Development of an x-ray klystron modulator with a pulse-forming line and magnetic switch

International Nuclear Information System (INIS)

Akemoto, M.; Takeda, S.

1992-01-01

A new type of klystron modulator has been developed for the Japan Linear Collider. It consists of a pulse-forming line (PFL), a pulse transformer and a magnetic switch. In order to realize a compact modulator, a triplate strip transmission line using deionized water as a dielectric was adapted. An Fe amorphous core was used for the magnetic switch and the pulse transformer to reduce the size and cost. A preliminary test has shown that an output pulse with a peak voltage of 550 kV, a pulse length (flat-top) of 440 ns and a rise time of 165 ns can be generated for a dummy load with an impedance of 412Ω. It was also experimentally confirmed that the power efficiency of the modulator is approximately 83%. (Author) 7 figs., 3 tabs., 2 refs

A unique power supply for the PEP II klystron at SLAC

International Nuclear Information System (INIS)

Cassel, R.; Nguyen, M.N.

1997-07-01

Each of the eight 1.2 MW RF klystrons for the PEP-II storage rings require a 2.5 MVA DC power supply of 83 Kv at 23 amps. The design for the supply was base on three factors, low cost, small size to fit existing substation pads, and good protection against damage to the klystron including klystron gun arcs. The supply uses a 12 pulse 12.5 KV primary thyristor star point controller with primary filter inductor to provide rapid voltage control, good voltage regulation, and fast turn off during klystron tube faults. The supply also uses a unique secondary rectifier, filter capacitor configuration to minimize the energy available under a klystron fault. The voltage control is from 0--90 KV with a regulation of < 0.1% and voltage ripple of < 1% P-P, (< 0.2% RMS) above 60 KV. The supply utilizes a thyristor crowbar, which under a klystron tube arc limits the energy in the klystron arc to < 5 joules. If the thyristor crowbar is disabled the energy supplied is < 40 joules into the arc. The size of the supply was reduced small enough to fit the existing PEP transformer yard pads. The cost of the power supply was < $140 per KVA

High power switches for ion induction linacs

International Nuclear Information System (INIS)

Humphries, S. Jr.; Savage, M.; Saylor, W.B.

1985-01-01

The success of linear induction ion accelerators for accelerator inertial fusion (AIF) applications depends largely on innovations in pulsed power technology. There are tight constraints on the accuracy of accelerating voltage waveforms to maintain a low momentum spread. Furthermore, the non-relativistic ion beams may be subject to a klystron-like interaction with the accelerating cavities leading to enhanced momentum spread. In this paper, the author describe a novel high power switch with a demonstrated ability to interrupt 300 A at 20 kV in less than 60 ns. The switch may allow the replacement of pulse modulators in linear induction accelerators with hard tube pulsers. A power system based on a hard tube pulser could solve the longitudinal instability problem while maintaining high energy transfer efficiency. The problem of longitudinal beam control in ion induction linacs is reviewed in Section 2. Section 3 describes the principles of the plasma flow switch. Experimental results are summarized in Section 4

High power ubitron-klystron

International Nuclear Information System (INIS)

Balkcum, A.J.; McDermott, D.B.; Luhmann, N.C. Jr.

1997-01-01

A coaxial ubitron is being considered as the rf driver for the Next Linear Collider (NLC). Prior simulation of a traveling-wave ubitron using a self-consistent code found that 200 MW of power and 53 dB of gain could be achieved with 37% efficiency. In a ubiron-klystron, a series of cavities are used to obtain an even tighter electron bunch for higher efficiency. A small-signal theory of the ubitron-klystron shows that gain scales with the square of the cavity separation distance. A linear stability theory has also been developed. Verification of the stability theory has been achieved using the 2-12-D PIC code, MAGIC, and the particle-tracing code. Saturation characteristics of the amplifier will be presented using both MAGIC and a simpler self-consistent slow-timescale code currently under development. The ubitron can also operate as a compact, highly efficient oscillator. Cavities only two wiggler periods in length have yielded up to 40% rf conversion efficiency in simulation. An initial oscillator design for directed energy applications will also be presented

New klystron technology

Science.gov (United States)

Faillon, G.

1985-10-01

It is pointed out that klystrons representing high-power RF sources are mainly used in applications related to radars and scientific instrumentation. High peak power pulsed klystrons are discussed. It is found that a large number of linacs are powered by S-band klystrons (2.856 or 2.9985 GHz) with pulse durations of a few microseconds. Special precautions are being taken to insure that the breakdown voltage will not be reached, and very thin titanium coatings are employed to protect the ceramic against discharges. Attention is given to very large pulse width tubes, CW tubes, and limits of the power-frequency domain.

Enhancing the power output of the VA-955 UHF-TV klystron

International Nuclear Information System (INIS)

Bowen, O.N.; Lawson, J.Q.

1977-01-01

The Varian VA-955 UHF-TV klystron is rated at 50 kW CW, and four of these klystrons were used to provide 200 kW of RF power for lower hybrid heating experiments on the ATC machine at 800 MHz. These proven, production-type tubes were wanted to generate more power for larger type machines, such as the PDX. Varian was asked whether the tubes were capable of higher-power operation in pulsed applications. They replied that they had no experimental data but felt that the tubes were capable of greatly enhanced performance under pulsed conditions. By using cathode modulation instead of modulating anode control of the klystron, and thus limiting the time that high voltage is applied to the cathode, it was shown that the tube is capable of an output power of 200 kW for tens of milliseconds compared to its normal CW rating of 50 kW. A description is given of the experimental results, the required modifications to the klystron and output transmission circuit, the details of operation of the regulating modulator used to perform the experiment. Upgrade kits are now being fabricated to allow 200 kW operation of the two 50 kW units which were lent to General Atomic for Doublet II experiments

High-power test of S-band klystron for long-pulse operation

International Nuclear Information System (INIS)

Morii, Y.; Oshita, E.; Abe, S.; Keishi, T.; Tomimasu, T.; Ohkubo, Y.; Yoshinao, M.; Yonezawa, H.

1994-01-01

FELI(Free Electron Laser Research Institute, Inc.) is constructing a free electron laser facility covering from 20μm (infra red region) to 0.35μm (ultra violet region), using an S-band linac. The linac is commissioning now. An RF system of the linac for FELs is required of long pulse duration and high stability. S-band klystrons (TOSHIBA E3729) of the FELI linac are operated in three pulse operation modes (pulse width and peak RF power; 24μs-24MW, 12.5μs-34MW, 0.5μs-70MW). The S-band klystron and its modulator were combined to test their performance. The high power test results of the S-band klystron are summarized in this paper. (author)

Klystron Gun Arcing and Modulator Protection

International Nuclear Information System (INIS)

Gold, S

2004-01-01

The demand for 500 kV and 265 amperes peak to power an X-Band klystron brings up protection issues for klystron faults and the energy dumped into the arc from the modulator. This situation is made worse when more than one klystron will be driven from a single modulator, such as the existing schemes for running two and eight klystrons. High power pulsed klystrons have traditionally be powered by line type modulators which match the driving impedance with the load impedance and therefore current limit at twice the operating current. Multiple klystrons have the added problems of a lower modulator source impedance and added stray capacitance, which converts into appreciable energy at high voltages like 500kV. SLAC has measured the energy dumped into klystron arcs in a single and dual klystron configuration at the 400 to 450 kV level and found interesting characteristics in the arc formation. The author will present measured data from klystron arcs powered from line-type modulators in several configurations. The questions arise as to how the newly designed solid-state modulators, running multiple tubes, will react to a klystron arc and how much energy will be dumped into the arc

Relativistic klystrons

International Nuclear Information System (INIS)

Allen, M.A.; Azuma, O.; Callin, R.S.

1989-03-01

Experimental work is underway by a SLAC-LLNL-LBL collaboration to investigate the feasibility of using relativistic klystrons as a power source for future high gradient accelerators. Two different relativistic klystron configurations have been built and tested to date: a high grain multicavity klystron at 11.4 GHz and a low gain two cavity subharmonic buncher driven at 5.7 GHz. In both configurations power is extracted at 11.4 GHz. In order to understand the basic physics issues involved in extracting RF from a high power beam, we have used both a single resonant cavity and a multi-cell traveling wave structure for energy extraction. We have learned how to overcome our previously reported problem of high power RF pulse shortening, and have achieved peak RF power levels of 170 MW with the RF pulse of the same duration as the beam current pulse. 6 refs., 3 figs., 3 tabs

Clipper circuit of pulse modulator used for klystron-5045 power supply

CERN Document Server

Akimov, A V

2001-01-01

While the operation of modulator to the pulsed transformer of klystron-5045, current through the primary winding of the pulse transformer (PT) continues to flow even upon the end of the klystron voltage operating pulse. This is determined by an energy stored in magnetizing inductance. The prolongation of magnetizing current passing process simultaneously with the premature choking of thyratron can cause high voltage of inverse polarity at the klystron, which cause the destruction of the cathode. We have considered the possibility of shortening time of magnetizing current passage for the charge of reasonable choice of clipper circuit parameters. The behavior of clipper circuit was studied in modulators used for the VEPP-5 (BINP, Russia) preinjector klystron power supply. The optimum operation run of the circuit was selected and its design features are described.

Pulsed klystrons with feedback controlled mod-anode modulators

Energy Technology Data Exchange (ETDEWEB)

Reass, William A [Los Alamos National Laboratory; Baca, David M [Los Alamos National Laboratory; Jerry, Davis L [Los Alamos National Laboratory; Rees, Daniel E [Los Alamos National Laboratory

2009-01-01

This paper describes a fast rise and fall, totem-pole mod-anode modulators for klystron application. Details of these systems as recently installed utilizing a beam switch tube ''on-deck'' and a planar triode ''off-deck'' in a grid-catch feedback regulated configuration will be provided. The grid-catch configuration regulates the klystron mod-anode voltage at a specified set-point during switching as well as providing a control mechanism that flat-top regulates the klystron beam current during the pulse. This flat-topped klystron beam current is maintained while the capacitor bank droops. In addition, we will review more modern on-deck designs using a high gain, high voltage planar triode as a regulating and switching element. These designs are being developed, tested, and implemented for the Los Alamos Neutron Science Center (LANSCE) accelerator refurbishment project, ''LANSCE-R''. An advantage of the planar triode is that the tube can be directly operated with solid state linear components and provides for a very compact design. The tubes are inexpensive compared to stacked semiconductor switching assemblies and also provide a linear control capability. Details of these designs are provided as well as operational and developmental results.

Thyratron-PFN, IGBT Hybrid, and Direct Switched Modulator R and D As it Effects Klystron Protection

International Nuclear Information System (INIS)

Gold, Saul L

2000-01-01

Modulator development is an ongoing program at SLAC. The Stanford Linear Accelerator with its approximately 240 klystrons and modulators operates for 6,000 plus hours a year. This operation gives SLAC an important insight into component and system reliability in the High Voltage environment. The planned NLC is approximately 10 times the size of SLAC and the High Voltage Modulator Klystron systems are one of the largest cost drivers. This paper will contain a brief progress report on the optimized Line Modulator and touch on Solid-State advances, which make Solid State, High Power pulse modulators the wave of the future. Klystron protection remains a critical issue along with modulator reliability, efficiency and cost. Configurations whereby multiple klystrons are paralleled on a single modulator may exacerbate the problem. The majority of this paper will discuss tests at SLAC of klystron arcs on Line-type modulators with single and double klystron loads. This talk may introduce and refer to other talks at this conference and other conferences by National and Foreign Laboratory collaborators and Industry, specifically in relation to DOE SBIR programs

Transient analysis of multicavity klystrons

International Nuclear Information System (INIS)

Lavine, T.L.; Miller, R.H.; Morton, P.L.; Ruth, R.D.

1988-09-01

We describe a model for analytic analysis of transients in multicavity klystron output power and phase. Cavities are modeled as resonant circuits, while bunching of the beam is modeled using linear space-charge wave theory. Our analysis has been implemented in a computer program which we use in designing multicavity klystrons with stable output power and phase. We present as examples transient analysis of a relativistic klystron using a magnetic pulse compression modulator, and of a conventional klystron designed to use phase shifting techniques for RF pulse compression. 4 refs., 4 figs

Klystron switching power supplies for the Internation Linear Collider

Energy Technology Data Exchange (ETDEWEB)

Fraioli, Andrea; /Cassino U. /INFN, Pisa

2009-12-01

The International Linear Collider is a majestic High Energy Physics particle accelerator that will give physicists a new cosmic doorway to explore energy regimes beyond the reach of today's accelerators. ILC will complement the Large Hadron Collider (LHC), a proton-proton collider at the European Center for Nuclear Research (CERN) in Geneva, Switzerland, by producing electron-positron collisions at center of mass energy of about 500 GeV. In particular, the subject of this dissertation is the R&D for a solid state Marx Modulator and relative switching power supply for the International Linear Collider Main LINAC Radio Frequency stations.

Simulation of Oscillations in High Power Klystrons

CERN Document Server

Ko, K

2003-01-01

Spurious oscillations can seriously limit a klystron's performance from reaching its design specifications. These are modes with frequencies different from the drive frequency, and have been found to be localized in various regions of the tube. If left unsuppressed, such oscillations can be driven to large amplitudes by the beam. As a result, the main output signal may suffer from amplitude and phase instabilities which lead to pulse shortening or reduction in power generation efficiency, as observed during the testing of the first 150MW S-band klystron, which was designed and built at SLAC as a part of an international collaboration with DESY. We present efficient methods to identify suspicious modes and then test their possibility of oscillation. In difference to [3], where each beam-loaded quality-factor Qbl was calculated by time-consuming PIC simulations, now only tracking-simulations with much reduced cpu-time and less sensitivity against noise are applied. This enables the determination of Qbl for larg...

APS linac klystron and accelerating structure gain measurements and klystron PFN voltage regulation requirements

International Nuclear Information System (INIS)

Sereno, N.S.

1997-01-01

This note details measurements of the APS positron linac klystron and accelerating structure gain and presents an analysis of the data using fits to simple mathematical models. The models are used to investigate the sensitivity of the energy dependence of the output positron beam to klystron parameters. The gain measurements are separated into two parts: first, the energy gains of the accelerating structures of the positron linac are measured as a function of output power of the klystron; second, the klystron output power is measured as a function of input drive power and pulse forming network (PFN) voltage. This note concentrates on the positron linac rf and its performance as it directly affects the energy stability of the positron beam injected into the positron accumulator ring (PAR). Ultimately it is important to be able to minimize beam energy variations to maximize the PAR accumulation efficiency

Performance of high power S-band klystrons focused with permanent magnet

International Nuclear Information System (INIS)

Fukuda, S.; Shidara, T.; Saito, Y.; Hanaki, H.; Nakao, K.; Homma, H.; Anami, S.; Tanaka, J.

1987-02-01

Performance of high power S-band klystrons focused with permanent magnet is presented. The axial magnetic field distribution and the transverse magnetic field play an important role in the tube performance. Effects of the reversal field in the collector and the cathode-anode region are discussed precisely. It is also shown that the tube efficiency is strongly affected with the residual transverse magnetic field. The allowable transverse field is less than 0.3 % of the longitudinal field in the entire rf interaction region of the klystron. (author)

Performance of high power S-band klystrons focused with permanent magnet

Science.gov (United States)

Fukuda, S.; Shidara, T.; Saito, Y.; Hanaki, H.; Nakao, K.; Homma, H.; Anami, S.; Tanaka, J.

1987-02-01

Performance of high power S-band klystrons focused with permanent magnet is presented. The axial magnetic field distribution and the transverse magnetic field play an important role in the tube performance. Effects of the reversal field in the collector and the cathode-anode region are discussed precisely. It is also shown that the tube efficiency is strongly affected with the residual transverse magnetic field. The allowable transverse field is less than 0.3 percent of the longitudinal field in the entire RF interaction region of the klystron.

PLC control of 50 MW klystron modulators

International Nuclear Information System (INIS)

Shang Lei; Liu Gongfa; Chen Liping; Lu Yeming; Hong Jun; Zhang Yi; Zhao Feng

2004-01-01

Upgrade project of the 50 MW klystron modulators of Hefei Light Source (HLS) was firstly introduced. PLC control system of modulators was employed to replace the old control and monitor system, which was based on relay logic circuit and manual operation method. the PLC system becomes a sub system of the new EPICS control system of HLS. Constant-current, switch-mode and high voltage power supplies were adopted to replace the old 50 Hz power supplies. The technology of modulators was improved and operation was more reliable. The design method, hardware and software of PLC control of modulators were described and the performance was presented. (authors)

Performance of the SLAC Linear Collider klystrons

International Nuclear Information System (INIS)

Allen, M.A.; Fowkes, W.R.; Koontz, R.F.; Schwarz, H.D.; Seeman, J.T.; Vlieks, A.E.

1987-01-01

There are now 200 new, high power 5045 klystrons installed on the two-mile Stanford Linear Accelerator. Peak power per klystron averages over 63 MW. Average energy contribution is above 240 MeV per station. Electron beam energy has been measured as high as 53 GeV. Energy instability due to kylstron malfunction is less than 0.2%. The installed klystrons have logged over one million operating hours with close to 20,00 klystron hours cumulative operating time between failures. Data is being accumulated on klystron operation and failure modes with failure signatures starting to become apparent. To date, no wholesale failure modes have surfaced that would impair the SLAC linear Collider (SLC) program

Performance review of an indigenously developed high power test stand built for the Indian S-band 5 MW pulsed klystron development

International Nuclear Information System (INIS)

Shrivastava, Purushottam; Baxy, D.; Mulchandani, J.; Hannurkar, P.R.; Joshi, L.M.

2003-01-01

CAT took up development of 5 MW S-Band klystrons indigenously in collaboration with CEERI Pilani. The development of klystron prototype is completed. These klystrons are very crucial devices, for energizing the 10-20 MeV electron accelerators, which are developed in the country for various industrial, medical and scientific applications. A test station has been developed indigenously at CAT for these klystrons. It consists of a 12 MW peak power 130 kV klystron pulse modulator, a 1 : 10 pulse transformer, 130 kV high voltage deck having high voltage pulse divider, pulse current transformer as well indigenously built klystron socket, filament supplies, klystron support structure and pulse transformer oil tank. After development/rigorous testing the test stand was shifted to CEERI and was installed and commissioned there by CAT. Gun collector test module and prototypes of the 5 MW klystron were tested, aged and conditioned at high power using this test stand. The details of the system / test results are discussed

Two generations of klystrons reunited

CERN Multimedia

Katarina Anthony

2015-01-01

As the newest accelerator on the block, Linac4 is a hotbed of fresh technology and innovation. But among its many new elements you’ll find some familiar pieces, including eleven klystrons from CERN’s former flagship, LEP.   View of the Linac4 hall. The LEP klystrons (front and centre of the image) are surrounded by grey lead shielding. (Image: Suitbert Ramberger.) The Linac4 accelerator is powered by both new, state-of-the-art klystrons and former LEP klystrons. In fact, the first Drift Tube Linac (DTL) module is powered completely by these LEP klystrons. The last of the DTL modules has only just been installed in the Linac4 tunnel – a milestone that will soon take the accelerator up to 50 MeV, allowing it to act as a back-up machine for Linac2 for a few years before the complete handover to the CERN accelerator chain. It’s been a long journey to this point. Linac4 was first conceived in the early 2000s, and its design overlapped with the end of th...

Relativistic klystron research for linear colliders

International Nuclear Information System (INIS)

Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Lee, T.G.; Loew, G.A.; Miller, R.H.; Morton, P.L.; Palmer, R.B.; Paterson, J.M.; Ruth, R.D.; Schwarz, H.D.; Vlieks, A.E.; Wilson, P.B.

1989-01-01

Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron-positron colliders, compact accelerators, and FEL sources. The authors have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. In this paper the authors report on the design of our relativistic klystrons, the results of our experiments so far, and some of our plans for the near future

Relativistic klystron research for linear colliders

International Nuclear Information System (INIS)

Allen, M.A.; Callin, R.S.; Deruyter, H.

1988-09-01

Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron-positron colliders, compact accelerators, and FEL sources. We have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our relativistic klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 9 figs., 1 tab

Analysis of RF section of 250 kW CW C-Band high power klystron

International Nuclear Information System (INIS)

Badola, Richa; Kaushik, Meenu; Baloda, Suman; Kirti; Vrati; Lamba, O.S.; Joshi, L.M.

2012-01-01

Klystron is a microwave tube which is used as a power amplifier in various applications like radar, particle accelerators and thermonuclear reactors. The paper deals with the analysis of RF section of 250 kW CW C band high power klystron for 50 to 60 kV beam voltage The simulation is done using Poisson's superfish and AJ disk software's Design of cavity is done using superfish. The result of superfish is used to decide the dimensions of the geometry of the cavity and AJ disk is used to determined the centre to centre distances between the cavities in order to obtain the desired powers. (author)

Relativistic klystron research for linear colliders

International Nuclear Information System (INIS)

Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Herrmannesfeldt, W.B.; Higo, T.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Lee, T.G.; Loew, G.A.; Miller, R.H.; Morton, P.L.; Palmer, R.B.; Paterson, J.M.; Ruth, R.D.; Schwarz, H.D.; Takeuchi, Y.; Vlieks, A.E.; Wang, J.W.; Wilson, P.B.; Hopkins, D.B.; Sessler, A.M.; Ryne, R.D.; Westenskow, G.A.; Yu, S.S.

1989-01-01

Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron-positron colliders, compact accelerators, and FEL sources. The authors have attained 200MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. They report here on the design of our relativistic klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 9 figs., 1 tab

X-band klystrons for Japan Linear Collider

International Nuclear Information System (INIS)

Mizuno, H.; Odagiri, J.; Higo, T.; Yonezawa, H.; Yamaguchi, N.

1992-01-01

To achieve the acceleration gradient of 100 MeV/m necessary for the future linear collider in X-band, an RF power source which could produce more than 100 MW peak power with the pulse duration of 500 nsec is needed even with the factor 4 RF pulse compression system. As the first step for the development of the 100 MW class klystrons in X-band (11.424 GHz), a 30 MW class klystron named XB-50K was tested several times since 1990. XB-50K was tested up to the peak power of 18 MW with the pulse duration of 100 ns. A new 100 MW class klystron named XB-72K was designed and fabricated. Some test results of this klystron are reported. (Author) 9 refs., 3 figs., 2 tabs

S-band 300 W pulsed solid state microwave amplifier development for driving high power klystrons for electron accelerators

International Nuclear Information System (INIS)

Mohania, Praveen; Shrivastava, Purushottam; Hannurkar, P.R.

2005-01-01

S-Band Microwave electron accelerators like microtrons and linear accelerators need pulsed microwaves from few megawatts to tens of megawatts to accelerator the electrons to desired energy and intensity. Klystron tube based driver amplifiers were used to drive the high power klystrons, which need microwave power from few tens of watts to 1 kW depending on tube output power and gain. A endeavour was initiated at Centre for Advanced Technology to develop state of art solid state S-band microwave amplifiers indigenously to drive the klystron tubes. A modular design approach was used and individual modules up to 160 W power levels were developed and tested. Finally combining 160 W modules will give up to 300 W output power. Several more modules can be combined to achieve even high power levels. Present paper describes the developmental efforts of 300 W S-band solid-state amplifiers and related microwave technologies. (author)

Relativistic klystron research for high gradient accelerators

International Nuclear Information System (INIS)

Allen, M.A.; Callin, R.S.; Deruyter, H.

1988-06-01

Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron--positron colliders, compact accelerators, and FEL sources. We have attained 200MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our first klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 7 figs

Development of High Power Vacuum Tubes for Accelerators and Plasma Heating

International Nuclear Information System (INIS)

Srivastava, Vishnu

2012-01-01

High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

Development of High Power Vacuum Tubes for Accelerators and Plasma Heating

Science.gov (United States)

Srivastava, Vishnu

2012-11-01

High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

Transient analysis of the output short-circuit fault of high power and high voltage DC power supply

International Nuclear Information System (INIS)

Yang Zhigang; Zhang Jian; Huang Yiyun; Hao Xu; Sun Haozhang; Guo Fei

2014-01-01

The transient conditions of output short-circuit fault of high voltage DC power supply was introduced, and the energy of power supply injecting into klystron during the protection process of three-electrode gas switch were analyzed and calculated in detail when klystron load happening electrode arc faults. The results of calculation and simulation are consistent with the results of the experiment. When the output short-circuit fault of high voltage power supply occurs, switch can be shut off in the microsecond, and the short circuit current can be controlled in 200 A. It has verified the rapidity and reliability of the three-electrode gas switch protection, and it has engineering application value. (authors)

Phase locking of an S-band wide-gap klystron amplifier with high power injection driven by a relativistic backward wave oscillator

Energy Technology Data Exchange (ETDEWEB)

Bai Xianchen; Zhang Jiande; Yang Jianhua; Jin Zhenxing [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2012-12-15

Theoretical analyses and preliminary experiments on the phase-locking characteristics of an inductively loaded 2-cavity wide-gap klystron amplifier (WKA) with high power injection driven by a GW-class relativistic backward wave oscillator (RBWO) are presented. Electric power of the amplifier and oscillator is supplied by a single accelerator being capable of producing dual electron beams. The well phase-locking effect of the RBWO-WKA system requires the oscillator have good frequency reproducibility and stability from pulse to pulse. Thus, the main switch of the accelerator is externally triggered to stabilize the diode voltage and then the working frequency. In the experiment, frequency of the WKA is linearly locked by the RBWO. With a diode voltage of 530 kV and an input power of {approx}22 MW, an output power of {approx}230 MW with the power gain of {approx}10.2 dB is obtained from the WKA. As the main switch is triggered, the relative phase difference between the RBWO and the WKA is less than {+-}15 Degree-Sign in a single shot, and phase jitter of {+-}11 Degree-Sign is obtained within a series of shots with duration of about 40 ns.

Phase locking of an S-band wide-gap klystron amplifier with high power injection driven by a relativistic backward wave oscillator

Science.gov (United States)

Bai, Xianchen; Zhang, Jiande; Yang, Jianhua; Jin, Zhenxing

2012-12-01

Theoretical analyses and preliminary experiments on the phase-locking characteristics of an inductively loaded 2-cavity wide-gap klystron amplifier (WKA) with high power injection driven by a GW-class relativistic backward wave oscillator (RBWO) are presented. Electric power of the amplifier and oscillator is supplied by a single accelerator being capable of producing dual electron beams. The well phase-locking effect of the RBWO-WKA system requires the oscillator have good frequency reproducibility and stability from pulse to pulse. Thus, the main switch of the accelerator is externally triggered to stabilize the diode voltage and then the working frequency. In the experiment, frequency of the WKA is linearly locked by the RBWO. With a diode voltage of 530 kV and an input power of ˜22 MW, an output power of ˜230 MW with the power gain of ˜10.2 dB is obtained from the WKA. As the main switch is triggered, the relative phase difference between the RBWO and the WKA is less than ±15° in a single shot, and phase jitter of ±11° is obtained within a series of shots with duration of about 40 ns.

Mode control in a high gain relativistic klystron amplifier with 3 GW output power

Science.gov (United States)

Wu, Yang; Xie, Hong-Quan; Xu, Zhou

2014-01-01

Higher mode excitation is very serious in the relativistic klystron amplifier, especially for the high gain relativistic amplifier working at tens of kilo-amperes. The mechanism of higher mode excitation is explored in the PIC simulation and it is shown that insufficient separation of adjacent cavities is the main cause of higher mode excitation. So RF lossy material mounted on the drift tube wall is adopted to suppress higher mode excitation. A high gain S-band relativistic klystron amplifier is designed for the beam current of 13 kA and the voltage of 1 MV. PIC simulation shows that the output power is 3.2 GW when the input power is only 2.8 kW.

Design and development of a 6 MW peak, 24 kW average power S-band klystron

Energy Technology Data Exchange (ETDEWEB)

Joshi, L.M.; Meena, Rakesh; Nangru, Subhash; Kant, Deepender; Pal, Debashis; Lamba, O.S.; Jindal, Vishnu; Jangid, Sushil Kumar, E-mail: joslm@rediffmail.com [Central Electronics Engineering Research Institute, Council of Scientific and Industrial Research, Pilani (India); Chakravarthy, D.P.; Dixit, Kavita [Bhabha Atomic Research Centre, Mumbai (India)

2011-07-01

A 6 MW peak, 24 kW average power S-band Klystron is under development at CEERI, Pilani under an MoU between BARC and CEERI. The design of the klystron has been completed. The electron gun has been designed using TRAK and MAGIC codes. RF cavities have been designed using HFSS and CST Microwave Studio while the complete beam wave interaction simulation has been done using MAGIC code. The thermal design of collector and RF window has been done using ANSYS code. A Gun Collector Test Module (GCTM) was developed before making actual klystron to validate gun perveance and thermal design of collector. A high voltage solid state pulsed modulator has been installed for performance valuation of the tube. The paper will cover the design aspects of the tube and experimental test results of GCTM and klystron. (author)

Design and development of a 6 MW peak, 24 kW average power S-band klystron

International Nuclear Information System (INIS)

Joshi, L.M.; Meena, Rakesh; Nangru, Subhash; Kant, Deepender; Pal, Debashis; Lamba, O.S.; Jindal, Vishnu; Jangid, Sushil Kumar; Chakravarthy, D.P.; Dixit, Kavita

2011-01-01

A 6 MW peak, 24 kW average power S-band Klystron is under development at CEERI, Pilani under an MoU between BARC and CEERI. The design of the klystron has been completed. The electron gun has been designed using TRAK and MAGIC codes. RF cavities have been designed using HFSS and CST Microwave Studio while the complete beam wave interaction simulation has been done using MAGIC code. The thermal design of collector and RF window has been done using ANSYS code. A Gun Collector Test Module (GCTM) was developed before making actual klystron to validate gun perveance and thermal design of collector. A high voltage solid state pulsed modulator has been installed for performance valuation of the tube. The paper will cover the design aspects of the tube and experimental test results of GCTM and klystron. (author)

Klystrons and modulators for SBLC

Energy Technology Data Exchange (ETDEWEB)

Bieler, M.; Choroba, S.; Hameister, J.; Lewin, H.-Ch. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany)

1997-04-01

For SBLC, the DESY/THD S-band linear collider study, klystrons with 150 MW rf-pulse power at 50 Hz repetition rate and 3 {mu}s pulse duration are required [1]. This paper will give a short overview of the SBLC parameters and the S-band test linac at DESY. Two different modulator schemes, the conventional line type pulser and the hard tube pulser, will be discussed. After a brief description of the 150 MW S-band klystron the first operating experience with the klystron and a line type pulser at DESY will be presented. (author)

Commissioning of the First Klystron-Based X-Band Power Source at CERN

CERN Document Server

Kovermann, J; Curt, S; Doebert, S; Naon, M; McMonagle, G; Paju, E; Rey, S; Riddone, G; Schirm, K; Syratchev, I; Timeo, L; Wuensch, W; Hamdi, A; Peauger, FF; Eichner, J; Haase, A; Sprehn, D

2012-01-01

A new klystron based X-band rf power source operating at 11.994 GHz has been installed and started to be commissioned at CERN in collaboration with CEA Saclay and SLAC for CLIC accelerating structure tests. The system comprises a solid state high voltage modulator, an XL5 klystron developed by SLAC, a cavity based SLED type pulse compressor, the necessary low level rf system including rf diagnostics and interlocks and the surrounding vacuum, cooling and controls infrastructure. The system is designed to produce up to 50 MW rf pulses of 1500 ns pulse width and 50 Hz repetition rate. After pulse compression, up to 100 MW of rf power at 250 ns pulse width will be available in the structure test bunker. This paper describes in more detail this setup and the process of commissioning which is necessary to arrive at the design performance.

PEP-II prototype klystron

International Nuclear Information System (INIS)

Fowkes, W.R.; Caryotakis, G.; Lee, T.G.; Pearson, C.; Wright, E.L.

1993-04-01

A 540-kW continuous-wave (cw) klystron operating at 476 MHz was developed for use as a power source for testing PEP-II rf accelerating cavities and rf windows. It also serves as a prototype for a 1.2 MW cw klystron presently being developed as a potential rf source for asymmetric colliding ring use. The design incorporates the concepts and many of the parts used in the original 353 MHz PEP klystron developed sixteen years ago. The superior computer simulation codes available today result in improved performance with the cavity frequencies, drift lengths, and output circuit optimized for the higher frequency.The design and operating results of this tube are described with particular emphasis on the factors which affect efficiency and stability

Performance of a high efficiency high power UHF klystron

International Nuclear Information System (INIS)

Konrad, G.T.

1977-03-01

A 500 kW c-w klystron was designed for the PEP storage ring at SLAC. The tube operates at 353.2 MHz, 62 kV, a microperveance of 0.75, and a gain of approximately 50 dB. Stable operation is required for a VSWR as high as 2 : 1 at any phase angle. The design efficiency is 70%. To obtain this value of efficiency, a second harmonic cavity is used in order to produce a very tightly bunched beam in the output gap. At the present time it is planned to install 12 such klystrons in PEP. A tube with a reduced size collector was operated at 4% duty at 500 kW. An efficiency of 63% was observed. The same tube was operated up to 200 kW c-w for PEP accelerator cavity tests. A full-scale c-w tube reached 500 kW at 65 kV with an efficiency of 55%. In addition to power and phase measurements into a matched load, some data at various load mismatches are presented

Development of X-band klystron technology at SLAC

International Nuclear Information System (INIS)

Caryotakis, G.

1997-05-01

The SLAC design for a 1-TeV collider (NLC) requires klystrons with a performance which is well beyond the state-of-the-art for microwave tubes in the United States or abroad. The electrical specifications for the NLC klystrons are not fully established, but they are approximately as follows: Frequency, 11.4 GHz; Peak Power, 75 MW; Pulse Length, 1.5 μs; Repetition Rate, 180 Hz; Gain, 50 dB; Efficiency, (including beam focusing) 50%. SLAC is in the seventh year of a program to develop these klystrons. The choice of X-band as the operating frequency, along with the sheer size of the NLC, have resulted in some new, most demanding standards for the klystrons which may power this future machine. These are related to the overall efficiency required, to the high rf gradients that must be supported at the output circuit without vacuum breakdown, and to the manufacturing cost of the 5,000-10,000 klystrons needed for the collider

Design of a Solid-State Fast Voltage Compensator for klystron modulators requiring constant AC power consumption

CERN Document Server

Aguglia, Davide; Viarouge, Philippe; Cros, Jerome

2014-01-01

This paper proposes a novel topological solution for klystron modulators integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This kind of solution is mandatory for the CLIC project under study, which requires several hundreds of synchronously operated klystron modulators for a total pulsed power of 39 GW. The topology is optimized for the challenging CLIC specifications, which require a very precise output voltage flat-top as well as fast rise and fall times (3µs). The Fast Voltage Compensator is integrated in the modulator such that it only has to manage the capacitor charger current and a fraction of the charging voltage. Consequently, its dimensioning power and cost is minimized.

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

Klystron 'efficiency loop' for the ALS storage ring RF system

International Nuclear Information System (INIS)

Kwiatkowski, Slawomir; Julian, Jim; Baptiste, Kenneth

2002-01-01

The recent energy crisis in California has led us to investigate the high power RF systems at the Advanced Light Source (ALS) in order to decrease the energy consumption and power costs. We found the Storage Ring Klystron Power Amplifier system operating as designed but with significant power waste. A simple proportional-integrator (PI) analog loop, which controls the klystron collector beam current, as a function of the output RF power, has been designed and installed. The design considerations, besides efficiency improvement, were to interface to the existing system without major expense. They were to also avoid the klystron cathode power supply filter's resonance in the loop's dynamics, and prevent a conflict with the existing Cavity RF Amplitude Loop dynamics. This efficiency loop will allow us to save up to 700 MW-hours of electrical energy per year and increase the lifetime of the klystron

50 MW C-band pulse klystron; 50MW C band pulse klystron

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

C-band pulse klystron E3746 with an output of 50 MW class was developed jointly with the High-Energy Accelerator Research Organization in the Ministry of Education as the klystron for a linear accelerator. For a large-sized linear accelerator in the next generation, a klystron with higher operating frequency has been required to obtain a compact and efficient accelerator. In E3746, the problem of power resistance during high-frequency operation was solved by mounting a traveling-wave multi-cell output circuit. Moreover, stable operation in the pulse width of 2.5 {mu}s and the output of 54 MW was performed at the same operation efficiency (44%) as the conventional S-band tube by using the frequency (in a C-band frequency band) that is two times as high as the conventional general accelerator. (translated by NEDO)

A high peak power S-band switching system for the Advanced Photon Source (APS) Linear Accelerator (Linac)

International Nuclear Information System (INIS)

Grelick, A. E.

