of 230nm to 460nm. Two to four HGHG stages downconvert the seed wavelength to the desired radiation range of 1.24nm to 51nm using higher harmonic bunching. As a surplus, higher harmonic radiation is intrinsically produced in each FEL stage. Radiation on a higher harmonic of the FEL frequency is of high interest because it yields the possibility to reduce the number of FEL stages. This paper details extensive studies of the higher harmonic content of the BESSY FEL radiation. Important aspects of FEL interaction on higher harmonics as resulting from theory and from numerical simulations are discussed. For the case of the BESSY FEL, methods for improving the harmonic content are present...

Hermitian harmonic maps into convex balls

International Nuclear Information System (INIS)

Li Zhenyang; Xi Zhang

2004-07-01

In this paper, we consider Hermitian harmonic maps from Hermitian manifolds into convex balls. We prove that there exist no non-trivial Hermitian harmonic maps from closed Hermitian manifolds into convex balls, and we use the heat flow method to solve the Dirichlet problem for Hermitian harmonic maps when the domain is compact Hermitian manifold with non-empty boundary. The case where the domain manifold is complete(noncompact) is also studied. (author)

Harmonic disturbance location by applying Bayesian inference

NARCIS (Netherlands)

Ye, G.; Xiang, Y.; Cuk, V.; Cobben, J.F.G.

2016-01-01

Harmonic pollution is one of the most important power quality issues in electric power systems. Correct location of the main harmonic disturbance source is a key step to solve the problem. This paper presents a method to detect the location of harmonic disturbance source in low voltage network

Introduction to classical and quantum harmonic oscillators

CERN Document Server

Bloch, Sylvan C

2013-01-01

From conch shells to lasers . harmonic oscillators, the timeless scientific phenomenon As intriguing to Galileo as they are to scientists today, harmonic oscillators have provided a simple and compelling paradigm for understanding the complexities that underlie some of nature's and mankind's most fascinating creations. From early string and wind instruments fashioned from bows and seashells to the intense precision of lasers, harmonic oscillators have existed in various forms, as objects of beauty and scientific use. And harmonic oscillation has endured as one of science's most fascinating con

Dual aperture dipole magnet with second harmonic component

Science.gov (United States)

Praeg, Walter F.

1985-01-01

An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

Evaluation of Harmonics Impact on Digital Relays

Directory of Open Access Journals (Sweden)

Kinan Wannous

2018-04-01

Full Text Available This paper presents the concept of the impact of harmonic distortion on a digital protection relay. The aim is to verify and determine the reasons of a mal-trip or failure to trip the protection relays; the suggested solution of the harmonic distortion is explained by a mathematical model in the Matlab Simulink programming environment. The digital relays have been tested under harmonic distortions in order to verify the function of the relays algorithm under abnormal conditions. The comparison between the protection relay algorithm under abnormal conditions and a mathematical model in the Matlab Simulink programming environment based on injected harmonics of high values is provided. The test is separated into different levels; the first level is based on the harmonic effect of an individual harmonic and mixed harmonics. The test includes the effect of the harmonics in the location of the fault point into distance protection zones. This paper is a new proposal in the signal processing of power quality disturbances using Matlab Simulink and the power quality impact on the measurements of the power system quantities; the test simulates the function of protection in power systems in terms of calculating the current and voltage values of short circuits and their faults. The paper includes several tests: frequency variations and decomposition of voltage waveforms with Fourier transforms (model and commercial relay, the effect of the power factor on the location of fault points, the relation between the tripping time and the total harmonic distortion (THD levels in a commercial relay, and a comparison of the THD capture between the commercial relay and the model.

Fast harmonic field mapper

International Nuclear Information System (INIS)

Au, R.; Fowler, M.; Hanawa, H.; Riedel, J.; Qua, Z.G.

1984-01-01

In early 1983 it was decided to mount coils on arms separated by 120 degrees and buck them out so that the third harmonic dphi/dt component would be cancelled and thus the first and second field harmonics could be very accurately measured. The original intention was to do as others had done, namely, use fast ADC's to read the voltages, and computer process the result to get the Fourier components. However, because of the 100 to 1 dynamic range of the fast ADC's and the likelihood that noise would be a problem, the authors decided to do things differently. Using a fast Fourier transform analyzer was considered, but this instrument is very expensive, so they decided to use a completely electronic analog approach: The authors decided to use active bandpass filters to render the harmonic components

Electromagnetic radiation by parametric decay of upper hybrid waves in ionospheric modification experiments

International Nuclear Information System (INIS)

Leyser, T.B.

1994-01-01

A nonlinear dispersion relation for the parametric decay of an electrostatic upper hybrid wave into an ordinary mode electromagnetic wave, propagating parallel to the ambient magnetic field, and an electrostatic low frequency wave, being either a lower hybrid wave or a high harmonic ion Bernstein wave, is derived. The coherent and resonant wave interaction is considered to take place in a weakly magnetized and collisionless Vlasov plasma. The instability growth rate is computed for parameter values typical of ionospheric modification experiments, in which a powerful high frequency electromagnetic pump wave is injected into the ionospheric F-region from ground-based transmitters. The electromagnetic radiation which is excited by the decaying upper hybrid wave is found to be consistent with the prominent and commonly observed downshifted maximum (DM) emission in the spectrum of stimulated electromagnetic emission

Detection of Harmonic Occurring using Kalman Filtering

DEFF Research Database (Denmark)

Hussain, Dil Muhammad Akbar; Shoro, Ghulam Mustafa; Imran, Raja Muhammed

2014-01-01

/current characteristic. These harmonics are not to be allowed to grow beyond a certain limit to avoid any grave consequence to the customer’s main supply. Filters can be implemented at the power source or utility location to eliminate these harmonics. In this paper we detect the instance at which these harmonics occur...

High order harmonic generation in rare gases

Energy Technology Data Exchange (ETDEWEB)

Budil, Kimberly Susan [Univ. of California, Davis, CA (United States)

1994-05-01

The process of high order harmonic generation in atomic gases has shown great promise as a method of generating extremely short wavelength radiation, extending far into the extreme ultraviolet (XUV). The process is conceptually simple. A very intense laser pulse (I ~10¹³-10¹⁴ W/cm²) is focused into a dense (~10¹⁷ particles/cm³) atomic medium, causing the atoms to become polarized. These atomic dipoles are then coherently driven by the laser field and begin to radiate at odd harmonics of the laser field. This dissertation is a study of both the physical mechanism of harmonic generation as well as its development as a source of coherent XUV radiation. Recently, a semiclassical theory has been proposed which provides a simple, intuitive description of harmonic generation. In this picture the process is treated in two steps. The atom ionizes via tunneling after which its classical motion in the laser field is studied. Electron trajectories which return to the vicinity of the nucleus may recombine and emit a harmonic photon, while those which do not return will ionize. An experiment was performed to test the validity of this model wherein the trajectory of the electron as it orbits the nucleus or ion core is perturbed by driving the process with elliptically, rather than linearly, polarized laser radiation. The semiclassical theory predicts a rapid turn-off of harmonic production as the ellipticity of the driving field is increased. This decrease in harmonic production is observed experimentally and a simple quantum mechanical theory is used to model the data. The second major focus of this work was on development of the harmonic "source". A series of experiments were performed examining the spatial profiles of the harmonics. The quality of the spatial profile is crucial if the harmonics are to be used as the source for experiments, particularly if they must be refocused.

Harmonic Instability Analysis of Single-Phase Grid Connected Converter using Harmonic State Space (HSS) modeling method

DEFF Research Database (Denmark)

Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

2015-01-01

The increasing number of renewable energy sources at the distribution grid is becoming a major issue for utility companies, since the grid connected converters are operating at different operating points due to the probabilistic characteristics of renewable energy. Besides, typically, the harmonics...... proposes a new model of a single phase grid connected renewable energy source using the Harmonic State Space modeling approach, which is able to identify such problems and the model can be extended to be applied in the multiple connected converter analysis. The modeling results show the different harmonic...... and impedance from other renewable energy sources are not taken carefully into account in the installation and design. However, this may bring an unknown harmonic instability into the multiple power sourced system and also make the analysis difficult due to the complexity of the grid network. This paper...

Linking high harmonics from gases and solids.

Science.gov (United States)

Vampa, G; Hammond, T J; Thiré, N; Schmidt, B E; Légaré, F; McDonald, C R; Brabec, T; Corkum, P B

2015-06-25

When intense light interacts with an atomic gas, recollision between an ionizing electron and its parent ion creates high-order harmonics of the fundamental laser frequency. This sub-cycle effect generates coherent soft X-rays and attosecond pulses, and provides a means to image molecular orbitals. Recently, high harmonics have been generated from bulk crystals, but what mechanism dominates the emission remains uncertain. To resolve this issue, we adapt measurement methods from gas-phase research to solid zinc oxide driven by mid-infrared laser fields of 0.25 volts per ångström. We find that when we alter the generation process with a second-harmonic beam, the modified harmonic spectrum bears the signature of a generalized recollision between an electron and its associated hole. In addition, we find that solid-state high harmonics are perturbed by fields so weak that they are present in conventional electronic circuits, thus opening a route to integrate electronics with attosecond and high-harmonic technology. Future experiments will permit the band structure of a solid to be tomographically reconstructed.

Double Harmonic Transmission (D.H.T.

Directory of Open Access Journals (Sweden)

Sava Ianici

2006-10-01

Full Text Available The paper presents the construction and functioning of a new type of harmonic drive named double harmonic transmission (D.H.T.. In the second part of this paper is presented the dynamic analysis of the double harmonic transmission, which is based on the results of the experimental researches on the D.H.T. This study of the stress status and the forces distribution is necessary for to determine the durability on the portant elements of the D.H.T.

Pseudo harmonic morphisms on Riemannian polyhedra

International Nuclear Information System (INIS)

Aprodu, M.A.; Bouziane, T.

2004-10-01

The aim of this paper is to extend the notion of pseudo harmonic morphism (introduced by Loubeau) to the case when the source manifold is an admissible Riemannian polyhedron. We define these maps to be harmonic in the sense of Eells-Fuglede and pseudo-horizontally weakly conformal in our sense. We characterize them by means of germs of harmonic functions on the source polyhedron, in the sense of Korevaar-Schoen, and germs of holomorphic functions on the Kaehler target manifold. (author)

Coherent harmonic production using a two-section undulator FEL

Energy Technology Data Exchange (ETDEWEB)

Jaroszynski, D.A. [Commissariat a l`Energie, Bruyeres-le-Chatel (France); Prazeres, R.; Glotin, F. [Centre Universitaire Paris-Sud (France)] [and others

1995-12-31

We present measurements and a theoretical analysis of a new method of generating harmonic radiation in a free-electron laser oscillator with a two section undulator in a single optical cavity. To produce coherent harmonic radiation the undulator is arranged so that the downstream undulator section resonance frequency matches a harmonic of the upstream undulator. Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction fractions using a hole in one of the cavity mirrors. We present measurements that show that the optical power at the second and third harmonic can be enhanced by more than an order of magnitude in this fundamental/harmonic configuration. We compare the production of harmonic radiation of a two sectioned fundamental/harmonic undulator with that produced from a FEL operating at its highest efficiency with a step-tapered undulator, where the bunching at the end of the first section is very large. We examine, the dependence of the harmonic power on the intracavity power by adjusting the optical cavity desynchronism, {delta}L. We also examine the evolution of the fundamental and harmonic powers as a function of cavity roundtrip number to evaluate the importance of the small signal gain at the harmonic. We compare our measurements with predictions of a multi-electron numerical model that follows the evolution of fundamental and harmonic power to saturation. This fundamental/harmonic mode, of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture.

Second harmonic generation imaging

CERN Document Server

2013-01-01

Second-harmonic generation (SHG) microscopy has shown great promise for imaging live cells and tissues, with applications in basic science, medical research, and tissue engineering. Second Harmonic Generation Imaging offers a complete guide to this optical modality, from basic principles, instrumentation, methods, and image analysis to biomedical applications. The book features contributions by experts in second-harmonic imaging, including many pioneering researchers in the field. Written for researchers at all levels, it takes an in-depth look at the current state of the art and possibilities of SHG microscopy. Organized into three sections, the book: Provides an introduction to the physics of the process, step-by-step instructions on how to build an SHG microscope, and comparisons with related imaging techniques Gives an overview of the capabilities of SHG microscopy for imaging tissues and cells—including cell membranes, muscle, collagen in tissues, and microtubules in live cells—by summarizing experi...