1998-01-01

An S-band linear accelerator is the source of particles and front end of the Advanced Photon Source [1] injector. Additionally, it will be used to support a low-energy undulator test line (LEUTL) and to drive a free-electron laser (FEL). To provide maximum linac availability for all uses, an additional modulator-klystron subsystem has been built,and a waveguide-switching and distribution subsystem is now under construction. The combined subsystems provide a hot spare for any of the five S-band transmitters that power the lina cand have been given the additional function of powering an rf gun test stand whenever they are not otherwise needed. Design considerations for the waveguide-switching subsystem, topology selection, timing, control, and system protection provisions are described

1-MW klystron for fusion plasma heating

International Nuclear Information System (INIS)

Okamoto, Tadashi; Miyake, Setsuo; Ohno, Hiroaki

1985-01-01

A plasma test apparatus to bring about the critical plasma conditions for nuclear fusion is now under construction in Japan Atomic Energy Research Institute. Among various means of plasma heating, the most promising is the lower hybrid resonance heating (LHRF) in the 2-GHz region. Although it has so far requied 7 to 8 MW of microwave power for the plasma test apparatus, the new klystron, E3778, now constructed by Toshiba has the world's highest output power of 1 MW in the 2-GHz region. In addition to the excellent high-power operation for 10 seconds, the wide operating frequency range of 1.7 to 2.26 GHz by dint of sophisticated high-speed tuning mechanism, and the high durability to reflected power of up to 2.0 of VSWR are the high-lighted features of this klystron, which have never been achieved by conventional klystrons. (author)

Relativistic klystron research at SLAC and LLNL

International Nuclear Information System (INIS)

Allen, M.A.; Callin, R.S.; Deruyter, H.

1988-06-01

We are developing relativistic klystrons as a power source for high gradient accelerator applications such as large linear electron-positron colliders and compact accelerators. We have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here briefly on our experiments so far. 5 refs., 1 fig., 1 tab

RF windows used at s-band pulsed klystrons in KEK linac

Energy Technology Data Exchange (ETDEWEB)

Michizono, S.; Saito, Y. [KEK, National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

1997-04-01

The breakdown of the alumina RF-windows used in high-power klystrons is one of the most serious problems in the development of klystrons. This breakdown results from excess heating of alumina due to multipactor bombardments and/or localized RF dissipations. A statistical research of window materials was carried out, and high-power tests were performed in order to develop RF windows having high durability for the KEKB klystrons. The breakdown mechanism of RF windows is being considered. An improved RF window installed in a KEKB klystron is also being tested. (J.P.N)

Design and construction of the advanced photon source 352-MHz rf system switching control

International Nuclear Information System (INIS)

Horan, D.; Solita, L.; Reigle, D.; Dimonte, N.

1997-01-01

A switching control system has been designed and built to provide the capability of rapidly switching the waveguide and low-level cabling between different klystrons to operate the Advanced Photon Source storage ring in the event of a failure of a klystron system or to perform necessary repairs and preventative maintenance. The twelve possible modes of operation allow for complete redundancy of the booster synchrotron rf system and either a maximum of two storage ring rf systems to be completely off-line or one system to be used as a power source for an rf test stand. A programmable controller is used to send commands to intermediate control panels which interface to WR2300 waveguide switches and phase shifters, rf cavity interlock and low-level rf distribution systems, and klystron power supply controls for rapid reconfiguration of the rf systems in response to a mode-selection command. Mode selection is a local manual operation using a keyswitch arrangement which prevents more than one mode from being selected at a time. The programmable controller also monitors for hardware malfunction and guards against open-quotes hot-switchingclose quotes of the rf systems. The rf switching controls system is monitored via the Experimental Physics and Industrial Control System (EPICS) for remote system status check

Pulse to pulse klystron diagnosis system

International Nuclear Information System (INIS)

Nowak, J.; Davidson, V.; Genova, L.; Johnson, R.; Reagan, D.

1981-03-01

This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 μs. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations

Performance of a 150-MW S-band klystron

International Nuclear Information System (INIS)

Sprehn, D.; Phillips, R.M.; Caryotakis, G.

1994-09-01

As part of an international collaboration, the Stanford Linear Accelerator Center (SLAC) klystron group has designed, fabricated, and tested a 60-Hz, 3-μs, 150-MW S-band klystron built for Deutsches Elektronen Synchrotron (DESY). A test diode with a 535-kV, 700-A electron beam was constructed to verify the gun operation. The first klystron was built and successfully met design specifications. The 375-MW electron beam represents a new record for SLAC accelerator klystrons in terms of voltage, current, energy, and ruggedness of design. The rf output power is a 150% increase over the S-band tubes currently used in the two-mile-long linear accelerator at SLAC. This paper discusses design issues and experimental results of the diode and klystron

Study of the emission performance of high-power klystrons: SLAC XK-5

International Nuclear Information System (INIS)

Zhao, Y.

1981-07-01

There are hundreds of high power klystrons operated in the Linac gallery and about fifty to sixty tubes fail every year. The lifetime ranges from a few thousand up to seventy thousand hours except those which fail during an early period. The overall percentage of failures due to emission problems is approximately 25%. It is also noted that a 10% increase in mean lifetime of klystrons will reduce the overall cost per hour as much as a 10% increase in efficiency. Therefore, it is useful to find some method to predict the expected life of an individual tube. The final goal has not been attained yet, but some useful information was obtained. It is thought that this information might be helpful for those people who will study this subject further

Study of the emission performance of high-power klystrons: SLAC XK-5

Energy Technology Data Exchange (ETDEWEB)

Zhao, Y.

1981-07-01

There are hundreds of high power klystrons operated in the Linac gallery and about fifty to sixty tubes fail every year. The lifetime ranges from a few thousand up to seventy thousand hours except those which fail during an early period. The overall percentage of failures due to emission problems is approximately 25%. It is also noted that a 10% increase in mean lifetime of klystrons will reduce the overall cost per hour as much as a 10% increase in efficiency. Therefore, it is useful to find some method to predict the expected life of an individual tube. The final goal has not been attained yet, but some useful information was obtained. It is thought that this information might be helpful for those people who will study this subject further.

Relativistic klystrons for high-gradient accelerators

International Nuclear Information System (INIS)

Westenskow, G.A.; Aalberts, D.P.; Boyd, J.K.; Deis, G.A.; Houck, T.L.; Orzechowski, T.J.; Ryne, R.D.; Yu, S.S.; Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Hoag, H.A.; Koontz, R.F.; Lavine, T.L.; Loew, G.A.; Miller, R.H.; Ruth, R.D.; Vlieks, A.E.; Wang, J.W.; Hopkins, D.B.; Sessler, A.M.; Haimson, J.; Mecklenburg, B.

1991-01-01

Experimental work is being performed by collaborators at LLNL, SLAC, and LBL to investigate relativistic klystrons as a possible rf power source for future high-gradient accelerators. The authors have learned how to overcome their previously reported problem of high power rf pulse shortening and have achieved peak rf power levels of 330 MW using an 11.4-GHz high-gain tube with multiple output structures. In these experiments the rf pulse is of the same duration as the beam current pulse. In addition, experiments have been performed on two short sections of a high-gradient accelerator using the rf power from a relativistic klystron. An average accelerating gradient of 84 MV/m has been achieved with 80-MW of rf power

HF electronic tubes. Technologies, grid tubes and klystrons

International Nuclear Information System (INIS)

Lemoine, Th.

2009-01-01

This article gives an overview of the basic technologies of electronic tubes: cathodes, electronic optics, vacuum and high voltage. Then the grid tubes, klystrons and inductive output tubes (IOT) are introduced. Content: 1 - context and classification; 2 - electronic tube technologies: cathodes, electronic optics, magnetic confinement (linear tubes), periodic permanent magnet (PPM) focussing, collectors, depressed collectors; 3 - vacuum technologies: vacuum quality, surface effects and interaction with electrostatic and RF fields, secondary emission, multipactor effect, thermo-electronic emission; 4 - grid tubes: operation of a triode, tetrodes, dynamic operation and classes of use, 'common grid' and 'common cathode' operation, ranges of utilisation and limitations, operation of a tetrode on unadjusted load, lifetime of a tetrode, uses of grid tubes; 5 - klystrons: operation, impact of space charge, multi-cavity klystrons, interaction efficiency, extended interaction klystrons, relation between interaction efficiency, perveance and efficiency, ranges of utilization and power limitations, multi-beam klystrons and sheet beam klystrons, operation on unadjusted load, klystron band pass and lifetime, uses; 6 - IOT: principle of operation, ranges of utilisation and limitations, interaction efficiency and depressed collector IOT, IOT lifetime and uses. (J.S.)

The Klynac: An integrated klystron and linear accelerator

International Nuclear Information System (INIS)

Potter, James M.; Schwellenbach, David; Meidinger, Alfred

2013-01-01

The Klynac concept integrates an electron gun, a radio frequency (RF) power source, and a coupled-cavity linear accelerator into a single resonant system. The klystron is essentially a conventional klystron structure with an input cavity, some number of intermediate cavities and an output cavity. The accelerator structure is, likewise, a conventional on-axis coupled structure. The uniqueness is the means of coupling the klystron output cavity to the accelerator. The coupler is a resonant coupler rather than an ordinary transmission line. The geometry of such a system need not be coaxial. However, if the klystron and accelerator are coaxial we can eliminate the need for a separate cathode for the accelerator by injecting some of the klystron beam into the accelerator. Such a device can be made cylindrical which is ideal for some applications.

Gigawatt peak power generation in a relativistic klystron amplifier driven by 1 kW seed-power

Energy Technology Data Exchange (ETDEWEB)

Wu, Y. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Science and Technology on High Power Microwave Laboratory, Mianyang 621900 (China); Xie, H. Q. [College of Science, Southwestern University of Science and Technology, Mianyang 621010 (China); Li, Z. H.; Zhang, Y. J.; Ma, Q. S. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China)

2013-11-15

An S-band high gain relativistic klystron amplifier driven by kW-level RF power is proposed and studied experimentally. In the device, the RF lossy material is introduced to suppress higher mode excitation. An output power of 1.95 GW with a gain of 62.8 dB is obtained in the simulation. Under conditions of an input RF power of 1.38 kW, a microwave pulse with power of 1.9 GW, frequency of 2.86 GHz, and duration of 105 ns is generated in the experiment, and the corresponding gain is 61.4 dB.

Gigawatt peak power generation in a relativistic klystron amplifier driven by 1 kW seed-power

Science.gov (United States)

Wu, Y.; Xie, H. Q.; Li, Z. H.; Zhang, Y. J.; Ma, Q. S.

2013-11-01

An S-band high gain relativistic klystron amplifier driven by kW-level RF power is proposed and studied experimentally. In the device, the RF lossy material is introduced to suppress higher mode excitation. An output power of 1.95 GW with a gain of 62.8 dB is obtained in the simulation. Under conditions of an input RF power of 1.38 kW, a microwave pulse with power of 1.9 GW, frequency of 2.86 GHz, and duration of 105 ns is generated in the experiment, and the corresponding gain is 61.4 dB.

Very broad bandwidth klystron amplifiers

Science.gov (United States)

Faillon, G.; Egloff, G.; Farvet, C.

Large surveillance radars use transmitters at peak power levels of around one MW and average levels of a few kW, and possibly several tens of kW, in S band, or even C band. In general, the amplification stage of these transmitters is a microwave power tube, frequently a klystron. Although designers often turn to klystrons because of their good peak and average power capabilities, they still see them as narrow band amplifiers, undoubtedly because of their resonant cavities which, at first sight, would seem highly selective. But, with the progress of recent years, it has now become quite feasible to use these tubes in installations requiring bandwidths in excess of 10 - 12 percent, and even 15 percent, at 1 MW peak for example, in S-band.

A new method for compensation of the effect of charging transformer's leakage inductance on PFN voltage regulation in Klystron pulse modulators

Energy Technology Data Exchange (ETDEWEB)

Patel, Akhil, E-mail: akhilpatel@rrcat.gov.in; Kale, Umesh; Shrivastava, Purushottam

2017-04-21

The Line type modulators have been widely used to generate high voltage rectangular pulses to power the klystron for high power RF generation. In Line type modulator, the Pulse Forming Network (PFN) which is a cascade combination of lumped capacitors and inductors is used to store the electrical energy. The charged PFN is then discharged into a klystron by firing a high voltage Thyratron switch. This discharge generates a high voltage rectangular pulse across the klystron electrodes. The amplitude and phase of Klystron's RF output is governed by the high voltage pulse amplitude. The undesired RF amplitude and phase stability issues arises at the klystron's output due to inter-pulse and during the pulse amplitude variations. To reduce inter-pulse voltage variations, the PFN is required to be charged at the same voltage after every discharge cycle. At present, the combination of widely used resonant charging and deQing method is used to regulate the pulse to pulse PFN voltage variations but the charging transformer's leakage inductance puts an upper bound on the regulation achievable by this method. Here we have developed few insights of the deQing process and devised a new compensation method to compensate this undesired effect of charging transformer's leakage inductance on the pulse to pulse PFN voltage stability. This compensation is accomplished by the controlled partial discharging of the split PFN capacitor using a low voltage MOSFET switch. Theoretically, very high values of pulse to pulse voltage stability may be achieved using this method. This method may be used in deQing based existing modulators or in new modulators, to increase the pulse to pulse voltage stability, without having a very tight bound on charging transformer's leakage inductance. Given a stable charging power supply, this method may be used to further enhance the inter-pulse voltage stability of modulators which employ the direct charging, after replacing the

Pulse modulator developments in support of klystron testing at SLAC

International Nuclear Information System (INIS)

Koontz, R.F.; Cassel, R.; Lamare, J. de; Ficklin, D.; Gold, S.; Harris, K.

1993-01-01

Several families of high power klystrons in S- and X-Band are being developed in the Klystron Laboratory at SLAC. To support these developments, a number of new pulse modulators are being designed from scratch, or upgraded from existing laboratory test modulators. This paper outlines the modulator parameters available in the SLAC Klystron Laboratory, and discuss two new modulators that are under construction

Large-Signal Klystron Simulations Using KLSC

Science.gov (United States)

Carlsten, B. E.; Ferguson, P.

1997-05-01

We describe a new, 2-1/2 dimensional, klystron-simulation code, KLSC. This code has a sophisticated input cavity model for calculating the klystron gain with arbitrary input cavity matching and tuning, and is capable of modeling coupled output cavities. We will discuss the input and output cavity models, and present simulation results from a high-power, S-band design. We will use these results to explore tuning issues with coupled output cavities.

Bandwidth Extension of an S-band, Fundamental-Mode Eight-Beam Klystron

Science.gov (United States)

2006-04-01

Extension of an S - band , Fundamental-Mode Eight-Beam Klystron Khanh T. Nguyen Beam-Wave Research, Inc. Bethesda, MD 20814 Dean E. Pershing ATK Mission...of a five-cavity, approximately 18 cm downstream from the center of the broadband, high - power multiple-beam klystron (MBK) first gap - the logical...the circuit generates >550 kW across the band with a peak power of more than 600 kW at -3.27 Keywords: Multiple-beam klystron ; MBK; bandwidth GHz. The 1

Advanced buck converter power supply ABCPS for APT

International Nuclear Information System (INIS)

Street, R.; Overett, T.; Bowles, E.

1998-01-01

The United States Department of Energy (DOE) is planning to fabricate an Accelerator for the Production of Tritium (APT) at their Savannah River Site, to provide Tritium for national defense. The 1700 million electron volt (MeV) proton beam accelerator will be powered by radio frequency (RF) klystrons. A direct current (DC) power supply is required for each of the approximately two hundred and fifty 1-megawatt (MW) continuous wave klystrons in the RF power system. The requirements are that the power supply meet output performance specifications, provide fault protection for the klystron, have high efficiency, high reliability, good maintainability, and be readily manufacturable. As the power supplies are one of the largest cost elements in the accelerator, a technology review was made to determine the most economical approach to satisfy the requirements. A switch-mode power supply employing a buck-regulator was identified as being potentially the lowest cost approach. As the switch represents a certain development risk, a small-scale prototype has been constructed for evaluation, and has resulted in the decision to fabricate a full-scale prototype power supply. A description of the hardware will be presented

10 MW, L-Band Klystron for Accelerators

Energy Technology Data Exchange (ETDEWEB)

Read, Michael [Calabazas Creek Research, Inc., San Mateo, CA (United States); Ives, Robert L. [Calabazas Creek Research, Inc., San Mateo, CA (United States); Ferguson, Patrick [Calabazas Creek Research, Inc., San Mateo, CA (United States)

2016-03-07

This program developed a 10 MW, pulsed, Annular Beam Klystron (ABK) for accelerator applications. This is an alternative RF source to multiple beam klystrons MBKs), which are more complex and considerably more expensive. The ABK uses a single, annular cathode and a single beam tunnel with fundamental mode cavities. The operating specifications (voltage, efficiency, power, bndwidth, duty, etc.) are the same as for comparable MBKs.

A 1 MEGAWATT POLYPHASE BOOST CONVERTER-MODULATOR FOR KLYSTRON PULSE APPLICATION

International Nuclear Information System (INIS)

Reass, W.A.; Doss, J.D.; Gribble, R.F.

2001-01-01

This paper describes electrical design criteria and first operational results a 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. PWM (pulse width modulation) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt-peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. A review of these design parameters and the first results of the performance characteristics will be presented

High Power Klystrons: Theory and Practice at the Stanford Linear Accelerator CenterPart I

Energy Technology Data Exchange (ETDEWEB)

Caryotakis, G.

2004-12-15

This is Part I of a two-part report on design and manufacturing methods used at SLAC to produce accelerator klystrons. Chapter 1 begins with the history and applications for klystrons, in both of which Stanford University was extensively involved. The remaining chapters review the theory of klystron operation, derive the principal formulae used in their design, and discuss the assumptions that they involve. These formulae are subsequently used in small-signal calculations of the frequency response of a particular klystron, whose performance is also simulated by two different computer codes. The results of calculations and simulations are compared to the actual performance of the klystron.

High-Efficiency Klystron Design for the CLIC Project

CERN Document Server

Mollard, Antoine; Peauger, Franck; Plouin, Juliette; Beunas, Armel; Marchesin, Rodolphe

2017-01-01

The CLIC project requests new type of RF sources for the high power conditioning of the accelerating cavities. We are working on the development of a new kind of high-efficiency klystron to fulfill this need. This work is performed under the EuCARD-2 European program and involves theoretical and experimental study of a brand new klystron concept.

Solid state high power amplifier for driving the SLC injector klystron

International Nuclear Information System (INIS)

Judkins, J.G.; Clendenin, J.E.; Schwarz, H.D.

1985-03-01

The SLC injector klystron rf drive is now provided by a recently developed solid-state amplifier. The high gain of the amplifier permits the use of a fast low-power electronic phase shifter. Thus the SLC computer control system can be used to shift the phase of the high-power rf rapidly during the fill time of the injector accelerator section. These rapid phase shifts are used to introduce a phase-energy relationship in the accelerated electron pulse in conjunction with the operation of the injector bunch compressor. The amplifier, the method of controlling the rf phase, and the operational characteristics of the system are described. 5 refs., 4 figs

The klystron: A microwave source of surprising range and endurance

International Nuclear Information System (INIS)

Caryotakis, G.

1998-04-01

This year marks the 60th anniversary of the birth of the klystron at Stanford University. The tube was the first practical source of microwaves and its invention initiated a search for increasingly more powerful sources, which continues to this day. This paper reviews the scientific uses of the klystron and outlines its operating principles. The history of the device is traced, from its scientific beginnings, to its role in World War II and the Cold War, and to its current resurgence as the key component in a major accelerator project. Finally, the paper describes the development of a modular klystron, which may someday power future accelerators at millimeter wavelengths

Utilization of a Vircator to drive a High Power Relativistic Klystron Amplifier

Science.gov (United States)

Gardelle, J.; Bardy, J.; Cassany, B.; Desanlis, T.; Eyl, P.; Galtié, A.; Modin, P.; Voisin, L.; Balleyguier, P.; Gouard, P.; Donohue, J.

2002-11-01

At CESTA, we have been producing electron beams for some fifteen years by using induction accelerators and pulse diodes. First we had performed Frre-Electron Lasers experiments and we are currently studying the production of High-Power microwaves in the S-band. Among the possible sources we have chosen to perform Relativistic Klystron (RK) experiments with a pulse diode capable of generating a 700kV, 15 kA, 100 ns annular electron beam. In an amplifier configuration, we are testing the idea of using a Vircator as the driver for the first cavity of the klystron. This Vircator uses a simple electrical generator (Marx capacitor bank) which operates in the S-band in the GW class. By reducing the power level to about 100 MW, a 200 ns reliable and reproducible input driver pulse is obtained. First, we present the results of a preliminary experiment for which a coaxial cavity has been built in order to be fed by the Vircator emission at 2.45 GHz. Secondly, we give the experimental results in an oscillator configuration which corresponds to the fisrt step of our RK studies. Comparisons with the results of numerical simulations performed with MAGIC and MAFIA will be given for both experiments.

An immersed field cluster klystron

International Nuclear Information System (INIS)

Palmer, R.B.; Herrmannsfeldt, W.B.; Eppley, K.R.

1989-08-01

Future linear colliders have a need for high power, high frequency, and short-pulse radio frequency sources. The proposed ''cluster klystron'' should give over 1 GW of 12 GHz radio frequency power, can employ direct current or a long high-voltage pulse, but can be gated to give pulses down to a few tens of nanoseconds. The device consists of 42 parallel 100 A channels. Each channel is fed from an individual magnetron-type gun employing a common 50 kV mod-anode. The beams are accelerated to 400 kV in common dc accelerating gaps and fed into the 42 separate klystron channels. Focusing of all channels is achieved by a single overall 4 kG magnetic field. Simulations of expected performance suggest that the efficiency could be above 70%. 10 refs., 6 figs., 5 tabs

SMES based power modulator - status August 2001

International Nuclear Information System (INIS)

Juengst, K.P.; Gehring, R.; Kudymow, A.; Suess, E.

2001-10-01

Based on a superconducting magnetic energy storage (SMES) a long-pulse klystron modulator has been designed for use in the TESLA test facility (TTF) at DESY, Hamburg. A proto-type with an output power of 25 MW is under development at Forschungszentrum Karlsruhe in cooperation with the office of engineering lbK at Karlsruhe. Including a pulse transformer (1:13/11.5), the system will deliver pulses of 130 kV or 115 kV, 1.7 ms pulse length with a flat top of ± 0.5%, at a repetition rate up to 10 Hz. This new system's main features are a highly dynamic SMES (> 100 T/s), a high current power supply (rated 27 V/2.6 kA), a switched-mode high voltage power supply (rated 14 kV/45 A), a fast thyristor power switch for 2.6 kA approx. continuous current/ 2 ms break, an IGCT power switch rated 2.6 kA/14 kV, a protection switch unit and a system control unit. This demonstration system is to serve alternatively two klystrons of 5 MW RF output or one multibeam klystron of 10 MW RF output. A significant part of the components of the system has been built. A first set of the system components had been arranged to form a model of the modulator and 1 MW pulses were generated. The next large step in the area of the power electronic part is to increase the power of this test arrangement up to 10 MW. The SMES and its cryostat have undergone initial testing. The data acquisition and control system under development at DESY has been taken over and adjusted to our computer and experimental environment. (orig.)

Klystron bias power supplies for Indus-2 synchrotron radiation source

International Nuclear Information System (INIS)

Badapanda, M.K.; Hannurkar, P.R.

2008-01-01

The functioning of an alternating current (AC) voltage regulator based high voltage direct current (HVDC) power supplies with better input and output performances has been presented in this paper. The authors have incorporated a 3-phase series limiting inductor, along with detuned passive filter in each power supply, to take care of line harmonics and the input power factor (IPF), which is simple, cost effective, reliable and provides input performance matching that of an equivalent active filter. Such arrangement has special significance for controlled HVDC power supplies supplying to fixed load but operated from widely varying input voltages. It achieves line voltage total harmonic distortion (THD) below 4% and IPF better than 0.97, for 415 V - 30% to 415 V + 10% variations in 3-phase input voltages. A properly designed crowbar, along with suitable limiting elements, is incorporated in each power supply and stringent wire survivability tests were carried out to limit klystron fault energy below 10 Joules. Several simulated waveforms and experiment results are also presented. (author)

A concept of a wide aperture klystron with RF absorbing drift tubes for linear collider

International Nuclear Information System (INIS)

Dolbilov, G.V.; Azorskij, N.I.; Fateev, A.A.

1997-01-01

This paper is devoted to a problem of optimal design of the electrodynamic structure of the X-band klystron for a linear collider. It is shown that optimal design should provide large aperture and a high power gain, about 80 dB. The most severe problem arising here is that of parasitic self-excitation of the klystron, which becomes more complicated at increasing aperture and power gain. Our investigations have shown that traditional methods for suppressing the self-excitation become ineffective at desired technical parameters of the klystron. A novel concept of a wide aperture klystron with distributed suppression of parasitic oscillations is presented. Results of experimental study of the wide-aperture relativistic klystron for VLEPP are presented. Investigations have been performed using the driving beam of the JINR LIA-3000 induction accelerator (E=1 MeV, I=250 A, τ=250 ns). To suppress self-excitation parasitic modes we have used technique of RF absorbing drift tubes. As a result, we have obtained design output parameters of the klystron and achieved level of 100 MW output power

Latest Results in SLAC 75-MW PPM Klystrons

International Nuclear Information System (INIS)

Sprehn, D.; Caryotakis, G.; Haase, A.; Jongewaard, E.; Laurent, L.; Pearson, C.; Phillips, R.

2006-01-01

75 MW X-band klystrons utilizing Periodic Permanent Magnet (PPM) focusing have been undergoing design, fabrication and testing at the Stanford Linear Accelerator Center (SLAC) for almost nine years. The klystron development has been geared toward realizing the necessary components for the construction of the Next Linear Collider (NLC). The PPM devices built to date which fit this class of operation consist of a variety of 50 MW and 75 MW devices constructed by SLAC, KEK (Tsukuba, Japan) and industry. All these tubes follow from the successful SLAC design of a 50 MW PPM klystron in 1996. In 2004 the latest two klystrons were constructed and tested with preliminary results reported at EPAC2004. The first of these two devices was tested to the full NLC specifications of 75 MW, 1.6 microseconds pulse length, and 120 Hz. This 14.4 kW average power operation came with a tube efficiency >50%. The most recent testing of these last two devices will be presented here. Design and manufacturing issues of the latest klystron, due to be tested by the Fall of 2005, are also discussed

Improvement of the long pulse operation of the s-band klystron

Energy Technology Data Exchange (ETDEWEB)

Sakai, T. [Graduate School of Sceince and Technology, Nihon Univ., Funabashi, Chiba (Japan); Sato, I.; Hayakawa, K. [Nihon Univ., Funabashi, Chiba (Japan). Atomic Energy Research Inst

2000-07-01

The long pulse operation of the PV3030 klystron for FEL linac at LEBRA in Nihon University has been improved considerably by the additional vacuum system placed immediately downstream the klystron output rf window. With the new vacuum system, the large conductance has enabled a high vacuum in normal operation and a quick recovery when the dielectric breakdown occurred. A high vacuum near the rf window may be essentially important for a stable operation of the high power klystron with long pulse duration. Now the PV3030 klystron can be operated at the condition of 20 MW x 20 {mu}s x 12.5 Hz. (author)

Novel Active Bouncer Topology for Klystron Modulators based on Pulsed Transformers

CERN Document Server

AUTHOR|(CDS)2079689; Aguglia, Davide; Viarouge, Philippe; Cros, Jérôme

2015-01-01

Active droop compensation systems, so called active bouncers, for klystron modulators based on monolithic pulse transformers perform the regulation of the output pulse voltage while simultaneously withstand all the primary current of the modulator. This imposes the utilization of high power semiconductors which can produce high switching losses and degrade the overall system efficiency. In order to overcome this issue, this paper proposes a new active bouncer topology based on the parallel connection of two different power converters: the first one is in charge of handling the majority of the primary current at high efficiency, and the second one is used to fine tune the bouncer voltage via a high bandwidth converter rated at a fraction of the first parallel connected converter. Detailed comparison between a classical active bouncer and two variants of the proposed topology are presented and based on numerical simulations.

The 5K70SK automatically tuned, high power, S-band klystron

Science.gov (United States)

Goldfinger, A.

1977-01-01

Primary objectives include delivery of 44 5K70SK klystron amplifier tubes and 26 remote tuner assemblies with spare parts kits. Results of a reliability demonstration on a klystron test cavity are discussed, along with reliability tests performed on a remote tuning unit. Production problems and one design modification are reported and discussed. Results of PAT and DVT are included.

Design and construction of a 500 KW CW, 400 MHz klystron to be used as RF power source for LHC/RF component tests

CERN Document Server

Frischholz, Hans; Pearson, C

1998-01-01

A 500 kW cw klystron operating at 400 MHz was developed and constructed jointly by CERN and SLAC for use as a high-power source at CERN for testing LHC/RF components such as circulators, RF absorbers and superconducting cavities with their input couplers. The design is a modification of the 353 MHz SLAC PEP-I klystron. More than 80% of the original PEP-I tube parts could thus be incorporated in the LHC test klystron which resulted in lower engineering costs as well as reduced development and construction time. The physical length between cathode plane and upper pole plate was kept unchanged so that a PEP-I tube focusing solenoid, available at CERN, could be re-used. With the aid of the klystron simulation codes JPNDISK and CONDOR, the design of the LHC tube was accomplished, which resulted in a tube with noticeably higher efficiency than its predecessor, the PEP-I klystron. The integrated cavities were redesigned using SUPERFISH and the output coupling circuit, which also required redesigning, was done with t...

150-MW S-Band klystron program at the Stanford Linear Accelerator Center

Energy Technology Data Exchange (ETDEWEB)

Sprehn, D.; Caryotakis, G.; Phillips, R.M. [Stanford Linear Accelerator Center, Stanford Univ., Stanford, CA (United States)

1997-04-01

Two S-Band klystrons operating at 150 MW have been designed, fabricated and tested at the Stanford Linear Accelerator Center (SLAC) during the past two years for use in an experimental accelerator at Deutsches Elektronen Synchrotron (DESY) in Hamburg, Germany. Both klystrons operate at the design power, 60 Hz repetition rate, 3 {mu}s pulsewidth, with an efficiency > 40%, and agreement between the experimental results and simulations is excellent. The 535 kV, 700 A electron gun was tested by constructing a solenoidal focused beam-stick which identified a source of oscillation, subsequently engineered out of the klystron guns. Design of the beam-stick and the two klystrons is discussed, along with observation and suppression of spurious oscillations. Differences in design and the resulting performance of the klystrons is emphasized. (author)

Detection of X-ray due to gun arcing of high power klystron

International Nuclear Information System (INIS)

Vogel, Vladimir; Matsumoto, Shuji

2004-01-01

X-ray due to a klystron gun arching was monitored by a detector consists of a plastic scintillation fiber and a photo-multiplier. Observation of the X-ray was done during the processing run of an X-band klystron. A clear signal of X-ray burst is observed when the gun arcing occurs. Possibility of the fast protection for a pulse modulator from the gun arcing is discussed. (author)

A high efficiency Ku-band radial line relativistic klystron amplifier

Energy Technology Data Exchange (ETDEWEB)

Dang, Fangchao; Zhang, Xiaoping, E-mail: zhangxiaoping@nudt.edu.cn; Zhong, Huihuang; Zhang, Jun; Ju, Jinchuan [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2016-07-15

To achieve the gigawatt-level microwave amplification output at Ku-band, a radial-line relativistic klystron amplifier is proposed and investigated in this paper. Different from the annular electron beam in conventional axial relativistic klystron amplifiers, a radial-radiated electron beam is employed in this proposed klystron. Owing to its radially spreading speciality, the electron density and space charge effect are markedly weakened during the propagation in the radial line drift tube. Additionally, the power capacity, especially in the output cavity, is enhanced significantly because of its large volume, which is profitable for the long pulse operation. Particle-in-cell simulation results demonstrate that a high power microwave with the power of 3 GW and the frequency of 14.25 GHz is generated with a 500 kV, 12 kA electron beam excitation and the 30 kW radio-frequency signal injection. The power conversion efficiency is 50%, and the gain is about 50 dB. Meanwhile, there is insignificant electron beam self-excitation in the proposed structure by the adoption of two transverse electromagnetic reflectors. The relative phase difference between the injected signals and output microwaves keeps stable after the amplifier saturates.

Role of advanced RF/microwave technology and high power switch technology for developing/upgrading compact/existing accelerators

International Nuclear Information System (INIS)

Shrivastava, Purushottam

2001-01-01

With the advances in high power microwave devices as well as in microwave technologies it has become possible to go on higher frequencies at higher powers as well as to go for newer devices which are more efficient and compact and hence reducing the power needs as well as space and weight requirement for accelerators. New devices are now available in higher frequency spectrum for example at C-Band, X-band and even higher. Also new devices like klystrodes/Higher Order Mode Inductive Output Tubes (HOM IOTs) are now becoming competitors for existing tubes which are in use at present accelerator complexes. The design/planning of the accelerators used for particle physics research, medical accelerators, industrial irradiation, or even upcoming Driver Accelerators for Sub Critical Reactors for nuclear power generation are being done taking into account the newer technologies. The accelerators which use magnetrons, klystrons and similar devices at S-Band can be modified/redesigned with devices at higher frequencies like X-Band. Pulsed accelerators need high power high voltage pulsed modulators whereas CW accelerators need high voltage power supplies for functioning of RF / Microwave tubes. There had been a remarkable growth in the development and availability of solid state switches both for switching the pulsed modulators for microwave tubes as well as for making high frequency switch mode power supplies. Present paper discusses some of the advanced devices/technologies in this field as well as their capability to make advanced/compact/reliable accelerators. Microwave systems developed/under development at Centre for Advanced Technology are also discussed briefly along with some of the efforts done to make them compact. An overview of state of art vacuum tube devices and solid state switch technologies is given. (author)

Development of multimegawatt klystrons for linear colliders

International Nuclear Information System (INIS)

Caryotakis, G.; Callin, R.; Eppley, K.

1993-04-01

A number of experimental klystrons have been constructed and evaluated at SLAC, KEK and INP, aiming toward output power objectives of 100 and 120 MW at 11.4 GHz (SLAC and KEK respectively) or 150 MW at 14 GHz (INP), with pulse lengths on the order of 1 μs. Since rf breakdown is considered to be the principal mechanism limiting power for such tubes, most of the effort has been concentrated on the design of output circuits that reduce rf gradients by distributing fields over a longer region of interaction. Another klystron component receiving emphasis has been the output window, where the approach for future tubes may be to use a circular TE01-mode, half-wave window. Rest results to date in this continuing international effort are: 50 MW with 1 μs pulses, using a traveling-wave output circuit (SLAC and INP), and 85 MW with 200 ns. pulse (SLAC), using two conventional reentrant, but uncoupled, output cavities. At KEK a klystron with a single, but not reentrant, cavity has produced 80 MW in 50 ns pulses. Finally, Haimson has demonstrated 100 MW at 50 ns with a traveling-wave output. This paper addresses primarily the work performed at SLAC during the last two years

Fundamentals of klystron testing

International Nuclear Information System (INIS)

Caldwell, J.W. Jr.

1978-08-01

Fundamentals of klystron testing is a text primarily intended for the indoctrination of new klystron group test stand operators. It should significantly reduce the familiarization time of a new operator, making him an asset to the group sooner than has been experienced in the past. The new employee must appreciate the mission of SLAC before he can rightfully be expected to make a meaningful contribution to the group's effort. Thus, the introductory section acquaints the reader with basic concepts of accelerators in general, then briefly describes major physical aspects of the Stanford Linear Accelerator. Only then is his attention directed to the klystron, with its auxiliary systems, and the rudiments of klystron tube performance checks. It is presumed that the reader is acquainted with basic principles of electronics and scientific notation. However, to preserve the integrity of an indoctrination guide, tedious technical discussions and mathematical analysis have been studiously avoided. It is hoped that the new operator will continue to use the text for reference long after his indoctrination period is completed. Even the more experienced operator should find that particular sections will refresh his understanding of basic principles of klystron testing

Development of high power CW and pulsed RF test facility based on 1 MW, 352.2 MHz klystron amplifier

International Nuclear Information System (INIS)

Badapanda, M.K.; Tripathi, Akhilesh; Upadhyay, Rinki; Rao, J.N.; Tiwari, Ashish; Jain, Akhilesh; Lad, M.R.; Hannurkar, P.R.

2013-01-01

A high power 1 MW, 352.2 MHz RF Test facility having CW and Pulse capability is being developed at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore for performance evaluation of various RF components, accelerating structures and related subsystems. Thales make 1 MW, 352.2 MHz klystron amplifier (TH 2089) will be employed in this high power test facility, which is thoroughly tested for its performance parameters at rated operating conditions. Auxiliary power supplies like filament, electromagnet, ion pump and mod anode power supply as well as 200 W solid state driver amplifier necessary for this high power test facility have been developed. A high voltage floating platform is created for floating filament and mod anode power supplies. Interconnection of various power supplies and other subsystems of this test facility are being carried out. A high voltage 100 kV, 25 Amp DC crowbar less power supply and low conductivity water (LCW) plant required for this klystron amplifier are in advanced stage of development. NI make cRIO 9081 real time (RT) controller based control and interlock system has been developed to realize proper sequence of operation of various power supplies and to monitor the status of crucial parameters in this test facility. This RF test facility will provide confidence for development of RF System of future accelerators like SNS and ADSS. (author)

Klystron equalization for RF feedback

International Nuclear Information System (INIS)

Corredoura, P.

1993-01-01

The next generation of colliding beam storage rings support higher luminosities by significantly increasing the number of bunches and decreasing the spacing between respective bunches. The heavy beam loading requires large RF cavity detuning which drives several lower coupled bunch modes very strongly. One technique which has proven to be very successful in reducing the coupled bunch mode driving impedance is RF feedback around the klystron-cavity combination. The gain and bandwidth of the feedback loop is limited by the group delay around the feedback loop. Existing klystrons on the world market have not been optimized for this application and contribute a large portion of the total loop group delay. This paper describes a technique to reduce klystron group delay by adding an equalizing filter to the klystron RF drive. Such a filter was built and tested on a 500 kill klystron as part of the on going PEP-II R ampersand D effort here at SLAC

PPM klystron operation in GLCTA

International Nuclear Information System (INIS)

Saeki, T.; Akemoto, M.; Shidara, T.

2004-01-01

High-gradient tests of X-band accelerator structure have been done with two solenoidal-type klystrons at Global Linear Collider Test Accelerator (GLCTA) facility in High Energy Accelerator Research Organization (KEK). In the GLCTA facility, a PPM-type klystron was installed and has been operated with dummy load from this April. In this article, the installation and the status of the PPM-type klystron operations are presented. (author)

Klystron control software in the SLC

International Nuclear Information System (INIS)

Jobe, R.K.; Thompson, K.; Phinney, N.

1985-05-01

Triggering, control, and monitoring of 240 high-power klystrons will be supported by the SLC control system this summer. The control software is distributed among a VAX host computer, a local microprocessor cluster, and a dedicated intelligent CAMAC module. The functions performed by these three components and the algorithms used are discussed

Design of a 100 MW X-band klystron

International Nuclear Information System (INIS)

Eppley, K.

1989-02-01

Future linear colliders will require klystrons with higher peak power at higher frequency than are currently in use. SLAC is currently designing a 100 MW klystron at 11.4 GHz as a prototype for such a tube. The gun has been designed for 440 KV and 510 amps. Transporting this beam through a 5 mm radius X-band drift tube presents the major design problem. The area convergence ratio of 190 to one is over ten times higher than is found in conventional klystrons. Even with high magnetic fields of 6 to 7 kilogauss careful matching is required to prevent excessive scalloping. Extensive EGUN and CONDOR simulations have been made to optimize the transmission and rf efficiency. The EGUN simulations indicate that better matching is possible by using resonant magnetic focusing. CONDOR calculations indicate efficiencies of 45 percent are possible with a double output cavity. We will discuss the results of the simulations and the status of the experimental program. 3 refs., 6 figs., 2 tabs

Design of a 100 MW X-band klystron

Science.gov (United States)

Eppley, Kenneth

1989-02-01

Future linear colliders will require klystrons with higher peak power at higher frequency than are currently in use. SLAC is currently designing a 100 MW klystron at 11.4 GHz as a prototype for such a tube. The gun has been designed for 440 kV and 510 amps. Transporting this beam through a 5 mm radius X-band drift tube presents the major design problem. The area convergence ratio of 190 to one is over ten times higher than is found in conventional klystrons. Even with high magnetic fields of 6 to 7 kilogauss careful matching is required to prevent excessive scalloping. Extensive EGUN and CONDOR simulations have been made to optimize the transmission and RF efficiency. The EGUN simulations indicate that better matching is possible by using resonant magnetic focusing. CONDOR calculations indicate efficiencies of 45 percent are possible with a double output cavity. We will discuss the results of the simulations and the status of the experimental program.

Multipactors in klystron cavities

International Nuclear Information System (INIS)

Hayashi, Kazutaka; Iyeki, Hiroshi; Kikunaga, Toshiyuki.

1993-01-01

A multipactor phenomenon in a klystron causes gain shortage or instability problem. Some tests using a prototype klystron input cavity revealed the microwave discharges in vacuum with magnetic field. The test results and the methods to avoid multipactors are discussed in this paper. (author)

TESLA: Large Signal Simulation Code for Klystrons

International Nuclear Information System (INIS)

Vlasov, Alexander N.; Cooke, Simon J.; Chernin, David P.; Antonsen, Thomas M. Jr.; Nguyen, Khanh T.; Levush, Baruch

2003-01-01

TESLA (Telegraphist's Equations Solution for Linear Beam Amplifiers) is a new code designed to simulate linear beam vacuum electronic devices with cavities, such as klystrons, extended interaction klystrons, twistrons, and coupled cavity amplifiers. The model includes a self-consistent, nonlinear solution of the three-dimensional electron equations of motion and the solution of time-dependent field equations. The model differs from the conventional Particle in Cell approach in that the field spectrum is assumed to consist of a carrier frequency and its harmonics with slowly varying envelopes. Also, fields in the external cavities are modeled with circuit like equations and couple to fields in the beam region through boundary conditions on the beam tunnel wall. The model in TESLA is an extension of the model used in gyrotron code MAGY. The TESLA formulation has been extended to be capable to treat the multiple beam case, in which each beam is transported inside its own tunnel. The beams interact with each other as they pass through the gaps in their common cavities. The interaction is treated by modification of the boundary conditions on the wall of each tunnel to include the effect of adjacent beams as well as the fields excited in each cavity. The extended version of TESLA for the multiple beam case, TESLA-MB, has been developed for single processor machines, and can run on UNIX machines and on PC computers with a large memory (above 2GB). The TESLA-MB algorithm is currently being modified to simulate multiple beam klystrons on multiprocessor machines using the MPI (Message Passing Interface) environment. The code TESLA has been verified by comparison with MAGIC for single and multiple beam cases. The TESLA code and the MAGIC code predict the same power within 1% for a simple two cavity klystron design while the computational time for TESLA is orders of magnitude less than for MAGIC 2D. In addition, recently TESLA was used to model the L-6048 klystron, code

Toroidal 12 cavity klystron : a novel approach

International Nuclear Information System (INIS)

Hazarika, A.B.R.

2013-01-01

A toroidal 12 cavity klystron is designed to provide with high energy power with the high frequency microwave RF- plasma generated from it. The cavities are positioned in clock hour positions. The theoretical modeling and designing is done to study the novel approach. (author)

Maintenance of a medical klystron linear accelerator and evaluation of the lifetime of the klystron

International Nuclear Information System (INIS)

Yokoyama, Koichi; Takita, Takenobu; Hashimoto, Shigeo; Koda, Yukio; Sawayanagi, Hisayoshi

1981-01-01

A 15 MeV Mitsubishi medical linear accelerator was installed at our center in June 1971. Clinical use and maintenance of the machine are reviewed. Special attention should be paid to the fact that only one klystron tube has been working for nine years. This tube has now recorded more than 17,000 filament hours, while the manufacturer's warranty time is 1,500 hours. Extension of the operating hours will significantly reduce the maintenance expenses of the machine. In this aspect, we intended to evaluate the lifetime of the Mitsubishi klystron used at several hospitals by means of a questionnaire. As a result, the following points are noticed: 1. It is advisable to keep in use a klystron tube which has been working normally for a quite long time. (Preventive replacement is unnecessary.) 2. A protective device should be provided to prevent the trouble which will follow the breakage in a klystron. 3. The present warranty time for the klystron may depend on the lifetime of individual products, including even some defective ones. If the occurrence of such products is minimized, the mean life of the klystron will be extended considerably and, consequently, the warranty time can also be prolonged to a great extent. (author)

The two-beam accelerator and the relativistic klystron power source

International Nuclear Information System (INIS)

Sessler, A.M.

1988-04-01

This paper discusses the concept of a two-beam accelerator. Two versions are discussed; one employing a free electron laser, the second employing a branched beam sent through ''transfer cavities'' as in a klystron. 14 refs., 26 figs., 1 tab

Ka-Band Klystron Amplifier for CUBESATs, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose a Ka-Band klystron amplifier for use in CubeSats. It will operate at 35.7 GHz, have 400 MHz of bandwidth, and output at least 32 watts of saturated power....

Switch mode power supply

International Nuclear Information System (INIS)

Kim, Hui Jun

1993-06-01

This book concentrates on switch mode power supply. It has four parts, which are introduction of switch mode power supply with DC-DC converter such as Buck converter boost converter, Buck-boost converter and PWM control circuit, explanation for SMPS with DC-DC converter modeling and power mode control, resonance converter like resonance switch, converter, multi resonance converter and series resonance and parallel resonance converters, basic test of SMPS with PWM control circuit, Buck converter, Boost converter, flyback converter, forward converter and IC for control circuit.

Mode control in a high-gain relativistic klystron amplifier

Science.gov (United States)

Li, Zheng-Hong; Zhang, Hong; Ju, Bing-Quan; Su, Chang; Wu, Yang

2010-05-01

Middle cavities between the input and output cavity can be used to decrease the required input RF power for the relativistic klystron amplifier. Meanwhile higher modes, which affect the working mode, are also easy to excite in a device with more middle cavities. In order for the positive feedback process for higher modes to be excited, a special measure is taken to increase the threshold current for such modes. Higher modes' excitation will be avoided when the threshold current is significantly larger than the beam current. So a high-gain S-band relativistic klystron amplifier is designed for the beam of current 5 kA and beam voltage 600 kV. Particle in cell simulations show that the gain is 1.6 × 105 with the input RF power of 6.8 kW, and that the output RF power reaches 1.1 GW.

Fast protection circuit for 1 MW Klystron based RF system of Low Energy High Intensity Proton Accelerator (LEHIPA)

International Nuclear Information System (INIS)

Shrotriya, Sandip; Shiju, A.; Patel, N.R.; Pande, Manjiri; Singh, P.

2014-01-01

This paper describes the details of a hardwired protection circuit designed and developed for 1 MW Klystron based Radio Frequency (RF) System. The hardwired protection circuit protects the klystron from fault conditions occurring in high power DC supplies, other bias supplies and inside the klystron itself. Fast response of the order of 1-2 microseconds is necessary in case of critical signals for the protection of such a high power system. The system needs to handle around 10 critical signals comprising of optical signals and different digital signals. In case of malfunction in the existing controller based interlock and protection system, klystron will be protected by this hardwired protection circuit. The hardwired circuit will provide redundant protection and protect the klystron from damage. This circuit and controller based protection system are operating in parallel. This paper describes details of a purely hardwired protection circuit developed for critical signals for achieving reliability and faster response time requirements of the RF system. (author)

The Klystron Engineering Model Development (KEMD) Task - A New Design for the Goldstone Solar System Radar (GSR)

Science.gov (United States)

Teitelbaum, L.; Liou, R.; Vodonos, Y.; Velazco, J.; Andrews, K.; Kelley, D.

2017-08-01

The Goldstone Solar System Radar (GSSR) is one of the world's great planetary radar facilities. The heart of the GSSR is its high-power transmitter, which radiates 450 kW from DSS-14, the Deep Space Network's 70-m antenna at Goldstone, by combining the output from two 250-kW klystrons. Klystrons are vacuum tube electron beam devices that are the key amplifying elements of most radio frequency telecommunications and radar transmitter systems. NASA's Science Mission Directorate sponsored the development of a new design for a 250-kW power, 50-MHz bandwidth, reliable klystron, intended to replace the aging operational devices that were developed in the mid-1990s. The design, developed in partnership with Communications & Power Industries, was verified by implementing and testing a first article prototype, the engineering model. Key elements of the design are new beam optics and focusing magnet, a seven-cavity RF body, and a modern collector able to reliably dissipate the full power of the electron beam. The first klystron based on the new VKX-7864C design was delivered to the DSN High-Power Transmitter Test Facility on November 1, 2016, the culmination of a six-year effort initiated to explore higher-resolution imaging of potentially hazardous near-Earth asteroids. The new design met or exceeded all requirements, including supporting advanced GSSR ranging modulations. The first article prototype was placed into operational service on July 26, 2017, after failure of one of the older klystrons, restoring the GSSR to full-power operations.

Design of a multi beam klystron cavity from its single beam parameters

Energy Technology Data Exchange (ETDEWEB)

Kant, Deepender, E-mail: dkc@ceeri.ernet.in; Joshi, L. M. [CSIR-Central Electronics Engineering Research Institute, Pilani (India); Janyani, Vijay [Department of ECE, MNIT, Jaipur (India)

2016-03-09

The klystron is a well-known microwave amplifier which uses kinetic energy of an electron beam for amplification of the RF signal. There are some limitations of conventional single beam klystron such as high operating voltage, low efficiency and bulky size at higher power levels, which are very effectively handled in Multi Beam Klystron (MBK) that uses multiple low purveyance electron beams for RF interaction. Each beam propagates along its individual transit path through a resonant cavity structure. Multi-Beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3D code only. The present paper shall discuss the design of multi beam RF cavities for klystrons operating at 2856 MHz (S-band) and 5 GHz (C-band) respectively. The design approach uses some scaling laws for finding the electron beam parameters of the multi beam device from their single beam counter parts. The scaled beam parameters are then used for finding the design parameters of the multi beam cavities. Design of the desired multi beam cavity can be optimized through iterative simulations in CST Microwave Studio.

Design of a multi beam klystron cavity from its single beam parameters

International Nuclear Information System (INIS)

Kant, Deepender; Joshi, L. M.; Janyani, Vijay

2016-01-01

The klystron is a well-known microwave amplifier which uses kinetic energy of an electron beam for amplification of the RF signal. There are some limitations of conventional single beam klystron such as high operating voltage, low efficiency and bulky size at higher power levels, which are very effectively handled in Multi Beam Klystron (MBK) that uses multiple low purveyance electron beams for RF interaction. Each beam propagates along its individual transit path through a resonant cavity structure. Multi-Beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3D code only. The present paper shall discuss the design of multi beam RF cavities for klystrons operating at 2856 MHz (S-band) and 5 GHz (C-band) respectively. The design approach uses some scaling laws for finding the electron beam parameters of the multi beam device from their single beam counter parts. The scaled beam parameters are then used for finding the design parameters of the multi beam cavities. Design of the desired multi beam cavity can be optimized through iterative simulations in CST Microwave Studio.

Practical switching power supply design

CERN Document Server

Brown, Martin C

1990-01-01

Take the ""black magic"" out of switching power supplies with Practical Switching Power Supply Design! This is a comprehensive ""hands-on"" guide to the theory behind, and design of, PWM and resonant switching supplies. You'll find information on switching supply operation and selecting an appropriate topology for your application. There's extensive coverage of buck, boost, flyback, push-pull, half bridge, and full bridge regulator circuits. Special attention is given to semiconductors used in switching supplies. RFI/EMI reduction, grounding, testing, and safety standards are also deta

IOT based RF power systems as an alternative to klystron amplifier in Indus-2 at the rate 505.812 MHz

International Nuclear Information System (INIS)

Deo, R.K.; Jain, M.K.; Kumar, Gautam; Lad, Mahendra; Badapanda, M.K.; Bagre, Sunil; Upadhyay, Rinki; Tripathi, Akhilesh; Rao, J.N.; Pandiyar, Mohan; Hannurkar, P.R.

2013-01-01

Due to non-availability of replacement Klystron tube in Indus-2, an IOT based high power RF amplifier system is realized. It is based on E2V make 80 kW IOTD2130 tube with its circuit assembly IMD2000ST. This amplifier system is easily available commercially due to its application in DTV broadcast. It has inherent advantages over klystron amplifier viz. high efficiency (η), less phase and amplitude sensitivity to HV ripple, higher linearity, compactness and less cooling requirement. This high power IOT amplifier is tested with its required control system, cooling system, electron gun auxiliary supplies, beam supply and focusing supply. The nominal beam voltage for this IOT is -36 kV however amplifier was tested successfully with indigenously developed -32 kV, crowbar less power supply. The optimum load impedance for IOT beam was calculated for this bias voltage ( 32kV). For the required load impedance, coupling coefficient (β) of output coupler to the O/P cavity was estimated and accordingly loop angle was adjusted. The amplifier has been tested up to 50 kW with amplifier efficiency 60% and gain 23 dB at - 32 kV beam voltage. (author)

Sequence Control System of 1-MW CW Klystron for the PEFP

CERN Document Server

Park, Byoung R; Chun Myung Hwan; Han Yeung Jin; Hyo Jeong Maeng; Kim Sung Chul; Yang Jae Seok; Yu In Ha

2005-01-01

Sequence control system of 1-MW CW klystron for the PEFP (Proton Engineering Frontier Project) has been developed in order to drive the 1-MW klystron amplifier. The system is able to control several power supplies and many environment conditions. The hardware of sequence control and the interlock system are based on the Allen-Bradley's SLC500 Program Logic Controller (PLC). Also the system can be controlled by a touch screen at local mode or Ethernet network with high level HMI at remote mode.

Recent performance, lifetime, and failure modes of the 5045 klystron population at SLAC

International Nuclear Information System (INIS)

Koontz, R.F.; Lee, T.G.; Pearson, C.; Vlieks, A.E.

1992-08-01

The 65 MW S-Band klystrons (5045) used to power SLC have been in service for over seven years. Currently, 244 of these tubes are in place on the accelerator, operating full power at 120 pulses per second. Enough tubes have now reached end of life, or experienced other failures to allow a good analysis of failure modes, and to project average lifetime for this type of tube. This paper describes the various modes of failure seen in klystrons rammed from SLC service, and provides data on expected lifetime from current production based on accumulated SLC operating experience

Recent performance, lifetime, and failure modes or the 5045 klystron population at SLAC

International Nuclear Information System (INIS)

Koontz, R.F.; Lee, T.G.; Pearson, C.; Vlieks, A.E.

1992-01-01

The 65 MW S-Band klystrons (5045) used to power SLC have been in service for over seven years. Currently, 244 of these tubes are in place on the accelerator, operating full power at 120 pulses per second. Enough tubes have now reached cathode end of life, or experienced other failures to allow a good analysis of failure modes, and to project average lifetime for this type of tube. This paper describes the various modes of failure seen in klystrons returned from SLC service, and provides data on expected lifetime from current production based on accumulated SLC operating experience. 3 refs., 6 figs

Simplified design of switching power supplies

CERN Document Server

Lenk, John

1995-01-01

* Describes the operation of each circuit in detail * Examines a wide selection of external components that modify the IC package characteristics * Provides hands-on, essential information for designing a switching power supply Simplified Design of Switching Power Supplies is an all-inclusive, one-stop guide to switching power-supply design. Step-by-step instructions and diagrams render this book essential for the student and the experimenter, as well as the design professional. Simplified Design of Switching Power Supplies concentrates on the use of IC regulators. All popular forms of swit

Modification of Modulating Anode Voltage Supply of Klystron for PEFP 20 MeV Linac

International Nuclear Information System (INIS)

Kim, Dae Il; Kwon, Hyeok Jung; Kim, Han Sung; Cho, Yong Sub

2011-01-01

The klystron (TH2089F, THALES) for PEFP 20MeV proton linear accelerator has a triode type electron gun and the modulating anode voltage should be supplied. The klystron has gone through some modification in the modulating anode voltage supply circuit. Formerly, the mod-anode voltage was supplied by using the tetrode-controlled voltage divider. This system requires addition power supply for the tetrode and the grid control circuit. Recently we modified the mod-anode supply from the tetrode-controlled voltage divider to a resistive voltage divider. The resistors for the previous voltage divider were installed at a supporter with high voltage bushing structure next to the klystron. In the previous system, the resistors were exposed to the air and their size was very bulky, length of which was about 1m long. To reduce the space occupied by the voltage divider and to improve the electrical insulation performance, the voltage dividing resistors were moved into the oil tank of the klystron. During the operation of the 20 MeV linac, the klystron parameters were measured. In this paper, the modification of the voltage divider and the operational characteristics of the klystron with modified voltage divider circuit are presented

Development of an X-Band 50 MW Multiple Beam Klystron

International Nuclear Information System (INIS)

Song Liqun; Ferguson, Patrick; Ives, R. Lawrence; Miram, George; Marsden, David; Mizuhara, Max

2003-01-01

Calabazas Creek Research, Inc. is developing an X-band 50 MW multiple beam klystron (MBK) on a DOE SBIR Phase II grant. The electrical design and preliminary mechanical design were completed on the Phase I. This MBK consists of eight discrete klystron circuits driven by eight electron beams located symmetrically on a circle with a radius of 6.3 cm. Each beam operates at 190 kV and 66 A. The eight beam electron gun is in development on a DOE SBIR Phase II grant. Each circuit consists of an input cavity, two gain cavities, three penultimate cavities, and a three cavity output circuit operating in the PI/2 mode. Ring resonators were initially proposed for the complete circuit; however, low beam -- wave interaction resulted in the necessity to use discrete cavities for all eight circuits. The input cavities are coupled via hybrid waveguides to ensure constant drive power amplitude and phase. The output circuits can either be combined using compact waveguide twists driving a TE01 high power window or combined into a TM04 mode converter driving the same TE01 window. The gain and efficiency for a single circuit has been optimized using KLSC, a 2 1/2D large signal klystron code. Simulations for a single circuit predict an efficiency of 53% for a single output cavity and 55% for the three cavity output resonator. The total RF output power for this MBK is 55 MW. During the Phase II emphasis will be given to cost reduction techniques resulting in a robust - high efficient - long life high power amplifier

Thermal deformation analysis and test of electron gun for high power klystron

International Nuclear Information System (INIS)

Zhou Zusheng; Chinese Academy of Sciences, Beijing; Dong Dong

2006-01-01

A 120 MW pulsed electron gun has been developed for 50 MW China-made klystron. It has a Pierce type dispenser cathode and it scans with a diameter of 85 mm. This paper describes the temperature field distribution in the gun and the gun deformation caused by this distribution by using ANSYS. According to the real complex structure and the energy conversion inside the electron gun, the authors took the thermal conduction as the main energy conversion form and got the temperature field. The coincidence between the temperature field and the structural deformation is also described. The beam optics simulated by EGUN with and without considering deformation is discussed, and the valuable results have been obtained. The high power test results and simulation results are analyzed and compared. (authors)

Study of the Reflex-Klystron

International Nuclear Information System (INIS)

Valencia A, R.

1981-01-01

The main purpose of this paper is the theoretical study and the development of a technique for designing. A low power Reflex-Klystron, in order to construct it in the graduated section laboratories of the Instituto Politecnico Nacional. It is pretended to attain a power of 15-45 m W in frequencies of 8-10 GHz with low acceleration potentials (300-400 V) and electric current of 15-25 m A; the device will be mechanically tuned and will have a fine tuning through the potential of the reflector (150-180 V negative with respect to the resonator). The International System of Units is used in this thesis. (Author)

Proceedings of the switched power workshop

International Nuclear Information System (INIS)

Fernow, R.C.

1988-01-01

These proceedings contain most of the presentations given at a workshop on the current state of research in techniques for switched power acceleration. The proceedings are divided, as was the workshop itself, into two parts. Part 1, contains the latest results from a number of groups active in switched power research. The major topic here is a method for switching externally supplied power onto a transmission line. Advocates for vacuum photodiode switching, solid state switching, gas switching, and synthetic pulse generation are all presented. Other important areas of research described in this section concern: external electrical and laser pulsing systems; the properties of the created electromagnetic pulse; structures used for transporting the electromagnetic pulse to the region where the electron beam is located; and possible applications. Part 2 of the proceedings considers the problem of designing a high brightness electron gun using switched power as the power source. This is an important first step in demonstrating the usefulness of switched power techniques for accelerator physics. In addition such a gun could have immediate practical importance for advanced acceleration studies since the brightness could exceed that of present sources by several orders of magnitude. I would like to take this opportunity to thank Kathleen Tuohy and Patricia Tuttle for their assistance in organizing and running the workshop. Their tireless efforts contribute greatly to a very productive meeting

Development of L-band, 10MW multi beam klystron

International Nuclear Information System (INIS)

Irikura, M.; Miyake, S.; Yano, A.; Kazakov, S.; Larionov, A.; Teryaev, V.; Chin, Y.H.

2004-01-01

A 10-MW, L-band multi beam klystron (MBK) for TESLA linear collider and TESLA XFEL has been under development at Toshiba Electron Tubes and Devices Co., Ltd. (TETD) in collaboration with KEK. The TESLA requires pulsed klystrons capable of 10 MW output power at 1300 MHz with 1.5 ms pulse length and a repetition rate of 10 pps. The MBK with 6 low-perveance beams in parallel enables us to operate at lower cathode voltage with higher efficiency. The design work has been accomplished and the fabrication is under way. We are going to start conditioning and testing of prototype no.0 in the middle of July 2004. The design overview will be presented. (author)

Relativistic-klystron two-beam-accelerator as a power source for a 1 TeV next linear collider: A systems study

International Nuclear Information System (INIS)

Yu, S.; Goffeney, N.; Deadrick, F.

1994-10-01

A physics, engineering, and costing study has been conducted to explore the feasibility of a relativistic-klystron two-beam-accelerator system as a power source candidate for a 1 TeV linear collider. We present a point design example which has acceptable transverse and longitudinal beam stability properties. Preliminary ''bottom-up'' cost estimate yields the full power source system at less than 1 billion dollars. The overall efficiency for rf production is estimated to be 36%

W-Band Sheet Beam Klystron Design

International Nuclear Information System (INIS)

Scheitrum, G.; Caryotakis, G.; Burke, A.; Jensen, A.; Jongewaard, E.; Krasnykh, A.; Neubauer, M.; Phillips, R.; Rauenbuehler, K.

2011-01-01

Sheet beam devices provide important advantages for very high power, narrow bandwidth RF sources like accelerator klystrons (1). Reduced current density and increased surface area result in increased power capabi1ity, reduced magnetic fields for focusing and reduced cathode loading. These advantages are offset by increased complexity, beam formation and transport issues and potential for mode competition in the ovennoded cavities and drift tube. This paper will describe the design issues encountered in developing a 100 kW peak and 2 kW average power sheet beam k1ystron at W-band including beam formation, beam transport, circuit design, circuit fabrication and mode competition.

Beam dynamics issues in an extended relativistic klystron

International Nuclear Information System (INIS)

Giordano, G.; Li, H.; Goffeney, N.; Henestroza, E.; Sessler, A.; Yu, S.

1995-04-01

Preliminary studies of beam dynamics in a relativistic klystron were done to support a design study for a 1 TeV relativistic klystron two-beam accelerator (RK-TBA), 11.424 GHz microwave power source. This paper updates those studies. An induction accelerator beam is modulated, accelerated to 10 MeV, and injected into the RK with a rf current of about 1.2 kA. The main portion of the RK is the 300-m long extraction section comprise of 150 traveling-wave output structures and 900 induction accelerator cells. A periodic system of permanent quadrupole magnets is used for focusing. One and two dimensional numerical studies of beam modulation, injection into the main RK, transport and longitudinal equilibrium are presented. Transverse beam instability studies including Landau damping and the ''Betatron Node Scheme'' are presented

Ultra-long-pulse microwave negative high voltage power supply with fast protection

International Nuclear Information System (INIS)

Xu Weihua; Wu Junshuan; Zheng Guanghua; Huang Qiaolin; Yang Chunsheng; Zhou Yuanwei; Chen Yonghao

1998-01-01

Two 1.4 MW high voltage power supply (HVPS) modules with 3-5 s pulse duration have been developed for LHCD experiment in the HT-7 tokamak. The power source consists of a pulsed generator and the electric circuit. Duration of the ultra-long-pulse is controlled by switching-on dc relay immediately and switching-off ac contactor after a given time, and the fast protection is executed by a crowbar. Due to the soft starting of the power source, the problem of overvoltage induced by dc relay switching-on has been solved. Each power supply module outputs a rated power (-35 kV, 40 A) on the dummy load. With the klystrons connected as the load of the power supply modules, LHCD experiments have been conducted successfully in the HT-7 tokamak

Klystron-modulator system availability of PLS 2 GeV electron linac

International Nuclear Information System (INIS)

Cho, M.H.; Park, S.S.; Oh, J.S.; Namkung, W.

1996-01-01

PLS Linac has been injecting 2 GeV electron beams to the Pohang Light Source (PLS) storage ring since September 1994. PLS 2 GeV linac employs 11 sets of high power klystron-modulator (K and M) system for the main RF source for the beam acceleration. The klystron has rated output peak power of 80 MW at 4 microsec pulse width and at 60 pps. The matching modulator has 200 MW peak output power. The total accumulated high voltage run time of the oldest unit has reached beyond 23,000 hour and the sum of all the high voltage run time is approximately 230,000 hour as of May 1996. In this paper, we review overall system performance of the high-power K and M system. A special attention is paid on the analysis of all failures and troubles of the K and M system which affected the linac high power RF operations as well as beam injection operations for the period of 1994 to May 1996. (author)

CMOS integrated switching power converters

CERN Document Server

Villar-Pique, Gerard

2011-01-01

This book describes the structured design and optimization of efficient, energy processing integrated circuits. The approach is multidisciplinary, covering the monolithic integration of IC design techniques, power electronics and control theory. In particular, this book enables readers to conceive, synthesize, design and implement integrated circuits with high-density high-efficiency on-chip switching power regulators. Topics covered encompass the structured design of the on-chip power supply, efficiency optimization, IC-compatible power inductors and capacitors, power MOSFET switches and effi

1995 second modulator-klystron workshop: A modulator-klystron workshop for future linear colliders

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

This second workshop examined the present state of modulator design and attempted an extrapolation for future electron-positron linear colliders. These colliders are currently viewed as multikilometer-long accelerators consisting of a thousand or more RF sources with 500 to 1,000, or more, pulsed power systems. The workshop opened with two introductory talks that presented the current approaches to designing these linear colliders, the anticipated RF sources, and the design constraints for pulse power. The cost of main AC power is a major economic consideration for a future collider, consequently the workshop investigated efficient modulator designs. Techniques that effectively apply the art of power conversion, from the AC mains to the RF output, and specifically, designs that generate output pulses with very fast rise times as compared to the flattop. There were six sessions that involved one or more presentations based on problems specific to the design and production of thousands of modulator-klystron stations, followed by discussion and debate on the material.

Reconstruction of -35 kV/200 kW HVPS for test of klystron units in LHCD system

International Nuclear Information System (INIS)

Huang Yiyun

2004-01-01

The paper introduces the -35 kV/200 kW high voltage power supply (HVPS) which is specially used to test klystron units in LHCD system. The new klystrons must be tested under high voltage level before operation and the old klystrons which have worked for a longtime must be exercised by HVPS in lower hybrid current drive (LHCD) system. As the former HVPS has some shortages in engineering design and operation design, the HVPS has to be modified and rebuilt by adopting new method and technology to solve existing bottle-neck problems. (author)

Switched-mode power supply apparatus and method

NARCIS (Netherlands)

2013-01-01

The present invention relates to a switched-mode power supply apparatus and a corresponding method. For an effective compensation of non-linearities caused by dead- time and voltage drops in the switching power amplifier of the apparatus, an apparatus is proposed comprising a switching power

Switched-mode power supply apparatus and method

NARCIS (Netherlands)

2013-01-01

The present invention relates to a switched-mode power supply apparatus and a corresponding method. For an effective compensation of non-linearities caused by dead-time and voltage drops in the switching power amplifier of the apparatus, an apparatus is proposed comprising a switching power

Development of an X-Band 50 MW Multiple Beam Klystron

Science.gov (United States)

Song, Liqun; Ferguson, Patrick; Ives, R. Lawrence; Miram, George; Marsden, David; Mizuhara, Max

2003-12-01

Calabazas Creek Research, Inc. is developing an X-band 50 MW multiple beam klystron (MBK) on a DOE SBIR Phase II grant. The electrical design and preliminary mechanical design were completed on the Phase I. This MBK consists of eight discrete klystron circuits driven by eight electron beams located symmetrically on a circle with a radius of 6.3 cm. Each beam operates at 190 kV and 66 A. The eight beam electron gun is in development on a DOE SBIR Phase II grant. Each circuit consists of an input cavity, two gain cavities, three penultimate cavities, and a three cavity output circuit operating in the PI/2 mode. Ring resonators were initially proposed for the complete circuit; however, low beam — wave interaction resulted in the necessity to use discrete cavities for all eight circuits. The input cavities are coupled via hybrid waveguides to ensure constant drive power amplitude and phase. The output circuits can either be combined using compact waveguide twists driving a TE01 high power window or combined into a TM04 mode converter driving the same TE01 window. The gain and efficiency for a single circuit has been optimized using KLSC, a 2 1/2D large signal klystron code. Simulations for a single circuit predict an efficiency of 53% for a single output cavity and 55% for the three cavity output resonator. The total RF output power for this MBK is 55 MW. During the Phase II emphasis will be given to cost reduction techniques resulting in a robust — high efficient — long life high power amplifier.

Isolated and soft-switched power converter

Science.gov (United States)

Peng, Fang Zheng; Adams, Donald Joe

2002-01-01

An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

AN INVESTIGATION OF THE BEAM MONITOR FOR THE CLUSTER KLYSTRON

International Nuclear Information System (INIS)

ZHAO, Y.

2001-01-01

The cluster klystron project required a beam monitor to check the quality of the hollow beam shape. Since the power density of the beam is very large, a common phosphorescent screen doesn't work. We investigated varies types of monitors. The related problems were also discussed

Hybrid switch for resonant power converters

Science.gov (United States)

Lai, Jih-Sheng; Yu, Wensong

2014-09-09

A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

Operating experience and reliability improvements on the 5 kW CW klystron at Jefferson Lab

International Nuclear Information System (INIS)

Nelson, R.; Holben, S.

1997-01-01

With substantial operating hours on the RF system, considerable information on reliability of the 5 kW CW klystrons has been obtained. High early failure rates led to examination of the operating conditions and failure modes. Internal ceramic contamination caused premature failure of gun potting material and ultimate tube demise through arcing or ceramic fracture. A planned course of reporting and reconditioning of approximately 300 klystrons, plus careful attention to operating conditions and periodic analysis of operational data, has substantially reduced the failure rate. It is anticipated that implementation of planned supplemental monitoring systems for the klystrons will allow most catastrophic failures to be avoided. By predicting end of life, tubes can be changed out before they fail, thus minimizing unplanned downtime. Initial tests have also been conducted on this same klystron operated at higher voltages with resultant higher output power. The outcome of these tests will provide information to be considered for future upgrades to the accelerator

Amended proposal for R ampersand D on a cluster klystron

International Nuclear Information System (INIS)

Fernow, R.C.; Fischer, J.; Gallardo, J.C.; Kirk, H.G.; Ko, S.K.; Palmer, R.B.; Ulc, S.; Wang, H.