Second-harmonic imaging of semiconductor quantum dots

DEFF Research Database (Denmark)

Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld

2000-01-01

Resonant second-harmonic generation is observed at room temperature in reflection from self-assembled InAlGaAs quantum dots grown on a GaAs (001) substrate. The detected second-harmonic signal peaks at a pump wavelength of similar to 885 nm corresponding to the quantum-dot photoluminescence maximum....... In addition, the second-harmonic spectrum exhibits another smaller but well-pronounced peak at 765 nm not found in the linear experiments. We attribute this peak to the generation of second-harmonic radiation in the AlGaAs spacer layer enhanced by the local symmetry at the quantum-dot interface. We further...

Harmonic Series Meets Fibonacci Sequence

Science.gov (United States)

Chen, Hongwei; Kennedy, Chris

2012-01-01

The terms of a conditionally convergent series may be rearranged to converge to any prescribed real value. What if the harmonic series is grouped into Fibonacci length blocks? Or the harmonic series is arranged in alternating Fibonacci length blocks? Or rearranged and alternated into separate blocks of even and odd terms of Fibonacci length?

Tuvan Throat Singing and Harmonics

Science.gov (United States)

Ruiz, Michael J.; Wilken, David

2018-01-01

Tuvan throat singing, also called overtone singing, provides for an exotic demonstration of the physics of harmonics as well as introducing an Asian musical aesthetic. A low fundamental is sung and the singer skillfully alters the resonances of the vocal system to enhance an overtone (harmonic above the fundamental). The result is that the…

New Evidence That Nonlinear Source-Filter Coupling Affects Harmonic Intensity and fo Stability During Instances of Harmonics Crossing Formants.

Science.gov (United States)

Maxfield, Lynn; Palaparthi, Anil; Titze, Ingo

2017-03-01

The traditional source-filter theory of voice production describes a linear relationship between the source (glottal flow pulse) and the filter (vocal tract). Such a linear relationship does not allow for nor explain how changes in the filter may impact the stability and regularity of the source. The objective of this experiment was to examine what effect unpredictable changes to vocal tract dimensions could have on fo stability and individual harmonic intensities in situations in which low frequency harmonics cross formants in a fundamental frequency glide. To determine these effects, eight human subjects (five male, three female) were recorded producing fo glides while their vocal tracts were artificially lengthened by a section of vinyl tubing inserted into the mouth. It was hypothesized that if the source and filter operated as a purely linear system, harmonic intensities would increase and decrease at nearly the same rates as they passed through a formant bandwidth, resulting in a relatively symmetric peak on an intensity-time contour. Additionally, fo stability should not be predictably perturbed by formant/harmonic crossings in a linear system. Acoustic analysis of these recordings, however, revealed that harmonic intensity peaks were asymmetric in 76% of cases, and that 85% of fo instabilities aligned with a crossing of one of the first four harmonics with the first three formants. These results provide further evidence that nonlinear dynamics in the source-filter relationship can impact fo stability as well as harmonic intensities as harmonics cross through formant bandwidths. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Theoretical description of high-order harmonic generation in solids

International Nuclear Information System (INIS)

Kemper, A F; Moritz, B; Devereaux, T P; Freericks, J K

2013-01-01

We consider several aspects of high-order harmonic generation in solids: the effects of elastic and inelastic scattering, varying pulse characteristics and inclusion of material-specific parameters through a realistic band structure. We reproduce many observed characteristics of high harmonic generation experiments in solids including the formation of only odd harmonics in inversion-symmetric materials, and the nonlinear formation of high harmonics with increasing field. We find that the harmonic spectra are fairly robust against elastic and inelastic scattering. Furthermore, we find that the pulse characteristics can play an important role in determining the harmonic spectra. (paper)

The Virasoro algebra from harmonic superspace

International Nuclear Information System (INIS)

Saidi, E.H.; Zakkari, M.

1990-08-01

Using harmonic superspace techniques, we construct a new field realization of the Virasoro algebra. The main conformal objects are U(1) Cartan tensors instead of the U(1) Lorentz ones. The new conformal model, which admits moreover a d=2 (4,0) global supersymmetry is constructed out of the infinitely relaxed HST and FS hypermultiplets. The conformal current T 4+ together with the harmonic superspace OPE rules are given. The Virasoro algebra and the harmonic superspace Schwarzian derivative S 4+ are also derived. (author). 14 refs

Hybrid Reactor Simulation and 3-D Information Display of BWR Out-of-Phase Oscillation

International Nuclear Information System (INIS)

Edwards, Robert; Huang, Zhengyu

2001-01-01

The real-time hybrid reactor simulation (HRS) capability of the Penn State TRIGA reactor has been expanded for boiling water reactor (BWR) out-of-phase behavior. During BWR out-of-phase oscillation half of the core can significantly oscillate out of phase with the other half, while the average power reported by the neutronic instrumentation may show a much lower amplitude for the oscillations. A description of the new HRS is given; three computers are employed to handle all the computations required, including real-time data processing and graph generation. BWR out-of-phase oscillation was successfully simulated. By adjusting the reactivity feedback gains from boiling channels to the TRIGA reactor and to the first harmonic mode power simulation, limit cycle can be generated with both reactor power and the simulated first harmonic power. A 3-D display of spatial power distributions of fundamental mode, first harmonic, and total powers over the reactor cross section is shown

Voltage harmonic elimination with RLC based interface smoothing filter

International Nuclear Information System (INIS)

Chandrasekaran, K; Ramachandaramurthy, V K

2015-01-01

A method is proposed for designing a Dynamic Voltage Restorer (DVR) with RLC interface smoothing filter. The RLC filter connected between the IGBT based Voltage Source Inverter (VSI) is attempted to eliminate voltage harmonics in the busbar voltage and switching harmonics from VSI by producing a PWM controlled harmonic voltage. In this method, the DVR or series active filter produces PWM voltage that cancels the existing harmonic voltage due to any harmonic voltage source. The proposed method is valid for any distorted busbar voltage. The operating VSI handles no active power but only harmonic power. The DVR is able to suppress the lower order switching harmonics generated by the IGBT based VSI. Good dynamic and transient results obtained. The Total Harmonic Distortion (THD) is minimized to zero at the sensitive load end. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of RLC filter. Simulated results are presented. (paper)

Three-dimensional harmonic control of a nuclear reactor

International Nuclear Information System (INIS)

Potapenko, P.T.

1989-01-01

Algorithms for neutron flux control based on harmonic three-dimensional core are considered. The essence of the considered approach includes determination of harmonics amplitudes by signals self-powered detectors placed in reactor channels and reconstruction of neutron field distribution over the reactor core volume using the data obtained. Neutron field harmonic control is shown to be reduced to independent measurement and calculation of height harmonics in channels using techniques developed for channel power control

Seeding High Gain Harmonic Generation with Laser Harmonics produced in Gases

CERN Document Server

Lambert, Guillaume; Couprie, Marie Emmanuelle; Garzella, David; Doria, Andrea; Giannessi, Luca; Hara, Toru; Kitamura, Hideo; Shintake, Tsumoru

2004-01-01

Free electron Lasers employing High Gain Harmonic generation (HGHG) schemes are very promising coherent ligth sources for the soft X-ray regime. They offer both transverse and longitudinal coherence, while Self Amplified Spontaneous Emission schemes have a longitudinal coherence limited. We propose here to seed HGHG with high harmonics produced by a Ti:Sa femtosecond laser focused on a gas jet, tuneable in the 100-10 nm spectral region. Specifities concerning the implementation of this particular laser source as a seed for HGHG are investigated. Semi analytical , numerical 1D and 3D calculations are given, for the cases of the SCSS, SPARC and ARC-EN-CIEL projects.

Recent progress of below-threshold harmonic generation

International Nuclear Information System (INIS)

Xiong, Wei-Hao; Peng, Liang-You; Gong, Qihuang

2017-01-01

The harmonics generated from the interaction of a strong laser field with atoms and molecules in the gas phase can be applied as coherent light sources and detecting techniques for structures and dynamics in matter. In the last three decades, the most prevailing experimental and theoretical studies have been focused on the high-order harmonic generation due to its applications in attosecond science. However, low-order harmonics near the ionization threshold of the target have been less explored, partially because the spectrum in this region is more complicated from both the theoretical and experimental point of view. After several pioneering investigations in the mid 1990s, near threshold harmonics (NTHs) begun to draw a great attention again because of the development of high repetition rate cavity enhanced harmonics about 10 years ago. Very recently, NTHs have attracted a lot of experimental and theoretical studies due to their potential applications as light sources and complicated mechanisms. In this topical review, we will summarize the progress of NTHs, including the early and recent experimental measurements in atoms and molecules, as well as the relevant theoretical explorations of these harmonics. (topical review)

Harmonic generation with a dual frequency pulse.

Science.gov (United States)

Keravnou, Christina P; Averkiou, Michalakis A

2014-05-01

Nonlinear imaging was implemented in commercial ultrasound systems over the last 15 years offering major advantages in many clinical applications. In this work, pulsing schemes coupled with a dual frequency pulse are presented. The pulsing schemes considered were pulse inversion, power modulation, and power modulated pulse inversion. The pulse contains a fundamental frequency f and a specified amount of its second harmonic 2f. The advantages and limitations of this method were evaluated with both acoustic measurements of harmonic generation and theoretical simulations based on the KZK equation. The use of two frequencies in a pulse results in the generation of the sum and difference frequency components in addition to the other harmonic components. While with single frequency pulses, only power modulation and power modulated pulse inversion contained odd harmonic components, with the dual frequency pulse, pulse inversion now also contains odd harmonic components.

Harmonic and geometric analysis

CERN Document Server

Citti, Giovanna; Pérez, Carlos; Sarti, Alessandro; Zhong, Xiao

2015-01-01

This book presents an expanded version of four series of lectures delivered by the authors at the CRM. Harmonic analysis, understood in a broad sense, has a very wide interplay with partial differential equations and in particular with the theory of quasiconformal mappings and its applications. Some areas in which real analysis has been extremely influential are PDE's and geometric analysis. Their foundations and subsequent developments made extensive use of the Calderón–Zygmund theory, especially the Lp inequalities for Calderón–Zygmund operators (Beurling transform and Riesz transform, among others) and the theory of Muckenhoupt weights.  The first chapter is an application of harmonic analysis and the Heisenberg group to understanding human vision, while the second and third chapters cover some of the main topics on linear and multilinear harmonic analysis. The last serves as a comprehensive introduction to a deep result from De Giorgi, Moser and Nash on the regularity of elliptic partial differen...

Harmonization versus Mutual Recognition

DEFF Research Database (Denmark)

Jørgensen, Jan Guldager; Schröder, Philipp

The present paper examines trade liberalization driven by the coordination of product standards. For oligopolistic firms situated in separate markets that are initially sheltered by national standards, mutual recognition of standards implies entry and reduced profits at home paired with the oppor......The present paper examines trade liberalization driven by the coordination of product standards. For oligopolistic firms situated in separate markets that are initially sheltered by national standards, mutual recognition of standards implies entry and reduced profits at home paired...... countries and three firms, where firms first lobby for the policy coordination regime (harmonization versus mutual recognition), and subsequently, in case of harmonization, the global standard is auctioned among the firms. We discuss welfare effects and conclude with policy implications. In particular......, harmonized standards may fail to harvest the full pro-competitive effects from trade liberalization compared to mutual recognition; moreover, the issue is most pronounced in markets featuring price competition....

[Harmonization of TSH Measurements.

Science.gov (United States)

Takeoka, Keiko; Hidaka, Yoh; Hishinuma, Akira; Ikeda, Katsuyoshi; Okubo, Shigeo; Tsuchiya, Tatsuyuki; Hashiguchi, Teruto; Furuta, Koh; Hotta, Taeko; Matsushita, Kazuyuki; Matsumoto, Hiroyuki; Murakami, Masami; Maekawa, Masato

2016-05-01

The measured concentration of thyroid stimulating hormone (TSH) differs depending on the reagents used. Harmonization of TSH is crucial because the decision limits are described in current clinical practice guide- lines as absolute values, e.g. 2.5 mIU/L in early pregnancy. In this study, we tried to harmonize the report- ed concentrations of TSH using the all-procedure trimmed mean. TSH was measured in 146 serum samples, with values ranging from 0.01 to 18.8 mIU/L, using 4 immunoassays. The concentration of TSH was highest with E test TOSOH and lowest with LUMIPULSE. The concentrations with each reagent were recalculated with the following formulas: E test TOSOH 0.855x-0.014; ECLusys 0.993x+0.079; ARCHITECT 1.041x- 0.010; and LUMIPULSE 1.096x-0.015. Recalculation eliminated the between-assay discrepancy. These formulas may be used until harmonization of TSH is achieved by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC).

Dissipative dynamics of superconducting hybrid qubit systems

International Nuclear Information System (INIS)

Montes, Enrique; Calero, Jesus M; Reina, John H

2009-01-01

We perform a theoretical study of composed superconducting qubit systems for the case of a coupled qubit configuration based on a hybrid qubit circuit made of both charge and phase qubits, which are coupled via a σ x x σ z interaction. We compute the system's eigen-energies in terms of the qubit transition frequencies and the strength of the inter-qubit coupling, and describe the sensitivity of the energy crossing/anti-crossing features to such coupling. We compute the hybrid system's dissipative dynamics for the cases of i) collective and ii) independent decoherence, whereby the system interacts with one common and two different baths of harmonic oscillators, respectively. The calculations have been performed within the Bloch-Redfield formalism and we report the solutions for the populations and the coherences of the system's reduced density matrix. The dephasing and relaxation rates are explicitly calculated as a function of the heat bath temperature.

Dissipative dynamics of superconducting hybrid qubit systems

Energy Technology Data Exchange (ETDEWEB)

Montes, Enrique; Calero, Jesus M; Reina, John H, E-mail: enriquem@univalle.edu.c, E-mail: j.reina-estupinan@physics.ox.ac.u [Departamento de Fisica, Universidad del Valle, A.A. 25360, Cali (Colombia)

2009-05-01

We perform a theoretical study of composed superconducting qubit systems for the case of a coupled qubit configuration based on a hybrid qubit circuit made of both charge and phase qubits, which are coupled via a sigma{sub x} x sigma{sub z} interaction. We compute the system's eigen-energies in terms of the qubit transition frequencies and the strength of the inter-qubit coupling, and describe the sensitivity of the energy crossing/anti-crossing features to such coupling. We compute the hybrid system's dissipative dynamics for the cases of i) collective and ii) independent decoherence, whereby the system interacts with one common and two different baths of harmonic oscillators, respectively. The calculations have been performed within the Bloch-Redfield formalism and we report the solutions for the populations and the coherences of the system's reduced density matrix. The dephasing and relaxation rates are explicitly calculated as a function of the heat bath temperature.

Frequency and zero-point vibrational energy scale factors for double-hybrid density functionals (and other selected methods): can anharmonic force fields be avoided?

Science.gov (United States)

Kesharwani, Manoj K; Brauer, Brina; Martin, Jan M L

2015-03-05

We have obtained uniform frequency scaling factors λ(harm) (for harmonic frequencies), λ(fund) (for fundamentals), and λ(ZPVE) (for zero-point vibrational energies (ZPVEs)) for the Weigend-Ahlrichs and other selected basis sets for MP2, SCS-MP2, and a variety of DFT functionals including double hybrids. For selected levels of theory, we have also obtained scaling factors for true anharmonic fundamentals and ZPVEs obtained from quartic force fields. For harmonic frequencies, the double hybrids B2PLYP, B2GP-PLYP, and DSD-PBEP86 clearly yield the best performance at RMSD = 10-12 cm(-1) for def2-TZVP and larger basis sets, compared to 5 cm(-1) at the CCSD(T) basis set limit. For ZPVEs, again, the double hybrids are the best performers, reaching root-mean-square deviations (RMSDs) as low as 0.05 kcal/mol, but even mainstream functionals like B3LYP can get down to 0.10 kcal/mol. Explicitly anharmonic ZPVEs only are marginally more accurate. For fundamentals, however, simple uniform scaling is clearly inadequate.

Harmonic Mitigation Methods in Large Offshore Wind Power Plants

DEFF Research Database (Denmark)

Kocewiak, Łukasz Hubert; Chaudhary, Sanjay; Hesselbæk, Bo

2013-01-01

Various sources of harmonic problems in large wind power plants (WPPs) and optimized harmonic mitigation methods are presented in this paper. The harmonic problems such as sources of harmonic emission and amplification as well as harmonic stability are identified. Also modern preventive...... and remedial harmonic mitigation methods in terms of passive and active filtering are described. It is shown that WPP components such as long HVAC cables and park transformers can introduce significant low-frequency resonances which can affect wind turbine control system operation and overall WPP stability...... as well as amplification of harmonic distortion. It is underlined that there is a potential in terms of active filtering in modern grid-side converters in e.g. wind turbines, STATCOMs or HVDC stations utilized in modern large WPPs. It is also emphasized that the grid-side converter controller should...

Two examples of escaping harmonic maps

International Nuclear Information System (INIS)

Pereira do Valle, A.; Verjovsky, A.

1988-12-01

This paper is part of a study on the existence of special harmonic maps on complete non-compact Riemannian manifolds. We generalize the notion of escaping geodesic and prove some results on the existence of escaping harmonic maps. 11 refs, 6 figs

An Efficient and Robust Hybrid Damper for LCL- or LLCL-Based Grid-Tied Inverter With Strong Grid-Side Harmonic Voltage Effect Rejection

DEFF Research Database (Denmark)

Liu, Yuan; Wu, Weimin; He, Yuanbin

2016-01-01

to resist the effect of the BHV, a feedforward voltage compensator and a proportional resonant regulator with harmonic compensation are often adopted. However, they still have their own limitations, particularly when there are higher order BHVs at the point of common coupling and when the equivalent grid......A high-order (LCL or LLCL) power filter with a small grid-side inductor is becoming more preferred for a grid-tied inverter due to less total inductance and reduced costs. In a microgrid, the background harmonic voltage (BHV) may distort the injected currents of the grid-tied inverters. In order...

High-order harmonic conversion efficiency in helium

International Nuclear Information System (INIS)

Crane, J.K.

1992-01-01

Calculated results are presented for the energy, number of photons, and conversion efficiency for high-order harmonic generation in helium. The results show the maximum values that we should expect to achieve experimentally with our current apparatus and the important parameters for scaling this source to higher output. In the desired operating regime where the coherence length, given by L coh =πb/(q-1), is greater than the gas column length, l, the harmonic output can be summarized by a single equation: N q =[(π z n z b 3 τ q |d q | z )/4h]{(p/q)(2l/b) z }. N q - numbers of photons of q-th harmonic; n - atom density; b - laser confocal parameter; τ q - pulse width of harmonic radiation; q - harmonic order; p - effective order of nonlinearity. (Note the term in brackets, the phase-matching function, has been separated from the rest of the expression in order to be consistent with the relevant literature)

Harmonic calculation software for industrial applications with ASDs

DEFF Research Database (Denmark)

Blaabjerg, Frede; Asiminoaei, Lucian; Hansen, Steffan

2007-01-01

This article describes the evaluation of new harmonic calculation software. By using a combination of a prestored database and new interpolation techniques the software can provide the harmonic data on real applications of a very fast speed. The harmonic results obtained with this software have a...

Audibility of high harmonics in a periodic pulse

NARCIS (Netherlands)

Duifhuis, H.

1970-01-01

A periodic pulse consisting of sufficiently narrow pulses has a frequency spectrum which contains all harmonics with equal amplitude. Owing to the limited resolving power of the hearing organ, only the low harmonics can be perceived separately. The high harmonics are heard together as one complex

Enhancement of harmonic generation using a two section undulator

International Nuclear Information System (INIS)

Prazeres, R.; Glotin, F.; Jaroszynski, D.A.; Ortega, J.M.; Rippon, C.

1999-01-01

Enhancement of the 2nd and 3rd harmonic of the wavelength of a Free-Electron Laser (FEL) has been measured when a single electron beam is crossing a two-section undulator. To produce the harmonic radiation enhancement, the undulator is arranged so that the resonance wavelength of the 2nd undulator (downstream) matches a harmonic of the 1st undulator (upstream). Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction efficiency, through a hole in one of the cavity mirrors. We present measurements that show that the optical power at the 2nd and 3rd harmonic can be enhanced, by about one order of magnitude, in two configurations: when the resonance wavelength of the 2nd undulator matches the harmonic of 1st one (harmonic configuration), or when the gap of the 2nd undulator is slightly larger than first one (step-tapered configuration). We examine the dependence of the harmonic power on the gap of the 2nd undulator. This fundamental/harmonic mode of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture

Effects of harmonic roving on pitch discrimination

DEFF Research Database (Denmark)

Santurette, Sébastien; de Kérangal, Mathilde le Gal; Joshi, Suyash Narendra

2015-01-01

Performance in pitch discrimination tasks is limited by variability intrinsic to listeners which may arise from peripheral auditory coding limitations or more central noise sources. The present study aimed at quantifying such “internal noise” by estimating the amount of harmonic roving required...... to impair pitch discrimination performance. Fundamental-frequency difference limens (F0DLs) were obtained in normal-hearing listeners with and without musical training for complex tones filtered between 1.5 and 3.5 kHz with F0s of 300 Hz (resolved harmonics) and 75 Hz (unresolved harmonics). The harmonicity...... that could be used to quantify the internal noise and provide strong constraints for physiologically inspired models of pitch perception....

Studies of harmonic generation in free electron lasers

International Nuclear Information System (INIS)

Goldammer, K.

2007-01-01

Nonlinear harmonic generation is one of the most interesting aspects of Free Electron Lasers under study today. It provides for coherent, high intensity radiation at higher harmonics of the FEL resonant frequency. The sources, numerical simulation and applications of harmonic radiation in cascaded High Gain Harmonic Generation FELs were the subject of this thesis. Harmonic emission in FELs originates from harmonic microbunching of the particles and the particular electron trajectory during FEL interaction. Numerical FEL simulation codes model these analytical equations and predict the performance of Free Electron Lasers with good accuracy. This thesis has relied heavily upon the FEL simulation code Genesis 1.3 which has been upgraded in the framework of this thesis to compute harmonic generation in a self-consistent manner. Tests against analytical predictions suggest that the harmonic power levels as well as harmonic gain lengths are simulated correctly. A benchmark with the FEL simulation code GINGER yields excellent agreement of the harmonic saturation length and saturation power. The new version of the simulation code Genesis was also tested against measurements from the VUV-FEL FLASH at DESY. The spectral power distributions of fundamental and third harmonic radiation were recorded at 25.9 nm and 8.6 nm, respectively. The relative bandwidths (FWHM) were in the range of 2 % for both the fundamental as well as the third harmonic, which was accurately reproduced by time-dependent simulations with Genesis. The new code was also used to propose and evaluate a new design for the BESSY Soft X-Ray FEL, a cascaded High Gain Harmonic Generation FEL proposed by BESSY in Berlin. The original design for the BESSY High Energy FEL line requires four HGHG stages to convert the initial seed laser wavelength of 297.5 nm down to 1.24 nm. A new scheme is proposed that makes use of fifth harmonic radiation from the first stage and reduces the number of HGHG stages to three. It

Studies of harmonic generation in free electron lasers

Energy Technology Data Exchange (ETDEWEB)

Goldammer, K.

2007-11-12

Nonlinear harmonic generation is one of the most interesting aspects of Free Electron Lasers under study today. It provides for coherent, high intensity radiation at higher harmonics of the FEL resonant frequency. The sources, numerical simulation and applications of harmonic radiation in cascaded High Gain Harmonic Generation FELs were the subject of this thesis. Harmonic emission in FELs originates from harmonic microbunching of the particles and the particular electron trajectory during FEL interaction. Numerical FEL simulation codes model these analytical equations and predict the performance of Free Electron Lasers with good accuracy. This thesis has relied heavily upon the FEL simulation code Genesis 1.3 which has been upgraded in the framework of this thesis to compute harmonic generation in a self-consistent manner. Tests against analytical predictions suggest that the harmonic power levels as well as harmonic gain lengths are simulated correctly. A benchmark with the FEL simulation code GINGER yields excellent agreement of the harmonic saturation length and saturation power. The new version of the simulation code Genesis was also tested against measurements from the VUV-FEL FLASH at DESY. The spectral power distributions of fundamental and third harmonic radiation were recorded at 25.9 nm and 8.6 nm, respectively. The relative bandwidths (FWHM) were in the range of 2 % for both the fundamental as well as the third harmonic, which was accurately reproduced by time-dependent simulations with Genesis. The new code was also used to propose and evaluate a new design for the BESSY Soft X-Ray FEL, a cascaded High Gain Harmonic Generation FEL proposed by BESSY in Berlin. The original design for the BESSY High Energy FEL line requires four HGHG stages to convert the initial seed laser wavelength of 297.5 nm down to 1.24 nm. A new scheme is proposed that makes use of fifth harmonic radiation from the first stage and reduces the number of HGHG stages to three. It

Analyzing correlation functions with tesseral and Cartesian spherical harmonics

International Nuclear Information System (INIS)

Danielewicz, Pawel; Pratt, Scott

2007-01-01

The dependence of interparticle correlations on the orientation of particle relative momentum can yield unique information on the space-time features of emission in reactions with multiparticle final states. In the present paper, the benefits of a representation and analysis of the three-dimensional correlation information in terms of surface spherical harmonics is presented. The harmonics include the standard complex tesseral harmonics and the real Cartesian harmonics. Mathematical properties of the lesser known Cartesian harmonics are illuminated. The physical content of different angular harmonic components in a correlation is described. The resolving power of different final-state effects with regard to determining angular features of emission regions is investigated. The considered final-state effects include identity interference, strong interactions, and Coulomb interactions. The correlation analysis in terms of spherical harmonics is illustrated with the cases of Gaussian and blast-wave sources for proton-charged meson and baryon-baryon pairs

Azimuthal anisotropy: The higher harmonics

International Nuclear Information System (INIS)

Poskanzer, Arthur M.; STAR Collaboration

2004-01-01

We report the first observations of the fourth harmonic (v 4 ) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v 4 is about a factor of 10 smaller than v 2 . For the sixth (v 6 ) and eighth (v 8 ) harmonics upper limits on the magnitudes are reported

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

International Nuclear Information System (INIS)

Shively, J.F.; Bier, R.E.; Caplan, M.