1993-01-01

This Proposal is an updated version of FWP submitted in March 1992. Significant work has been done since the original proposal, and much of this is reported on in this update. In addition there have been several changes made, some in response to suggestions made by the three reviews sent to us in December, 1992. The new information and changes include: Technical information on the proposed design of the magnetron gun, the magnet, acceleration gap, and electrical system (including a comment on efficiency loss due to high-voltage leakage current). Modification of the phase I and II tests to allow operation of the gun and klystron off the axis of the magnet, thus simulating the magnet situation when multiple beams are used. Modification of phases III and IV to test a cluster of three beams: first a three beam gun, and then three beams with a klystron on one of them. We have added a phase V which would be the testing of a full three-beam demonstration klystron. The mod-anode pulser would now be located on the high voltage deck instead of externally. Power for the pulser and other high voltage components would now be provided by an isolation transformer instead of from a lead battery. We believe these changes have improved the proposed program and thank the reviewers for their constructive suggestions. The design is still evolving. Relatively little work has been done on the detailed klystron design, and none on the beam dump

Design of a New Water Load for S-band 750 kW Continuous Wave High Power Klystron Used in EAST Tokamak

Science.gov (United States)

Liu, Liang; Liu, Fukun; Shan, Jiafang; Kuang, Guangli

2007-04-01

In order to test the klystrons operated at a frequency of 3.7 GHz in a continuous wave (CW) mode, a type of water load to absorb its power up to 750 kW is presented. The distilled water sealed with an RF ceramic window is used as the absorbent. At a frequency range of 70 MHz, the VSWR (Voltage Standing Wave Ratio) is below 1.2, and the rise in temperature of water is about 30 oC at the highest power level.

Operation of a 1.3 GHz, 10 MW Multiple Beam Klystron

CERN Document Server

Bohlen, H P; Cattelino, M; Cox, L; Cusick, M; Forrest, S; Friedlander, F; Staprans, A; Wright, E; Zitelli, L

2004-01-01

Results will be reported for a 1.3 GHz, 10 MW multiple beam klystron that is being developed for the TESLA linear accelerator facility. The design parameters for the device are 10 MW peak RF output power with 150 kW average power, 1.5 ms pulse length, 65% efficiency, 50 dB gain, and 2.0 A/cm2

RF Power Generation in LHC

CERN Document Server

Brunner, O C; Valuch, D

2003-01-01

The counter-rotating proton beams in the Large Hadron Collider (LHC) will be captured and then accelerated to their final energies of 2 x 7 TeV by two identical 400 MHz RF systems. The RF power source required for each beam comprises eight 300 kW klystrons. The output power of each klystron is fed via a circulator and a waveguide line to the input coupler of a single-cell super-conducting (SC) cavity. Four klystrons are powered by a 100 kV, 40A AC/DC power converter, previously used for the operation of the LEP klystrons. A five-gap thyratron crowbar protects the four klystrons in each of these units. The technical specification and measured performance of the various high-power elements are discussed. These include the 400MHz/300kW klystrons with emphasis on their group delay and the three-port circulators, which have to cope with peak reflected power levels up to twice the simultaneously applied incident power of 300 kW. In addition, a novel ferrite loaded waveguide absorber, used as termination for port No...

Lasers for switched-power linacs

International Nuclear Information System (INIS)

Bigio, I.J.

1988-01-01

Laser-switched power surges for particle accelerators, just as with direct laser-driven accelerator schemes, place unique demands on the specifications of the invoked laser systems. We review the laser requirements for switched power sources of the types described in other chapters of this volume. The relative advantages and disadvantages of selected lasers are listed, and the appropriateness and scalability of existing technology is discussed. 4 refs., 2 figs., 2 tabs

Numerical simulation of the SLAC X-100 klystron using RKTW2D

International Nuclear Information System (INIS)

Ryne, R.D.; Vlieks, A.E.

1991-05-01

We have performed numerical simulations of the X-100 klystron being developed at Stanford Linear Accelerator Center. The X-100 is being developed as a possible source for the next generation of linear collider, and will be required to produce ∼100 MW of power for a duration of ∼800 ns. Our simulations were performed using the simulation programs RKTW1D and RKTW2D, developed at Lawrence Livermore National Laboratory. The codes were used to investigate the operation of the klystron over a wide range of operating conditions. We will present comparisons of the simulation results with experimental results. 3 refs., 5 figs

The design and performance of 150-MW S-band klystrons

International Nuclear Information System (INIS)

Sprehn, D.; Phillips, R.M.; Caryotakis, G.

1994-09-01

As part of an international collaboration, the Stanford Linear Accelerator Center (SLAC) klystron group has designed, fabricated and tested a 60 Hz, 3 μs, 150 MW klystron built for Deutsches Elektronen Synchrotron (DESY). A test diode with a 535 kV, 700 A electron beam was constructed to verify the gun operation. The first klystron was built and successfully met design specifications. This paper discusses design issues and experimental results of the diode and klystron including the suppression of gun oscillations

Rf power amplification by energy storage and switching

International Nuclear Information System (INIS)

Vernon, W.

1989-01-01

This paper reports that during the last decade there have been several suggestions for RF storage and switching schemes. The principle behind these schemes is simply that energy from a source which is on for a long time at moderate power can be stored in a resonant cavity and dumped (switched) in a short time to yield higher power. This is also the basis of SLED which is driving the SLC, but the major difference is in the switching and the proposed power gains. In the case of SLED there is no switch only a phase agile RF source, and the maximum power gain is about a factor of 3. Proposed storage and switching schemes are often based on large ratios of charge to discharge times, say 5 μsec/50 nsec = 100 which could be the power amplification ratio. An early demonstration of the switching of a superconducting cavity was reported. It was observed that a peak power gain of 9 at low power levels with a cold cavity and a room-temperature switch. The switch was a He gas filled tube positioned in the leg of a waveguide T so that a η/2 stub turned into a η/4 stub when the gas broke down and became a good conductor. All switches encountered to date are some variant of this technique; the stubs reflects back an out-of-phase signal which cancels the one from the cavity so that no power escapes while the low-loss dielectric tube is non-conducting

A power measuring device

International Nuclear Information System (INIS)

As, R. van.

1985-01-01

As a part of the klystron test facility of the Dutch NIKHEF-K accelerator, a sensitive power measuring device has been built. The high-frequency power of a klystron is stored in a water-cooled dummy load. Using a microcomputer, the increase of the water temperature and the water flow rate are transformed to a digital indication of the klystron power. (Auth.)

Reliability and lifetime predictions of SLC klystrons

International Nuclear Information System (INIS)

Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Lee, T.G.; Vlieks, A.E.

1989-01-01

The energy upgrade of SLAC, with the first of the new 67 MW SLAC Linear Collider (SLC) klystrons, began over four years ago. Today there are over 200 of these klystrons in operation. As a result, there is a wealth of klystron performance and failure information that enables reasonable predictions to be made on life expectancy and reliability. Data from initial tests, follow-up tests and daily operation monitoring on the accelerator is stored for analysis. Presented here are life expectancy predictions with particular emphasis on cathode life. Also, based on this data, the authors will discuss some of the principal modes of failure. 3 refs., 2 figs., 1 tab

Reliability and lifetime predictions of SLC klystrons

International Nuclear Information System (INIS)

Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Lee, T.G.; Vlieks, A.E.

1989-03-01

The energy upgrade of SLAC, with the first of the new 67 MW SLAC Linear Collider (SLC) klystrons, began over four years ago. Today there are over 200 of these klystrons in operation. As a result, there is a wealth klystron performance and failure information that enables reasonable predictions to be made on life expectancy and reliability. Data from initial tests, follow-up tests and daily operation monitoring on the accelerator is stores for analysis. Presented here are life expectancy predictions with particular emphasis on cathode life. Also, based on this data, we will discuss some of the principal modes of failure. 3 refs., 2 figs

L-band pulsed klystron for the JHP

International Nuclear Information System (INIS)

Fukuda, S.; Takeuchi, Y.; Hisamatsu, H.; Anami, S.; Kihara, M.; Takahashi, A.

1994-01-01

An L-band high-power klystron for the JHP (6 MW output power and 600 μsec pulse width) was designed at KEK. High-power tests of the test diodes were performed up to a beam voltage of 140 kV, a pulse width of 600 μsec and a repetition rate of 50 pps. The capability to meet the specifications of the gun and the collector was confirmed. High-power tests of the rf window were also performed up to rf powers of 4 MW (600 μsec pulse width) and 5 MW (375 μsec pulse width). We obtained good results for an rf window using high-purity alumina (99.7%). The design considerations and manufacturing process are also described. Manufacturing a prototype tube has been completed and the tube is undergoing the high-power tests. (author)

Sheet Beam Klystron Instability Analysis

International Nuclear Information System (INIS)

Bane, K.

2009-01-01

Using the principle of energy balance we develop a 2D theory for calculating growth rates of instability in a two-cavity model of a sheet beam klystron. An important ingredient is a TE-like mode in the gap that also gives a longitudinal kick to the beam. When compared with a self-consistent particle-in-cell calculation, with sheet beam klystron-type parameters, agreement is quite good up to half the design current, 65 A; at full current, however, other, current-dependent effects come in and the results deviate significantly

High-power semiconductor RSD-based switch

Energy Technology Data Exchange (ETDEWEB)

Bezuglov, V G; Galakhov, I V; Grusin, I A [All-Russian Scientific Research Inst. of Experimental Physics, Sarov (Russian Federation); and others

1997-12-31

The operating principle and test results of a high-power semiconductor RSD-based switch with the following operating parameters is described: operating voltage 25 kV, peak operating current 200 kA, maximum transferred charge 70 C. The switch is intended for use by high-power capacitor banks of state-of-the-art research facilities. The switch was evaluated for applicability in commercial pulsed systems. The possibility of increasing the peak operating current to 500 kA is demonstrated. (author). 4 figs., 2 refs.

Reliability-cost models for the power switching devices of wind power converters

DEFF Research Database (Denmark)

Ma, Ke; Blaabjerg, Frede

2012-01-01

In order to satisfy the growing reliability requirements for the wind power converters with more cost-effective solution, the target of this paper is to establish a new reliability-cost model which can connect the relationship between reliability performances and corresponding semiconductor cost...... temperature mean value Tm and fluctuation amplitude ΔTj of power devices, are presented. With the proposed reliability-cost model, it is possible to enable future reliability-oriented design of the power switching devices for wind power converters, and also an evaluation benchmark for different wind power...... for power switching devices. First the conduction loss, switching loss as well as thermal impedance models of power switching devices (IGBT module) are related to the semiconductor chip number information respectively. Afterwards simplified analytical solutions, which can directly extract the junction...

A 200 MHz 35 MW Multiple Beam Klystron for Accelerator Applications. Final Report

International Nuclear Information System (INIS)

Ives, R. Lawrence; Read, Michael; Ferguson, Patrick; Marsden, David

2011-01-01

Calabazas Creek Research, Inc. (CCR) performed initial development of a compact and reliable 35 MW, multiple beam klystron (MBK) at 200 MHz with a pulse length of 0.125 ms and a 30 Hz repetition rate. The device was targeted for acceleration and ionization cooling of a muon collider, but there are several other potential applications in this frequency range. The klystron uses multiple beams propagating in individual beam tunnels to reduce space charge and allow reduction in the accelerating voltage. This allows a significant reduction in length over a single beam source. More importantly this allows more efficient and less expensive power supplies. At 200 MHz, the interaction circuit for a single beam klystron would be more than six meters long to obtain 50% efficiency and 50 dB gain. This would require a beam voltage of approximately 400 kV and current of 251 A for a microperveance of 1.0. For an eight beam MBK with the same beam perveance, a three meter long interaction circuit achieves the same power and gain. Each beam operates at 142 kV and 70A. The Phase I demonstrated that this device could be fabricated with funding available in a Phase II program and could achieve the program specifications.

Power gating of VLSI circuits using MEMS switches in low power applications

KAUST Repository

Shobak, Hosam; Ghoneim, Mohamed T.; El Boghdady, Nawal; Halawa, Sarah; Iskander, Sophinese M.; Anis, Mohab H.

2011-01-01

-designed MEMS switch to power gate VLSI circuits, such that leakage power is efficiently reduced while accounting for performance and reliability. The designed MEMS switch is characterized by an 0.1876 ? ON resistance and requires 4.5 V to switch. As a result

Study on the Effects of the Modulator Output Ripple on the RF System of the KOMAC 100-MeV Proton Linear Accelerator

Energy Technology Data Exchange (ETDEWEB)

Kwon, Hyeok Jung; Kim, Han Sung; Seol, Kyung Tae; Jeong, Hae Sung; Kim, Sung Gu; Cho, Yong Sub [KAERI, Daejeon (Korea, Republic of)

2016-05-15

The high power system of the proton linear accelerator consists of accelerating cavities such as Radio Frequency Quadrupole (RFQ) and Drift Tube Linac (DTL), high power radio frequency (RF) systems such as klystrons, RF transmission lines and modulators as a klystron power supply. The modulator used at KOMAC adopted a high frequency switching technology using a 3-phase full bridge converter topology to produce 5.8 MW peak power at -105 kV with 9 % duty and produces a current ripple corresponding to the harmonics of the switching frequency. In this paper, the output ripple from the modulator is analyzed and its effects on the high power RF system are presented. The ripple current of the modulator was measured and analyzed. The higher harmonics of the switching frequency were measured and the dominant one was the third harmonic. And this ripple had an effect on the RF signal which was amplified through the klystron and delivered to the DTL. The dominant ripple component of the RF signal was also the third harmonics of the IGBT switching frequency of the modulator.

Phase synchronization of multiple klystrons in RF system

International Nuclear Information System (INIS)

Kwon, S.; Regan, A.; Wang, Y.M.; Rohlev, T.

1998-01-01

The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of the Acceleration Production of Tritium (APT) accelerator. The first LEDA RF system includes three, 1.2 MW, 350 MHz, continuous wave, klystrons driving a radio frequency quadrupole (RFQ). A phase control loop is necessary for each individual klystron in order to guarantee the phase matching of these klystrons. To meet this objective, they propose adaptive PI controllers which are based on simple adaptive control. These controllers guarantee not only phase matching but also amplitude matching

Relativistic klystron

International Nuclear Information System (INIS)

Marks, R.

1985-09-01

Theoretical analysis is presented of a relativisic klystron; i.e. a high-relativistic bunched electron beam which is sent through a succession of tuned cavities and has its energy replenished by periodic induction accelerator units. Parameters are given for a full-size device and for an experimental device using the FEL at the ETA; namely the ELF Facility. 6 refs., 2 figs

Modulators for the S-band test linac at DESY

Science.gov (United States)

Bieler, M.; Choroba, S.; Hameister, J.; Lewin, H.-Ch.

1995-07-01

The development of adequate modulators for high peak power klystrons is one of the focus points for linear collider R&D programs. For the DESY/THD S-band linear collider study 150 MW rf-pulse power at 50 Hz repetition rate and 3 μs pulse duration is required [1]. Two different modulator schemes are under investigation. One is the conventional line type pulser, using a pulse forming network and a step up transformer, the other one is a hard tube pulser, using a dc power source at the full klystron voltage and a switch tube. This paper is focused on the modulator development for the S-band Test Linac at DESY. After a short overview over the test linac and a brief description of the 150 MW S-band klystron the circuitry of the line type pulse (LTP) is given. A hard tube pulser (HTP), which switches the high voltage directly from a storage capacitor to the klystron, has been built up at DESY. Circuitry and the results of the commissioning of the switch tube are reported.

A non-uniform three-gap buncher cavity with suppression of transverse-electromagnetic mode leakage in the triaxial klystron amplifier

Energy Technology Data Exchange (ETDEWEB)

Qi, Zumin; Zhang, Jun, E-mail: zhangjun-nudt@126.com; Zhong, Huihuang; Zhu, Danni; Qiu, Yongfeng [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China)

2014-01-15

The triaxial klystron amplifier is an efficient high power relativistic klystron amplifier operating at high frequencies due to its coaxial structure with large radius. However, the coaxial structures result in coupling problems among the cavities as the TEM mode is not cut-off in the coaxial tube. Therefore, the suppression of the TEM mode leakage, especially the leakage from the buncher cavity to the input cavity, is crucial in the design of a triaxial klystron amplifier. In this paper, a non-uniform three-gap buncher cavity is proposed to suppress the TEM mode leakage. The cold cavity analysis shows that the non-uniform three-gap buncher cavity can significantly suppress the TEM mode generation compared to a uniform three-gap buncher cavity. Particle-in-cell simulation shows that the power leakage to the input cavity is less than 1.5‰ of the negative power in the buncher cavity and the buncher cavity can efficiently modulate an intense relativistic electron beam free of self-oscillations. A fundamental current modulation depth of 117% is achieved by employing the proposed non-uniform buncher cavity into an X-band triaxial amplifier, which results in the high efficiency generation of high power microwave.

Testing and Implementation Progress on the Advanced Photon Source (APS) Linear Accelerator (Linac) High-Power S-band Switching System

OpenAIRE

Grelick, A. E.; Arnold, N.; Berg, S.; Dohan, D.; Goeppner, G.; Kang, Y. W.; Nassiri, A.; Pasky, S.; Pile, G.; Smith, T.; Stein, S. J.

2000-01-01

An S-band linear accelerator is the source of particles and the front end of the Advanced Photon Source injector. In addition, it supports a low-energy undulator test line (LEUTL) and drives a free-electron laser (FEL). A waveguide-switching and distribution system is now under construction. The system configuration was revised to be consistent with the recent change to electron-only operation. There are now six modulator-klystron subsystems, two of which are being configured to act as hot sp...

New method for pumping an optical klystron

International Nuclear Information System (INIS)

Vignola, G.; Freemen, R.R.; Kincaid, B.M.; Pellegrini, C.; Luccio, A.; Murphy, J.; Galayda, J.; Van Steenbergen, A.

1985-01-01

A novel method of operation for a transverse optical klystron (TOK) is proposed. The TOK is a device in which a relativistic electron beam produces tunable coherent radiation at short wavelengths by interacting with a powerful external laser and an undulator field. Here we show that by selecting the external laser wavelengths to be one of the harmonics in the undulator radiation spectrum, excellent output at short wavelength can be realized with significantly reduced performance requirements for the undulator magnet and the storage ring providing the electron beam

Study of solar array switching power management technology for space power system

Science.gov (United States)

Cassinelli, J. E.

1982-01-01

This report documents work performed on the Solar Array Switching Power Management Study. Mission characteristics for three missions were defined to the depth necessary to determine their power management requirements. Solar array switching concepts which could satisfy the mission requirements were identified. The switching concepts were compared with a conventional buck regulator system for cost, weight and volume, reliability, efficiency and thermal control. Solar array switching provided significant advantages in all areas of comparison for the reviewed missions.

Multilevel tracking power supply for switch-mode audio power amplifiers

DEFF Research Database (Denmark)

Iversen, Niels Elkjær; Lazarevic, Vladan; Vasic, Miroslav

2018-01-01

to the power supply in order to improve efficiency. A 100 W prototype system was designed. Measured results show that systems employing envelope tracking can improve system efficiency from 2% to 12%, i.e. a factor of 6. The temperature rise is strongly reduced, especially for the switching power MOSFETs where......Switch-mode technology is the common choice for high efficiency audio power amplifiers. The dynamic nature of real audio reduces efficiency as less continuous output power can be achieved. Based on methods used for RF amplifiers this paper proposes to employ envelope tracking techniques...

Low-level feedback control for the phase regulation of CLIC Drive Beam Klystrons

CERN Document Server

AUTHOR|(SzGeCERN)752526

2015-01-01

The requirement of luminosity loss below 1% raises tight tolerances for the phase and power stability of the CLIC drive beam (DB) klystrons and consequently for the high voltage pulse ripple of the modulators. A low-level RF (LLRF) feedback system needs to be developed and combined with the modulator in order to guarantee the phase and amplitude tolerances. To this aim, three feedback control strategies were investigated, i) Proportional Integral (PI) controller, ii) Linear Quadratic Integral Regulator (LQI) and iii) Model Predictive Controller (MPC). The klystron, as well as the incident phase noise were modelled and used for the design and evaluation of the controllers. First simulation results are presented along with future steps and directions.

Klystron life results in particle accelerator applications

International Nuclear Information System (INIS)

Bohlen, Heinz

2002-01-01

Based on reports contributed by various particle accelerator sites, among them DESY, CERN, and LANL, Weibull life time characteristics have been calculated for the klystrons used at these institutions. Supported by evaluations of the technologies and the operational conditions involved, the results, sometimes surprising and unexpected, present material that can be valuable for logistic considerations, the planning of future accelerators, and naturally for the design of future klystrons

Fast-opening vacuum switches for high-power inductive energy storage

International Nuclear Information System (INIS)

Cooperstein, G.

1988-01-01

The subject of fast-opening vacuum switches for high-power inductive energy storage is emerging as an exciting new area of plasma science research. This opening switch technology, which generally involves the use of plasmas as the switching medium, is key to the development of inductive energy storage techniques for pulsed power which have a number of advantages over conventional capacitive techniques with regard to cost and size. This paper reviews the state of the art in this area with emphasis on applications to inductive storage pulsed power generators. Discussion focuses on fast-opening vacuum switches capable of operating at high power (≥10 12 W). These include plasma erosion opening switches, ion beam opening switches, plasma filled diodes, reflex diodes, plasma flow switches, and other novel vacuum opening switches

Relativistic Klystron Two-Beam Accelerator studies at the RTA test facility

International Nuclear Information System (INIS)

Westenskow, G.A.; Houck, T.L.; Anderson, D.

1996-01-01

A prototype rf power source based on the Relativistic Klystron Two- Beam Accelerator (RK-TBA) concept is being constructed at LBNL to study physics, engineering, and costing issues. The prototype, called RTA, is described and compared to a full scale design appropriate for driving the Next Linear Collider. Specific details of the induction core test and pulsed power system are presented. Details of the 1-MeV, 1.2-kA induction gun currently under construction are described

Relativistic-Klystron two-beam accelerator as a power source for future linear colliders

International Nuclear Information System (INIS)

Lidia, S. M.; Anderson, D. E.; Eylon, S.; Henestroza, E.; Vanecek, D. L.; Yu, S. S.; Houck, T. L.; Westenskow, G. A.

1999-01-01

The technical challenge for making two-beam accelerators into realizable power sources for high-energy colliders lies in the creation of the drive beam and in its propagation over long distances through multiple extraction sections. This year we have been constructing a 1.2-kA, 1-MeV, induction gun for a prototype relativistic klystron two-beam accelerator (RK-TBA). The electron source will be a 8.9 cm diameter, thermionic, flat-surface cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150-ns flat top (1% energy variation), and a normalized edge emittance of less than 300 pi-mm-mr. The prototype accelerator will be used to study, physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. We have also been studying optimization parameters, such as frequency, for the application of the RK-TBA concept to multi-TeV linear colliders. As an rf power source the RK-TBA scales favorably up to frequencies around 35 GHz. An overview of this work with details of the design and performance of the prototype injector, beam line, and diagnostics will be presented

Fast and low power Michelson interferometer thermo-optical switch on SOI.

Science.gov (United States)

Song, Junfeng; Fang, Q; Tao, S H; Liow, T Y; Yu, M B; Lo, G Q; Kwong, D L

2008-09-29

We designed and fabricated silicon-on-insulator based Michelson interferometer (MI) thermo-optical switches with deep etched trenches for heat-isolation. Switch power was reduced approximately 20% for the switch with deep etched trenches, and the MI saved approximately 50% power than that of the Mach-Zehnder interferometer. 10.6 mW switch power, approximately 42 micros switch time for the MI with deep trenches, 13.14 mW switch power and approximately 34 micros switch time for the MI without deep trenches were achieved.

A Simulator of Periodically Switching Channels for Power Line Communications

Science.gov (United States)

Hayasaki, Taro; Umehara, Daisuke; Denno, Satoshi; Morikura, Masahiro

An indoor power line is one of the most attractive media for in-home networks. However, there are many technical problems for achieving in-home power line communication (PLC) with high rate and high reliability. One of such problem is the degradation in the performance of the in-home PLC caused by periodically time-varying channel responses, particularly when connecting the switching power supply equipment. We present a measurement method for power line channel responses and reveal the switching of the channel responses synchronized with power-frequency voltage when connecting switching power supply equipment in sending or receiving outlets. In this paper, we term them periodically switching channel responses. The performance of PLC adapters is seriously affected by the periodically switching channel responses. Therefore, we provide a modeling of the periodically switching channel responses by using finite impulse response (FIR) filters with a shared channel memory and construct a simulator for in-home power line channels including the periodically switching channel responses in order to evaluate the various communication systems through the power line. We present the validity of the proposed simulator through the performance evaluation of OFDM/64QAM over periodically switching channels with additive white Gaussian noise. Furthermore, we evaluate the influence of the periodically switching channel responses on the communication quality of a time-invariant modulation scheme by using the proposed simulator.

Induction linac driven relativistic klystron and cyclotron autoresonance maser experiments

International Nuclear Information System (INIS)

Goodman, D.L.; Birx, D.L.; Danly, B.G.

1991-01-01

In this paper design and experimental results are presented from two high power microwave generation experiments utilizing a high repetition rate induction linac generated electron beam. A relativistic klystron has generated more than 100 MW microwave pulses in X-band for 50 ns without pulse shortening or breakdown. design studies for the first cyclotron autoresonance maser (CARM) amplifier using an induction linac electron beam are also presented

A new switched power linac structure

International Nuclear Information System (INIS)

Villa, F.

1989-03-01

A new pulse power structure has been described that utilizes an easily accessible rectilinear switch. The new structure is more ''forgiving'' (as far as risetime is concerned) than the radial line transformer, and contains fewer switching structures/unit length. The combination of the new structure with the switch proposed seems to offer interesting possibilities for a future linear collider. 13 refs., 6 figs., 2 tabs

Application of high power microwave vacuum electron devices

International Nuclear Information System (INIS)

Ding Yaogen; Liu Pukun; Zhang Zhaochuan; Wang Yong; Shen Bin

2011-01-01

High power microwave vacuum electron devices can work at high frequency, high peak and average power. They have been widely used in military and civil microwave electron systems, such as radar, communication,countermeasure, TV broadcast, particle accelerators, plasma heating devices of fusion, microwave sensing and microwave heating. In scientific research, high power microwave vacuum electron devices are used mainly on high energy particle accelerator and fusion research. The devices include high peak power klystron, CW and long pulse high power klystron, multi-beam klystron,and high power gyrotron. In national economy, high power microwave vacuum electron devices are used mainly on weather and navigation radar, medical and radiation accelerator, TV broadcast and communication system. The devices include high power pulse and CW klystron, extended interaction klystron, traveling wave tube (TWT), magnetron and induced output tube (IOT). The state of art, common technology problems and trends of high power microwave vacuum electron devices are introduced in this paper. (authors)

Power gating of VLSI circuits using MEMS switches in low power applications

KAUST Repository

Shobak, Hosam

2011-12-01

Power dissipation poses a great challenge for VLSI designers. With the intense down-scaling of technology, the total power consumption of the chip is made up primarily of leakage power dissipation. This paper proposes combining a custom-designed MEMS switch to power gate VLSI circuits, such that leakage power is efficiently reduced while accounting for performance and reliability. The designed MEMS switch is characterized by an 0.1876 ? ON resistance and requires 4.5 V to switch. As a result of implementing this novel power gating technique, a standby leakage power reduction of 99% and energy savings of 33.3% are achieved. Finally the possible effects of surge currents and ground bounce noise are studied. These findings allow longer operation times for battery-operated systems characterized by long standby periods. © 2011 IEEE.

RF extraction issues in the relativistic klystron amplifiers

Science.gov (United States)

Serlin, Victor; Friedman, Moshe; Lampe, Martin; Hubbard, Richard F.

1994-05-01

Relativistic klystron amplifiers (RKAs) were successfully operated at NRL in several frequency regimes and power levels. In particular, an L-band RKA was optimized for high- power rf extraction into the atmosphere and an S-band RKA was operated, both in a two-beam and a single-beam configuration. At L-band the rf extraction at maximum power levels (>= 15 GW) was hindered by pulse shortening and poor repeatability. Preliminary investigation showed electron emission in the radiating horn, due to very high voltages associated with the multi-gigawatt rf power levels. This electron current constituted an electric load in parallel with the radiating antenna, and precipitated the rf pulse collapse. At S-band the peak extracted power reached 1.7 GW with power efficiency approximately 50%. However, pulse shortening limited the duration to approximately 50 nanoseconds. The new triaxial RKA promises to solve many of the existing problems.

Design and optimization of G-band extended interaction klystron with high output power

Science.gov (United States)

Li, Renjie; Ruan, Cunjun; Zhang, Huafeng

2018-03-01

A ladder-type Extended Interaction Klystron (EIK) with unequal-length slots in the G-band is proposed and designed. The key parameters of resonance cavities working in the π mode are obtained based on the theoretical analysis and 3D simulation. The influence of the device fabrication tolerance on the high-frequency performance is analyzed in detail, and it is found that at least 5 μm of machining precision is required. Thus, the dynamic tuning is required to compensate for the frequency shift and increase the bandwidth. The input and output coupling hole dimensions are carefully designed to achieve high output power along with a broad bandwidth. The effect of surface roughness of the metallic material on the output power has been investigated, and it is proposed that lower surface roughness leads to higher output power. The focusing magnetic field is also optimized to 0.75 T in order to maintain the beam transportation and achieve high output power. With 16.5 kV operating voltage and 0.30 A beam current, the output power of 360 W, the efficiency of 7.27%, the gain of 38.6 dB, and the 3 dB bandwidth of 500 MHz are predicted. The output properties of the EIK show great stability with the effective suppression of oscillation and mode competition. Moreover, small-signal theory analysis and 1D code AJDISK calculations are carried out to verify the results of 3D PIC simulations. A close agreement among the three methods proves the relative validity and the reliability of the designed EIK. Thus, it is indicated that the EIK with unequal-length slots has potential for power improvement and bandwidth extension.

Switching power converters medium and high power

CERN Document Server

Neacsu, Dorin O

2013-01-01

An examination of all of the multidisciplinary aspects of medium- and high-power converter systems, including basic power electronics, digital control and hardware, sensors, analog preprocessing of signals, protection devices and fault management, and pulse-width-modulation (PWM) algorithms, Switching Power Converters: Medium and High Power, Second Edition discusses the actual use of industrial technology and its related subassemblies and components, covering facets of implementation otherwise overlooked by theoretical textbooks. The updated Second Edition contains many new figures, as well as

Neutron and gamma irradiation effects on power semiconductor switches

International Nuclear Information System (INIS)

Schwarze, G.E.; Frasca, A.J.

1990-01-01

The performance characteristics of high power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN bipolar junction transistors (BJTs), and metal-oxide-semiconductor field effect transistors (MOSFETs)

Conventional power sources for colliders

International Nuclear Information System (INIS)

Allen, M.A.

1987-07-01

At SLAC we are developing high peak-power klystrons to explore the limits of use of conventional power sources in future linear colliders. In an experimental tube we have achieved 150 MW at 1 μsec pulse width at 2856 MHz. In production tubes for SLAC Linear Collider (SLC) we routinely achieve 67 MW at 3.5 μsec pulse width and 180 pps. Over 200 of the klystrons are in routine operation in SLC. An experimental klystron at 8.568 GHz is presently under construction with a design objective of 30 MW at 1 μsec. A program is starting on the relativistic klystron whose performance will be analyzed in the exploration of the limits of klystrons at very short pulse widths

Design and development of permanent magnet based focusing lens for J-Band Klystron

Energy Technology Data Exchange (ETDEWEB)

Singh, Kumud; Itteera, Janvin; Ukarde, Priti; Malhotra, Sanjay; Taly, Y.K., E-mail: kumuds@barc.gov.in [Control Instrumentation Division, Bhabha Atomic Research Centre, Mumbai (India); Bandyopadhay, Ayan; Meena, Rakesh; Rawat, Vikram; Joshi, L.M [Microwave Tubes Division, Central Electronics Engineering Research Institute, Pilani (India)

2014-07-01

Applying permanent magnet technology to beam focusing in klystrons can reduce their power consumption and increase their reliability of operation. Electromagnetic design of the beam focusing elements, for high frequency travelling wave tubes, is very critical. The magnitude and profile of the magnetic field need to match the optics requirement from beam dynamics studies. The rise of the field from cathode gun region to the uniform field region (RF section) is important as the desired transition from zero to peak axial field must occur over a short axial distance. Confined flow regime is an optimum choice to minimize beam scalloping but demands an axial magnetic field greater than 2 - 3 times the Brillouin flow field. This necessitates optimization in the magnet design achieve high magnetic field within given spatial constraints. Electromagnetic design and simulations were done using 3D Finite element method (FEM) analysis software. A permanent magnet based focusing lens for a miniature J-Band klystron has been designed and developed at Control Instrumentation Division, BARC. This paper presents the design, simulation studies, beam transmission and RF tests results for J Band klystron with permanent magnet focusing lens. (author)

Repetitive plasma opening switch for powerful high-voltage pulse generators

International Nuclear Information System (INIS)

Dolgachev, G.I.; Zakatov, L.P.; Nitishinskii, M.S.; Ushakov, A.G.

1998-01-01

Results are presented of experimental studies of plasma opening switches that serve to sharpen the pulses of inductive microsecond high-voltage pulse generators. It is demonstrated that repetitive plasma opening switches can be used to create super-powerful generators operating in a quasi-continuous regime. An erosion switching mechanism and the problem of magnetic insulation in repetitive switches are considered. Achieving super-high peak power in plasma switches makes it possible to develop new types of high-power generators of electron beams and X radiation. Possible implementations and the efficiency of these generators are discussed

The theoretical study of the optical klystron free electron laser

International Nuclear Information System (INIS)

Yang Zhenhua

2001-01-01

The work of the theoretical study and numerical simulation of optical klystron free electron laser is supported by National 863 Research Development Program and National Science Foundation of China. The object of studying UV band free electron laser (FEL) is to understand the physical law of optical klystron FEL and to gain experience for design. A three-dimensional code OPFEL are made and it is approved that the code is correct completely. The magnetic field of the optical klystron, the energy modulation of the electron beam, the density modulation of the electron beam, spontaneous emission of the electron beam in optical klystron, the harmonic super-radiation of the electron beam, and the effects of the undulator magnetic field error on modulation of the electron beam energy are simulated. These results are useful for the future experiments

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

International Nuclear Information System (INIS)

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

1991-01-01

Los Alamos is investigating a number of high power microwave (HPM) sources for their potential to power advanced accelerators. Included in this investigation are the large orbit gyrotron amplifier and oscillator (LOG) and the relativistic klystron amplifier (RKA). LOG amplifier development is newly underway. Electron beam power levels of 3 GW, 70 ns duration, are planned, with anticipated conversion efficiencies into RF on the order of 20 percent. Ongoing investigations on this device include experimental improvement of the electron beam optics (to allow injection of a suitable fraction of the electron beam born in the gun into the amplifier structure), and computational studies of resonator design and RF extraction. Recent RKA studies have operated at electron beam powers into the device of 1.35 GW in microsecond duration pulses. The device has yielded modulated electron beam power approaching 300 MW using 3-5 kW of RF input drive. RF powers extracted into waveguide have been up to 70 MW, suggesting that more power is available from the device than has been converted to-date in the extractor

Switching overvoltages in offshore wind power grids

DEFF Research Database (Denmark)

Arana Aristi, Ivan

and cables are presented. In Chapter 4 results from time domain measurements and simulations of switching operations in offshore wind power grids are described. Specifically, switching operations on a single wind turbine, the collection grid, the export system and the external grid measured in several real...... offshore wind farms are shown together with simulation results. Switching operations in offshore wind power grids can be simulated with different electromagnetic transient programs. Different programs were used in the project and compared results are included in Chapter 4. Also in Chapter 4 different......Switching transients in wind turbines, the collection grid, the export system and the external grid in offshore wind farms, during normal or abnormal operation, are the most important phenomena when conducting insulation coordination studies. However, the recommended models and methods from...