1986-01-01

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

Optical klystron and harmonic generation free electron laser

Directory of Open Access Journals (Sweden)

Qika Jia

2005-06-01

Full Text Available The optical field evolution of an optical klystron free electron laser is analytically described for both low gain and high gain cases. The harmonic optical klystron (HOK in which the second undulator is resonant on the higher harmonic of the first undulator is analyzed as a harmonic amplifier. The optical field evolution equation of the HOK is derived analytically for both the CHG mode (coherent harmonic generation, the quadratic gain regime and the HGHG mode (high gain harmonic generation, the exponential gain regime, the effects of energy spread, energy modulation, and dispersion in the whole process are taken into account. The linear theory is given and discussed for the HGHG mode. The analytical formula is given for the CHG mode.

General Criterion for Harmonicity

Science.gov (United States)

Proesmans, Karel; Vandebroek, Hans; Van den Broeck, Christian

2017-10-01

Inspired by Kubo-Anderson Markov processes, we introduce a new class of transfer matrices whose largest eigenvalue is determined by a simple explicit algebraic equation. Applications include the free energy calculation for various equilibrium systems and a general criterion for perfect harmonicity, i.e., a free energy that is exactly quadratic in the external field. As an illustration, we construct a "perfect spring," namely, a polymer with non-Gaussian, exponentially distributed subunits which, nevertheless, remains harmonic until it is fully stretched. This surprising discovery is confirmed by Monte Carlo and Langevin simulations.

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Measurement and Analysis of Power in Hybrid System

Directory of Open Access Journals (Sweden)

Vartika Keshri

2016-12-01

Full Text Available Application with renewable energy  sources  such   as solar cell array, wind turbines, or fuel cells have increased significantly during the past decade. To obtain the clean energy, we are using the hybrid solar-wind power generation. Consumers prefer quality power from suppliers. The quality of power can be measured by using parameters such as voltage sag, harmonic and power factor.   To   obtain   quality   power   we   have different topologies. In our paper we present a new possible topology which improves power quality. This paper presents modeling analysis and design of a pulse width modulation voltage source inverter (PWM-VSI to be connected between sources, which supplies energy from a hybrid solar wind energy system to the ac grid. The objective of this paper is to show that, with an adequate control, the converter not only can transfer the dc from hybrid solar wind energy system, but also can improve the power factor and quality power of electrical system. Whenever a disturbance occurs on load side, this disturbance can be minimized using open loop and closed loop control systems.

Harmonic superspaces of extended supersymmetry

International Nuclear Information System (INIS)

Ivanov, E.; Kalitzin, S.; Nguyen Ai Viet; Ogievetsky, V.

1984-01-01

The main technical apparatus of the harmonic superspace approach to extended SUSY, the calculus of harmonic variables on homogeneous spaces of the SUSY automorphism groups, is presented in detail for N=2, 3, 4. The basic harmonics for the coset manifolds G/H with G=SU(2), H=U(1); G=SU(3), H=SU(2)xU(1) and H=U(1)xU(1); G=SU(4), H=SU(3)xU(1), H=SU(2)xSU(2)xU(1), H=SU(2)xU(1)xU(1) and H=U(1)xU(1)xU(1); G=USp(2), H=SU(2)xSU(2), H=SU(2)xU(1) and H=U(1)xU(1) are tabulated a number of useful relations among them

Tunneling ionization and harmonic generation in two-color fields

International Nuclear Information System (INIS)

Kondo, K.; Kobayashi, Y.; Sagisaka, A.; Nabekawa, Y.; Watanabe, S.

1996-01-01

Tunneling ionization and harmonic generation in two-color fields were studied with a fundamental beam (ω) and its harmonics (2ω,3ω), which were generated by a 100-fs Ti:sapphire laser. Ion yields of atoms and molecules were successfully controlled by means of a change in the relative phase between ω and 3ω pulses. Two-color interference was clearly observed in photoelectron spectra and harmonic spectra. In the ω endash 2ω field even-order harmonics were observed in which the intensity was almost equal to that of the odd harmonics because of an asymmetric optical field. These results were compared with the quasi-static model for ionization and with the quantum theory for harmonic generation. copyright 1996 Optical Society of America

An Application of Spectral Kurtosis to Separate Hybrid Power Quality Events

Directory of Open Access Journals (Sweden)

Juan José González de la Rosa

2015-09-01

Full Text Available For the development of the future smart grid, the detection of power quality events is a key issue for the power system monitoring. Voltage sags, swells, harmonics (variations and interruptions, which produce large losses for commercial and industrial consumers, are the main events to be considered due to the sensitivity of equipment to these electrical anomalies. The steady-state events are even more frequently accompanied by transients, the discrimination and localization being far more exigent and requiring advanced signal separating tools to be incorporated in the measurement equipment. This paper shows the event detection performance of the spectral kurtosis as a signal separating tool in the frequency domain. The disturbances under test are hybrid signals resulting from the coupling between amplitude defects and non-desired higher frequencies. Being a fourth-order spectrum, the kurtosis is confirmed as a noise-resistant tool that enhances impulsiveness, therefore characterizing the electrical anomalies. In the beginning of the analysis, the voltage sag is established as a reference; then, the disturbances (oscillatory transients and harmonics are coupled at the starting and ending instants of the sag, resulting in complex hybrid events. The results show that the spectral kurtosis enhances the detection Energies 2015, 8 9778 of both types of events (steady state and transients, which are outlined in a bump shape in the fourth-order frequency pattern and centered in the main carrier frequency. Indeed, while the oscillatory transients are associated with softer and lower-amplitude peaks, the harmonics correspond to crisper and higher ones. As these mixed electrical faults are very common in the actual power grid, the article postulates the higher-order spectra to be implemented in prospective online measurement instruments.

High-order harmonic generation with short-pulse lasers

International Nuclear Information System (INIS)

Schafer, K.J.; Krause, J.L.; Kulander, K.C.

1992-12-01

Recent progress in the understanding of high-order harmonic conversion from atoms and ions exposed to high-intensity, short-pulse optical lasers is reviewed. We find that ions can produce harmonics comparable in strength to those obtained from neutral atoms, and that the emission extends to much higher order. Simple scaling laws for the strength of the harmonic emission and the maximium observable harmonic are suggested. These results imply that the photoemission observed in recent experiments in helium and neon contains contributions from ions as well as neutrals

Analysis of second order harmonic distortion due to transmitter non-linearity and chromatic and modal dispersion of optical OFDM SSB modulated signals in SMF-MMF fiber links

Science.gov (United States)

Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

2017-01-01

Single mode fibers (SMF) are typically used in Wide Area Networks (WAN), Metropolitan Area Networks (MAN) and also find applications in Radio over Fiber (RoF) architectures supporting data transmission in Fiber to the Home (FTTH), Remote Antenna Units (RAUs), in-building networks etc. Multi-mode fibers (MMFs) with low cost, ease of installation and low maintenance are predominantly (85-90%) deployed in-building networks providing data access in local area networks (LANs). The transmission of millimeter wave signals through the SMF in WAN and MAN, along with the reuse of MMF in-building networks will not levy fiber reinstallation cost. The transmission of the millimeter waves experiences signal impairments due to the transmitter non-linearity and modal dispersion of the MMF. The MMF exhibiting large modal dispersion limits the bandwidth-length product of the fiber. The second and higher-order harmonics present in the optical signal fall within the system bandwidth. This causes degradation in the received signal and an unwanted radiation of power at the RAU. The power of these harmonics is proportional to the non-linearity of the transmitter and the modal dispersion of the MMF and should be maintained below the standard values as per the international norms. In this paper, a mathematical model is developed for Second-order Harmonic Distortion (HD2) generated due to non-linearity of the transmitter and chromatic-modal dispersion of the SMF-MMF optic link. This is also verified using a software simulation. The model consists of a Mach Zehnder Modulator (MZM) that generates two m-QAM OFDM Single Sideband (SSB) signals based on phase shift of the hybrid coupler (90° and 120°). Our results show that the SSB signal with 120° hybrid coupler has suppresses the higher-order harmonics and makes the system more robust against the HD2 in the SMF-MMF optic link.

Challenges and Opportunities for Harmonizing Research Methodology

DEFF Research Database (Denmark)

van Hees, V. T.; Thaler-Kall, K.; Wolf, K. H.

2016-01-01

Objectives: Raw accelerometry is increasingly being used in physical activity research, but diversity in sensor design, attachment and signal processing challenges the comparability of research results. Therefore, efforts are needed to harmonize the methodology. In this article we reflect on how...... increased methodological harmonization may be achieved. Methods: The authors of this work convened for a two-day workshop (March 2014) themed on methodological harmonization of raw accelerometry. The discussions at the workshop were used as a basis for this review. Results: Key stakeholders were identified...... as manufacturers, method developers, method users (application), publishers, and funders. To facilitate methodological harmonization in raw accelerometry the following action points were proposed: i) Manufacturers are encouraged to provide a detailed specification of their sensors, ii) Each fundamental step...

Reduction of Harmonics by 18-Pulse Rectifier

Directory of Open Access Journals (Sweden)

Stanislav Kocman

2008-01-01

Full Text Available Operation of such electrical devices as data processing and electronics devices, adjustable speed drives or uninterruptible power supply can cause problems by generating harmonic currents into the network, from which they are supplied. Effects of these harmonic currents are various, they can get worse the quality of supply voltage in the network or to have negative influences on devices connected to this network. There are various technical solutions for reduction of harmonics. One of them is using of multi-pulse rectifiers, whereas the 18-pulse rectifier in the structure of adjustable speed drive is briefly presented in this paper including some results of its behaviour. The examined experimental measurements confirmed its very good efficiency in the harmonic mitigation.

Cohabiting with the harmonic pollution

International Nuclear Information System (INIS)

Garcia C, Antonio A

1999-01-01

The Norm IEEE 519 tries of the permissible limits of harmonic distortion in the point of common joining between the energy supplier company and the industry. However fulfilling these limits of distortion doesn't guarantee that the problem for the company has finished, on the contrary will have to counteract the effects created by the harmonic distortion toward the interior of its electric system and to cohabit with this distortion

Light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities based on hybrid simplified spherical harmonics with radiosity model.

Science.gov (United States)

Yang, Defu; Chen, Xueli; Peng, Zhen; Wang, Xiaorui; Ripoll, Jorge; Wang, Jing; Liang, Jimin

2013-01-01

Modeling light propagation in the whole body is essential and necessary for optical imaging. However, non-scattering, low-scattering and high absorption regions commonly exist in biological tissues, which lead to inaccuracy of the existing light transport models. In this paper, a novel hybrid light transport model that couples the simplified spherical harmonics approximation (SPN) with the radiosity theory (HSRM) was presented, to accurately describe light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities. In the model, the radiosity theory was used to characterize the light transport in non-scattering regions and the SPN was employed to handle the scattering problems, including subsets of low-scattering and high absorption. A Neumann source constructed by the light transport in the non-scattering region and formed at the interface between the non-scattering and scattering regions was superposed into the original light source, to couple the SPN with the radiosity theory. The accuracy and effectiveness of the HSRM was first verified with both regular and digital mouse model based simulations and a physical phantom based experiment. The feasibility and applicability of the HSRM was then investigated by a broad range of optical properties. Lastly, the influence of depth of the light source on the model was also discussed. Primary results showed that the proposed model provided high performance for light transport in turbid media with non-scattering, low-scattering and high absorption heterogeneities.

Quasi-phase-matching of only even-order high harmonics.