High voltage, fast turn-on and turn-off switch: Final report for period September 2, 1998 - March 17, 1999

International Nuclear Information System (INIS)

Jochen Schein; Xiaoxi Xu; Niansheng Qi; Steven Gensler; Rahul Prasad; Mahadevan Krishnan

1999-01-01

The aspect to be investigated during this contract was an electron-beam triggered diamond switch to be used in high power modulators. Today's high power modulators require higher voltage switches than those developed to date. Specifically, the proposed 1 TeV linear collider, the NLC/ILC at the Stanford Linear Accelerator Center (SLAC), consists of two linacs with 6600 X-Band klystrons powered by 3300 high power modulators. These modulators require switches capable of handling 80 kV, switching 8 kA with pulse durations ranging from 2 ps (linac) to 6 micros (pre-linac) with switching times <50 ns at pulse repetition frequencies up to 180 Hz. In addition the large number of switches and other components dictate a pulse to pulse jitter of <10 ns and a mean time between failures of at least 50,000 hours. The present approach is to use hydrogen filled thyratrons. While these switches meet the voltage and conduction current requirements they lack the required reliability (pulse to pulse jitter) and lifetime. Research to improve these aspects is in progress. A solid state switch inherently offers the required reliability and lifetime. However, Si-based switches developed to date are limited to about 5 kV and several must be stacked in series to deliver the required voltage. This further increases the already large parts count and compromises reliability and lifetime. A monolithic, solid state switch capable of meeting all the requirements for X-Band modulators would be ideal. DOE selected this proposal for a Phase 1 SBIR award and this final report describes the progress made during the contract

High voltage, fast turn-on and turn-off switch: Final report for period September 2, 1998 - March 17, 1999

Energy Technology Data Exchange (ETDEWEB)

Jochen Schein; Xiaoxi Xu; Niansheng Qi; Steven Gensler; Rahul Prasad; Mahadevan Krishnan

1999-04-10

The aspect to be investigated during this contract was an electron-beam triggered diamond switch to be used in high power modulators. Today's high power modulators require higher voltage switches than those developed to date. Specifically, the proposed 1 TeV linear collider, the NLC/ILC at the Stanford Linear Accelerator Center (SLAC), consists of two linacs with 6600 X-Band klystrons powered by 3300 high power modulators. These modulators require switches capable of handling 80 kV, switching 8 kA with pulse durations ranging from 2 ps (linac) to 6 {micro}s (pre-linac) with switching times <50 ns at pulse repetition frequencies up to 180 Hz. In addition the large number of switches and other components dictate a pulse to pulse jitter of <10 ns and a mean time between failures of at least 50,000 hours. The present approach is to use hydrogen filled thyratrons. While these switches meet the voltage and conduction current requirements they lack the required reliability (pulse to pulse jitter) and lifetime. Research to improve these aspects is in progress. A solid state switch inherently offers the required reliability and lifetime. However, Si-based switches developed to date are limited to about 5 kV and several must be stacked in series to deliver the required voltage. This further increases the already large parts count and compromises reliability and lifetime. A monolithic, solid state switch capable of meeting all the requirements for X-Band modulators would be ideal. DOE selected this proposal for a Phase 1 SBIR award and this final report describes the progress made during the contract.

High voltage superconducting switch for power application

International Nuclear Information System (INIS)

Mawardi, O.; Ferendeci, A.; Gattozzi, A.

1983-01-01

This paper reports the development of a novel interrupter which meets the requirements of a high voltage direct current (HVDC) power switch and at the same time doubles as a current limiter. The basic concept of the interrupter makes use of a fast superconducting, high capacity (SHIC) switch that carries the full load current while in the superconducting state and reverts to the normal resistive state when triggered. Typical design parameters are examined for the case of a HVDC transmission line handling 2.5KA at 150KVDC. The result is a power switch with superior performance and smaller size than the ones reported to date

Practical test of the LINAC4 RF power system

CERN Document Server

Schwerg, N

2011-01-01

The high RF power for the Linac4 accelerating structures will be generated by thirteen 1.3 MW klystrons, previously used for the CERN LEP accelerator, and six new klystrons of 2.8 MW all operating at a frequency of 352.2 MHz. The power distribution scheme features a folded magic tee feeding the power from one 2.8 MW klystron to two LEP circulators. We present first results from the Linac4 test place, validating the approach and the used components as well as reporting on the klystron re-tuning activities.

Comparison between the performance of some KEK-klystrons and simulation results

Energy Technology Data Exchange (ETDEWEB)

Fukuda, Shigeki [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

1997-04-01

Recent developments of various klystron simulation codes have enabled us to realistically design klystrons. This paper presents various simulation results using the FCI code and the performances of tubes manufactured based on this code. Upgrading a 30-MW S-band klystron and developing a 50-MW S-band klystron for the KEKB projects are successful examples based on FCI-code predictions. Mass-productions of these tubes have already started. On the other hand, a discrepancy has been found between the FCI simulation results and the performance of real tubes. In some cases, the simulation results lead to high-efficiency results, while manufactured tubes show the usual value, or a lower value, of the efficiency. One possible cause may come from a data mismatch between the electron-gun simulation and the input data set of the FCI code for the gun region. This kind of discrepancy has been observed in 30-MW S-band pulsed tubes, sub-booster pulsed tubes and L-band high-duty pulsed klystrons. Sometimes, JPNDSK (one-dimensional disk-model code) gives similar results. Some examples using the FCI code are given in this article. An Arsenal-MSU code could be applied to the 50-MW klystron under collaboration with Moscow State University; a good agreement has been found between the prediction of the code and performance. (author)

Design of diode electron gun for 250 kW CW klystron

International Nuclear Information System (INIS)

Prasad, M.; Pande, S.A.; Hannurkar, P.R.

2005-01-01

A 250 kW CW klystron at frequencies 350 MHz and 700 MHz is being developed at Centre for Advanced Technology. These klystrons are required for forthcoming project like 100 MeV proton Linac for Spallation Neutron Source (SNS) as a main rf sources. In order to develop klystrons, we have designed the diode electron gun, which delivers more than 10 A beam current at 50 kV. This paper describes the simulation results of electron gun with computer code EGUN. (author)

Neutron and gamma irradiation effects on power semiconductor switches

Science.gov (United States)

Schwarze, G. E.; Frasca, A. J.

1990-01-01

The performance characteristics of high power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN Bipolar Junction Transistors (BJTs), and Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). BJTs show a rapid decrease in gain, blocking voltage, and storage time for neutron irradiation, and MOSFETs show a rapid decrease in the gate threshold voltage for gamma irradiation.

Production of Coherent xuv and soft-x-ray light using a transverse optical klystron

International Nuclear Information System (INIS)

Kincaid, B.M.; Freeman, R.R.

1984-01-01

This section describes the theory of the production of coherent xuv radiation and soft x rays using a transverse optical klystron (TOK). A TOK uses a high-power laser in conjunction with an undulator magnet to produce laserlike output of xuv radiation from a relativistic electron beam. 16 references, 5 figures

Preliminary design report of a relativistic-Klystron two-beam-accelerator based power source for a 1 TeV center-of-mass next linear collider

International Nuclear Information System (INIS)

Yu, S.; Goffeney, N.; Henestroza, E.

1995-01-01

A preliminary point design for an 11.4 GHz power source for a 1 TeV center-of-mass Next Linear Collider (NLC) based on the Relativistic-Klystron Two-Beam-Accelerator (RK-TBA) concept is presented. The present report is the result of a joint LBL-LLNL systems study. consisting of three major thrust areas: physics, engineering, and costing. The new RK-TBA point design, together with our findings in each of these areas, are reported

State-of-the-art piezoelectric transformer-based switch mode power supplies

DEFF Research Database (Denmark)

Ekhtiari, Marzieh; Zhang, Zhe; Andersen, Michael A. E.

2014-01-01

Inductorless switch mode power supplies based on piezoelectric transformers are used to replace conventional transformers in high power density switch mode power supplies. Even though piezoelectric-based converters exhibit a high d egree of nonlinearity, it is desirable to use piezoelectric transfo...... discusses power supplies with the trend evaluation of piezoelectric transformer-based converter topologies and control methods. The challenges of piezoelectric transformers regarding soft switching capability and nonlinearity are addressed. This paper can be used as a guideline f or choosing a proper...... topology of piezoelectric-based switch mode power supply and a control method for the required application....

Design of a relativistic klystron two-beam accelerator prototype

International Nuclear Information System (INIS)

Westenskow, G.; Caporaso, G.; Chen, Y.

1995-01-01

We are designing an experiment to study physics, engineering, and costing issues of an extended Relativistic Klystron Two-Beam Accelerator (RK-TBA). The experiment is a prototype for an RK-TBA based microwave power source suitable for driving a 1 TeV linear collider. Major components of the experiment include a 2.5-MV, 1.5-kA electron source, a 11.4-GHz modulator, a bunch compressor, and a 8-m extraction section. The extraction section will be comprised of 4 traveling-wave output structures, each generating about 360 MW of rf power. Induction cells will be used in the extraction section to maintain the average beam energy at 5 MeV. Status of the design is presented

Solenoid fringe field compensation for the Cluster Klystron

International Nuclear Information System (INIS)

Wang, H.; Fernow, R.C.; Kirk, H.G.; Palmer, R.B.; Zhao, Y.

1996-04-01

Optimization of the solenoid pancake currents so as to have a uniform axial magnetic field over an extended volume, is very important for the successful operation of the Cluster Klystron. By boosting the first and the last pancake currents by 35%, a uniform field Br/Bz ≤ 0.1% at radius R ≤ 2 cm can be extended from ± 7 cm to ± 16 cm. The result confirms simulations and the requirements for a 3-beam Cluster Klystron Experiment are achieved

Liquid Nitrogen Temperature Operation of a Switching Power Converter

Science.gov (United States)

Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

1995-01-01

The performance of a 42/28 V, 175 W, 50 kHz pulse-width modulated buck dc/dc switching power converter at liquid nitrogen temperature (LNT) is compared with room temperature operation. The power circuit as well as the control circuit of the converter, designed with commercially available components, were operated at LNT and resulted in a slight improvement in converter efficiency. The improvement in power MOSFET operation was offset by deteriorating performance of the output diode rectifier at LNT. Performance of the converter could be further improved at low temperatures by using only power MOSFET's as switches. The use of a resonant topology will further improve the circuit performance by reducing the switching noise and loss.

High power switches for ion induction linacs

International Nuclear Information System (INIS)

Humphries, S.; Savage, M.; Saylor, W.B.

1985-01-01

The success of linear induction ion accelerators for accelerator inertial fusion (AIF) applications depends largely on innovations in pulsed power technology. There are tight constraints on the accuracy of accelerating voltage waveforms to maintain a low momentum spread. Furthermore, the non-relativistic ion beams may be subject to a klystronlike interaction with the accelerating cavities, leading to enhanced momentum spread. In this paper, we describe a novel high power switch with a demonstrated ability to interrupt 300 A at 20 kV in less than 60 ns. The switch may allow the replacement of pulse modulators in linear induction accelerators with hard tube pulsers. A power system based on a hard tube pulser could solve the longitudinal instability problem while maintaining high energy transfer efficiency. The problem of longitudinal beam control in ion induction linacs is reviewed in Section 2. Section 3 describes the principles of the plasma flow switch. Experimental results are summarized in Section 4

Experimental Performance of the NRL 8-Beam, 4-Cavity Multiple-Beam Klystron

Science.gov (United States)

Abe, D. K.; Pershing, D. E.; Nguyen, K. T.; Wood, F. N.; Myers, R. E.; Eisen, E. L.; Cusick, M.; Levush, B.

2006-01-01

Multiple-beam amplifiers (MBAs) represent a device technology with the potential to produce high-power, efficient amplifiers with relatively wide bandwidths that are compact, low-weight, low-noise, and operate at reduced voltages relative to comparable single-beam devices. To better understand the device physics and technical issues involved in the design, fabrication, and operation of these devices, the U.S. Naval Research Laboratory (NRL) has an on-going program to develop high peak power (> 600 kW) multiple-beam klystrons (MBKs) operating in S-band (˜3.3 GHz).

Spallation Neutron Source High Power RF Installation and Commissioning Progress

CERN Document Server

McCarthy, Michael P; Bradley, Joseph T; Fuja, Ray E; Gurd, Pamela; Hardek, Thomas; Kang, Yoon W; Rees, Daniel; Roybal, William; Young, Karen A

2005-01-01

The Spallation Neutron Source (SNS) linac will provide a 1 GeV proton beam for injection into the accumulator ring. In the normal conducting (NC) section of this linac, the Radio Frequency Quadupole (RFQ) and six drift tube linac (DTL) tanks are powered by seven 2.5 MW, 402.5 MHz klystrons and the four coupled cavity linac (CCL) cavities are powered by four 5.0 MW, 805 MHz klystrons. Eighty-one 550 kW, 805 MHz klystrons each drive a single cavity in the superconducting (SC) section of the linac. The high power radio frequency (HPRF) equipment was specified and procured by LANL and tested before delivery to ensure a smooth transition from installation to commissioning. Installation of RF equipment to support klystron operation in the 350-meter long klystron gallery started in June 2002. The final klystron was set in place in September 2004. Presently, all RF stations have been installed and high power testing has been completed. This paper reviews the progression of the installation and testing of the HPRF Sys...

ICC Experiment Performance Improvement through Advanced Feedback Controllers for High-Power Low-Cost Switching Power Amplifiers

International Nuclear Information System (INIS)

Nelson, Brian A.

2006-01-01

Limited resources force most smaller fusion energy research experiments to have little or no feedback control of their operational parameters, preventing achievement of their full operational potential. Recent breakthroughs in high-power switching technologies have greatly reduced feedback-controlled power supply costs, primarily those classified as switching power amplifiers. However, inexpensive and flexible controllers for these power supplies have not been developed. A uClinux-based micro-controller (Analog Devices Blackfin BF537) was identified as having the capabilities to form the base of a digital control system for switching power amplifiers. A control algorithm was created, and a Linux character device driver was written to realize the algorithm. The software and algorithm were successfully tested on a switching power amplifier and magnetic field coil using University of Washington (subcontractor) resources

Second generation SLAC modulator

International Nuclear Information System (INIS)

Donaldson, A.R.; Cron, J.C.; Hanselman, R.R.

1986-06-01

The Stanford Linear Accelerator Laboratory has undertaken the construction of a single pass electron-positron collider. In order to reach required beam energy 235 new klystrons needed upgraded modulator systems. The collider will use 50 GeV electrons and positrons. The increase in accelerator energy from the present 30 GeV necessitates the replacement of existing 35 MW klystrons with new 67 MW units. The doubling of klystron output power required a redesign of the modulator system. The 67 MW klystron needs a 350 kV beam voltage pulse with a 3.7 μs pulse width. A new pulse transformer was designed to deliver the increased voltage and pulse width. Pulse cable design was evaluated to obtain increased reliability of that critical element. The modulator, with the exception of its power supply, was rebuilt to produce the required power increase while enhancing reliability and improving maintainability. An investigation of present thyratron switch tube performance under the new operating conditions resulted in agitation and some warranted panic but these conditions were mitigated after several successful experiments and some evolutionary narrowing of the klystron pulse width. The discussion will cover the upgraded modulator system specifications and some details of the new pulse transformer tank, pulse cable, modulator, and modulator switch tube

Development of the C-band (5712 MHz) 50 MW class PPM klystron (2)

International Nuclear Information System (INIS)

Matsumoto, H.; Shintake, T.; Ohkubo, Y.; Taoka, H.; Ohhashi, K.; Kakuno, K.

2001-01-01

Hot isostatic pressing (HIP) technique has been firstly applied to fabricate a magnetic circuit in a PPM klystron. Simply stacking disks of the magnetic stainless-steel (Mag-SUS) and oxygen-free-copper (OFC) alternatively, and processing in a HIP vessel filled with pressurised Ar-gas at 1200-kgf/cm 2 and temperature of 800degC for 2 hours, they were bonded in one block with diffusion bonding. No brazing-alloys were used in this process. After machining the rf-cavities and beam drift-tube on the bonded PPM stack, they were assembled together in one body by means of conventional brazing method. The C-band PPM klystron based on this technique was fabricated in the course of the Linear Collider R and D. Out-put power of 37 MW was generated with 2.5-μsec pulse width and 50 pps repetition rate. (author)

A study on the high-order mode oscillation in a four-cavity intense relativistic klystron amplifier

Energy Technology Data Exchange (ETDEWEB)

Liu, Ying-Hui; Niu, Xin-Jian; Wang, Hui [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu (China); Jia, Nan; Duan, Yaoyong [The Chinese People' s Armed Police Force Academy, Hebei (China); Li, Zheng-Hong [Science and Technology on High Power Microwave Laboratory, Institute of Applied Electronics, CAEP, Mianyang (China); Cheng, Hui [Microwave Department, Sichuan Jiuzhou Electric Appliance Group Co., Ltd., Mianyang (China); Yang, Xiao-Chuan [Computational Aerodynamics Institute, China Aerodynamics Research and Development Center, Mianyang (China)

2016-07-15

The high-order mode oscillation is studied in designing a four-cavity intense relativistic klystron amplifier. The reason for the oscillation caused by high-order modes and a method to suppress these kinds of spurious modes are found through theoretical analyses and the study on the influence of major parameters of a high frequency structure (such as the oscillation frequency of cavities, the cavity Q value, the length of drift tube section, and the characteristic impedance). Based on much simulation, a four-cavity intense relativistic klystron amplifier with a superior performance has been designed, built, and tested. An output power of 2.22 GW corresponding to 27.4% efficiency and 61 dB gain has been obtained. Moreover, the high-order mode oscillation is suppressed effectively, and an output power of 1.95 GW corresponding to 26% efficiency and 62 dB gain has been obtained in our laboratory.

Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

Science.gov (United States)

Bai, Xianchen; Yang, Jianhua; Zhang, Jiande

2012-08-01

By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

Energy Technology Data Exchange (ETDEWEB)

Bai Xianchen; Yang Jianhua; Zhang Jiande [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2012-08-15

By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

International Nuclear Information System (INIS)

Bai Xianchen; Yang Jianhua; Zhang Jiande

2012-01-01

By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

Computer-aided design of the RF-cavity for a high-power S-band klystron

Science.gov (United States)

Kant, D.; Bandyopadhyay, A. K.; Pal, D.; Meena, R.; Nangru, S. C.; Joshi, L. M.

2012-08-01

This article describes the computer-aided design of the RF-cavity for a S-band klystron operating at 2856 MHz. State-of-the-art electromagnetic simulation tools SUPERFISH, CST Microwave studio, HFSS and MAGIC have been used for cavity design. After finalising the geometrical details of the cavity through simulation, it has been fabricated and characterised through cold testing. Detailed results of the computer-aided simulation and cold measurements are presented in this article.

High voltage power supplies for INDUS-2 RF system

International Nuclear Information System (INIS)

Badapanda, M.K.; Hannurkar, P.R.

2003-01-01

The RF system of Indus-2 employs klystron amplifiers operating at 505.812 MHz. A precession controlled high voltage DC supply of appropriate rating is needed for each klystron amplifier, as its bias supply. Since internal flashover and arcing are common with the operation of these klystrons and stored energies beyond particular limit inside its bias power supply is detrimental to this device, a properly designed crowbar is incorporated between each klystron and its power supply. This crowbar bypass these stored energies and helps protecting klystron under any of these unfavorable conditions. In either case, power supply sees a near short circuit across its load. So, its power circuit is designed to reduce the fault current level and its various components are also designed to withstand these fault currents, as and when it appears. Finally, operation of these high voltage power supplies (HVPS) generates lot of harmonics on the source side, which distort the input waveform substantially and reduces the input power factor also. Source multiplication between two power supplies are planned to improve upon above parameters and suitable detuned line filters are incorporated to keep the input voltage total harmonics distortion (THD) below 5 % and input power factor (IFF) near unity. (author)

A systems study of an RF power source for a 1 TeV next linear collider based upon the relativistic-klystron two-beam accelerator

International Nuclear Information System (INIS)

Yu, S.; Goffeney, N.; Deadrick, F.

1994-11-01

A systems study, including physics, engineering and costing, has been conducted to assess the feasibility of a relativistic-klystron two-beam-accelerator (RK-TBA) system as a RF power source candidate for a 1 TeV linear collider. Several key issues associated with a realizable RK-TBA system have been addressed, and corresponding schemes have been developed and examined quantitatively. A point design example has been constructed to present a concrete conceptual design which has acceptable transverse and longitudinal beam stability properties. The overall efficiency of RF production for such a power source is estimated to be 36%, and the cost of the full system is estimated to be less than 1 billion dollars

Very High Frequency Switch-Mode Power Supplies

DEFF Research Database (Denmark)

Madsen, Mickey Pierre

The importance of technology and electronics in our daily life is constantly increasing. At the same time portability and energy efficiency are currently some of the hottest topics. This creates a huge need for power converters in a compact form factor and with high efficiency, which can supply...... these electronic devices. This calls for new technologies in order to miniaturize the power electronics of today. One way to do this is by increasing the switching frequency dramatically and develop very high frequency switch mode power supplies. If these converters can be designed to operate efficiently, a huge...... size, weight and cost reduction can be achieved due to the smaller energy storing elements needed at these frequencies. The research presented in this thesis focuses on exactly this. First various technologies for miniaturization of power supplies are studied, e.g. piezo electric transformers, wide...

FPGA based control system for -100 kV, 25 A Crowbarless DC power supply

International Nuclear Information System (INIS)

Upadhyay, R.; Tripathi, A.; Badapanda, M.K.; Lad, M.

2015-01-01

FPGA based digital control system has been developed for -100 kV, 25 A solid state modular crowbarless DC klystron bias power supply of 1 MW, 352.2 MHz RF test stand. The control system has capability to operate this power supply either in CW or pulse mode. Central controller, PSM controller and graphical user interface are key parts of this control system. Central controller monitors the status of various subsystems of this power supply like 11 kV step start unit, four numbers of main transformers each having 44 numbers of secondary windings and 176 numbers of switch power modules for deciding the number of power modules to be put ON and their duty cycles depending on the set output voltage and current. PSM controller sends appropriate control signal to the switch power modules through fibre optic lines and communicates it to the central controller. Linux based graphical user interface has been developed which enables the user to set the operating parameters along with their trip limits and displays the information of critical parameters of this power supply on a local touch screen panel. Provision for remote control and supervision is also provided through a separate PC connected to the main control system via Ethernet. The control system has capability to trip the power supply within 5 μsec in case any parameter exceeds its set limit. Suitable data logging feature is incorporated for offline fault analysis. The control system architecture along with its software protection interlocks are presented in this paper. The performance of the control system has been verified during operation of -100 kV, 25 A DC power supply with 1 MW, 352.2 MHz klystron amplifier. (author)

Pulsed power opening switch research at the University of New Mexico

International Nuclear Information System (INIS)

Humphries, S. Jr.

1987-01-01

Opening switch research at the University of New Mexico (UNM) is directed toward moderate-current (--10 kA) devices with potential applications to high-power charged particle accelerators. Two devices with the capacity for controlling gigawatt high-voltage circuits, the grid-controlled plasma flow switch and the scanned-beam switch, are under investigation. Both switches are conceptually simple; they involve little collective physics and are within the capabilities of current technology. In the plasma flow switch, the flux of electrons into a high-voltage power gap is controlled by a low-voltage control grid. Plasma generation is external to, and independent of, the power circuit. In the closed phase, plasma fills the gap so that the switch has a low on-state impedance. Pulse repetition rates in the megahertz range should be feasible. In single-shot proof-of-principle experiments, a small area switch modulated a 3-MW circuit; a 20-ns opening time was observed. The scanned-beam switch will utilize electric field deflection to direct the power of a sheet electron beam. The beam is to be alternately scanned to two inverse diodes connected to output transmission lines. The switch is expected to generate continuous-wave pulse trains for applications such as high-frequency induction linacs. Theoretical studies indicate that 10-GW devices in the 100-MHz range with 70-percent efficiency should be technologically feasible

High-current relativistic klystron amplifier development for microsecond pulse lengths

International Nuclear Information System (INIS)

Fazio, M.V.; Carlsten, B.E.; Faehl, R.; Kwan, T.J.; Rickel, D.G.; Stringfield, R.M.; Tallerico, P.J.

1991-01-01

Los Alamos is extending the performance of the Friedman-type, high-current relativistic klystron amplifier (RKA) to the microsecond regime while attempting to achieve the gigawatt-level peak power capability that has been characteristic of the RKA at shorter pulse lengths. Currently the electron beam power into the device is about 1 GW in microsecond duration pulses, with an effort underway to increase the beam power to 2.5 GW. To data the device has yielded an rf modulated electron beam power of 350 MW, with up to 50 MW coupled into waveguide. Several aspects of RKA operation under investigation that affect RKA beam bunching efficiency and amplifier gain include cavity tuning, beam diameter, beam current, and input rf drive power, and the development of an output coupler that efficiently couples the microwave power from the low impedance beam into rectangular waveguide operating in the dominant mode. Current results from experimental testing and code modeling are presented

High-current relativistic klystron amplifier development for microsecond pulse lengths

International Nuclear Information System (INIS)

Fazio, M.V.; Carlsten, B.E.; Faehl, R.J.; Kwan, T.J.; Rickel, D.G.; Stringfield, R.M.; Tallerico, P.J.

1991-01-01

Los Alamos is extending the performance of the Friedman-type, high-current relativistic klystron amplifier (RKA) to the microsecond regime while attempting to achieve the gigawatt-level peak power capability that has been characteristic of the RKA at shorter pulse lengths. Currently the electron beam power into the device is about 1 GW in microsecond duration pulses, with an effort underway to increase the beam power to 2.5 GW. To date the device has yielded an rf modulated electron beam power of 350 MW, with up to 50 MW coupled into waveguide. Several aspects of RKA operation under investigation that affect RKA beam bunching efficiency and amplifier gain include cavity tuning, beam diameter, beam current, and input rf drive power, and the development of an output coupler that efficiently couples the microwave power from the low impedance beam into rectangular waveguide operating in the dominant mode. Current results from experimental testing and code modelling are presented. 5 refs., 5 figs

Line Capacity Expansion and Transmission Switching in Power Systems With Large-Scale Wind Power

DEFF Research Database (Denmark)

Villumsen, Jonas Christoffer; Bronmo, Geir; Philpott, Andy B.

2013-01-01

In 2020 electricity production from wind power should constitute nearly 50% of electricity demand in Denmark. In this paper we look at optimal expansion of the transmission network in order to integrate 50% wind power in the system, while minimizing total fixed investment cost and expected cost...... of power generation. We allow for active switching of transmission elements to reduce congestion effects caused by Kirchhoff's voltage law. Results show that actively switching transmission lines may yield a better utilization of transmission networks with large-scale wind power and increase wind power...

Design Of Load-klystron Equivalent For Jlc

CERN Document Server

Grishanov, B I

2004-01-01

In this paper a design of a resistive load - an equivalent of a klystron for the Japan Linear Collider JLC is described. The load should operate in a pulse mode at high voltage and high averege power. Different design variants were considered. The choice in favour of ceramic bulk resistor with longitudinal conductivity was done. A caloric and hydraulic calculation was executed. A mesurements of ceramics thermal conductivity of the bulk resistor and of a single radiator produced warmth remooval were done. Unfortunataly the last events on JLC forbad us to realys the project "in metall". But authours houp that this design experience could be usefull for another accelerating centers. The load can find an application as a absorbing resistor in high voltage schemes.

METHOD FOR STABILIZING KLYSTRONS

Science.gov (United States)

Magnuson, D.W.; Smith, D.F.

1959-04-14

High-frequency oscillators for the generation of microwaves, particularly a system for stabilizing frequency-modulated klystron oscillators of the reflex type, are described. The system takos advantage of the fact that a change in oscillator frequency will alter the normal phase displacement between the cavity and its modulator, creating an error voltage which is utilized to regulate the frequency of the oscillator and stabilize it.

Programmable Power Supply for AC Switching Magnet of Proton Accelerator

CERN Document Server

Jeong, Seong-Hun; Kang Heung Sik; Lee, Chi-Hwan; Lee, Hong-Gi; Park, Ki-Hyeon; Ryu, Chun-Kil; Sik Han, Hong; Suck Suh, Hyung

2005-01-01

The 100-MeV PEFP proton linac has two proton beam extraction lines for user' experiment. Each extraction line has 5 beamlines and has 5 Hz operating frequency. An AC switching magnet is used to distribute the proton beam to the 5 beamlines, An AC switching magnet is powered by PWM-controlled bipolar switching-mode converters. This converter is designed to operate at ±350A, 5 Hz programmable step output. The power supply is employed IGBT module and has controlled by a DSP (Digital Signal Process). This paper describes the design and test results of the power supply.

Modelling switching-time effects in high-frequency power conditioning networks

Science.gov (United States)

Owen, H. A.; Sloane, T. H.; Rimer, B. H.; Wilson, T. G.

1979-01-01

Power transistor networks which switch large currents in highly inductive environments are beginning to find application in the hundred kilohertz switching frequency range. Recent developments in the fabrication of metal-oxide-semiconductor field-effect transistors in the power device category have enhanced the movement toward higher switching frequencies. Models for switching devices and of the circuits in which they are imbedded are required to properly characterize the mechanisms responsible for turning on and turning off effects. Easily interpreted results in the form of oscilloscope-like plots assist in understanding the effects of parametric studies using topology oriented computer-aided analysis methods.

Presentation of klystron history and statistics by World-Wide Web

International Nuclear Information System (INIS)

Kamikubota, N.; Furukawa, K.

2000-01-01

A web-based system for browsing klystron histories and statistics has been developed for the KEKB e-/e+ linac. This system enables linac staffs to investigate various klystron histories, such as recent trends of ES (down frequency/reflection/high voltage), at his/her convenient PC/Mac/console, where a web-browser is available. This system started in January 2000, and now becomes an inevitable tool for the linac staffs. (author)

High Power Microwave Tubes: Basics and Trends, Volume 2

Science.gov (United States)

Kesari, Vishal; Basu, B. N.

2018-01-01

Volume 2 of the book begins with chapter 6, in which we have taken up conventional MWTs (such as TWTs, klystrons, including multi-cavity and multi-beam klystrons, klystron variants including reflex klystron, IOT, EIK, EIO and twystron, and crossed-field tubes, namely, magnetron, CFA and carcinotron). In chapter 7, we have taken up fast-wave tubes (such as gyrotron, gyro-BWO, gyro-klystron, gyro-TWT, CARM, SWCA, hybrid gyro-tubes and peniotron). In chapter 8, we discuss vacuum microelectronic tubes (such as klystrino module, THz gyrotron and clinotron BWO); plasma-assisted tubes (such as PWT, plasma-filled TWT, BWO, including PASOTRON, and gyrotron); and HPM (high power microwave) tubes (such as relativistic TWT, relativistic BWO, RELTRON (variant of relativistic klystron), relativistic magnetron, high power Cerenkov tubes including SWO, RDG or orotron, MWCG and MWDG, bremsstrahlung radiation type tube, namely, vircator, and M-type tube MILO). In Chapter 9, we provide handy information about the frequency and power ranges of common MWTs, although more such information is provided at relevant places in the rest of the book as and where necessary. Chapter 10 is an epilogue that sums up the authors' attempt to bring out the various aspects of the basics of and trends in high power MWTs.

Study of nonlinear interaction between bunched beam and intermediate cavities in a relativistic klystron amplifier

Energy Technology Data Exchange (ETDEWEB)

Wu, Y. [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Science and Technology on High Power Microwave Laboratory, Mianyang 621900 (China); Xu, Z.; Li, Z. H. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Tang, C. X. [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2012-07-15

In intermediate cavities of a relativistic klystron amplifier (RKA) driven by intense relativistic electron beam, the equivalent circuit model, which is widely adopted to investigate the interaction between bunched beam and the intermediate cavity in a conventional klystron design, is invalid due to the high gap voltage and the nonlinear beam loading in a RKA. According to Maxwell equations and Lorentz equation, the self-consistent equations for beam-wave interaction in the intermediate cavity are introduced to study the nonlinear interaction between bunched beam and the intermediate cavity in a RKA. Based on the equations, the effects of modulation depth and modulation frequency of the beam on the gap voltage amplitude and its phase are obtained. It is shown that the gap voltage is significantly lower than that estimated by the equivalent circuit model when the beam modulation is high. And the bandwidth becomes wider as the beam modulation depth increases. An S-band high gain relativistic klystron amplifier is designed based on the result. And the corresponding experiment is carried out on the linear transformer driver accelerator. The peak output power has achieved 1.2 GW with an efficiency of 28.6% and a gain of 46 dB in the corresponding experiment.

Study of nonlinear interaction between bunched beam and intermediate cavities in a relativistic klystron amplifier

Science.gov (United States)

Wu, Y.; Xu, Z.; Li, Z. H.; Tang, C. X.

2012-07-01

In intermediate cavities of a relativistic klystron amplifier (RKA) driven by intense relativistic electron beam, the equivalent circuit model, which is widely adopted to investigate the interaction between bunched beam and the intermediate cavity in a conventional klystron design, is invalid due to the high gap voltage and the nonlinear beam loading in a RKA. According to Maxwell equations and Lorentz equation, the self-consistent equations for beam-wave interaction in the intermediate cavity are introduced to study the nonlinear interaction between bunched beam and the intermediate cavity in a RKA. Based on the equations, the effects of modulation depth and modulation frequency of the beam on the gap voltage amplitude and its phase are obtained. It is shown that the gap voltage is significantly lower than that estimated by the equivalent circuit model when the beam modulation is high. And the bandwidth becomes wider as the beam modulation depth increases. An S-band high gain relativistic klystron amplifier is designed based on the result. And the corresponding experiment is carried out on the linear transformer driver accelerator. The peak output power has achieved 1.2 GW with an efficiency of 28.6% and a gain of 46 dB in the corresponding experiment.

S-band 45 MW peak power test facility at RRCAT

International Nuclear Information System (INIS)

Wanmode, A. Yashwant; Reddy, Sivananda; Mulchandani, J.; Mohania, Praveen; Shrivastava, B. Purushottam

2015-01-01

RRCAT is engaged in the design and development of high energy electron LINAC as future injectors for the Booster Synchrotron for Indus-1 and Indus-2 SRS. The high energy LINAC will need microwave power over 30 MW depending on the number of structures to be energized. In order to have advance preparations for this development a 45 MW S-Band test facility has been designed and developed at RRCAT. The test stand is built around a 45 MW peak power S-band pulsed klystron, A conventional pulse forming network based modulator for klystron has been designed and developed. The WR-284 waveguide transmission system consisting of dual directional couplers, SF 6 gas pressurization unit, high power waveguide load and arc sensor has been developed and interfaced with the klystron. The klystron has been successfully tested up to 30 MW peak power at 2856 MHz on SF 6 pressurized waveguide line. A solid state S Band driver amplifier up to 1 kW output power was designed developed for driving the klystron. This paper describes the results of 30 MW peak power test of this facility. (author)

Application of M-type cathodes to high-power cw klystrons

Science.gov (United States)

Isagawa, S.; Higuchi, T.; Kobayashi, K.; Miyake, S.; Ohya, K.; Yoshida, M.

1999-05-01

Two types of high-power cw klystrons have been widely used at KEK in both TRISTAN and KEKB e +e - collider projects: one is a 0.8 MW/1.0 MW tube, called YK1302/YK1303 (Philips); the other is a 1.2 MW tube, called E3786/E3732 (Toshiba). Normally, the dispenser cathodes of the `B-type' and the `S-type' have been used, respectively, but for improved versions they have been replaced by low-temperature cathodes, called the `M-type'. An Os/Ru coating was applied to the former, whereas an Ir one was applied to the latter. Until now, all upgraded tubes installing M-type cathodes, 9 and 8 in number, respectively, have worked successfully without any dropout. A positive experience concerning the lifetime under real operation conditions has been obtained. M-type cathodes are, however, more easily poisoned. One tube installing an Os/Ru-coated cathode showed a gradual, and then sudden decrease in emission during an underheating test, although the emission could fortunately be recovered by aging at the KEK test field. Once sufficiently aged, the emission of an Ir-coated cathode proved to be very high and stable, and its lifetime is expected to be very long. One disadvantage of this cathode is, however, susceptibility to gas poisoning and the necessity of long-term initial aging. New techniques, like ion milling and fine-grained tungsten top layers, were not as successful as expected from their smaller scale applications to shorten the initial aging period. A burn-in process at higher cathode loading was efficient to make the poisoned cathode active and to decrease unwanted Wehnelt emission. On top of that, the emission cooling, and thus thermal conductivity near the emitting layer could play an important role in such large-current cathodes as ours.

GaN Power Stage for Switch-mode Audio Amplification

DEFF Research Database (Denmark)

Ploug, Rasmus Overgaard; Knott, Arnold; Poulsen, Søren Bang

2015-01-01

Gallium Nitride (GaN) based power transistors are gaining more and more attention since the introduction of the enhancement mode eGaN Field Effect Transistor (FET) which makes an adaptation from Metal-Oxide Semiconductor (MOSFET) to eGaN based technology less complex than by using depletion mode Ga......N FETs. This project seeks to investigate the possibilities of using eGaN FETs as the power switching device in a full bridge power stage intended for switch mode audio amplification. A 50 W 1 MHz power stage was built and provided promising audio performance. Future work includes optimization of dead...