Science.gov (United States)

Diskin, Tzvi; Cohen, Oren

2014-03-24

High harmonic spectrum of a quasi-monochromatic pump that interacts with isotropic media consists of only odd-order harmonics. Addition of a secondary pump, e.g. a static field or the second harmonic of the primary pump, can results with generation of both odd and even harmonics of the primary pump. We propose a method for quasi-phase matching of only the even-order harmonics of the primary pump. We formulate a theory for this process and demonstrate it numerically. We also show that it leads to attosecond pulse trains with constant carrier envelop phase and high repetition rate.

Analysis of Even Harmonics Generation in an Isolated Electric Power System

Science.gov (United States)

Kanao, Norikazu; Hayashi, Yasuhiro; Matsuki, Junya

Harmonics bred from loads are mainly odd order because the current waveform has half-wave symmetry. Since the even harmonics are negligibly small, those are not generally measured in electric power systems. However, even harmonics were measured at a 500/275/154kV substation in Hokuriku Electric Power Company after removal of a transmission line fault. The even harmonics caused malfunctions of protective digital relays because the relays used 4th harmonics at the input filter as automatic supervisory signal. This paper describes the mechanism of generation of the even harmonics by comparing measured waveforms with ATP-EMTP simulation results. As a result of analysis, it is cleared that even harmonics are generated by three causes. The first cause is a magnetizing current of transformers due to flux deviation by DC component of a fault current. The second one is due to harmonic conversion of a synchronous machine which generates even harmonics when direct current component or even harmonic current flow into the machine. The third one is that increase of harmonic impedance due to an isolated power system produces harmonic voltages. The design of the input filter of protective digital relays should consider even harmonics generation in an isolated power system.

Stabilization of the potential multi-steady-state absolute instabilities in a gyrotron traveling-wave amplifier

International Nuclear Information System (INIS)

Du Chaohai; Liu Pukun

2009-01-01

The problem of spurious oscillations induced by absolute instabilities is the most challenging one that hinders the development of the millimeter-wave gyrotron traveling-wave amplifiers (gyro-TWTs). A spurious oscillation exists as a high order axial mode (HOAM) in the interaction circuit. This paper is devoted to demonstrating the complicated steady states of these HOAMs and exploring corresponding techniques to stabilize these potential multi-steady-state absolute instabilities. The stability-oriented design principle is conveyed in a start-to-end design flow of a Ka-band TE 11 mode gyro-TWT. Strong magnetic tapering near the downstream port, which is capable of cutting short the effective interaction circuit of a spurious oscillation and simultaneously boosting the amplification performance, is for the first time proposed to further improve the system stability. It is also found that an ideal prebunched electron beam in the linear stage is the necessary condition to efficient amplification in the nonlinear stage, suggesting that it is feasible to design a stable prebunching stage to replace the distributed-loss-loaded linear stage. The stability-oriented design principle provides more explicit reference for future design of a zero-drive stable gyro-TWT.

Probabilistic Aspects of Harmonic Emission of Large Offshore Wind Farms

DEFF Research Database (Denmark)

Jensen, Christian Flytkjær; Bak, Claus Leth; Kocewiak, Lukasz Hubert

2011-01-01

In this article, a new probabilistic method of as-sessment of harmonic emission of large offshore wind farms is presented. Based on measurements from the British wind farm Burbo Banks, probability density functions are estimated for the dominating low order harmonic currents injected by a single...... turbine. The degree and type of dependence between the harmonic emission and the operating point of a single turbine is established. A model of Burbo Banks, suitable for harmonic load flow studies, is created in DIgSILENT Power Factory along with a DPL-script that deals with the probabilistic issues...... of the harmonic emission. The simulated harmonic distortion at the PCC is compared to measurement. This reveals some diffi-culties regarding harmonic load flow studies. The harmonic background distortion in the grid to where the wind farm is connected must be included in the study. Furthermore, a very detailed...

Solid-state harmonics beyond the atomic limit.

Science.gov (United States)

Ndabashimiye, Georges; Ghimire, Shambhu; Wu, Mengxi; Browne, Dana A; Schafer, Kenneth J; Gaarde, Mette B; Reis, David A

2016-06-23

Strong-field laser excitation of solids can produce extremely nonlinear electronic and optical behaviour. As recently demonstrated, this includes the generation of high harmonics extending into the vacuum-ultraviolet and extreme-ultraviolet regions of the electromagnetic spectrum. High harmonic generation is shown to occur fundamentally differently in solids and in dilute atomic gases. How the microscopic mechanisms in the solid and the gas differ remains a topic of intense debate. Here we report a direct comparison of high harmonic generation in the solid and gas phases of argon and krypton. Owing to the weak van der Waals interaction, rare (noble)-gas solids are a near-ideal medium in which to study the role of high density and periodicity in the generation process. We find that the high harmonic generation spectra from the rare-gas solids exhibit multiple plateaus extending well beyond the atomic limit of the corresponding gas-phase harmonics measured under similar conditions. The appearance of multiple plateaus indicates strong interband couplings involving multiple single-particle bands. We also compare the dependence of the solid and gas harmonic yield on laser ellipticity and find that they are similar, suggesting the importance of electron-hole recollision in these solids. This implies that gas-phase methods such as polarization gating for attosecond pulse generation and orbital tomography could be realized in solids.

Harmonic-hopping in Wallacea's bats.

Science.gov (United States)

Kingston, Tigga; Rossiter, Stephen J

2004-06-10

Evolutionary divergence between species is facilitated by ecological shifts, and divergence is particularly rapid when such shifts also promote assortative mating. Horseshoe bats are a diverse Old World family (Rhinolophidae) that have undergone a rapid radiation in the past 5 million years. These insectivorous bats use a predominantly pure-tone echolocation call matched to an auditory fovea (an over-representation of the pure-tone frequency in the cochlea and inferior colliculus) to detect the minute changes in echo amplitude and frequency generated when an insect flutters its wings. The emitted signal is the accentuated second harmonic of a series in which the fundamental and remaining harmonics are filtered out. Here we show that three distinct, sympatric size morphs of the large-eared horseshoe bat (Rhinolophus philippinensis) echolocate at different harmonics of the same fundamental frequency. These morphs have undergone recent genetic divergence, and this process has occurred in parallel more than once. We suggest that switching harmonics creates a discontinuity in the bats' perception of available prey that can initiate disruptive selection. Moreover, because call frequency in horseshoe bats has a dual function in resource acquisition and communication, ecological selection on frequency might lead to assortative mating and ultimately reproductive isolation and speciation, regardless of external barriers to gene flow.

Determination of nonlinear resistance voltage-current relationships by measuring harmonics

Science.gov (United States)

Stafford, J. M.

1971-01-01

Test configuration measures harmonic signal amplitudes generated in nonlinear resistance. Vacuum-type voltmeter measures low frequency sinusoidal input signal amplitude and wave-analyzer measures amplitude of harmonic signals generated in junction. Input signal harmonics amplitude must not exceed that of harmonics generated in nonlinear resistance.

RHIC susceptibility to variations in systematic magnetic harmonic errors

International Nuclear Information System (INIS)

Dell, G.F.; Peggs, S.; Pilat, F.; Satogata, T.; Tepikian, S.; Trbojevic, D.; Wei, J.

1994-01-01

Results of a study to determine the sensitivity of tune to uncertainties of the systematic magnetic harmonic errors in the 8 cm dipoles of RHIC are reported. Tolerances specified to the manufacturer for tooling and fabrication can result in systematic harmonics different from the expected values. Limits on the range of systematic harmonics have been established from magnet calculations, and the impact on tune from such harmonics has been established

Direct computation of harmonic moments for tomographic reconstruction

International Nuclear Information System (INIS)

Nara, Takaaki; Ito, Nobutaka; Takamatsu, Tomonori; Sakurai, Tetsuya

2007-01-01

A novel algorithm to compute harmonic moments of a density function from its projections is presented for tomographic reconstruction. For projection p(r, θ), we define harmonic moments of projection by ∫ π 0 ∫ ∞ -∞ p(r,θ)(re iθ ) n drd θ and show that it coincides with the harmonic moments of the density function except a constant. Furthermore, we show that the harmonic moment of projection of order n can be exactly computed by using n+ 1 projection directions, which leads to an efficient algorithm to reconstruct the vertices of a polygon from projections.

Optimal design of permanent magnet flux switching generator for wind applications via artificial neural network and multi-objective particle swarm optimization hybrid approach

International Nuclear Information System (INIS)

Meo, Santolo; Zohoori, Alireza; Vahedi, Abolfazl

2016-01-01

Highlights: • A new optimal design of flux switching permanent magnet generator is developed. • A prototype is employed to validate numerical data used for optimization. • A novel hybrid multi-objective particle swarm optimization approach is proposed. • Optimization targets are weight, cost, voltage and its total harmonic distortion. • The hybrid approach preference is proved compared with other optimization methods. - Abstract: In this paper a new hybrid approach obtained combining a multi-objective particle swarm optimization and artificial neural network is proposed for the design optimization of a direct-drive permanent magnet flux switching generators for low power wind applications. The targets of the proposed multi-objective optimization are to reduce the costs and weight of the machine while maximizing the amplitude of the induced voltage as well as minimizing its total harmonic distortion. The permanent magnet width, the stator and rotor tooth width, the rotor teeth number and stator pole number of the machine define the search space for the optimization problem. Four supervised artificial neural networks are designed for modeling the complex relationships among the weight, the cost, the amplitude and the total harmonic distortion of the output voltage respect to the quantities of the search space. Finite element analysis is adopted to generate training dataset for the artificial neural networks. Finite element analysis based model is verified by experimental results with a 1.5 kW permanent magnet flux switching generator prototype suitable for renewable energy applications, having 6/19 stator poles/rotor teeth. Finally the effectiveness of the proposed hybrid procedure is compared with the results given by conventional multi-objective optimization algorithms. The obtained results show the soundness of the proposed multi objective optimization technique and its feasibility to be adopted as suitable methodology for optimal design of permanent

Harmonic arbitrary waveform generator

Science.gov (United States)

Roberts, Brock Franklin

2017-11-28

High frequency arbitrary waveforms have applications in radar, communications, medical imaging, therapy, electronic warfare, and charged particle acceleration and control. State of the art arbitrary waveform generators are limited in the frequency they can operate by the speed of the Digital to Analog converters that directly create their arbitrary waveforms. The architecture of the Harmonic Arbitrary Waveform Generator allows the phase and amplitude of the high frequency content of waveforms to be controlled without taxing the Digital to Analog converters that control them. The Harmonic Arbitrary Waveform Generator converts a high frequency input, into a precision, adjustable, high frequency arbitrary waveform.

Probabilistic aspects of harmonic emission of large offshore wind farms

Energy Technology Data Exchange (ETDEWEB)

Jensen, Christian F. [Energinet.dk, Fredericia (Denmark); Bak, Claus L. [Aalborg Univ. (Denmark). Dept. of Energy Technology; Kocewiak, Lukasz; Hjerrild, Jesper [DONG Energy, Skaerbaek (Denmark); Berthelsen, Kasper K. [Aalborg Univ. (Denmark). Dept. of Mathematical Sciences

2011-07-01

In this article, a new probabilistic method of assessment of harmonic emission of large offshore wind farms is presented. Based on measurements from the British wind farm Burbo Banks, probability density functions are estimated for the dominating low order harmonic currents injected by a single turbine. The degree and type of dependence between the harmonic emission and the operating point of a single turbine is established. A model of Burbo Banks, suitable for harmonic load flow studies, is created in DIgSILENT Power Factory along with a DPL-script that deals with the probabilistic issues of the harmonic emission. The simulated harmonic distortion at the PCC is compared to measurement. This reveals some difficulties regarding harmonic load flow studies. The harmonic background distortion in the grid to where the wind farms is connected must be included in the study. Furthermore, a very detailed representation of the frequency dependent short circuit impedance must be used before sufficiently accurate results can be obtained from the model. (orig.)

Transformation of Real Spherical Harmonics under Rotations

Science.gov (United States)

Romanowski, Z.; Krukowski, St.; Jalbout, A. F.

2008-08-01

The algorithm rotating the real spherical harmonics is presented. The convenient and ready to use formulae for l = 0, 1, 2, 3 are listed. The rotation in R3 space is determined by the rotation axis and the rotation angle; the Euler angles are not used. The proposed algorithm consists of three steps. (i) Express the real spherical harmonics as the linear combination of canonical polynomials. (ii) Rotate the canonical polynomials. (iii) Express the rotated canonical polynomials as the linear combination of real spherical harmonics. Since the three step procedure can be treated as a superposition of rotations, the searched rotation matrix for real spherical harmonics is a product of three matrices. The explicit formulae of matrix elements are given for l = 0, 1, 2, 3, what corresponds to s, p, d, f atomic orbitals.

Multisite EPR oximetry from multiple quadrature harmonics.

Science.gov (United States)

Ahmad, R; Som, S; Johnson, D H; Zweier, J L; Kuppusamy, P; Potter, L C

2012-01-01

Multisite continuous wave (CW) electron paramagnetic resonance (EPR) oximetry using multiple quadrature field modulation harmonics is presented. First, a recently developed digital receiver is used to extract multiple harmonics of field modulated projection data. Second, a forward model is presented that relates the projection data to unknown parameters, including linewidth at each site. Third, a maximum likelihood estimator of unknown parameters is reported using an iterative algorithm capable of jointly processing multiple quadrature harmonics. The data modeling and processing are applicable for parametric lineshapes under nonsaturating conditions. Joint processing of multiple harmonics leads to 2-3-fold acceleration of EPR data acquisition. For demonstration in two spatial dimensions, both simulations and phantom studies on an L-band system are reported. Copyright © 2011 Elsevier Inc. All rights reserved.

Estimation and reduction of harmonic currents from power converters

DEFF Research Database (Denmark)

Asiminoaei, Lucian

-based method depends very much on the amount and accuracy of collected data in the development stage. The outcome of this investigation is a Harmonic Calculation Software compiled into a Graphical User Interface PC-software application, which can be applied for fast estimations of the harmonic currents...... control of the proposed topologies are given together with laboratory tests. One harmonic current mitigation solution found is to connect (two) smaller power APF's in parallel, sharing the same ac- and dc-bus. It is proven that parallel APF's may have lower passive components although other issues arises......, like circulation currents, which is removed here by common mode coils. Another harmonic solution is to use cascade connection of (two) independent APF's that cooperatively share the task of the harmonic mitigation. Two cooperative control methods are proposed called load-sharing and harmonic-sharing...

Sequence Domain Harmonic Modeling of Type-IV Wind Turbines

DEFF Research Database (Denmark)

Guest, Emerson; Jensen, Kim Høj; Rasmussen, Tonny Wederberg

2017-01-01

-sampled pulsewidth modulation and an analysis of converter generated voltage harmonics due to compensated dead-time. The decoupling capabilities of the proposed the SD harmonic model are verified through a power quality (PQ) assessment of a 3MW Type-IV wind turbine. The assessment shows that the magnitude and phase...... of low-order odd converter generated voltage harmonics are dependent on the converter operating point and the phase of the fundamental component of converter current respectively. The SD harmonic model can be used to make PQ assessments of Type-IV wind turbines or incorporated into harmonic load flows...... for computation of PQ in wind power plants....

Mitigation of Voltage and Current Harmonics in Grid-Connected Microgrids

DEFF Research Database (Denmark)

Savaghebi, Mehdi; Guerrero, Josep M.; Jalilian, Alireza

2012-01-01

In this paper, a control approach is proposed for selective compensation of main voltage and current harmonics in grid-connected microgrids. Two modes of compensation are considered, i.e. voltage and current compensation modes. In the case that sensitive loads are connected to the point of common...... coupling (PCC), voltage compensation mode is activated in order to provide a high voltage quality at PCC. Otherwise, grid current harmonics are mitigated (current compensation mode) in order to avoid excessive harmonic supply by the grid. In both modes, harmonic compensation is achieved through proper...... control of distributed generators (DGs) interface converters. The compensation effort of each harmonic is shared considering the corresponding current harmonic supplied by the DGs. The control system of each DG comprises harmonic compensator, power controllers, voltage and current controllers and virtual...

Unlocking higher harmonics in atomic force microscopy with gentle interactions.

Science.gov (United States)

Santos, Sergio; Barcons, Victor; Font, Josep; Verdaguer, Albert

2014-01-01

In dynamic atomic force microscopy, nanoscale properties are encoded in the higher harmonics. Nevertheless, when gentle interactions and minimal invasiveness are required, these harmonics are typically undetectable. Here, we propose to externally drive an arbitrary number of exact higher harmonics above the noise level. In this way, multiple contrast channels that are sensitive to compositional variations are made accessible. Numerical integration of the equation of motion shows that the external introduction of exact harmonic frequencies does not compromise the fundamental frequency. Thermal fluctuations are also considered within the detection bandwidth of interest and discussed in terms of higher-harmonic phase contrast in the presence and absence of an external excitation of higher harmonics. Higher harmonic phase shifts further provide the means to directly decouple the true topography from that induced by compositional heterogeneity.

Harmonic lasing in x-ray free electron lasers

Directory of Open Access Journals (Sweden)

E. A. Schneidmiller

2012-08-01

Full Text Available Harmonic lasing in a free electron laser with a planar undulator (under the condition that the fundamental frequency is suppressed might be a cheap and efficient way of extension of wavelength ranges of existing and planned x-ray free electron laser (FEL facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental frequency. In this paper we perform a parametrization of the solution of the eigenvalue equation for lasing at odd harmonics, and present an explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental harmonic. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of x-ray beam at saturation. Considering 3rd harmonic lasing as a practical example, we come to the conclusion that it is much more robust than usually thought, and can be widely used in the existing or planned x-ray FEL (XFEL facilities. In particular, Linac Coherent Light Source (LCLS after a minor modification can lase to saturation at the 3rd harmonic up to the photon energy of 25–30 keV providing multigigawatt power level and narrow bandwidth. As for the European XFEL, harmonic lasing would allow one to extend operating range (ultimately up to 100 keV, to reduce FEL bandwidth and to increase brilliance, to enable two-color operation for pump-probe experiments, and to provide more flexible operation at different electron energies. Similar improvements can be realized in other x-ray FEL facilities with gap-tunable undulators like FLASH II, SACLA, LCLS II, etc. Harmonic lasing can be an attractive option for compact x-ray FELs (driven by electron beams with a relatively low energy, allowing the use of the standard undulator technology instead of

HARMONICS SURFACES OF GRAPHIC TYPE IN R3

Directory of Open Access Journals (Sweden)

Carlos Carrión Riveros

2016-06-01

Full Text Available In this research we study harmonic surfaces immersed in R3. We dened Harmonic surfaces of graphic type and showed that a harmonious surface graphic type is minimal if and only if it is part of a plane or a helix. Also, we give a characterization of harmonic surfaces graphic type parameterized by asymptotic lines and some examples.

Hybrid acoustic energy harvesting using combined electromagnetic and piezoelectric conversion

Science.gov (United States)

Khan, Farid Ullah; Izhar

2016-02-01

This paper reports a novel hybrid acoustic energy harvester. The harvester utilizes both the electromagnetic and piezoelectric conversion mechanisms simultaneously to convert the ambient acoustical noise into electrical power for self-powered wireless sensor nodes. The proposed harvester is comprised of a Helmholtz resonator, two magnets mounted on a piezoelectric plate, and a wound coil located under the magnets. The harvester is characterized both under harmonic and real random acoustical excitations. In-lab, under harmonic acoustical excitation at a sound pressure level of 130 dB and frequency of 2.1 kHz, an optimum power of 2.86 μW (at 114 Ω optimum load) is obtained from electromagnetic conversion and 50 μW (at 1000 Ω optimum load) is generated by the piezoelectric harvester's part. Moreover, in real acoustical environment of a domestic electric generator the peak voltages of 40 and 123 mV are produced by the electromagnetic and piezoelectric portions of the acoustic energy harvester.

Hyperspherical Harmonics and Their Physical Applications

DEFF Research Database (Denmark)

Avery, James Emil; Avery, John Scales

Hyperspherical harmonics are extremely useful in nuclear physics and reactive scattering theory. However, their use has been confined to specialists with very strong backgrounds in mathematics. This book aims to change the theory of hyperspherical harmonics from an esoteric field, mastered....... The book is accompanied by programs and exercises designed for teaching and practical use....

Harmonic Function of Poincare Cone Condition In Solving Dirichlet ...

African Journals Online (AJOL)

Harmonic Function of Poincare Cone Condition In Solving Dirichlet Problem. ... Journal of the Nigerian Association of Mathematical Physics ... theorem, the dirichlet problem and maximum principle where we conclude that the application of sums , differences and scalar multiples of harmonic functions are again harmonic.

Harmonic Distortion of Rectifier Topologies for Adjustable Speed Drives

DEFF Research Database (Denmark)

Hansen, Steffan

This thesis deals with the harmonic distortion of the diode rectifier and a number of alternative rectifier topologies for adjustable speed drives. The main intention of this thesis is to provide models and tools that allow easy prediction of the harmonic distortion of ASD’s in a given system...... rectifier are presented. The first level is an ideal model where the diode rectifier basically is treated as an independent (harmonic) current source. The second level is an empirical model, where simulated (or measured) values of the harmonic currents of the diode rectifier for different parameters......-angle of the individual harmonic currents of different diode rectifier types is analyzed. Four selected rectifier topologies with a high input power factor are presented. It is shown that using ac- or dc-coils is a very simple and efficient method to reduce the harmonic currents compared to the basic diode rectifier...

Harmonic current prediction by impedance modeling of grid-tied inverters

DEFF Research Database (Denmark)

Pereira, Heverton A.; Freijedo, Francisco D.; Silva, M. M.

2017-01-01

and harmonic voltage profiles. Results reinforce that impedance models can represent with relatively accuracy the harmonic current emitted by the PV plants at the point of common coupling (PCC). Lastly, a stress test is performed to show how a variation in the harmonic voltage phase angle impacts the PV plant...... impedance models when used in harmonic integration studies. It is aimed to estimate the harmonic current contribution as a function of the background harmonic voltages components. Time domain simulations based on detailed and average models are compared with the impedance model developed in frequency domain....... In grids with harmonic voltages, impedance models can predict the current distortion for all active power injection scenarios. Furthermore, measurements in a 1.4 MW PV plant connected in a distributed grid are used to validate the simulation based on impedance models during different power injections...

Coherent bremsstrahlung generation of harmonics in a laser-produced plasma

International Nuclear Information System (INIS)

Silin, Viktor P

1999-01-01

Foundations of a theory of generation of the harmonics of a laser pump in a fully ionised plasma are proposed. This theory makes it possible to describe the relationships governing harmonic generation in an analytical form. For an elliptically polarised pump field with a low degree of circular polarisation A, the range of plasma parameters is established in which the number of harmonics is found to be of the order of A -1 . Anomalous polarisation properties of the harmonics are predicted. In this case, their polarisation is seen to be nearly perpendicular to the pump polarisation and the degree of circular polarisation increases with the harmonic order number. The harmonic-order-dependent intensity of the pump field which results in circular polarisation of a harmonic is determined making allowance for thermal plasma motion. The conditions under which increasing the low degree of circular pump polarisation increases the efficiency of harmonic generation are established. The nonlinear dependence of the pump polarisation on its intensity under the conditions of collisional absorption in a plasma are identified and an instability of the circular polarisation is revealed. For a plane-polarised pump, it is shown how the maximum power of a harmonic and the pump power corresponding to this maximum scale up with the harmonic order number. The conditions under which the number of harmonics generated is limited owing to the relativistic nature of electron motion in the pump field are established. This effect appears for an unexpectedly weak relativity. (invited paper)

Tides and tidal harmonics at Umbharat, Gujarat

Digital Repository Service at National Institute of Oceanography (India)

Suryanarayana, A.; Swamy, G.N.

A part of the data on tides recorded at Machiwada near Umbharat, Gulf of Cambay during April 1978 was subjected to harmonic analysis following the Admiralty procedure. The general tidal characteristics and the value of four major harmonic...

Generation of intense high-order vortex harmonics.

Science.gov (United States)

Zhang, Xiaomei; Shen, Baifei; Shi, Yin; Wang, Xiaofeng; Zhang, Lingang; Wang, Wenpeng; Xu, Jiancai; Yi, Longqiong; Xu, Zhizhan

2015-05-01

This Letter presents for the first time a scheme to generate intense high-order optical vortices that carry orbital angular momentum in the extreme ultraviolet region based on relativistic harmonics from the surface of a solid target. In the three-dimensional particle-in-cell simulation, the high-order harmonics of the high-order vortex mode is generated in both reflected and transmitted light beams when a linearly polarized Laguerre-Gaussian laser pulse impinges on a solid foil. The azimuthal mode of the harmonics scales with its order. The intensity of the high-order vortex harmonics is close to the relativistic region, with the pulse duration down to attosecond scale. The obtained intense vortex beam possesses the combined properties of fine transversal structure due to the high-order mode and the fine longitudinal structure due to the short wavelength of the high-order harmonics. In addition to the application in high-resolution detection in both spatial and temporal scales, it also presents new opportunities in the intense vortex required fields, such as the inner shell ionization process and high energy twisted photons generation by Thomson scattering of such an intense vortex beam off relativistic electrons.