Digital control of high-frequency switched-mode power converters

CERN Document Server

Corradini, Luca; Mattavelli, Paolo; Zane, Regan

This book is focused on the fundamental aspects of analysis, modeling and design of digital control loops around high-frequency switched-mode power converters in a systematic and rigorous manner Comprehensive treatment of digital control theory for power converters Verilog and VHDL sample codes are provided Enables readers to successfully analyze, model, design, and implement voltage, current, or multi-loop digital feedback loops around switched-mode power converters Practical examples are used throughout the book to illustrate applications of the techniques developed Matlab examples are also

Modulator R and D for the NLC

International Nuclear Information System (INIS)

Koontz, Roland F

2000-01-01

Planning for the Next Linear Collider (NLC) continues at SLAC, Fermilab, and Lawrence Livermore Lab with help from many other members of the high energy physics community. The frequency of the proposed accelerator is X-band. An X-band klystron developed at SLAC has produced 75 MW peak power capable of driving the NLC. Modulator development to drive this klystron is proceeding on two interconnected paths, one using IGBT (Insulated Gate Bipolar Transistors) switched induction cores to drive multiple (8) klystrons, and the second path supported by SBIR grants looking at direct IGBT switching or IGBT switches in conjunction with optimized conventional pulse transformers. Conventional thyratron modulators are not yet out of the picture as the long term reliability of IGBT's in pulse service must still be proved. This paper reviews some of the modulator designs current in development

Protection and switching system for the RFX power supply

International Nuclear Information System (INIS)

Browning, J.L.; Gray, J.W.; Mace, T.A.; Varley, G.L.

1986-01-01

The RFX toroidal field power supply comprises a large 4.8MJ (max) modular capacitor bank and four 14MW AC/DC converter flat-top power supply modules. The high fault level associated with the capacitor banks presents a problem in the design of the switching system, since mistiming could produce large currents in the flat-top supplies. The poloidal circuit consists of four groups of magnetising windings connected in series, each with its own flat-top convertor supply and opening switch transfer system. The flat-top converter supplies are needed when the transfer voltage has fallen from approximately 40kV to 1kV. Solutions to the problem of designing a fault-tolerant system which presents no danger to the flat-top converters are described in the paper. The adopted methods make use of hybrid ignitron/mechanical switches to give the required combination of switching speed and current carrying capacity, together with careful attention to the circuit layout of different switching elements. (author)

Performance characterization of gallium nitride HEMT cascode switch for power conditioning applications

International Nuclear Information System (INIS)

Chou, Po-Chien; Cheng, Stone

2015-01-01

Highlights: • We develop TO-257 cascoded GaN switch configuration in power conversion applications. • The normally-off cascode circuit provides 14.6 A/600 V characteristics. • Analysis of resistive and inductive switching performances shown in loaded circuits. • A 48-to-96 V boost converter is used to evaluate the benefit of GaN cascode switches. - Abstract: A hybrid cascoded GaN switch configuration is demonstrated in power conversion applications. A novel metal package is proposed for the packaging of a D-mode GaN MIS-HEMT cascoded with an integrated power MOSFET and a SBD. The normally-off cascode circuit provides a maximum drain current of 14.6 A and a blocking capability of 600 V. Analysis of 200 V/1 A power conversion characteristics are discussed and show the excellent switching performance in load circuits. Switching characteristics of the integral SiC SBD are also demonstrated. Finally, a 48-to-96 V boost converter is used to evaluate the benefit of GaN cascode switches. These results show that high-voltage GaN-HEMTs can be switching devices for an ultralow-loss converter circuit

Performance characterization of gallium nitride HEMT cascode switch for power conditioning applications

Energy Technology Data Exchange (ETDEWEB)

Chou, Po-Chien; Cheng, Stone, E-mail: stonecheng@mail.nctu.edu.tw

2015-08-15

Highlights: • We develop TO-257 cascoded GaN switch configuration in power conversion applications. • The normally-off cascode circuit provides 14.6 A/600 V characteristics. • Analysis of resistive and inductive switching performances shown in loaded circuits. • A 48-to-96 V boost converter is used to evaluate the benefit of GaN cascode switches. - Abstract: A hybrid cascoded GaN switch configuration is demonstrated in power conversion applications. A novel metal package is proposed for the packaging of a D-mode GaN MIS-HEMT cascoded with an integrated power MOSFET and a SBD. The normally-off cascode circuit provides a maximum drain current of 14.6 A and a blocking capability of 600 V. Analysis of 200 V/1 A power conversion characteristics are discussed and show the excellent switching performance in load circuits. Switching characteristics of the integral SiC SBD are also demonstrated. Finally, a 48-to-96 V boost converter is used to evaluate the benefit of GaN cascode switches. These results show that high-voltage GaN-HEMTs can be switching devices for an ultralow-loss converter circuit.

JLab High Efficiency Klystron Baseline Design for 12 GeV Upgrade

International Nuclear Information System (INIS)

Hovater, J.; Delayen, Jean; Harwood, Leigh; Nelson, Richard; Wang, Haipeng

2003-01-01

A computer design of a 13.5 kW, 1497 MHz, CW type, 55% efficiency, 0.8 microPv beam perveance, ∼40 dB gain, 5-cavity klystron has been developed for JLab 12 GeV Upgrade project.The design uses TRICOMP codes to simulate the gun, mod-anode section, solenoid focus channel and beam dump. The klystron tube was designed by JPNDISK (1D) code initially and then optimized by MASK (2D) code for the baseline parameters. All of these codes have been bunch marked by JLab 5 kW operational klystrons. The details of design parameters and the simulations by MAFIA (3D) for the cavity couplings tuners, and window are also going to be presented.

Continuing studies of plasma erosion switches for power conditioning on multiterawatt pulsed power accelerators

International Nuclear Information System (INIS)

Stringfield, R.; Gilman, C.; James, G.; Peters, T.; Sincerny, P.; Wong, S.

1983-01-01

Recent PITHON experiments with plasma erosion switches (PES) have extended the range of operation of the switches by about 50 percent, in terms of closed time and charge passing through the switch. The quantity of charge passed through the switch has been increased to as much as 35 mC. Currents as large as 1 MA and voltages as great as 1.8 MV have been switched off to be diverted to a downstream load. The impedance of the erosion switch can be described as having three stages: 1) essentially zero impedance, 2) a transitional opening phase, and 3) an impedance which is very large (greater than 5 Ω) in comparison with the subohm downstream load. Current diagnostics, consisting of Rogowski coils and segmented shunts, have been successfully developed to monitor the current which propagates to the load region. These monitors have measured rise times as short as 38 ns and slew rates as great as 10 14 A/s at the load. With wire array loads, the pulse conditioning of the switch has been observed to reduce the magnitude of the current losses in the feed which are present when no switch is used. Correlations have been made between the switch closed time, voltage, current, and power with the feed inductance and the generator power injected into the magnetic insulated transmission line (MITL)

A 380 V High Efficiency and High Power Density Switched-Capacitor Power Converter using Wide Band Gap Semiconductors

DEFF Research Database (Denmark)

Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

2018-01-01

. This paper presents such a high voltage low power switched-capacitor DC-DC converter with an input voltage upto 380 V (compatible with rectified European mains) and an output power experimentally validated up to 21.3 W. The wideband gap semiconductor devices of GaN switches and SiC diodes are combined...... to compose the proposed power stage. Their switching and loss characteristics are analyzed with transient waveforms and thermal images. Different isolated driving circuits are compared and a compact isolated halfbridge driving circuit is proposed. The full-load efficiencies of 98.3% and 97.6% are achieved......State-of-the-art switched-capacitor DC-DC power converters mainly focus on low voltage and/or high power applications. However, at high voltage and low power levels, new designs are anticipated to emerge and a power converter that has both high efficiency and high power density is highly desirable...

Conducted noise analysis and protection of 45 kJ/s, ±50 kV capacitor charging power supply when interfaced with repetitive Marx based pulse power system

Science.gov (United States)

Naresh, P.; Patel, Ankur; Sharma, Archana

2015-09-01

Pulse power systems with highly dynamic loads like klystron, backward wave oscillator (BWO), and magnetron generate highly dynamic noise. This noise leads to frequent failure of controlled switches in the inverter stage of charging power supply. Designing a reliable and compatible power supply for pulse power applications is always a tricky job when charging rate is in multiples of 10 kJ/s. A ±50 kV and 45 kJ/s capacitor charging power supply based on 4th order LCLC resonant topology has been developed for a 10 Hz repetitive Marx based system. Conditions for load independent constant current and zero current switching (ZCS) are derived mathematically. Noise generated at load end due to dynamic load is tackled effectively and reduction in magnitude noise voltage is achieved by providing shielding between primary and secondary of high voltage high frequency transformer and with LCLC low pass filter. Shielding scales down the ratio between coupling capacitance (Cc) and the collector-emitter capacitance of insulated gate bi-polar transistor switch, which in turn reduces the common mode noise voltage magnitude. The proposed 4th order LCLC resonant network acts as a low pass filter for differential mode noise in the reverse direction (from load to source). Power supply has been tested repeatedly with 5 Hz repetition rate with repetitive Marx based system connected with BWO load working fine without failure of single switch in the inverter stage.

Dynamic optimum dead time in piezoelectric transformer-based switch-mode power supplies

DEFF Research Database (Denmark)

Ekhtiari, Marzieh; Andersen, Thomas; Andersen, Michael A. E.

2016-01-01

to charge and discharge the input capacitance of piezoelectric transformers in order to achieve zero-voltage switching. This paper proposes a method for detecting the optimum dead time in piezoelectric transformer-based switch-mode power supplies. The provision of sufficient dead time in every cycle......Soft switching is required to attain high efficiency in high-frequency power converters. Piezoelectric transformerbased converters can benefit from soft switching in terms of significantly diminished switching losses and stresses. Adequate dead time is needed in order to deliver sufficient energy...

Advantages of using a two-switch forward in single-stage power factor corrected power supplies

DEFF Research Database (Denmark)

Petersen, Lars

2000-01-01

A single-stage power factor corrected power supply using a two-switch forward is proposed to increase efficiency. The converter is operated in the DCM (discontinues conduction mode) and it is shown that this operation mode ensures the intermediate DC-bus to be controlled only by means of circuit...... supply has been implemented. The measured efficiency is between 85% and 88.5% in the range 30 W-500 W and the measured power factor at full load is 0.95....... parameters and therefore independent of load variations. The DCM operation often has a diminishing effect on the efficiency but by use of the two-switch topology high efficiency with minimum circuit complexity can be achieved in this mode. A 500 W 70 V prototype of the two-switch boost-forward PFC power...

Analytical Modeling and Simulation of Four-Switch Hybrid Power Filter Working with Sixfold Switching Symmetry

Czech Academy of Sciences Publication Activity Database

Tlustý, J.; Škramlík, Jiří; Švec, J.; Valouch, Viktor

2012-01-01

Roč. 2012, č. 292178 (2012), s. 1-17 ISSN 1024-123X Institutional support: RVO:61388998 Keywords : analytical modeling * four-switch hybrid power filter * sixfold switching symmetry Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.383, year: 2012 http://www.hindawi.com/journals/mpe/2012/292178/

Practical computer analysis of switch mode power supplies

CERN Document Server

Bennett, Johnny C

2006-01-01

When designing switch-mode power supplies (SMPSs), engineers need much more than simple "recipes" for analysis. Such plug-and-go instructions are not at all helpful for simulating larger and more complex circuits and systems. Offering more than merely a "cookbook," Practical Computer Analysis of Switch Mode Power Supplies provides a thorough understanding of the essential requirements for analyzing SMPS performance characteristics. It demonstrates the power of the circuit averaging technique when used with powerful computer circuit simulation programs. The book begins with SMPS fundamentals and the basics of circuit averaging models, reviewing most basic topologies and explaining all of their various modes of operation and control. The author then discusses the general analysis requirements of power supplies and how to develop the general types of SMPS models, demonstrating the use of SPICE for analysis. He examines the basic first-order analyses generally associated with SMPS performance along with more pra...

An S-band high gain relativistic klystron amplifier with high phase stability

Energy Technology Data Exchange (ETDEWEB)

Wu, Y. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Science and Technology on High Power Microwave Laboratory, Mianyang 621900 (China); Li, Z. H.; Xu, Z.; Ma, Q. S. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Xie, H. Q. [College of Science, Southwestern University of Science and Technology, Mianyang 621010 (China)

2014-11-15

For the purpose of coherent high power microwave combining, an S-band high gain relativistic klystron amplifier with high phase stability is presented and studied. By the aid of 3D particle-in-cell code and circuit simulation software, the mechanism of parasitic oscillation in the device is investigated. And the RF lossy material is adopted in the simulation and experiment to suppress the oscillation. The experimental results show that with an input RF power of 10 kW, a microwave pulse with power of 1.8 GW is generated with a gain of 52.6 dB. And the relative phase difference fluctuation between output microwave and input RF signal is less than ±10° in 90 ns.

Low prepulse, high power density water dielectric switching

International Nuclear Information System (INIS)

Johnson, D.L.; VanDevender, J.P.; Martin, T.H.

1979-01-01

Prepulse voltage suppression has proven difficult in high power, high voltage accelerators employing self-breakdown water dielectric switches. A novel and cost effective water switch has been developed at Sandia Laboratories which reduces prepulse voltage by reducing the capacity across the switch. This prepulse suppression switch causes energy formerly stored in the switch capacity and dissipated in the arc to be useful output energy. The switching technique also allows the pulse forming lines to be stacked in parallel and electrically isolated from the load after the line has been discharged. The switch consists of a ground plane, with several holes, inserted between the switch electrodes. The output line switch electrodes extend through the holes and face electrodes on the pulse forming line (PFL). The capacity between the PFL and the output transmission line is reduced by about 80%. The gap spacing between the output line electrode and the hole in the ground plane is adjusted so that breakdown occurs after the main pulse and provides a crow bar between the load and the source. Performance data from the Proto II, Mite and Ripple test facilities are presented

Optimization of Modulation Waveforms for Improved EMI Attenuation in Switching Frequency Modulated Power Converters

Directory of Open Access Journals (Sweden)

Deniss Stepins

2015-01-01

Full Text Available Electromagnetic interference (EMI is one of the major problems of switching power converters. This paper is devoted to switching frequency modulation used for conducted EMI suppression in switching power converters. Comprehensive theoretical analysis of switching power converter conducted EMI spectrum and EMI attenuation due the use of traditional ramp and multislope ramp modulation waveforms is presented. Expressions to calculate EMI spectrum and attenuation are derived. Optimization procedure of the multislope ramp modulation waveform is proposed to get maximum benefits from switching frequency modulation for EMI reduction. Experimental verification is also performed to prove that the optimized multislope ramp modulation waveform is very useful solution for effective EMI reduction in switching power converters.

Advances in high voltage power switching with GTOs

International Nuclear Information System (INIS)

Podlesak, T.F.

1990-01-01

The control of high voltage at high power, particularly opening switches, has been difficult in the past. Using gate turnoff thyristors (GTOs) arranged in series enables large currents to be switched at high voltage. The authors report a high voltage opening switch has been successfully demonstrated. This switch uses GTOs in series and successfully operates at voltages higher than the rated voltage of the individual devices. It is believed that this is the first time this has been successfully demonstrated, in that GTOs have been operated in series before, but always in a manner as to not exceed the voltage capability of the individual devices. In short, the devices have not worked together, sharing the voltage, but one device has been operated using several backup devices. Of particular interest is how well the individual devices share the voltage applied to them. Equal voltage sharing between devices is absolutely essential, in order to not exceed the voltage rating of any of the devices in the series chain. This is accomplished at high (microsecond) switching speeds. Thus, the system is useful for high frequency applications as well as high power, making for a flexible circuit system element. This demonstration system is rated at 5 KV and uses 1 KV devices. A larger 24 KV system is under design and will use 4.5 KV devices. In order to design the 24 KV switch, the safe operating area of the large devices must be known thoroughly

An approach to evaluate switching overvoltages during power system restoration

Directory of Open Access Journals (Sweden)

Sadeghkhani Iman

2012-01-01

Full Text Available Transformer switching is one of the important stages during power system restoration. This switching can cause harmonic overvoltages that might damage some equipment and delay power system restoration. Core saturation on the energisation of a transformer with residual flux is a noticeable factor in harmonic overvoltages. This work uses artificial neural networks (ANN in order to estimate the temporary overvoltages (TOVs due to transformer energisation. In the proposed methodology, the Levenberg-Marquardt method is used to train the multilayer perceptron. The developed ANN is trained with the worst case of switching condition, and tested for typical cases. Simulated results for a partial 39-bus New England test system, show the proposed technique can accurately estimate the peak values and durations of switching overvoltages.

A Switched Capacitor Based AC/DC Resonant Converter for High Frequency AC Power Generation

Directory of Open Access Journals (Sweden)

Cuidong Xu

2015-09-01

Full Text Available A switched capacitor based AC-DC resonant power converter is proposed for high frequency power generation output conversion. This converter is suitable for small scale, high frequency wind power generation. It has a high conversion ratio to provide a step down from high voltage to low voltage for easy use. The voltage conversion ratio of conventional switched capacitor power converters is fixed to n, 1/n or −1/n (n is the switched capacitor cell. In this paper, A circuit which can provide n, 1/n and 2n/m of the voltage conversion ratio is presented (n is stepping up the switched capacitor cell, m is stepping down the switching capacitor cell. The conversion ratio can be changed greatly by using only two switches. A resonant tank is used to assist in zero current switching, and hence the current spike, which usually exists in a classical switching switched capacitor converter, can be eliminated. Both easy operation and efficiency are possible. Principles of operation, computer simulations and experimental results of the proposed circuit are presented. General analysis and design methods are given. The experimental result verifies the theoretical analysis of high frequency AC power generation.

Improvements in X-band transmitter phase stability through Klystron body temperature regulation

Science.gov (United States)

Perez, R. M.

1992-01-01

This article describes the techniques used and experimental results obtained in improving transmitter stability by control of the klystron body temperature. Related work in the measurement of klystron phase control parameters (pushing factors) is also discussed. The contribution of wave guide temperature excursions to uplink phase stability is presented. Suggestions are made as to the direction of future work in this area.

SNS AC Power Distribution and Reliability of AC Power Supply

CERN Document Server

Holik, Paul S

2005-01-01

The SNS Project has 45MW of installed power. A design description under the Construction Design and Maintenance (CDM) with regard to regulations (OSHA, NFPA, NEC), reliability issues and maintenance of the AC power distribution system are herewith presented. The SNS Project has 45MW of installed power. The Accelerator Systems are Front End (FE)and LINAC KLYSTRON Building (LK), Central Helium Liquefier (CHL), High Energy Beam Transport (HEBT), Accumulator Ring and Ring to Target Beam Transport (RTBT) Support Buildings have 30MW installed power. FELK has 16MW installed, majority of which is klystron and magnet power supply system. CHL, supporting the super conducting portion of the accelerator has 7MW installed power and the RING Systems (HEBT, RING and RTBT) have also 7MW installed power.*

Computer-aided analysis of power-electronic systems simulation of a high-voltage power converter

International Nuclear Information System (INIS)

Bordry, F.; Isch, H.W.; Proudlock, P.

1987-01-01

In the study of semiconductor devices, simulation methods play an important role in both the design of systems and the analysis of their operation. The authors describe a new and efficient computer-aided package program for general power-electronic systems. The main difficulty when taking into account non-linear elements, such as semiconductors, lies in determining the existence and the relations of the elementary sequences defined by the conduction or nonconduction of these components. The method does not require a priori knowledge of the state sequences of the semiconductor nor of the commutation instants, but only the circuit structure, its parameters and the commands to the controlled switches. The simulation program computes automatically both transient and steady-state waveforms for any circuit configuration. The simulation of a high-voltage power converter is presented, both for its steady-state and transient overload conditions. This 100 kV power converter (4 MW) will feed two klystrons in parallel

The Application of High Temperature Superconducting Materials to Power Switches

CERN Document Server

March, S A; Ballarino, A

2009-01-01

Superconducting switches may find application in superconducting magnet systems that require energy extraction. Such superconducting switches could be bypass-switches that are operated in conjunction with a parallel resistor or dump-switches where all of the energy is dissipated in the switch itself. Bypass-switches are more suited to higher energy circuits as a portion of the energy can be dissipated in the external dump resistor. Dump- switches require less material and triggering energy as a lower switch resistance is needed to achieve the required total dump resistance. Both superconducting bypass-switches and superconducting dump-switches can be ther- mally activated. Switching times that are comparable to those obtained with mechanical bypass-switch systems can be achieved using a co-wound heater that is powered by a ca- pacitor discharge. Switches that have fast thermal diffusion times through the insulation can be modelled as a lumped system whereas those with slow thermal diffusion times were modelle...

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.

Active high-power RF pulse compression using optically switched resonant delay lines

International Nuclear Information System (INIS)

Tantawi, S.G.; Ruth, R.D.; Vlieks, A.E.

1996-11-01

The authors present the design and a proof of principle experimental results of an optically controlled high power rf pulse compression system. The design should, in principle, handle few hundreds of Megawatts of power at X-band. The system is based on the switched resonant delay line theory. It employs resonant delay lines as a means of storing rf energy. The coupling to the lines is optimized for maximum energy storage during the charging phase. To discharge the lines, a high power microwave switch increases the coupling to the lines just before the start of the output pulse. The high power microwave switch, required for this system, is realized using optical excitation of an electron-hole plasma layer on the surface of a pure silicon wafer. The switch is designed to operate in the TE 01 mode in a circular waveguide to avoid the edge effects present at the interface between the silicon wafer and the supporting waveguide; thus, enhancing its power handling capability

Multi Carrier Modulator for Switch-Mode Audio Power Amplifiers

DEFF Research Database (Denmark)

Knott, Arnold; Pfaffinger, Gerhard; Andersen, Michael Andreas E.

2008-01-01

While switch-mode audio power amplifiers allow compact implementations and high output power levels due to their high power efficiency, they are very well known for creating electromagnetic interference (EMI) with other electronic equipment, in particular radio receivers. Lowering the EMI of swit...

Low Power Very High Frequency Switch-Mode Power Supply with 50 V Input and 5 V Output

DEFF Research Database (Denmark)

Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.

2014-01-01

This paper presents the design of a resonant converter with a switching frequency in the very high frequencyrange (30-300 MHz), a large step down ratio (10 times) and low output power (1 W). Several different invertersand rectifiers are analyzed and compared. The class E inverter and rectifier...... are selected based on complexity andefficiency estimates. Three different power stages are implemented; one with a large input inductor, one with a switch with small capacitances and one with a switch with low on resistance. The power stages are designed with the same specifications and efficiencies from 60...

Application of plasma erosion opening switches to high power accelerators for pulse compression and power multiplication

International Nuclear Information System (INIS)

Meyer, R.A.; Boller, J.R.; Commisso, R.J.

1983-01-01

A new vacuum opening switch called a plasma erosion opening switch is described. A model of its operation is presented and the energy efficiency of such a switch is discussed. Recent high power experiments on the Gamble II accelerator are described and compared to previous experiments

Design of an RF window for L-band CW klystron based on thermal-stress analysis

International Nuclear Information System (INIS)

Yamaguchi, Seiya; Sato, Isamu; Konashi, Kenji; Ohshika, Junji.

1993-01-01

Design of klystron RF window has been performed based on a thermal-stress analysis for L-band CW electron linac for nuclear wastes transmutation. It was shown that the hoop stress for a modified disk is 46% of that of normal disk. Thermal load test has been done which indicated that the modified disk is proof against power twice as much as that for the normal disk. (author)

High efficiency three-phase power factor correction rectifier using SiC switches

DEFF Research Database (Denmark)

Kouchaki, Alireza; Nymand, Morten

2017-01-01

This paper presents designing procedure of a high efficiency 5 kW silicon-carbide (SiC) based threephase power factor correction (PFC). SiC switches present low capacitive switching loss compared to the alternative Si switches. Therefore, the switching frequency can be increased and hence the siz...

Nanoelectromechanical Switches for Low-Power Digital Computing

Directory of Open Access Journals (Sweden)

Alexis Peschot

2015-08-01

Full Text Available The need for more energy-efficient solid-state switches beyond complementary metal-oxide-semiconductor (CMOS transistors has become a major concern as the power consumption of electronic integrated circuits (ICs steadily increases with technology scaling. Nano-Electro-Mechanical (NEM relays control current flow by nanometer-scale motion to make or break physical contact between electrodes, and offer advantages over transistors for low-power digital logic applications: virtually zero leakage current for negligible static power consumption; the ability to operate with very small voltage signals for low dynamic power consumption; and robustness against harsh environments such as extreme temperatures. Therefore, NEM logic switches (relays have been investigated by several research groups during the past decade. Circuit simulations calibrated to experimental data indicate that scaled relay technology can overcome the energy-efficiency limit of CMOS technology. This paper reviews recent progress toward this goal, providing an overview of the different relay designs and experimental results achieved by various research groups, as well as of relay-based IC design principles. Remaining challenges for realizing the promise of nano-mechanical computing, and ongoing efforts to address these, are discussed.

7.5 MeV High Average Power Linear Accelerator System for Food Irradiation Applications

International Nuclear Information System (INIS)

Eichenberger, Carl; Palmer, Dennis; Wong, Sik-Lam; Robison, Greg; Miller, Bruce; Shimer, Daniel

2005-09-01

In December 2004 the US Food and Drug Administration (FDA) approved the use of 7.5 MeV X-rays for irradiation of food products. The increased efficiency for treatment at 7.5 MeV (versus the previous maximum allowable X-ray energy of 5 MeV) will have a significant impact on processing rates and, therefore, reduce the per-package cost of irradiation using X-rays. Titan Pulse Sciences Division is developing a new food irradiation system based on this ruling. The irradiation system incorporates a 7.5 MeV electron linear accelerator (linac) that is capable of 100 kW average power. A tantalum converter is positioned close to the exit window of the scan horn. The linac is an RF standing waveguide structure based on a 5 MeV accelerator that is used for X-ray processing of food products. The linac is powered by a 1300 MHz (L-Band) klystron tube. The electrical drive for the klystron is a solid state modulator that uses inductive energy store and solid-state opening switches. The system is designed to operate 7000 hours per year. Keywords: Rf Accelerator, Solid state modulator, X-ray processing

Performance of the Crowbar of the LHC High Power RF System

CERN Document Server

Ravidà, G; Valuch, D

2012-01-01

The counter-rotating proton beams in the Large Hadron Collider (LHC) are captured and accelerated to their final energies by two identical 400 MHz Radio Frequency (RF) systems. The RF power source required for each beam comprises eight 300 kW klystrons. The output power of each klystron is fed via a circulator and a waveguide line to the input coupler of a single-cell superconducting (SC) cavity. Each unit of four klystrons is powered by a -100kV/40A AC/DC power converter. A fast protection system (crowbar) protects the four klystrons in each of these units. Although the LHC RF system has shown has very good performance, operational experience has shown that the five-gap double-ended thyratrons used in the crowbar system suffer, from time to time, from auto-firing, which result in beam dumps. This paper presents the recent results obtained with an alternative solution based on solid state thyristors. Comparative measurements with the thyratron are shown.

Ferroelectric switch for a high-power Ka-band active pulse compressor

Energy Technology Data Exchange (ETDEWEB)

Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT (United States)

2013-12-18

Results are presented for design of a high-power microwave switch for operation at 34.3 GHz, intended for use in an active RF pulse compressor. The active element in the switch is a ring of ferroelectric material, whose dielectric constant can be rapidly changed by application of a high-voltage pulse. As envisioned, two of these switches would be built into a pair of delay lines, as in SLED-II at SLAC, so as to allow 30-MW μs-length Ka-band pulses to be compressed in time by a factor-of-9 and multiplied in amplitude to generate 200 MW peak power pulses. Such high-power pulses could be used for testing and evaluation of high-gradient mm-wave accelerator structures, for example. Evaluation of the switch design was carried out with an X-band (11.43 GHz) prototype, built to incorporate all the features required for the Ka-band version.

Research on control function switch of nuclear power plant control room

International Nuclear Information System (INIS)

Mei Shibo; Mao Ting; Cheng Bo; Zhang Gang

2014-01-01

The nuclear power plant provides main control room (MCR) to the unit operators for the plant monitoring and control, and provides the remote shutdown station (RSS) as the back-up control room, which is used only when MCR is unavailable. The RSS could be used to monitor and control the plant, bring the plant into shutdown state and remove the residual heat. The command from MCR and RSS is blocked by each other and can not be executed at the same time. The operation mode switch function between MCR and RSS is carried out by MCR/RSS mode switches. The operation mode switch scheme of CPR1000, ERP and AP1000 were compared and researched, and some design bases for new nuclear power plant were submitted in this paper. These design bases could be referred during the design of control function switch for the new nuclear power plants, in order to put forward a more practical, simple, safe and convenient scheme. (authors)

Phase shift PWM with double two-switch bridge for high power capacitor charging

International Nuclear Information System (INIS)

Karandikar, U.S.; Singh, Yashpal; Thakurta, A.C.

2013-01-01

Pulse power supply systems working at higher voltage and high repetition rate demands for higher power from capacitor chargers. Capacitor charging requirement become more challenging in such cases. In pulse power circuits, energy storage capacitor should be charged to its desired voltage before the next switching occurs. It is discharged within a small time, delivering large pulse power. A capacitor charger has to work with wide load variation repeatedly. Many schemes are used for this purpose. The proposed scheme aims at reducing stresses on switches by reducing peak current and their evils. A high voltage power supply is designed for capacitor charging. The proposed scheme is based on a Phase-Shifted PWM without using any extra component to achieve soft switching. Indirect constant average current capacitor charging is achieved with a simple control scheme. A double two-switch bridge is proposed to enhance reliability. Power supply has been developed to charge a capacitor of 50 μF to 2.5 kV at 25 Hz. (author)

Ka-Band Klystron Amplifier for CUBESATs, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — We offer an ultra-compact klystron amplifier for remote sensing on CubeSats. It will operate at 35.7 GHz, have 400 MHz bandwidth, and output greater than 32 watts...

180 MW/180 KW pulse modulator for S-band klystron of LUE-200 linac of IREN installation of JINR

Science.gov (United States)

Su, Kim Dong; Sumbaev, A. P.; Shvetsov, V. N.

2014-09-01

The offer on working out of the pulse modulator with 180 MW pulse power and 180 kW average power for pulse S-band klystrons of LUE-200 linac of IREN installation at the Laboratory of neutron physics (FLNP) at JINR is formulated. Main requirements, key parameters and element base of the modulator are presented. The variant of the basic scheme on the basis of 14 (or 11) stage 2 parallel PFN with the thyratron switchboard (TGI2-10K/50) and six parallel high voltage power supplies (CCPS Power Supply) is considered.

DC switching regulated power supply for driving an inductive load

Science.gov (United States)

Dyer, George R.

1986-01-01

A power supply for driving an inductive load current from a dc power supply hrough a regulator circuit including a bridge arrangement of diodes and switching transistors controlled by a servo controller which regulates switching in response to the load current to maintain a selected load current. First and second opposite legs of the bridge are formed by first and second parallel-connected transistor arrays, respectively, while the third and fourth legs of the bridge are formed by appropriately connected first and second parallel connected diode arrays, respectively. The regulator may be operated in three "stages" or modes: (1) For current runup in the load, both first and second transistor switch arrays are turned "on" and current is supplied to the load through both transistor arrays. (2) When load current reaches the desired level, the first switch is turned "off", and load current "flywheels" through the second switch array and the fourth leg diode array connecting the second switch array in series with the load. Current is maintained by alternating between modes 1 and 2 at a suitable duty cycle and switching rate set by the controller. (3) Rapid current rundown is accomplished by turning both switch arrays "off", allowing load current to be dumped back into the source through the third and fourth diode arrays connecting the source in series opposition with the load to recover energy from the inductive load. The three operating states are controlled automatically by the controller.

Markov switching of the electricity supply curve and power prices dynamics

Science.gov (United States)

Mari, Carlo; Cananà, Lucianna

2012-02-01

Regime-switching models seem to well capture the main features of power prices behavior in deregulated markets. In a recent paper, we have proposed an equilibrium methodology to derive electricity prices dynamics from the interplay between supply and demand in a stochastic environment. In particular, assuming that the supply function is described by a power law where the exponent is a two-state strictly positive Markov process, we derived a regime switching dynamics of power prices in which regime switches are induced by transitions between Markov states. In this paper, we provide a dynamical model to describe the random behavior of power prices where the only non-Brownian component of the motion is endogenously introduced by Markov transitions in the exponent of the electricity supply curve. In this context, the stochastic process driving the switching mechanism becomes observable, and we will show that the non-Brownian component of the dynamics induced by transitions from Markov states is responsible for jumps and spikes of very high magnitude. The empirical analysis performed on three Australian markets confirms that the proposed approach seems quite flexible and capable of incorporating the main features of power prices time-series, thus reproducing the first four moments of log-returns empirical distributions in a satisfactory way.

Switching power supplies with multiple isolated output and unitary power factor with an only switch; Fonte chaveada com multiplas saidas isoladas e fator de potencia unitario com um unico interruptor

Energy Technology Data Exchange (ETDEWEB)

Canesin, Carlos Alberto

1990-09-01

The analysis and implementation of switching power supplies with multiple output, through the use of the D C/D C Single Ended Primary Inductance Converter - SEPIC is presented. The structure has a single switch mode processing stage, improved input power factor, with the use of the variable current hysteresis control, or, constant on time control. The analysis of the D C/D C SEPIC, output characteristics and computer simulation is presented. A switching power supply practical design and experimental results are presented to demonstrate the validity of the theoretical analysis. (author)

Float level switch for a nuclear power plant containment vessel

International Nuclear Information System (INIS)

Powell, J.G.

1993-01-01

This invention is a float level switch used to sense rise or drop in water level in a containment vessel of a nuclear power plant during a loss of coolant accident. The essential components of the device are a guide tube, a reed switch inside the guide tube, a float containing a magnetic portion that activates a reed switch, and metal-sheathed, ceramic-insulated conductors connecting the reed switch to a monitoring system outside the containment vessel. Special materials and special sealing techniques prevent failure of components and allow the float level switch to be connected to a monitoring system outside the containment vessel. 1 figures

Float level switch for a nuclear power plant containment vessel

Science.gov (United States)

Powell, James G.

1993-01-01

This invention is a float level switch used to sense rise or drop in water level in a containment vessel of a nuclear power plant during a loss of coolant accident. The essential components of the device are a guide tube, a reed switch inside the guide tube, a float containing a magnetic portion that activates a reed switch, and metal-sheathed, ceramic-insulated conductors connecting the reed switch to a monitoring system outside the containment vessel. Special materials and special sealing techniques prevent failure of components and allow the float level switch to be connected to a monitoring system outside the containment vessel.

Design and development of bipolar 4-quadrant switch-mode power converter for superconducting magnets

International Nuclear Information System (INIS)

Yashwant Kumar; Thakur, S.K.; Ghosh, M.K.; Tiwari, T.P.; De, Anirban; Kumari, S.; Saha, S.

2011-01-01

A uniform zero crossing magnetic field in a magnet can be achieved by using bipolar power converter with four quadrant operation. A high current bipolar switch-mode power converter (rated ±27 V max , ±7V flat top, ±300A, 100 ppm) has been designed and developed indigenously at VECC Kolkata. Four quadrants operation is accomplished by using power IGBTs in an H-bridge configuration with switching frequency around 20 kHz. The switch-mode power converter is used because of high dynamic response, low output ripple, high efficiency and low input current harmonics. In this paper, circuit topology, function of system components and key system specifications of high current bipolar switch mode power converter is discussed. (author)

Problems and solutions of the IFSMTF power and switch system

International Nuclear Information System (INIS)

Wood, R.J.; Wintenberg, R.E.; Googe, J.M.; Nickels, L.E.

1985-01-01

Solutions have been found for the problems encountered with the coil power and switching systems of the International Fusion Superconducting Magnet Test Facility (IFSMTF). The coil power system provides the filtered dc sources (+- 12 V dc; 25,000 A) for charging and discharging the coils of the IFSMTF experiment. The switching system provides the means of transferring the coil current into a dump resistor when a rapid discharge of a coil is required due to a coil failure (quench) or other system abnormalities

Modeling and forecasting of wind power generation - Regime-switching approaches

DEFF Research Database (Denmark)

Trombe, Pierre-Julien

The present thesis addresses a number of challenges emerging from the increasing penetration of renewable energy sources into power systems. Focus is placed on wind energy and large-scale offshore wind farms. Indeed, offshore wind power variability is becoming a serious obstacle to the integration...... of more renewable energy into power systems since these systems are subjected to maintain a strict balance between electricity consumption and production, at any time. For this purpose, wind power forecasts offer an essential support to power system operators. In particular, there is a growing demand...... case study is the Horns Rev wind farm located in the North Sea. Regime-switching aspects of offshore wind power fluctuations are investigated. Several formulations of Markov-Switching models are proposed in order to better characterize the stochastic behavior of the underlying process and improve its...