Some theorems on a class of harmonic manifolds

International Nuclear Information System (INIS)

Rahman, M.S.; Chen Weihuan.

1993-08-01

A class of harmonic n-manifold, denoted by HM n , is, in fact, focussed on a Riemannian manifold with harmonic curvature. A variety of results, with properties, on HM n is presented in a fair order. Harmonic manifolds are then touched upon manifolds with recurrent Ricci curvature, biRicci-recurrent curvature and recurrent conformal curvature, and, in consequence, a sequence of theorems are deduced. (author). 21 refs

On the harmonic starlike functions with respect to symmetric ...

African Journals Online (AJOL)

In the present paper, we introduce the notions of functions harmonic starlike with respect to symmetric, conjugate and symmetric conjugate points. Such results as coefficient inequalities and structural formulae for these function classes are proved. Keywords: Harmonic functions, harmonic starlike functions, symmetric points, ...

Lenore White Harmon: One Woman's Career Development.

Science.gov (United States)

Fouad, Nadya A.

1997-01-01

Presents biographical information on Lenore White Harmon, noted professor, counselor, and researcher. In a question-and-answer section, Harmon describes her early career decisions, work history, research efforts, professional contributions, important influences and reflections on her career development. (KW)

On harmonicity in some Moufang-Klingenberg planes

OpenAIRE

ÇELİK, Basri; AKPINAR, Atilla; ÇİFTÇİ, Süleyman

2010-01-01

In this paper we study Moufang-Klingenberg planes M (A) defined over a local alternative ring A of dual numbers. We show that some collineations of M (A) preserve cross-ratio and thus establish a relation between harmonicity and harmonic position.

Femtosecond envelope of the high-harmonic emission from ablation plasmas

International Nuclear Information System (INIS)

Haessler, S; Gobert, O; Hergott, J-F; Lepetit, F; Perdrix, M; Carré, B; Salières, P; Bom, L B Elouga; Ozaki, T

2012-01-01

We characterize the temporal profile of the high-order harmonic emission from ablation plasma plumes using cross-correlations with the infrared (IR) laser beam provided by two-photon harmonic+IR ionization of rare gas atoms. We study both non-resonant plasmas (lead, gold and chrome) and resonant plasmas (indium and tin), i.e. plasmas presenting in the singly charged ions a strong radiative transition coinciding with a harmonic order. The cross-correlation traces are found to be very similar for all harmonic orders and all plasma targets. The recovered harmonic pulse durations are very similar to the driving laser, with a tendency towards being shorter, demonstrating that the emission is a directly laser-driven process even in the case of resonant harmonics. This provides a valuable input for theories describing resonant-harmonic emission and opens the perspective of a very high flux tabletop XUV source for applications. (paper)

Polarization-Resolved Study of High Harmonics from Bulk Semiconductors

Science.gov (United States)

Kaneshima, Keisuke; Shinohara, Yasushi; Takeuchi, Kengo; Ishii, Nobuhisa; Imasaka, Kotaro; Kaji, Tomohiro; Ashihara, Satoshi; Ishikawa, Kenichi L.; Itatani, Jiro

2018-06-01

The polarization property of high harmonics from gallium selenide is investigated using linearly polarized midinfrared laser pulses. With a high electric field, the perpendicular polarization component of the odd harmonics emerges, which is not present with a low electric field and cannot be explained by the perturbative nonlinear optics. A two-dimensional single-band model is developed to show that the anisotropic curvature of an energy band of solids, which is pronounced in an outer part of the Brillouin zone, induces the generation of the perpendicular odd harmonics. This model is validated by three-dimensional quantum mechanical simulations, which reproduce the orientation dependence of the odd-order harmonics. The quantum mechanical simulations also reveal that the odd- and even-order harmonics are produced predominantly by the intraband current and interband polarization, respectively. These experimental and theoretical demonstrations clearly show a strong link between the band structure of a solid and the polarization property of the odd-order harmonics.

Phase-matched third harmonic generation in a plasma

International Nuclear Information System (INIS)

Rax, J.M.; Fisch, N.J.

1993-01-01

Relativistic third harmonic generation in a plasma is investigated. The growth of a third harmonic wave is limited by the difference between the phase velocity of the pump and driven waves. This phase velocity mismatch results in a third harmonic amplitude saturation and oscillation. In order to overcome this saturation, the authors describe a phase-matching scheme based on a resonant density modulation. The limitations of this scheme are analyzed

Renewable Energy Systems: Development and Perspectives of a Hybrid Solar-Wind System

Directory of Open Access Journals (Sweden)

C. Shashidhar

2012-02-01

Full Text Available Considering the intermittent natural energy resources and the seasonal un-balance, a phtovoltaic-wind hybrid electrical power supply system was developed to accommodate remote locations where a conventional grid connection is inconvenient or expensive. However, the hybrid system can also be applied with grid connection and owners are allowed to sell excessive power back to the electric utility. The proposed set-up consists of a photo-voltaic solar-cell array, a mast mounted wind generator, lead-acid storage batteries, an inverter unit to convert DC to AC, electrical lighting loads, electrical heating loads, several fuse and junction boxes and associated wiring, and test instruments for measuring voltages, currents, power factors, and harmonic contamination data throughout the system. The proposed hybrid solar-wind power generating system can be extensively used to illustrate electrical concepts in hands-on laboratories and also for demonstrations in the Industrial Technology curriculum. This paper describes an analysis of local PV-wind hybrid systems for supplying electricity to a private house, farmhouse or small company with electrical power depending on the site needs. The major system components, work principle and specific working condition are presented.

Optical Third-Harmonic Generation in Graphene

Directory of Open Access Journals (Sweden)

Sung-Young Hong

2013-06-01

Full Text Available We report strong third-harmonic generation in monolayer graphene grown by chemical vapor deposition and transferred to an amorphous silica (glass substrate; the photon energy is in three-photon resonance with the exciton-shifted van Hove singularity at the M point of graphene. The polarization selection rules are derived and experimentally verified. In addition, our polarization- and azimuthal-rotation-dependent third-harmonic-generation measurements reveal in-plane isotropy as well as anisotropy between the in-plane and out-of-plane nonlinear optical responses of graphene. Since the third-harmonic signal exceeds that from bulk glass by more than 2 orders of magnitude, the signal contrast permits background-free scanning of graphene and provides insight into the structural properties of graphene.

HARMONIZED EUROPE OR EUROPEAN HARMONY?

Directory of Open Access Journals (Sweden)

Cosmin Marinescu

2007-07-01

Full Text Available Recent evolutions in Europe raise questions on the viability of the present economic and social model that defines the European construction project. In this paper, the author will try to explain the viability of institutional European model that sticks between free market mechanisms and protectionism. The main challenge for the EU is about the possibility to bring together the institutional convergence and the welfare for all Europeans. This is the result of the view, still dominant, of European politics elite, according to which institutional harmonization is the solution of a more dynamic and prosper Europe. But, economic realities convince us that, more and more, a harmonized, standardized Europe is not necessarily identical with a Europe of harmony and social cooperation. If „development through integration” seems to be harmonization through „institutional transplant”, how could then be the European model one sufficiently wide open to market, which creates the prosperity so long waited for by new member countries?

DSOGI-PLL Based Power Control Method to Mitigate Control Errors Under Disturbances of Grid Connected Hybrid Renewable Power Systems

Directory of Open Access Journals (Sweden)

Mehmet Emin Meral

2018-01-01

Full Text Available The control of power converter devices is one of the main research lines in interfaced renewable energy sources, such as solar cells and wind turbines. Therefore, suitable control algorithms should be designed in order to regulate power or current properly and attain a good power quality for some disturbances, such as voltage sag/swell, voltage unbalances and fluctuations, long interruptions, and harmonics. Various synchronisation techniques based control strategies are implemented for the hybrid power system applications under unbalanced conditions in literature studies. In this paper, synchronisation algorithms based Proportional-Resonant (PR power/current controller is applied to the hybrid power system (solar cell + wind turbine + grid, and Dual Second Order Generalized Integrator-Phase Locked Loop (DSOGI-PLL based PR controller in stationary reference frame provides a solution to overcome these problems. The influence of various cases, such as unbalance, and harmonic conditions, is examined, analysed and compared to the PR controllers based on DSOGI-PLL and SRF-PLL. The results verify the effectiveness and correctness of the proposed DSOGI-PLL based power control method.

Harmonic modeling of induction motors

Energy Technology Data Exchange (ETDEWEB)

Pedra, J.; Sainz, L.; Corcoles, F. [Department of Electrical Engineering, ETSEIB-UPC, Av. Diagonal 647, 08028 Barcelona (Spain)

2006-07-15

The paper proposes an induction motor model for the study of harmonic load flow in balanced and unbalanced conditions. The parameters of this model are obtained from motor manufacturer data and the positive- and negative-sequence equivalent circuits of the single- and double-cage models. An approximate harmonic model based on motor manufacturer data only is also proposed. In addition, the paper includes manufacturer data and the calculated parameters of 36 induction motors of different rated powers. This database is used to analyze the proposed models. (author)

Second-harmonic generation of practical Bessel beams

Science.gov (United States)

Huang, Jin H.; Ding, Desheng; Hsu, Yin-Sung

2009-11-01

A fast Gaussian expansion approach is used to investigate fundamental and second-harmonic generation in practical Bessel beams of finite aperture. The analysis is based on the integral solutions of the KZK equation under the quasilinear approximation. The influence of the medium's attenuation on the beam profile is considered. Analysis results show that the absorption parameter has a significant effect on the far-field beam profile of the second harmonic. Under certain circumstances, the second harmonic of a practical Bessel beam still has the main properties of an ideal Bessel beam of infinite aperture when it propagates within its depth of field.

Feasibility study of generating ultra-high harmonic radiation with a single stage echo-enabled harmonic generation scheme

Energy Technology Data Exchange (ETDEWEB)

Zhou, Kaishang, E-mail: zhoukaishang@sinap.ac.cn; Feng, Chao, E-mail: fengchao@sinap.ac.cn; Wang, Dong, E-mail: wangdong@sinap.ac.cn

2016-10-21

The echo enabled harmonic generation (EEHG) scheme holds the ability for the generation of fully coherent soft x-ray free-electron laser (FEL) pulses directly from external UV seeding sources. In this paper, we study the feasibility of using a single stage EEHG to generate coherent radiation in the “water window” and beyond. Using the high-order operating modes of the EEHG scheme, intensive numerical simulations have been performed considering various three-dimensional effects. The simulation results demonstrated that coherent soft x-ray radiation at 150th harmonic (1.77 nm) of the seed can be produced by a single stage EEHG. The decreasing of the final bunching factor at the desired harmonic caused by intra beam scattering (IBS) effect has also been analyzed.

Symmetry properties of second harmonics generated by antisymmetric Lamb waves

Science.gov (United States)

Zhu, Wujun; Xiang, Yanxun; Liu, Chang-Jun; Deng, Mingxi; Xuan, Fu-Zhen

2018-03-01

Symmetry properties of second harmonics generated by antisymmetric primary Lamb waves are systematically studied in this work. In theory, the acoustic field of second harmonic Lamb waves is obtained by using the perturbation approximation and normal modal method, and the energy flux transfer from the primary Lamb waves to second harmonics is mainly explored. Symmetry analyses indicate that either the symmetric or antisymmetric Lamb waves can merely generate the symmetric second harmonics. Finite element simulations are performed on the nonlinear Lamb wave propagation of the antisymmetric A0 mode in the low frequency region. The signals of the second harmonics and the symmetric second harmonic s0 mode are found to be exactly equivalent in the time domain. The relative acoustic nonlinearity parameter A2/A12 oscillates with the propagation distance, and the oscillation amplitude and spatial period are well consistent with the theoretical prediction of the A0-s0 mode pair, which means that only the second harmonic s0 mode is generated by the antisymmetric primary A0 mode. Experiments are further conducted to examine the cumulative generation of symmetric second harmonics for the antisymmetric-symmetric mode pair A3-s6. Results show that A2/A12 increases linearly with the propagation distance, which means that the symmetric second harmonic s6 mode is generated cumulatively by the antisymmetric primary A3 mode. The present investigation systematically corroborates the proposed theory that only symmetric second harmonics can be generated accompanying the propagation of antisymmetric primary Lamb waves in a plate.