Production of coherent XUV and soft x-rays using a transverse optical klystron

International Nuclear Information System (INIS)

Freeman, R.R.; Kincaid, B.J.

1984-01-01

An optical klystron is a device in which a relativistic electron beam produces coherent electromagnetic radiation by interacting with an external laser beam in an undulator magnetic field. Such a device represents the relativistic generalization of the microwave klystron. The device is called transverse optical klystron (TOK), because the energy exchange between the electrons and the light in this case is due to the transverse electric field of the laser. The generation of coherent light by the TOK can be considered as a three step process, including energy modulation, compaction or bunching, and radiation. In the present paper, a description is provided of the general physical principles underlying the operation of each of the three sections of the TOK, taking into account the modulator, the compactor, and the radiator. 14 references

Retrofitting the 5045 Klystron for Higher Efficiency

International Nuclear Information System (INIS)

Jensen, Aaron; Fazio, Michael; Haase, Andy; Jongewaard, Erik; Kemp, Mark; Neilson, Jeff

2015-01-01

The 5045 klystron has been in production and accelerating particles at SLAC National Accelerator Laboratory for over 25 years. Although the design has undergone some changes there are still significant opportunities for improvement in performance. Retrofitting the 5045 for higher efficiencies and a more mono-energetic spent beam profile is presented.

Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

Energy Technology Data Exchange (ETDEWEB)

Ljusev, P.; Andersen, Michael A.E.

2005-07-01

This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify design, increase efficiency and integration level, reduce product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented. (au)

Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

DEFF Research Database (Denmark)

Ljusev, Petar; Andersen, Michael Andreas E.

2005-01-01

This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify the design, increase...... efficiency, reduce the product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented....

Suppression of SBO and stability improvements of TRISTAN 1 MW high power Klystrons

International Nuclear Information System (INIS)

Isagawa, Shigeru; Yoshida, Masato; Takeuchi, Yasunao; Ono, Masaaki; Yoshimoto, Shin-ichi; Schweppe, E.G.; Demmel, E.; Seifert, H.

1994-01-01

Philips 1 MW CW Klystrons have been well operated in TRISTAN for almost 7 years. Problems like degradation of gun insulation and abnormal anode emission, both caused by excess barium evaporation from cathode and by emission of electrons from hot electrodes of electron gun, have been successfully solved by the use of M-type cathode as well as of redesigned gun with decreased electrode temperatures. The electrode temperatures are, however, still yet to be optimized. Modifications should be refined much more. Positive spikes of anode current and Side Band Oscillations (SBO) which are caused by back streaming electrons from collector and/or output gap have been studied intensively. Much improvements have been made so far by taking a good combination of modified drift tubes, anode shape, number of cavities and redesigned output transitions. (author)

One-dimensional disk model simulation for klystron design

International Nuclear Information System (INIS)

Yonezawa, H.; Okazaki, Y.

1984-05-01

In 1982, one of the authors (Okazaki), of Toshiba Corporation, wrote a one-dimensional, rigid-disk model computer program to serve as a reliable design tool for the 150 MW klystron development project. This is an introductory note for the users of this program. While reviewing the so-called disk programs presently available, hypotheses such as gridded interaction gaps, a linear relation between phase and position, and so on, were found. These hypotheses bring serious limitations and uncertainties into the computational results. JPNDISK was developed to eliminate these defects, to follow the equations of motion as rigorously as possible, and to obtain self-consistent solutions for the gap voltages and the electron motion. Although some inaccuracy may be present in the relativistic region, JPNDISK, in its present form, seems a most suitable tool for klystron design; it is both easy and inexpensive to use

A fast switch, combiner and narrow-band filter for high-power millimetre wave beams

Science.gov (United States)

Kasparek, W.; Petelin, M. I.; Shchegolkov, D. Yu; Erckmann, V.; Plaum, B.; Bruschi, A.; ECRH Groups at IPP Greifswald; Karlsruhe, FZK; Stuttgart, IPF

2008-05-01

A fast directional switch (FADIS) is described, which allows controlled switching of high-power microwaves between two outputs. A possible application could be synchronous stabilization of neoclassical tearing modes (NTMs). Generally, the device can be used to share the installed EC power between different types of launchers or different applications (e.g. in ITER, midplane/upper launcher). The switching is performed electronically without moving parts by a small frequency-shift keying of the gyrotron (some tens of megahertz), and a narrow-band diplexer. The device can be operated as a beam combiner also, which offers attractive transmission perspectives in multi-megawatt ECRH systems. In addition, these diplexers are useful for plasma diagnostic systems employing high-power sources due to their filter characteristics. The principle and the design of a four-port quasi-optical resonator diplexer is presented. Low-power measurements of switching contrast, mode purity and efficiency show good agreement with theory. Preliminary frequency modulation characteristics of gyrotrons are shown, and first results from high-power switching experiments using the ECRH system for W7-X are presented.

A fast switch, combiner and narrow-band filter for high-power millimetre wave beams

International Nuclear Information System (INIS)

Kasparek, W.; Plaum, B.; Petelin, M.I.; Shchegolkov, D.Yu; Erckmann, V.; Bruschi, A.

2008-01-01

A fast directional switch (FADIS) is described, which allows controlled switching of high-power microwaves between two outputs. A possible application could be synchronous stabilization of neoclassical tearing modes (NTMs). Generally, the device can be used to share the installed EC power between different types of launchers or different applications (e.g. in ITER, midplane/upper launcher). The switching is performed electronically without moving parts by a small frequency-shift keying of the gyrotron (some tens of megahertz), and a narrow-band diplexer. The device can be operated as a beam combiner also, which offers attractive transmission perspectives in multi-megawatt ECRH systems. In addition, these diplexers are useful for plasma diagnostic systems employing high-power sources due to their filter characteristics. The principle and the design of a four-port quasi-optical resonator diplexer is presented. Low-power measurements of switching contrast, mode purity and efficiency show good agreement with theory. Preliminary frequency modulation characteristics of gyrotrons are shown, and first results from high-power switching experiments using the ECRH system for W7-X are presented

Unity power factor switching regulator

Science.gov (United States)

Rippel, Wally E. (Inventor)

1983-01-01

A single or multiphase boost chopper regulator operating with unity power factor, for use such as to charge a battery is comprised of a power section for converting single or multiphase line energy into recharge energy including a rectifier (10), one inductor (L.sub.1) and one chopper (Q.sub.1) for each chopper phase for presenting a load (battery) with a current output, and duty cycle control means (16) for each chopper to control the average inductor current over each period of the chopper, and a sensing and control section including means (20) for sensing at least one load parameter, means (22) for producing a current command signal as a function of said parameter, means (26) for producing a feedback signal as a function of said current command signal and the average rectifier voltage output over each period of the chopper, means (28) for sensing current through said inductor, means (18) for comparing said feedback signal with said sensed current to produce, in response to a difference, a control signal applied to the duty cycle control means, whereby the average inductor current is proportionate to the average rectifier voltage output over each period of the chopper, and instantaneous line current is thereby maintained proportionate to the instantaneous line voltage, thus achieving a unity power factor. The boost chopper is comprised of a plurality of converters connected in parallel and operated in staggered phase. For optimal harmonic suppression, the duty cycles of the switching converters are evenly spaced, and by negative coupling between pairs 180.degree. out-of-phase, peak currents through the switches can be reduced while reducing the inductor size and mass.

The Impact of Power Switching Devices on the Thermal Performance of a 10 MW Wind Power NPC Converter

Directory of Open Access Journals (Sweden)

Ke Ma

2012-07-01

Full Text Available Power semiconductor switching devices play an important role in the performance of high power wind energy generation systems. The state-of-the-art device choices in the wind power application as reported in the industry include IGBT modules, IGBT press-pack and IGCT press-pack. Because of significant deviation in the packaging structure, electrical characteristics, as well as thermal impedance, these available power switching devices may have various thermal cycling behaviors, which will lead to converter solutions with very different cost, size and reliability performance. As a result, this paper aimed to investigate the thermal related characteristics of some important power switching devices. Their impact on the thermal cycling of a 10 MW three-level Neutral-Point-Clamped wind power converter is then evaluated under various operating conditions; the main focus will be on the grid connected inverter. It is concluded that the thermal performances of the 3L-NPC wind power converter can be significantly changed by the power device technology as well as their parallel configurations.

Power loss benchmark of nine-switch converters in three-phase online-UPS application

DEFF Research Database (Denmark)

Qin, Zian; Loh, Poh Chiang; Blaabjerg, Frede

2014-01-01

Three-phase online-UPS is an appropriate application for the nine-switch converter, where its high voltage stress of the power device caused by the reduced switch feature can be relieved significantly. Its power loss and loss distribution still have the flexibility from the control point of view...... as parameters like modulation index and phase angle of the load are taken into account. The benchmark of power loss will become a guidance for the users to make best use of the advantages and bypass the disadvantages of nine-switch converters. The results are finally verified on a 1.5 kW prototype....

Self-Oscillating Soft Switching Envelope Tracking Power Supply for Tetra2 Base Station

DEFF Research Database (Denmark)

Høyerby, Mikkel Christian Wendelboe; Andersen, Michael Andreas E.

2007-01-01

This paper presents a high-efficiency, high-bandwidth solution to implementing an envelope tracking power supply for the RF power amplifier (RFPA) in a Tetra2 base station. The solution is based on synchronous rectified buck topology, augmented with high-side switch zero-current switching (ZCS......) implemented with a series inductor and an external clamping power supply. Combined with advanced power stage components (die-size MOSFETs), a high-performance fixed-frequency self-oscillating (sliding mode) control strategy and a 4th-order output filter, this leads to a compact, effective and efficient...... overall solution switching at 1MHz with 88-95% efficiency. In a class-AB RFPA amplifying a 50kHz bandwidth QAM Tetra2 signal at 4.6W average output power, the use of tracking supply voltage reduced power dissipation by 25W....

Fiber-Optic Pyrometer with Optically Powered Switch for Temperature Measurements.

Science.gov (United States)

Vázquez, Carmen; Pérez-Prieto, Sandra; López-Cardona, Juan D; Tapetado, Alberto; Blanco, Enrique; Moreno-López, Jorge; Montero, David S; Lallana, Pedro C

2018-02-06

We report the experimental results on a new infrared fiber-optic pyrometer for very localized and high-speed temperature measurements ranging from 170 to 530 °C using low-noise photodetectors and high-gain transimpedance amplifiers with a single gain mode in the whole temperature range. We also report a shutter based on an optical fiber switch which is optically powered to provide a reference signal in an optical fiber pyrometer measuring from 200 to 550 °C. The tests show the potential of remotely powering via optical means a 300 mW power-hungry optical switch at a distance of 100 m, avoiding any electromagnetic interference close to the measuring point.

Fiber-Optic Pyrometer with Optically Powered Switch for Temperature Measurements

Directory of Open Access Journals (Sweden)

Carmen Vázquez

2018-02-01

Full Text Available We report the experimental results on a new infrared fiber-optic pyrometer for very localized and high-speed temperature measurements ranging from 170 to 530 °C using low-noise photodetectors and high-gain transimpedance amplifiers with a single gain mode in the whole temperature range. We also report a shutter based on an optical fiber switch which is optically powered to provide a reference signal in an optical fiber pyrometer measuring from 200 to 550 °C. The tests show the potential of remotely powering via optical means a 300 mW power-hungry optical switch at a distance of 100 m, avoiding any electromagnetic interference close to the measuring point.

DC switch power supply for vacuum-arc coatings deposition

International Nuclear Information System (INIS)

Zalesskij, D.Yu.; Volkov, Yu.Ya.; Vasil'ev, V.V.; Kozhushko, V.V.; Luchaninov, A.A.; Strel'nitskij, V.E.

2008-01-01

Special DC Switch Power Supply for vacuum-arc deposition was developed and tested in the mode of depositing Al and AlN films. Maximum output power was 6 kW, maximum output current - 120 A, open-circuit voltage - 150 V. The Power Supply allows to adjust and stabilize output current in a wide range. Testing of the Power Supply revealed an advantages over the standard 'Bulat-6' power supply, especially for deposition of non-conductive AlN films.

High-power RF controls for the NBS-Los Alamos racetrack microtron

International Nuclear Information System (INIS)

Young, L.M.; Biddl, R.S.

1985-01-01

The high-power rf system for the National Bureau of Standards (NBS)-Los Alamos racetrack microtron (RTM) uses waveguide power splitters and waveguide phase shifters to distribute rf power from a single 500-kw cw klystron to four side-coupled accelerating structures. The amplitude and phase of each structure is controlled by a feedback system that uses the waveguide variable power splitters, waveguide phase shifters, and klystron drive as the active control elements. The feedback controls on the capture section use low-level rf amplitude and phase controls on the rf drive to the klystron. These controls are very fast with an open loop gain bandwidth of approximately 40 kHz. The feedback loop is identical to the feedback loop used in the chopper/buncher system described in another paper at this conference

Module Integrated GaN Power Stage for High Switching Frequency Operation

DEFF Research Database (Denmark)

Nour, Yasser; Knott, Arnold

2017-01-01

is integrated on a high glass transition temperature 0.4 mmthick FR4 substrate configured as a 70 pin ball grid arraypackage. The power stage is tested up to switching frequency of12 MHz. The power stage achieved 88.5 % peak efficiency whenconfigured as a soft switching buck converter operating at 7MHz......An increased attention has been detected todevelop smaller and lighter high voltage power converters in therange of 50 V to 400 V domains. The applications for theseconverters are mainly focused for Power over Ethernet (PoE),LED lighting and ac adapters. Design for high power density isone...... of the targets for next generation power converters. Thispaper presents an 80 V input capable multi-chip moduleintegration of enhancement mode gallium nitride (GaN) fieldeffect transistors (FETs) based power stage. The module design ispresented and validated through experimental results. The powerstage...

Advanteges of using Two-Switch Forward in Single-Stage Power Factor Corrected Power Supplies

DEFF Research Database (Denmark)

Petersen, Lars

2000-01-01

A single-Stage power factor corrected power supply using a two-switch forward is proposed to increase efficiency. The converter is operated in the DCM (Discontinues Conduction Mode). This will insure the intermediate DC-bus to be controlled only by means of circuit parameters and therefore...... power supply has been implemented. The measured efficiency and power factor are about 87% and 0.96 respectively....

New solid state opening switches for repetitive pulsed power technology

Energy Technology Data Exchange (ETDEWEB)

Lyubutin, S K; Mesyats, G A; Rukin, S N; Slovikovskii, B G; Turov, A M [Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Electrophysics

1997-12-31

In 1991 the authors discovered a semiconductor opening switch (SOS) effect that occurs in p{sup +}-p-n-n{sup +} silicon structures at a current density of up to 60 kA/cm{sup 2}. This effect was used to develop high-power semiconductor opening switches in intermediate inductive storage circuits. The breaking power of the opening switches was as high as 5 GW, the interrupted current being up to 45 kA, reverse voltage up to 1 MV and the current interruption time between 10 and 60 ns. The opening switches were assembled from quantity-produced Russian-made rectifying diodes type SDL with hard recovery characteristic. On the basis of experimental and theoretical investigations of the SOS effect, new SOS diodes were designed and manufactured by the Electrophysical Institute. The paper gives basic parameters of the SOS diodes. The new diodes offer higher values of interrupted current and shorter times of current interruption together with a considerable increase in the energy switching efficiency. The new SOS diodes were used to develop repetitive all-solid-state pulsed generators with an output voltage of up to 250 kV, pulse repetition rate up to 5 kHz, and pulse duration between 10 and 30 ns. (author). 2 tabs., 3 figs., 4 refs.

Periodic permanent magnet focused klystron

Science.gov (United States)

Ferguson, Patrick; Read, Michael; Ives, R Lawrence

2015-04-21

A periodic permanent magnet (PPM) klystron has beam transport structures and RF cavity structures, each of which has permanent magnets placed substantially equidistant from a beam tunnel formed about the central axis, and which are also outside the extent of a cooling chamber. The RF cavity sections also have permanent magnets which are placed substantially equidistant from the beam tunnel, but which include an RF cavity coupling to the beam tunnel for enhancement of RF carried by an electron beam in the beam tunnel.

Iaverage current mode (ACM) control for switching power converters

OpenAIRE

2014-01-01

Providing a fast current sensor direct feedback path to a modulator for controlling switching of a switched power converter in addition to an integrating feedback path which monitors average current for control of a modulator provides fast dynamic response consistent with system stability and average current mode control. Feedback of output voltage for voltage regulation can be combined with current information in the integrating feedback path to limit bandwidth of the voltage feedback signal.

Optimization,Modeling, and Control: Applications to Klystron Designing and Hepatitis C Virus Dynamics

Science.gov (United States)

Lankford, George Bernard

In this dissertation, we address applying mathematical and numerical techniques in the fields of high energy physics and biomedical sciences. The first portion of this thesis presents a method for optimizing the design of klystron circuits. A klystron is an electron beam tube lined with cavities that emit resonant frequencies to velocity modulate electrons that pass through the tube. Radio frequencies (RF) inserted in the klystron are amplified due to the velocity modulation of the electrons. The routine described in this work automates the selection of cavity positions, resonant frequencies, quality factors, and other circuit parameters to maximize the efficiency with required gain. The method is based on deterministic sampling methods. We will describe the procedure and give several examples for both narrow and wide band klystrons, using the klystron codes AJDISK (Java) and TESLA (Python). The rest of the dissertation is dedicated to developing, calibrating and using a mathematical model for hepatitis C dynamics with triple drug combination therapy. Groundbreaking new drugs, called direct acting antivirals, have been introduced recently to fight off chronic hepatitis C virus infection. The model we introduce is for hepatitis C dynamics treated with the direct acting antiviral drug, telaprevir, along with traditional interferon and ribavirin treatments to understand how this therapy affects the viral load of patients exhibiting different types of response. We use sensitivity and identifiability techniques to determine which parameters can be best estimated from viral load data. We use these estimations to give patient-specific fits of the model to partial viral response, end-of-treatment response, and breakthrough patients. We will then revise the model to incorporate an immune response dynamic to more accurately describe the dynamics. Finally, we will implement a suboptimal control to acquire a drug treatment regimen that will alleviate the systemic cost

Soft switching buck-boost converter for photovoltaic power generation; Taiyoko hatsuden no tame no soft switching shokoatsu converter

Energy Technology Data Exchange (ETDEWEB)

Lee, H. [Kyungnam University (Korea, Republic of)

1996-10-27

A soft switching method with small switching loss was proposed for the purpose of increasing the efficiency of a DC-DC boost converter which converted a DC current generated by solar cells to a variable DC current. Existing current converters are supplemented by using a snubber circuit around the switch so as to protect the switch by a hard switching action. However, with an increase of the output current, snubber loss is increased, reducing the efficiency. In order to solve this problem, the partial resonant switch method was applied to the converter; with this method of partially forming a resonant circuit only at the time of turning on/off of the switch, the switching loss was reduced through the soft switching, thereby making the proposed converter operate with high efficiency. Moreover, the resonant element of the partial resonant circuit using a snubber condenser, the energy accumulated in the condenser was regenerated on the power supply side without loss of snubber. With the regenerated energy, the proposed converter was provided with a smaller ratio of switching to use than the conventional converter. 4 refs., 7 figs., 1 tab.

Very High Frequency Switch-Mode Power Supplies.:Miniaturization of Power Electronics.

OpenAIRE

Madsen, Mickey Pierre; Andersen, Michael A. E.; Knott, Arnold

2015-01-01

The importance of technology and electronics in our daily life is constantly increasing. At the same time portability and energy efficiency are currently some of the hottest topics. This creates a huge need for power converters in a compact form factor and with high efficiency, which can supply these electronic devices. This calls for new technologies in order to miniaturize the power electronics of today. One way to do this is by increasing the switching frequency dramatically and develop ve...

Development of bouncer-type pulse modulator for the ILC

International Nuclear Information System (INIS)

Akemoto, Mitsuo; Honma, Hiroyuki; Nakajima, Hiromitsu; Shidara, Tetsuo; Fukuda, Shigeki

2009-01-01

This paper describes a long-pulse 1.3 GHz klystron modulator that was recently developed for the Superconducting RF Test Facility (STF) at High Energy Accelerator Research Organization (KEK). The modulator has a direct-switched-type design with a 1:15 step-up transformer and a bouncer circuit to compensate the output phase droop within ±0.5%; it can drive a klystron up to 10 MW peak power, 1.5 ms rf pulse width, and 5 pps repetition rate. The main features of this modulator are four 50 kW switching power supplies in parallel to charge storage capacitors to 10 kV, self-healing-type storage capacitors to realize a compact capacitor bank, and a highly reliable IGBT switch which enables elimination of a crowbar circuit. Design considerations and its performance are presented. An IEGT (Injection Enhanced Gate Transistor) switch, composed of six series devices with a rating of 4.5 kV and 2100 A-DC, has been also developed and tested for R and D to realize a compact modulator. (author)

Current-Driven Switch-Mode Audio Power Amplifiers

DEFF Research Database (Denmark)

Knott, Arnold; Buhl, Niels Christian; Andersen, Michael A. E.

2012-01-01

The conversion of electrical energy into sound waves by electromechanical transducers is proportional to the current through the coil of the transducer. However virtually all audio power amplifiers provide a controlled voltage through the interface to the transducer. This paper is presenting...... a switch-mode audio power amplifier not only providing controlled current but also being supplied by current. This results in an output filter size reduction by a factor of 6. The implemented prototype shows decent audio performance with THD + N below 0.1 %....

Hybrid Design Optimization of High Voltage Pulse Transformers for Klystron Modulators

CERN Document Server

Sylvain, Candolfi; Davide, Aguglia; Jerome, Cros

2015-01-01

This paper presents a hybrid optimization methodology for the design of high voltage pulse transformers used in klystron modulators. The optimization process is using simplified 2D FEA design models of the 3D transformer structure. Each intermediate optimal solution is evaluated by 3D FEA and correction coefficients of the 2D FEA models are derived. A new optimization process using 2D FEA models is then performed. The convergence of this hybrid optimal design methodology is obtained with a limited number of time consuming 3D FEA simulations. The method is applied to the optimal design of a monolithic high voltage pulse transformer for the CLIC klystron modulator.

Digital measurement system for the LHC klystron high voltage modulator.

CERN Document Server

Mikkelsen, Anders

Accelerating voltage in the Large Hadron Collider (LHC) is created by a means of 16 superconducting standing wave RF cavities, each fed by a 400MHz/300kW continuous wave klystron amplifier. Part of the upgrade program for the LHC long shutdown one is to replace the obsolete analogue current and voltage measurement circuitry located in the high voltage bunkers by a new, digital system, using ADCs and optical fibres. A digital measurement card is implemented and integrated into the current HV modulator oil tank (floating at -58kV) and interfaced to the existing digital VME boards collecting the data for several klystrons at the ground potential. Measured signals are stored for the logging, diagnostics and post-mortem analysis purposes.

Simulation study of transverse optical klystron radiation

International Nuclear Information System (INIS)

Xu Hongliang; Diao Caozheng; Liu Jinying; He Duohui; Jia Qika; Wang Xiangqi

1997-01-01

The radiation from a transverse optical klystron (TOK) is calculated by far field approximation equation and numerical integration, in which the effects of electron-beam emittance and energy spread are considered. Accurate electron-beam profiles have been experimentally determined and modeled by the Monte Carlo method. The calculated spectra illustrate the emittance of Hefei storage ring imposes on the spontaneous radiation of TOK

49 CFR 1242.67 - Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power...

Science.gov (United States)

2010-10-01

... 49 Transportation 9 2010-10-01 2010-10-01 false Switch crews; controlling operations; yard and terminal clerical; locomotive fuel; electric power purchased/produced for motive power; operating switches... SERVICE FOR RAILROADS 1 Operating Expenses-Transportation § 1242.67 Switch crews; controlling operations...

Development and advances in conventional high power RF systems

International Nuclear Information System (INIS)

Wilson, P.B.

1995-06-01

The development of rf systems capable of producing high peak power (hundreds of megawatts) at relatively short pulse lengths (0.1--5 microseconds) is currently being driven mainly by the requirements of future high energy linear colliders, although there may be applications to industrial, medical and research linacs as well. The production of high peak power rf typically involves four basic elements: a power supply to convert ac from the ''wall plug'' to dc; a modulator, or some sort of switching element, to produce pulsed dc power; an rf source to convert the pulsed dc to pulsed rf power; and possibly an rf pulse compression system to further enhance the peak rf power. Each element in this rf chain from wall plug to accelerating structure must perform with high efficiency in a linear collider application, such that the overall system efficiency is 30% or more. Basic design concepts are discussed for klystrons, modulators and rf pulse compression systems, and their present design status is summarized for applications to proposed linear colliders

Development of the power system for accelerator

International Nuclear Information System (INIS)

Kwon, Hyeokjung; Kim, D. I.; Kim, H. S.; Park, B. S.; Seol, K. T.; Yun, S. P.; Song, Y. G.; Jang, J. H.; Cho, Y. S.

2013-02-01

The 100-MeV proton linac needs 4 modulators whose specification is as follows, -115kV, 55A, and 9%. The development of the modulators were successfully finished and installed at Gyeongju site of KAERI. One of them was used and successfully tested in the 20-MeV linac operation at Daejeon site. The klystron is used to supply the high power RF into the accelerating structure. There are 2 klystrons for 20-MeV part of the linac and 7 klystrons from 20-MeV to 100-MeV region. The maximum voltage is ?105kV, the peak power is 1.6 MW, and the duty is 9%. All of the 7 klystrons have been fabricated, tested and installed. The high power RF system includes circulators, dummy lodes, RF windows, and wave-guides. The development of the high power RF components was finished and they were installed at the Gyeongju site. The 11 sets of RCCS (resonant control cooling system) will be used to control the cooling water temperature inside the accelerating structure. The temperature range of the cooling water covers between 21 .deg. C and 33 .deg. C with the 0.1 .deg. C control. All RCCSs were installed in the klystron gallery. Purposes of the 20-MeV linac operation at Daejeon site of KAERI (2007∼2011) are to supply proton beams to user, to porve the accelerator performance, to test the developed components including LLRF, diagnostics, and control system, and to measure the proton beam properties. During the period, the total number of samples reaches to 1,603 and the average machine availability becomes 96.2%. The 20-MeV linac was disassembled, moved and installed at Gyeongju site after finishing the test operation

High power tests of X-band RF windows at KEK

Energy Technology Data Exchange (ETDEWEB)

Otake, Yuji [Earthquake Research Inst., Tokyo Univ., Tokyo (Japan); Tokumoto, Shuichi; Kazakov, Sergei Yu.; Odagiri, Junichi; Mizuno, Hajime

1997-04-01

Various RF windows comprising a short pill-box, a long pill-box, a TW (traveling wave)-mode and three TE11-mode horn types have been developed for an X-band high-power pulse klystron with two output windows for JLC (Japan Linear Collider). The output RF power of the klystron is designed to be 130 MW with the 800 ns pulse duration. Since this X-band klystron has two output windows, the maximum RF power of the window must be over 85 MW. The design principle for the windows is to reduce the RF-power density and/or the electric-field strength at the ceramic part compared with that of an ordinary pill-box-type window. Their reduction is effective to increase the handling RF power of the window. To confirm that the difference among the electric-field strengths depends on their RF structures, High-power tests of the above-mentioned windows were successfully carried out using a traveling-wave resonator (TWR) for the horns and the TW-mode type and, installing them directly to klystron output waveguides for the short and long pill-box type. Based upon the operation experience of S-band windows, two kinds of ceramic materials were used for these tests. The TE11-mode 1/2{lambda}g-1 window was tested up to the RF peak-power of 84 MW with the 700 ns pulse duration in the TWR. (J.P.N)

Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants

Science.gov (United States)

Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

2014-09-09

A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

Characterization of a High-Power, High-Frequency, Soft-Switching Power Converter for EMC Considerations

National Research Council Canada - National Science Library

Li, S

2001-01-01

This report presents the setup, experimental techniques, and results of the radiated emissions tests on the PCM-3 soft-switching power converter using the Gigahertz Transverse Electromagnetic (GTEM) facility...

Prospects for a soft x-ray FEL powered by a relativistic-klystron high-gradient accelerator (RK-HGA)

International Nuclear Information System (INIS)

Shay, H.D.; Barletta, W.A.; Yu, S.S.; Schlueter, R.; Deis, G.A.

1989-01-01

We present here the concept of x-ray FELs using high gain, single-pass amplifiers with electron beams accelerated in high gradient structures powered by relativistic klystrons. Other authors have also considered x-ray FELs; the unique aspect of this paper is the use of high gradient acceleration. One of the authors has previously presented preliminary studies on this concept. The intent in this paper is to display the results of a top level design study on a high gain FEL, to present its sensitivity to a variety of fabrication and tuning errors, to discuss several mechanisms for increasing gain yet more, and to present explicitly the output characteristics of such an FEL. The philosophy of the design study is to find a plausible operating point which employs existing or nearly existing state-of-the-art technologies while minimizing the accelerator and wiggler lengths. The notion is to distribute the technical risk as evenly as possible over the several technologies so that each must advance only slightly in order to make this design feasible. This study entailed no systematic investigation of possible costs so that, for example, the sole criterion for balancing the trade-off between beam energy and wiggler length is that the two components have comparable lengths. 20 refs., 10 figs., 1 tab

A combined source of electron bunches and microwave power

International Nuclear Information System (INIS)

Xie, J.L.; Wang, F.Y.; Yang, X.P.; Shen, B.; Gu, W.; Zhang, L.W.

2003-01-01

In this article, the possibility of using a high power klystron amplifier simultaneously as a microwave power source as usual and an electron bunches source by extracting the spent beam with a magnet and also as an oscillator by feedback is investigated. The purpose of this study is to demonstrate the feasibility of constructing a very compact electron linear accelerator or for other applications of electron bunches. The feasibility of the idea was first examined by computer simulation of the electron motion in a 5 MW klystron and the characteristics of the klystron spent beam. Experimental study was then carried out by installing a radio frequency cavity and a Faraday cage in sequence at the exit end of a bending magnet located at the top of the klystron collector. The energy and current of the chopped spent electron beam can then be measured. By properly choosing the feedback circuit elements, the frequency stability of the klystron in oscillator mode was proved to be good enough for linac operation. According to the results presented in this article, it is evident that an extremely compact linac for research and education with better affordability can be constructed to promote the applications of linacs

A high-order mode extended interaction klystron at 0.34 THz

Science.gov (United States)

Wang, Dongyang; Wang, Guangqiang; Wang, Jianguo; Li, Shuang; Zeng, Peng; Teng, Yan

2017-02-01

We propose the concept of high-order mode extended interaction klystron (EIK) at the terahertz band. Compared to the conventional fundamental mode EIK, it operates at the TM31-2π mode, and its remarkable advantage is to obtain a large structure and good performance. The proposed EIK consists of five identical cavities with five gaps in each cavity. The method is discussed to suppress the mode competition and self-oscillation in the high-order mode cavity. Particle-in-cell simulation demonstrates that the EIK indeed operates at TM31-2π mode without self-oscillation while other modes are well suppressed. Driven by the electron beam with a voltage of 15 kV and a current of 0.3 A, the saturation gain of 43 dB and the output power of 60 W are achieved at the center frequency of 342.4 GHz. The EIK operating at high-order mode seems a promising approach to generate high power terahertz waves.

SiC MOSFET Switching Power Amplifier Project Summary

Science.gov (United States)

Miller, Kenneth E.; Ziemba, Timothy; Prager, James; Slobodov, Ilia; Henson, Alex

2017-10-01

Eagle Harbor Technologies has completed a Phase I/II program to develop SiC MOSFET based Switching Power Amplifiers (SPA) for precision magnet control in fusion science applications. During this program, EHT developed several units have been delivered to the Helicity Injected Torus (HIT) experiment at the University of Washington to drive both the voltage and flux circuits of the helicity injectors. These units are capable of switching 700 V at 100 kHz with an adjustable duty cycle from 10 - 90% and a combined total output current of 96 kA for 4 ms (at max current). The SPAs switching is controlled by the microcontroller at HIT, which adjusts the duty cycle to maintain a specific waveform in the injector. The SPAs include overcurrent and shoot-through protection circuity. EHT will present an overview of the program including final results for the SPA waveforms. With support of DOE SBIR.

High power RF systems for LEHIPA of ADS

International Nuclear Information System (INIS)

Pande, Manjiri; Shrotriya, Sandip; Sharma, Sonal; Rao, B.V.R.; Mishra, J.K.; Patel, Niranjan; Gupta, S.K.

2011-01-01

Worldwide accelerator driven sub-critical system (ADS) has generated a huge interest for various reasons. In India, as a part of accelerator driven sub-critical system (ADS) program, a normal conducting, low energy high intensity proton accelerator (LEHIPA) of energy 20 MeV and beam current of 30 mA is being developed in Bhabha Atomic Research Centre (BARC). LEHIPA comprises of Electron Cyclotron Resonance (ECR) ion source (50 KeV), Radio Frequency Quadrupole (RFQ) accelerator (3 MeV) and Drift tube Linac (DTL) 1 and 2 (10 MeV and 20 MeV respectively). As per the accelerator physics design, RFQ requires nearly 530 kW RF power while each of DTL need 900 kW. Each accelerating cavity will be driven by a one- megawatt (CW) klystron based high power RF (HPRF) system at 352.21 MHz. Three such RF systems will be developed. The RF system has been designed around five cavity klystron tube TH2089F (Thales make) capable of delivering 1 MW continuous wave power at 352.21 MHz. The klystron has a gain of 40 dB and efficiency around 62 %. Each of the RF system comprises of a low power solid state driver (∼ 100 W), klystron tube, harmonic filter, directional coupler, Y-junction circulator (AFT make), RF load and WR2300 wave guide based RF transmission line each of 1 MW capacity. It also includes other subsystems like bias supplies (high voltage (HV) and low voltage (LV)), HV interface system, interlock and protection circuits, dedicated low conductivity water-cooling, pulsing circuitry/mechanisms etc. WR 2300 based RF transmission line transmits and feeds the RE power from klystron source to respective accelerating cavity. This transmission line starts from second port of the circulator and consists of straight sections, full height to half height transition, magic Tee, termination load at the centre of magic tee, half height sections, directional couplers and RE windows. For X-ray shielding, klystron will be housed in a lead (3 mm) based shielded cage. This system set up has a

Current measurement method for characterization of fast switching power semiconductors with Silicon Steel Current Transformer

DEFF Research Database (Denmark)

Li, Helong; Beczkowski, Szymon; Munk-Nielsen, Stig

2015-01-01

This paper proposes a novel current measurement method with Silicon Steel Current Transformer (SSCT) for the characterization of fast switching power semiconductors. First, the existing current sensors for characterization of fast switching power semiconductors are experimentally evaluated...

Development of a diagnostic system for Klystron modulators using a neural network

International Nuclear Information System (INIS)

Mutoh, M.; Oonuma, T.; Shibasaki, Y.; Abe, I.; Nakahara, K.

1992-01-01

The diagnostic system for klystron modulators using a neural network has been developed. Large changes in the voltage and current of the main circuit in a klystron modulator were observed just several ten milli-seconds before the modulator experienced trouble. These changes formed a peculiar pattern that depended on the parts with problems. Diagnosis was possible by means of pattern recognition. The recognition test of patterns using a neutral network has shown good results. This system, which is built in a linac control system, is presently being operated so as to collect new trouble patterns and to carry out tests for practical use. (author)

Investigation of crosstalk in self oscillating switch mode audio power amplifier

DEFF Research Database (Denmark)

Birch, Thomas Haagen; Ploug, Rasmus Overgaard; Iversen, Niels Elkjær

2012-01-01

channel self oscillating switch mode power amplier (class D). A step by step reduction of elements in an amplier built for this task, is used for methodically determining the actual presence and origins of crosstalk. The investigation shows that the crosstalk is caused by couplings in the self oscillating......Self oscillating switch mode power ampliers are known to be susceptible to interchannel disturbances also known as crosstalk. This phenomenon has a signicant impact on the performance of an amplier of this type. The goal of this paper is to investigate the presence and origins of crosstalk in a two...