Harmonic analysis in integrated energy system based on compressed sensing

International Nuclear Information System (INIS)

Yang, Ting; Pen, Haibo; Wang, Dan; Wang, Zhaoxia

2016-01-01

Highlights: • We propose a harmonic/inter-harmonic analysis scheme with compressed sensing theory. • Property of sparseness of harmonic signal in electrical power system is proved. • The ratio formula of fundamental and harmonic components sparsity is presented. • Spectral Projected Gradient-Fundamental Filter reconstruction algorithm is proposed. • SPG-FF enhances the precision of harmonic detection and signal reconstruction. - Abstract: The advent of Integrated Energy Systems enabled various distributed energy to access the system through different power electronic devices. The development of this has made the harmonic environment more complex. It needs low complexity and high precision of harmonic detection and analysis methods to improve power quality. To solve the shortages of large data storage capacities and high complexity of compression in sampling under the Nyquist sampling framework, this research paper presents a harmonic analysis scheme based on compressed sensing theory. The proposed scheme enables the performance of the functions of compressive sampling, signal reconstruction and harmonic detection simultaneously. In the proposed scheme, the sparsity of the harmonic signals in the base of the Discrete Fourier Transform (DFT) is numerically calculated first. This is followed by providing a proof of the matching satisfaction of the necessary conditions for compressed sensing. The binary sparse measurement is then leveraged to reduce the storage space in the sampling unit in the proposed scheme. In the recovery process, the scheme proposed a novel reconstruction algorithm called the Spectral Projected Gradient with Fundamental Filter (SPG-FF) algorithm to enhance the reconstruction precision. One of the actual microgrid systems is used as simulation example. The results of the experiment shows that the proposed scheme effectively enhances the precision of harmonic and inter-harmonic detection with low computing complexity, and has good

Characterization of Harmonic Signal Acquisition with Parallel Dipole and Multipole Detectors

Science.gov (United States)

Park, Sung-Gun; Anderson, Gordon A.; Bruce, James E.

2018-04-01

Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a powerful instrument for the study of complex biological samples due to its high resolution and mass measurement accuracy. However, the relatively long signal acquisition periods needed to achieve high resolution can serve to limit applications of FTICR-MS. The use of multiple pairs of detector electrodes enables detection of harmonic frequencies present at integer multiples of the fundamental cyclotron frequency, and the obtained resolving power for a given acquisition period increases linearly with the order of harmonic signal. However, harmonic signal detection also increases spectral complexity and presents challenges for interpretation. In the present work, ICR cells with independent dipole and harmonic detection electrodes and preamplifiers are demonstrated. A benefit of this approach is the ability to independently acquire fundamental and multiple harmonic signals in parallel using the same ions under identical conditions, enabling direct comparison of achieved performance as parameters are varied. Spectra from harmonic signals showed generally higher resolving power than spectra acquired with fundamental signals and equal signal duration. In addition, the maximum observed signal to noise (S/N) ratio from harmonic signals exceeded that of fundamental signals by 50 to 100%. Finally, parallel detection of fundamental and harmonic signals enables deconvolution of overlapping harmonic signals since observed fundamental frequencies can be used to unambiguously calculate all possible harmonic frequencies. Thus, the present application of parallel fundamental and harmonic signal acquisition offers a general approach to improve utilization of harmonic signals to yield high-resolution spectra with decreased acquisition time. [Figure not available: see fulltext.

International Harmonization of Reactor Licensing Regulations

International Nuclear Information System (INIS)

Kuhnt, Dietmar.

1977-01-01

The purpose of a harmonization policy for reactor licensing regulations on the basis of already considerable experience is to attain greater rationalisation in this field, in the interest of economic policy and healthy competition, and most important, radiation protection and safety of installations. This paper considers the legal instruments for such harmonization and the conditions for their implementation, in particular within the Communities framework. (NEA) [fr

Generalized Harmonic Functions and the Dewetting of Thin Films

International Nuclear Information System (INIS)

Auchmuty, Giles; Kloucek, Petr

2007-01-01

This paper describes the solvability of Dirichlet problems for Laplace's equation when the boundary data is not smooth enough for the existence of a weak solution in H 1 Ω. Scales of spaces of harmonic functions and of boundary traces are defined and the solutions are characterized as limits of classical harmonic functions in special norms. The generalized harmonic functions, and their norms, are defined using series expansions involving harmonic Steklov eigenfunctions on the domain. It is shown that the usual trace operator has a continuous extension to an isometric isomorphism of specific spaces. This provides a characterization of the generalized solutions of harmonic Dirichlet problems. Numerical simulations of a model problem are described. This problem is related to the dewetting of thin films and the associated phenomenology is described

The harmonized INFOGEST in vitro digestion method

NARCIS (Netherlands)

Egger, Lotti; Ménard, Olivia; Delgado-Andrade, Cristina; Alvito, Paula; Assunção, Ricardo; Balance, Simon; Barberá, Reyes; Brodkorb, Andre; Cattenoz, Thomas; Clemente, Alfonso; Comi, Irene; Dupont, Didier; Garcia-Llatas, Guadalupe; Lagarda, María Jesús; Feunteun, Le Steven; Janssen Duijghuijsen, Lonneke; Karakaya, Sibel; Lesmes, Uri; Mackie, Alan R.; Martins, Carla; Meynier, Anne; Miralles, Beatriz; Murray, B.S.; Pihlanto, Anne; Picariello, Gianluca; Santos, C.N.; Simsek, Sebnem; Recio, Isidra; Rigby, Neil; Rioux, Laurie Eve; Stoffers, Helena; Tavares, Ana; Tavares, Lucelia; Turgeon, Sylvie; Ulleberg, E.K.; Vegarud, G.E.; Vergères, Guy; Portmann, Reto

2016-01-01

Within the active field of in vitro digestion in food research, the COST Action INFOGEST aimed to harmonize in vitro protocols simulating human digestion on the basis of physiologically inferred conditions. A harmonized static in vitro digestion (IVD) method was recently published as a primary

Analysis on h-harmonics and Dunkl transforms

CERN Document Server

2015-01-01

As a unique case in this Advanced Courses book series, the authors have jointly written this introduction to h-harmonics and Dunkl transforms. These are extensions of the ordinary spherical harmonics and Fourier transforms, in which the usual Lebesgue measure is replaced by a reflection-invariant weighted measure. The theory, originally introduced by C. Dunkl, has been expanded on by many authors over the last 20 years. These notes provide an overview of what has been developed so far. The first chapter gives a brief recount of the basics of ordinary spherical harmonics and the Fourier transform. The Dunkl operators, the intertwining operators between partial derivatives and the Dunkl operators are introduced and discussed in the second chapter. The next three chapters are devoted to analysis on the sphere, and the final two chapters to the Dunkl transform. The authors’ focus is on the analysis side of both h-harmonics and Dunkl transforms. The need for background knowledge on reflection groups is kept to a...

Harmonic Content of the BESSY FEL Radiation

CERN Document Server

Meseck, Atoosa

2005-01-01

BESSY proposes a linac-based cascaded High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) multi-user facility. The BESSY soft X-ray FEL will consist of three undulator lines. The associated tunable lasers will cover the spectral range of 230nm to 460nm. Two to four HGHG stages reduce the seed wavelength to the desired radiation range of 1.24nm < λ < 51nm. The harmonic content of the high-intensity radiator output can be used to reduce the number of necessary HGHG stages. Moreover the higher harmonic content of the final output extends the offered spectral range and thus is of high interest for the user community. In this paper, the higher harmonic content of the final output as well as of the output of several radiators are investigated. The main parameters such as output power, pulse duration and bandwidth as well as their suitability for seeding are discussed.

Intelligent harmonic load model based on neural networks

Science.gov (United States)

Ji, Pyeong-Shik; Lee, Dae-Jong; Lee, Jong-Pil; Park, Jae-Won; Lim, Jae-Yoon

2007-12-01

In this study, we developed a RBFNs(Radial Basis Function Networks) based load modeling method with harmonic components. The developed method implemented by using harmonic information as well as fundamental frequency and voltage which are essential input factors in conventional method. Thus, the proposed method makes it possible to effectively estimate load characteristics in power lines with harmonics. The RBFNs have certain advantage such as simple structure and rapid computation ability compared with multilayer perceptron which is extensively applied for load modeling. To show the effectiveness, the proposed method has been intensively tested with various dataset acquired under the different frequency and voltage and compared it with conventional methods such as polynominal 2nd equation method, MLP and RBF without considering harmonic components.

Optical third-harmonic generation using ultrashort laser pulses

International Nuclear Information System (INIS)

Stoker, D.; Keto, J.W.; Becker, M.F.

2005-01-01

To better predict optical third-harmonic generation (THG) in transparent dielectrics, we model a typical ultrashort pulsed Gaussian beam, including both group velocity mismatch and phase mismatch of the fundamental and harmonic fields. We find that competition between the group velocity mismatch and phase mismatch leads to third-harmonic generation that is sensitive only to interfaces. In this case, the spatial resolution is determined by the group velocity walk-off length. THG of modern femtosecond lasers in optical solids is a bulk process, without a surface susceptibility, but bears the signature of a surface enhancement effect in z-scan measurements. We demonstrate the accuracy of the model, by showing the agreement between the predicted spectral intensity and the measured third-harmonic spectrum from a thin sapphire crystal

Harmonics in large offshore wind farms

DEFF Research Database (Denmark)

Kocewiak, Lukasz Hubert

and nature of various harmonic components. A comprehensive comparison of harmonic voltages and currents based on probability distribution estimation and appropriate statistics calculation (mean, variance, probability density function, etc.) is applied. Such approach gives a better overview and comparison...... and analysis, and ϐinally ending up on modelling and models application. Different aspects of validation in time domain, frequency domain, and by application of statistical methods are mentioned in relation to respective problems. Measurements constitute a core part in industry-oriented research. Due...... that it is of great importance to know the nature of generated harmonics in large offshore wind farms in order to apply the most suitable data processing technique. Time-frequency analysis based on multiresolution wavelet transform is used in order to perform time-frequency domain analysis helpful to distinguish...

Diffractive-refractive optics: (+,-,-,+) X-ray crystal monochromator with harmonics separation.

Science.gov (United States)

Hrdý, Jaromír; Mikulík, Petr; Oberta, Peter

2011-03-01

A new kind of two channel-cut crystals X-ray monochromator in dispersive (+,-,-,+) position which spatially separates harmonics is proposed. The diffracting surfaces are oriented so that the diffraction is inclined. Owing to refraction the diffracted beam is sagittally deviated. The deviation depends on wavelength and is much higher for the first harmonics than for higher harmonics. This leads to spatial harmonics separation. The idea is supported by ray-tracing simulation.

Elements of abstract harmonic analysis

CERN Document Server

Bachman, George

2013-01-01

Elements of Abstract Harmonic Analysis provides an introduction to the fundamental concepts and basic theorems of abstract harmonic analysis. In order to give a reasonably complete and self-contained introduction to the subject, most of the proofs have been presented in great detail thereby making the development understandable to a very wide audience. Exercises have been supplied at the end of each chapter. Some of these are meant to extend the theory slightly while others should serve to test the reader's understanding of the material presented. The first chapter and part of the second give

Conformal invariance in harmonic superspace

International Nuclear Information System (INIS)

Galperin, A.; Ivanov, E.; Ogievetsky, V.; Sokatchev, E.

1987-01-01

In the present paper we show how the N = 2 superconformal group is realised in harmonic superspace and examine conformal invariance of N = 2 off-shell theories. We believe that the example of N = O self-dual Yang-Mills equations can serve as an instructive introduction to the subject of harmonic superspace and this is examined. The rigid N = 2 conformal supersymmetry and its local version, i.e. N = 2 conformal supergravity is also discussed. The paper is a contribution to the book commemorating the sixtieth birthday of E.S. Fradkin. (author)

Axis-encircling electron beam generation using a smooth magnetic cusp for gyrodevices

International Nuclear Information System (INIS)

He, W.; Whyte, C. G.; Rafferty, E. G.; Cross, A. W.; Phelps, A. D. R.; Ronald, K.; Young, A. R.; Robertson, C. W.; Speirs, D. C.; Rowlands, D. H.

2008-01-01

The generation of an annular-shaped axis-encircling electron beam using a smooth magnetic cusp was studied through numerical simulations and experiments for harmonic operation of a gyrodevice. Two magnetic coils were used to form a magnetic cusp located just downstream from the velvet cathode of an accelerator diode. An electron beam of current 34 A and voltage 130 kV with an adjustable velocity ratio α up to 1.2 was fully transported to the downstream uniform magnetic field region and used to drive a gyrotron traveling wave amplifier into saturation

Dynamics of harmonically-confined systems: Some rigorous results