Pulse transformer R and D for NLC klystron pulse modulator

International Nuclear Information System (INIS)

Akemoto, M.; Gold, S.; Krasnykh, A.; Koontz, R.

1997-07-01

The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and a pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests using a klystron load are also presented

CMOS single-stage input-powered bridge rectifier with boost switch and duty cycle control

Science.gov (United States)

Radzuan, Roskhatijah; Mohd Salleh, Mohd Khairul; Hamzah, Mustafar Kamal; Ab Wahab, Norfishah

2017-06-01

This paper presents a single-stage input-powered bridge rectifier with boost switch for wireless-powered devices such as biomedical implants and wireless sensor nodes. Realised using CMOS process technology, it employs a duty cycle switch control to achieve high output voltage using boost technique, leading to a high output power conversion. It has only six external connections with the boost inductance. The input frequency of the bridge rectifier is set at 50 Hz, while the switching frequency is 100 kHz. The proposed circuit is fabricated on a single 0.18-micron CMOS die with a space area of 0.024 mm2. The simulated and measured results show good agreement.

High-power rf controls for the NBS-Los Alamos racetrack microtron

International Nuclear Information System (INIS)

Young, L.M.; Biddle, R.S.

1985-01-01

The high-power rf system for the National Bureau of Standards (NBS)-Los Alamos racetrack microtron (RTM) uses waveguide power splitters and waveguide phase shifters to distribute rf power from a single 500-kW cw klystron to four side-coupled accelerating structures. The amplitude and phase of each structure is controlled by a feedback system that uses the waveguide variable power splitters, waveguide phase shifters, and klystron drive as the active control elements. A block diagram of this system is shown, as is a subset of the complete system on which the measurements reported in this paper were performed. The feedback controls on the capture section use low-level rf amplitude and phase controls on the rf drive to the klystron. These controls are very fast with an open loop gain bandwidth of approximately 40 kHz. The feedback loop is identical to the feedback loop used in the chopper/buncher system described in another paper at this conference. 4 refs., 8 figs

HIGH POWER TESTS OF A MULTIMODE X-BAND RF DISTRIBUTION SYSTEMS

International Nuclear Information System (INIS)

Tantawi, S

2004-01-01

We present a multimode X-band rf pulse compression system suitable for the Next Linear Collider (NLC). The NLC main linacs operate at 11.424 GHz. A single NLC rf unit is required which produce 400 ns pulses with 600 MW of peak power. Each rf unit should power approximately 5 meters of accelerator structures. These rf units consist of two 75 MW klystrons and a dual-moded resonant delay line pulse compression system [1] that produce a flat output pulse. The pulse compression system components are all over moded and most components are design to operate with two modes at the same time. This approach allows increasing the power handling capabilities of the system while maintain a compact inexpensive system. We detail the design of this system and present experimental cold test results. The high power testing of the system is verified using four 50-MW solenoid focused klystrons. These Klystrons should be able to push the system beyond NLC requirements

Evaluation of DC/DC switching power regulation with small-scale integrated inductors for PET/MR

Energy Technology Data Exchange (ETDEWEB)

Biagi, Laura [IRCCS Fondazione Stella Maris and Fondazione Imago 7, Calambrone, Pisa (Italy); Bisogni, Maria Giuseppina; Camarlinghi, Niccolo [Department of Physics, University of Pisa and INFN, Pisa (Italy); Costagli, Mauro [IRCCS Fondazione Stella Maris and Fondazione Imago 7, Calambrone, Pisa (Italy); Sportelli, Giancarlo [Department of Physics, University of Pisa and INFN, Pisa (Italy); Tosetti, Michela [IRCCS Fondazione Stella Maris and Fondazione Imago 7, Calambrone, Pisa (Italy); Del Guerra, Alberto; Belcari, Nicola [Department of Physics, University of Pisa and INFN, Pisa (Italy)

2015-05-18

We present a feasibility study that has been carried out to determine the best power regulation strategy for the PET front-end electronics of the trimodal PET/MRI/EEG TRIMAGE scanner. Conventional power regulation strategies cannot be applied to PET/MRI because standard switching regulators stop working in presence of a high magnetic field. At the state of the art, linear regulators are used instead. However, linear regulators are inefficient and might not allow to fulfill power and thermal constraints if the electronics becomes more power demanding, such as in the case of FPGA based front-ends. Very recently, a new generation of switching power supplies has been introduced for EMI critical applications where the discrete inductor energy buffer is not allowed. These supplies have very small footprint, need few biasing peripherals and they use on-chip integrated inductors for energy storage. These switching power regulators coupled with an adequate EMI shield could be an achievable power solution for our PET front-end electronics. Test procedures for Enpirion. EN2390QI and the Enpirion. EN6347QI switching power regulators are presented. Measurements have been performed at GE 1.5T MRI scanner with the support of IRCCS Fondazione Stella Maris. All the board have been tested in two different configurations: with and without an additional EMI shield. Performance of these two switching power regulators have been compared with a linear power regulator (Enpirion. EY1501DI). Output voltage, output current and temperature have been measured. The stability of these three main characteristic will be presented in different operation conditions and will be discussed (output voltage vs. temperature, output voltage vs. output current and output current vs. temperature).

High-power subnanosecond operation of a bistable optically controlled semiconductor switch (BOSS)

International Nuclear Information System (INIS)

Stoudt, D.C.; Richardson, M.A.; Demske, D.L.; Roush, R.A.; Eure, K.W.

1994-01-01

Recent high-power, subnanosecond-switching results of the Bistable Optically controlled Semiconductor Switch (BOSS) are presented. The process of persistent photoconductivity followed by photo-quenching have been demonstrated at megawatt power levels in copper-compensated, silicon-doped, semi-insulating gallium arsenide. These processes allow a switch to be developed that can be closed by the application of one laser pulse and opened by the application of a second laser pulse with a wavelength equal to twice that of the first laser. Switch closure is primarily achieved by elevating electrons from a deep copper center which has been diffused into the material. The opening phase is a two-step process which relies initially on the absorption of the 2-μm laser causing electrons to be elevated from the valance band back into the copper center, and finally on the recombination of electrons in the conduction band with boles in the valance band. The second step requires a sufficient concentration of recombination centers (RC) in the material for opening to occur in the subnanosecond regime. These RC's are generated in the bulk GaAs material by fast-neutron irradiation (∼ 1 MeV) at a fluence of about 3 x 10 15 cm -2 . High-power switching results which demonstrate that the BOSS switch can be opened in the subnanosecond regime are presented for the first time. Neutron-irradiated BOSS devices have been opened against a rising electric field of about 20 kV/cm (10 kV) in a time less than one nanosecond. Kilovolt electrical pulses have been generated with a FWHM of roughly 250 picoseconds

Resonant High Power Combiners

CERN Document Server

Langlois, Michel; Peillex-Delphe, Guy

2005-01-01

Particle accelerators need radio frequency sources. Above 300 MHz, the amplifiers mostly used high power klystrons developed for this sole purpose. As for military equipment, users are drawn to buy "off the shelf" components rather than dedicated devices. IOTs have replaced most klystrons in TV transmitters and find their way in particle accelerators. They are less bulky, easier to replace, more efficient at reduced power. They are also far less powerful. What is the benefit of very compact sources if huge 3 dB couplers are needed to combine the power? To alleviate this drawback, we investigated a resonant combiner, operating in TM010 mode, able to combine 3 to 5 IOTs. Our IOTs being able to deliver 80 kW C.W. apiece, combined power would reach 400 kW minus the minor insertion loss. Values for matching and insertion loss are given. The behavior of the system in case of IOT failure is analyzed.

High-power electro-optic switch technology based on novel transparent ceramic

International Nuclear Information System (INIS)

Zhang Xue-Jiao; Ye Qing; Qu Rong-Hui; Cai Hai-wen

2016-01-01

A novel high-power polarization-independent electro-optic switch technology based on a reciprocal structure Sagnac interferometer and a transparent quadratic electro-optic ceramic is proposed and analyzed theoretically and experimentally. The electro-optic ceramic is used as a phase retarder for the clockwise and counter-clockwise polarized light, and their polarization directions are adjusted to their orthogonal positions by using two half-wave plates. The output light then becomes polarization-independent with respect to the polarization direction of the input light. The switch characteristics, including splitter ratios and polarization states, are theoretically analyzed and simulated in detail by the matrix multiplication method. An experimental setup is built to verify the analysis and experimental results. A new component ceramic is used and a non-polarizing cube beam splitter (NPBS) replaces the beam splitter (BS) to lower the ON/OFF voltage to 305 V and improve the extinction ratio by 2 dB. Finally, the laser-induced damage threshold for the proposed switch is measured and discussed. It is believed that potential applications of this novel polarization-independent electro-optic switch technology will be wide, especially for ultrafast high-power laser systems. (paper)

High voltage, high power operation of the plasma erosion opening switch

International Nuclear Information System (INIS)

Neri, J.M.; Boller, J.R.; Ottinger, P.F.; Weber, B.V.; Young, F.C.

1987-01-01

A Plasma Erosion Opening Switch (PEOS) is used as the opening switch for a vacuum inductive storage system driven by a 1.8-MV, 1.6-TW pulsed power generator. A 135-nH vacuum inductor is current charged to ∼750 kA in 50 ns through the closed PEOS which then opens in <10 ns into an inverse ion diode load. Electrical diagnostics and nuclear activations from ions accelerated in the diode yield a peak load voltage (4.25 MV) and peak load power (2.8 TW) that are 2.4 and 1.8 times greater than ideal matched load values for the same generator pulse

275 C Downhole Switched-Mode Power Supply

Energy Technology Data Exchange (ETDEWEB)

Chris Hutchens; Vijay Madhuravasal

2008-08-31

A vee-square (V2) control based controller IC is developed for a switch mode power supply capable of operating at extreme temperature/harsh environment conditions. A buck type regulator with silicon carbide power junction field effect transistors (JFET) as power devices is used to analyze the performance of controller. Special emphases are made on the analog sub-blocks--voltage reference, operational transconductance amplifier and comparator as individual building blocks. Transformer coupled gate drives and high temperature operable magnetic cores and capacitors are identified and tested for use in the design. Conventional ceramic chip packaging of ICs combined with lead carrier type mounting of passive filter components is introduced for hybrid packaging of the complete product. The developed SMPS is anticipated to support the operation of down-hole microcontrollers and other electronics devices that require low/medium power filtered dc inputs over an operating temperature of 275 C.

Study on Power Switching Process of a Hybrid Electric Vehicle with In-Wheel Motors

Directory of Open Access Journals (Sweden)

Shaohua Wang

2016-01-01

Full Text Available Hybrid electric vehicles with in-wheel motors (IWM achieve a variety of driving modes by two power sources—the engine and the IWM. One of the critical problems that exists in such vehicle is the different transient characteristics between the engine and the IWM. Therefore, switching processes between the power sources have noteworthy impacts on vehicle dynamics and driving performance. For the particular switching process of the pure electric mode to the engine driving mode, a specific control strategy coordinating clutch torque, motor torque, and engine torque was proposed to solve drivability issues caused by inconsistent responses of different power sources during the mode transition. The specific switching process could be described as follows: the engine was started by IWM with the clutch serving as a key enabling actuator, dynamic torque compensation through IWM was implemented after engine started, and, meanwhile, engine speed was controlled to track the target speed through the closed loop PID control strategy. The bench tests results showed that the vehicle jerk caused during mode switching was reduced and fast and smooth mode switching was realized, which leads to the improvement of vehicle’s riding comfort.

Power requirements reducing of FBG based all-optical switching

Science.gov (United States)

Scholtz, Ľubomír.; Solanská, Michaela; Ladányi, Libor; Müllerová, Jarmila

2017-12-01

Although Fiber Bragg gratings (FBGs) are well known devices, their using as all-optical switching elements has been still examined. Current research is focused on optimization of their properties for their using in future all-optical networks. The main problem are high switching intensities needed for achieving the changes of the transmission state. Over several years switching intensities have been reduced from hundreds of GW/cm2 to tens of MW/cm2 by selecting appropriate gratings and signal parameters or using suitable materials. Two principal nonlinear effects with similar power requirements can result in the bistable transmission/reflection of an input optical pulse. In the self-phase modulation (SPM) regime switching is achieved by the intense probe pulse itself. Using cross-phase modulation (XPM) a strong pump alters the FBG refractive index experienced by a weak probe pulse. As a result of this the detuning of the probe pulse from the center of the photonic band gap occurs. Using of XPM the effect of modulation instability is reduced. Modulation instability which is the main SPM degradation mechanism. We focused on nonlinear FBGs based on chalcogenide glasses which are very often used in various applications. Thanks to high nonlinear parameters chalcogenide glasses are suitable candidates for reducing switching intensities of nonlinear FBGs.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Science.gov (United States)

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

2014-05-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-05-15

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

High power semiconductor switching in the nanosecond regime

International Nuclear Information System (INIS)

Zucker, O.S.; Long, J.R.; Smith, V.L.; Page, D.J.; Roberts, J.S.

1975-12-01

Light activated multilayered silicon semiconductor devices have been used to switch at megawatt power levels with nanosecond turnon time. Current rate of rise of 700 kA/μs at 10 kA, with 1 kV across the load have been achieved. Recovery time of 1 millisec has been obtained. Applicability to fusion research needs is discussed

Modern thyratron crowbar protection systems

International Nuclear Information System (INIS)

Judd, D.A.; Kettle, L.J.; Menown, H.; Newton, B.P.; Nicholls, N.S.; Sheldrake, R.

1992-01-01

Two thyratron crowbar systems for high-power klystrons used in linear accelerators are described. The first, contained in an oil filled tank, is a complete system to protect a klystron powered from a 100-kV, 20-A d.c. supply. In the second system a CX1722 glass thyratron, operating in air, has been retrofitted to a test equipment, in place of a spark gap, to protect an Inductive Output Tube (IOT). An important parameter in the choice of the crowbar thyratron is the total coulombs to be switched. Measurements of these follow-on currents are presented. (R.P.) 4 refs.; 10 figs

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.)

Production of fast switching power thyristors by proton irradiation

International Nuclear Information System (INIS)

Sawko, D.C.; Bartko, J.

1983-01-01

There are several techniques currently employed by various manufacturers in the fabrication of fast switching power thyristors. Gold doping and irradiation by electron beams are among the more common ones. In all cases, the fast switching capability results from a reduction of the minority carrier lifetime of the host material by the introduction of carrier traps or recombination centers. However, accompanying this beneficial reduction in switching speed is a deleterious increase in forward voltage drop which also results from the introduction of carrier traps. Methods which minimize the voltage drop increase as the switching speed is reduced are highly desirable. One such method would achieve this by introducing the traps or recombination centers into well defined narrow regions where they will be more effective in reducing the switching speed than in increasing the forward voltage drop. Because the proton range-energy relationship in materials is relatively well defined and the lifetime reducing displacements occur near the end of their ranges, the lifetime in silicon can be reduced where desired by the precise control of proton energy. Dual energy proton beams from a tandem Van de Graaff accelerator were used in the experiments to determine whether proton beam irradiations offer advantages over other techniques. This was the subject of the present work. The results indicate that this is the preferred technique for reproducibly and rapidly processing fast switching thyristors with superior characteristics. The experimental procedure is discussed and comparisons are made with electron and neutron irradiated thyristors

Design of High-Voltage Switch-Mode Power Amplifier Based on Digital-Controlled Hybrid Multilevel Converter

Directory of Open Access Journals (Sweden)

Yanbin Hou

2016-01-01

Full Text Available Compared with conventional Class-A, Class-B, and Class-AB amplifiers, Class-D amplifier, also known as switching amplifier, employs pulse width modulation (PWM technology and solid-state switching devices, capable of achieving much higher efficiency. However, PWM-based switching amplifier is usually designed for low-voltage application, offering a maximum output voltage of several hundred Volts. Therefore, a step-up transformer is indispensably adopted in PWM-based Class-D amplifier to produce high-voltage output. In this paper, a switching amplifier without step-up transformer is developed based on digital pulse step modulation (PSM and hybrid multilevel converter. Under the control of input signal, cascaded power converters with separate DC sources operate in PSM switch mode to directly generate high-voltage and high-power output. The relevant topological structure, operating principle, and design scheme are introduced. Finally, a prototype system is built, which can provide power up to 1400 Watts and peak voltage up to ±1700 Volts. And the performance, including efficiency, linearity, and distortion, is evaluated by experimental tests.

Power quality improvement in highly varying loads using thyristor-switched capacitor

Energy Technology Data Exchange (ETDEWEB)

Poshtan, M. [Petroleum Inst., Abu Dhabi (United Arab Emirates). Dept. of Electrical Engineering; Mokhtari, H.; Esmaeili, A. [Sharif Univ. of Technology, Tehran (Iran, Islamic Republic of). Dept. of Electrical Engineering

2007-07-01

Ordinary contactor-based-capacitor (CBC) banks may not be able to response quickly enough in highly varying electrical loads such as welding machines or arc furnace loads. Thyristor-switched capacitor (TSC) banks are therefore used to compensate for reactive power of highly varying loads. In this paper, the performance of a TSC was compared to CBC banks. The 2 systems, were also compared in terms of energy saving in transmission systems. Simulations carried out using PSCAD/EMTDC software showed that there was a considerable difference in the performance of the 2 systems. The shortcomings of existing CBC systems include slow response of mechanical switching systems; problem of switching more than one bank into the system; and, voltage/current transients during on-off switching. 3 refs., 6 tabs., 14 figs.

Design of inductively detuned RF extraction cavities for the Relativistic Klystron Two Beam Accelerator

International Nuclear Information System (INIS)

Henestroza, E.; Yu, S.S.; Li, H.

1995-04-01

An inductively detuned traveling wave cavity for the Relativistic Klystron Two Beam Accelerator expected to extract high RF power at 11. 424 GHz for the 1 TeV Center of Mass Next Linear Collider has been designed. Longitudinal beam dynamics studies led to the following requirements on cavity design: (a) Extraction of 360 MW of RF power with RF component of the current being 1.15 kAmps at 11.424 GHz, (b) Inductively detuned traveling wave cavity with wave phase velocity equal to 4/3 the speed of light, (c) Output cavity with appropriate Q ext and eigenfrequency for proper matching. Furthermore, transverse beam dynamics require low shunt impedances to avoid the beam break-up instability. We describe the design effort to meet these criteria based on frequency-domain and time-domain computations using 2D- and 3D- electromagnetic codes

Fuel switching in power-plants: Modelling and impact on the analysis of energy projects

International Nuclear Information System (INIS)

Varympopiotis, G.; Tolis, A.; Rentizelas, A.

2014-01-01

Highlights: • The impact of fuel-switching in electricity generation is researched. • 15 Scenarios of fuel-technology combinations are compared using a computational model. • Fuel-switching results to higher yields compared to single-fuelled plants. • Plants with natural gas combined cycle and solid fuel supercritical boilers are optimal. • Fuel-switching, offers higher flexibility and security of fuel supply. - Abstract: In electricity markets, where conditions are uncertain, the choice of the best technology and the optimisation of production processes may not anymore be enough to ensure optimal investment yield of energy business plans. Providing some aspects of flexibility might enhance their financial performance; fuel switching may prove to be an alternative option, offering operational flexibility over time, as well as significant financial benefits. Traditional investment analysis methods are considered marginally useful to analyse this case. Instead, the recent tools of time-dependent investment analysis are more appropriate, since they are not inherently restricted to immediate, irreversible decisions. In the present work, a time-dependent computational model is presented and applied in the case study of the Greek Power Sector, in order to estimate the potential advantages of the fuel switching concept. Moreover, the optimal timing of switching is derived, to ensure increasing yields of an average-capacity power-plant. The results of the research indicate significant financial benefits anticipated in most scenarios from applying fuel switching, compared to single-fuelled electricity generation units. Security of fuel supply and enhanced flexibility may also be offered to the power plant since more than one technology and fuels may be engaged

High-power electro-optic switch technology based on novel transparent ceramic

Science.gov (United States)

Xue-Jiao, Zhang; Qing, Ye; Rong-Hui, Qu; Hai-wen, Cai

2016-03-01

A novel high-power polarization-independent electro-optic switch technology based on a reciprocal structure Sagnac interferometer and a transparent quadratic electro-optic ceramic is proposed and analyzed theoretically and experimentally. The electro-optic ceramic is used as a phase retarder for the clockwise and counter-clockwise polarized light, and their polarization directions are adjusted to their orthogonal positions by using two half-wave plates. The output light then becomes polarization-independent with respect to the polarization direction of the input light. The switch characteristics, including splitter ratios and polarization states, are theoretically analyzed and simulated in detail by the matrix multiplication method. An experimental setup is built to verify the analysis and experimental results. A new component ceramic is used and a non-polarizing cube beam splitter (NPBS) replaces the beam splitter (BS) to lower the ON/OFF voltage to 305 V and improve the extinction ratio by 2 dB. Finally, the laser-induced damage threshold for the proposed switch is measured and discussed. It is believed that potential applications of this novel polarization-independent electro-optic switch technology will be wide, especially for ultrafast high-power laser systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61137004, 61405218, and 61535014).

Design study of beam dynamics issues for 1 TeV next linear collider based upon the relativistic-klystron two-beam accelerator

International Nuclear Information System (INIS)

Li, H.; Goffeney, N.; Henestroza, E.; Sessler, A.; Yu, S.; Houck, T.; Westenskow, G.

1994-11-01

A design study has recently been conducted for exploring the feasibility of a relativistic-klystron two-beam accelerator (RK-TBA) system as a rf power source for a 1 TeV linear collider. The author present, in this paper, the beam dynamics part of this study. They have achieved in their design study acceptable transverse and longitudinal beam stability properties for the resulting high efficiency and low cost RK-TBA

The Impact of Power Switching Devices on the Thermal Performance of a 10 MW Wind Power NPC Converter

DEFF Research Database (Denmark)

Ma, Ke; Blaabjerg, Frede

2012-01-01

Power semiconductor switching devices play an important role in the performance of high power wind energy generation systems. The state-of-the-art device choices in the wind power application as reported in the industry include IGBT modules, IGBT press-pack and IGCT press-pack. Because...

Proposed high voltage power supply for the ITER relevant lower hybrid current drive system

International Nuclear Information System (INIS)

Sharma, P.K.; Kazarian, F.; Garibaldi, P.; Gassman, T.; Artaud, J.F.; Bae, Y.S.; Belo, J.; Berger-By, G.; Bernard, J.M.; Cara, Ph.; Cardinali, A.; Castaldo, C.; Ceccuzzi, S.; Cesario, R.; Decker, J.; Delpech, L.; Ekedahl, A.; Garcia, J.; Goniche, M.; Guilhem, D.

2011-01-01

In the framework of the EFDA task HCD-08-03-01, the ITER lower hybrid current drive (LHCD) system design has been reviewed. The system aims to generate 24 MW of RF power at 5 GHz, of which 20 MW would be coupled to the plasmas. The present state of the art does not allow envisaging a unitary output of the klystrons exceeding 500 kW, so the project is based on 48 klystron units, leaving some margin when the transmission lines losses are taken into account. A high voltage power supply (HVPS), required to operate the klystrons, is proposed. A single HVPS would be used to feed and operate four klystrons in parallel configuration. Based on the above considerations, it is proposed to design and develop twelve HVPS, based on pulse step modulator (PSM) technology, each rated for 90 kV/90 A. This paper describes in details, the typical electrical requirements and the conceptual design of the proposed HVPS for the ITER LHCD system.

Minimizing Crosstalk in Self Oscillating Switch Mode Audio Power Amplifiers

DEFF Research Database (Denmark)

Knott, Arnold; Ploug, Rasmus Overgaard

2012-01-01

a method to minimize this phenomenon by improving the integrity of the various power distribution systems of the amplifier. The method is then applied to an amplifier built for this investigation. The results show that the crosstalk is suppressed with 30 dB, but is not entirely eliminated......The varying switching frequencies of self oscillating switch mode audio amplifiers have been known to cause interchannel intermodulation disturbances in multi channel configurations. This crosstalk phenomenon has a negative impact on the audio performance. The goal of this paper is to present...

Modernization of the Electric Power Systems (transformers, rods and switches) in the Laguna Verde Nuclear Power Plant (Mexico)

International Nuclear Information System (INIS)

Gonzalez Solarzano, J. J.; Gabaldon Martin, M. A.; Pallisa Nunez, J.; Florez Ordeonez, A.; Fernandez Corbeira, A.; Prieto Diez, I.

2010-01-01

Description of the changes made in the Electric Power Systems as a part of the power increase project in the Laguna Verde Nuclear Power Plant (Mexico). The main electrical changes to make, besides the turbo group, are the main generation transformers, the isolated rods and the generation switch.

Development of high power X-band semiconductor microwave switch for pulse compression systems of future linear colliders

Directory of Open Access Journals (Sweden)

Fumihiko Tamura

2002-06-01

Full Text Available We describe concepts for high power semiconductor rf switches, designed to handle signals at X-band with power level near 100 MW. We describe an abstract design methodology and derive a general scaling law for these switches. We also present a design and experimental work of a switch operating at the TE_{01} mode in overmoded circular waveguides. The switch is composed of an array of tee junction elements that have a p-i-n diode array window in the third arm.

High-power continuous wave and passively Q-switched laser operations of a Nd:GGG crystal

International Nuclear Information System (INIS)

Qin, L J; Tang, D Y; Xie, G Q; Dong, C M; Jia, Z T; Tao, X T

2008-01-01

We report on the continuous wave (CW) and passive Q-switching performance of a high-power diode-pumped Nd:GGG laser. A CW output power of 7.20 W was obtained under an absorbed pump power of 14.97 W, which gives a slop efficiency of 52.7%. With a Cr 4+ doped yttrium aluminum garnet crystal as the saturable absorber, the shortest passively Q-switched pulse width, largest pulse energy, and highest peak power achieved were 7.7 ns, 126.25 μJ, and 15.5 kW, respectively

A High-Voltage Low-Power Switched-Capacitor DC-DC Converter Based on GaN and SiC Devices for LED Drivers

DEFF Research Database (Denmark)

Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

2018-01-01

Previous research on switched-capacitor DC-DC converters has focused on low-voltage and/or high-power ranges where the efficiencies are dominated by conduction loss. Switched-capacitor DC-DC converters at high-voltage (> 100 V) low-power (high efficiency and high power density...... are anticipated to emerge. This paper presents a switched-capacitor converter with an input voltage up to 380 V (compatible with rectified European mains) and a maximum output power of 10 W. GaN switches and SiC diodes are analytically compared and actively combined to properly address the challenges at high......-voltage low-current levels, where switching loss becomes significant. Further trade-off between conduction loss and switching loss is experimentally optimized with switching frequencies. Three variant designs of the proposed converter are implemented, and the trade-off between the efficiency and the power...

Design of Jet lower hybrid current drive generator and operation of high power test bed

International Nuclear Information System (INIS)

Dobbing, J.A.; Bosia, G.; Brandon, M.; Gammelin, M.; Gormezano, C.; Jacquinot, J.; Jessop, G.; Lennholm, M.; Pain, M.; Sibley, A.

1989-01-01

The JET Lower Hybrid Current Drive (LHCD) generator consists of 24 klystrons each rated for 650 KW operating at 3.7 GHz, giving a nominal generator power of 15.6 MW for 10 seconds or 12 MW for 20 seconds. This power will be transmitted through 24 waveguides to a phased array launcher on one of the main ports of the JET machine. In addition, two klystrons are currently being operated on a high power test bed to establish reliable operation of the generators components and test high power microwave components prior to their installation

Performance of RF power and phase control on JT-60 LHRF heating system

International Nuclear Information System (INIS)

Fujii, T.; Ikeda, Y.; Imai, T.; Honda, M.; Kiyono, K.; Maebara, S.; Saigusa, M.; Sakamoto, K.; Sawahata, M.; Seki, M.

1987-01-01

The performance of RF power and phase control on the JT-60 LHRFD heating system are presented. The JT-60 LHRF heating system has three units of huge RF source with a total output of 24 MW, each unit consisting of eight amplifier chains. A high power klystron generating 1 MW for 10 s at 2 GHz is used in each chain. Automatic gain control is employed to regulate the output power not only against gain fluctuations in the chain but also against the unstable plasma load without any output circulator for the klystron

The RF power system for the SNS linac

International Nuclear Information System (INIS)

Tallerico, P.J.; Reass, W.A.

1998-01-01

The initial goal of the SNS project is to produce a 1 MW average beam of protons with short pulse lengths onto a neutron-producing target. The objective of the SNS RF system is to generate 117 MW peak of pulsed 805 MHz microwave power with an accelerated beam pulse length of 1.04 ms at a 60 Hz repetition rate. The power system must be upgradeable in peak power to deliver 2 MW average power to the neutron target. The RF system also requires about 3 MW peak of RF power at 402.5 MHz, but that system is not discussed here. The design challenge is to produce an RF system at minimum cost, that is very reliable and economical to operate. The combination of long pulses and high repetition rates make conventional solutions, such as the pulse transformer and transmission line method, very expensive. The klystron, with a modulating anode, and 1.5 MW of peak output power is the baseline RF amplifier, an 56 are required in the baseline design. The authors discuss four power system configurations that are the candidates for the design. The baseline design is a floating-deck modulating anode system. A second power system being investigated is the fast-pulsed power supply, that can be turned on and off with a rise time of under 0.1 ms. This could eliminate the need for a modulator, and drastically reduce the energy storage requirements. A third idea is to use a pulse transformer with a series IGBT switch and a bouncer circuit on the primary side, as was done for the TESLA modulator. A fourth method is to use a series IGBT switch at high voltage, and not use a pulse transformer. The authors discuss the advantages and problems of these four types of power systems, but they emphasize the first two

Energy reversible switching from amorphous metal based nanoelectromechanical switch

KAUST Repository

Mayet, Abdulilah M.; Smith, Casey; Hussain, Muhammad Mustafa

2013-01-01

We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young's modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young's modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

Energy reversible switching from amorphous metal based nanoelectromechanical switch

KAUST Repository

Mayet, Abdulilah M.

2013-08-01

We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young\\'s modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young\\'s modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

Long-Term Reliability of a Hard-Switched Boost Power Processing Unit Utilizing SiC Power MOSFETs

Science.gov (United States)

Ikpe, Stanley A.; Lauenstein, Jean-Marie; Carr, Gregory A.; Hunter, Don; Ludwig, Lawrence L.; Wood, William; Iannello, Christopher J.; Del Castillo, Linda Y.; Fitzpatrick, Fred D.; Mojarradi, Mohammad M.;

Performance and modelling of 70kVdc power supply with solid-state crowbar

International Nuclear Information System (INIS)

Yellamraju, Sham Sunder Srinivas; Kulkarni, Sanjay V.

2013-01-01

The experimental activities of tokamak research involve development of high power RF and microwave sources for fusion related heating and current drive applications. High power RF and microwave tubes like Klystron, Gyrotron and Tetrode are in general operated with high voltage DC power supplies. These HVDC power supplies of the order of 70 kVdc, must be equipped with necessary arc fault protection in addition to general over current and over voltage protection. The arc fault protection must act within few microseconds to prevent permanent damage to the RF tube, window, etc. When an arc fault is detected, output voltage of the DC power supply is short circuited using a crowbar device (generally Ignitron, Thyratron, thyristor, rail-gap, etc.) that operates in few microseconds. This diverts the fault current from the load to crowbar device, thereby protecting the load. This is necessary as conventional protection in the power supply input takes ∼100 ms to switch-off. The crowbar device must be able to take the fault current till the circuit breaker placed at power supply input is switched off. The arc fault protection is tested for its effectiveness by “wire-burn” test. Full power short circuit of ∼1.5 MW DC power supply puts enormous stress on the power supply, utility and the crowbar, therefore frequent wire-burn testing is to be avoided. This report presents simulation of wire-burn test using PSIM software. Optimization of the component values without conducting actual wire-burn test could be achieved

Performance and modelling of 70kVdc power supply with solid-state crowbar

Energy Technology Data Exchange (ETDEWEB)

Yellamraju, Sham Sunder Srinivas, E-mail: ysssrinivas@gmail.com [Institute for Plasma Research, BHAT, Gandhinagar 382428 (India); Kulkarni, Sanjay V. [Institute for Plasma Research, BHAT, Gandhinagar 382428 (India)

2013-10-15

The experimental activities of tokamak research involve development of high power RF and microwave sources for fusion related heating and current drive applications. High power RF and microwave tubes like Klystron, Gyrotron and Tetrode are in general operated with high voltage DC power supplies. These HVDC power supplies of the order of 70 kVdc, must be equipped with necessary arc fault protection in addition to general over current and over voltage protection. The arc fault protection must act within few microseconds to prevent permanent damage to the RF tube, window, etc. When an arc fault is detected, output voltage of the DC power supply is short circuited using a crowbar device (generally Ignitron, Thyratron, thyristor, rail-gap, etc.) that operates in few microseconds. This diverts the fault current from the load to crowbar device, thereby protecting the load. This is necessary as conventional protection in the power supply input takes ∼100 ms to switch-off. The crowbar device must be able to take the fault current till the circuit breaker placed at power supply input is switched off. The arc fault protection is tested for its effectiveness by “wire-burn” test. Full power short circuit of ∼1.5 MW DC power supply puts enormous stress on the power supply, utility and the crowbar, therefore frequent wire-burn testing is to be avoided. This report presents simulation of wire-burn test using PSIM software. Optimization of the component values without conducting actual wire-burn test could be achieved.

Field-Distortion Air-Insulated Switches for Next-Generation Pulsed-Power Accelerators

Energy Technology Data Exchange (ETDEWEB)

Wisher, Matthew Louis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Johns, Owen M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Breden, Eric Wayne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Calhoun, Jacob Daniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gruner, Frederick Rusticus [Kinetech LLC, Cedar Crest, NM (United States); Hohlfelder, Robert James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mulville, Thomas D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Muron, David J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stoltzfus, Brian S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stygar, William A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-09-01

We have developed two advanced designs of a field-distortion air-insulated spark-gap switch that reduce the size of a linear-transformer-driver (LTD) brick. Both designs operate at 200 kV and a peak current of ~50 kA. At these parameters, both achieve a jitter of less than 2 ns and a prefire rate of ~0.1% over 5000 shots. We have reduced the number of switch parts and assembly steps, which has resulted in a more uniform, design-driven assembly process. We will characterize the performance of tungsten-copper and graphite electrodes, and two different electrode geometries. The new switch designs will substantially improve the electrical and operational performance of next-generation pulsed-power accelerators.

Low-field permanent magnet quadrupoles in a new relativistic-klystron two-beam accelerator design

Energy Technology Data Exchange (ETDEWEB)

Yu, S.; Sessler, A. [Lawrence Berkeley Lab., CA (United States)

1995-02-01

Permanent magnets play a central role in the new relativistic klystron two-beam-accelerator design. The two key goals of this new design, low cost and the suppression of beam break-up instability are both intimately tied to the permanent magnet quadrupole focusing system. A recently completed systems study by a joint LBL-LLNL team concludes that a power source for a 1 TeV center-of-mass Next Linear Collider based on the new TBA design can be as low as $1 billion, and the efficiency (wall plug to rf) is estimated to be 36%. End-to-end simulations of longitudinal and transverse beam dynamics show that the drive beam is stable over the entire TBA unit.

Improvement of out-of-band Behaviour in Switch-Mode Amplifiers and Power Supplies by their Modulation Topology

DEFF Research Database (Denmark)

Knott, Arnold

2010-01-01

Switch-mode power electronics is disturbing other electronic circuits by emission of electromagnetic waves and signals. To allow transmission of information, a set of regulatory rules (electromagnetic compatibility (EMC)) were created to limit this disturbance. To fulfill those rules in power...... electronics, shielding and filtering is required, which is limiting the size reduction. The motivation for this project was to find alternative ways to avoid trouble with interference of switch-mode power electronics and transmission and receiver circuits. An especial focus is given to audio power amplifiers....... After a historical overview and description of interaction between power electronics and electromagnetic compatibility (chapter 1), the thesis will first show the impact of the high frequency signals on the audio performance of switch-mode audio power amplifiers (chapter 2). Therefore the work of others...

Nanosecond high-power dense microplasma switch for visible light

Energy Technology Data Exchange (ETDEWEB)

Bataller, A., E-mail: bataller@physics.ucla.edu; Koulakis, J.; Pree, S.; Putterman, S. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States)

2014-12-01

Spark discharges in high-pressure gas are known to emit a broadband spectrum during the first 10 s of nanoseconds. We present calibrated spectra of high-pressure discharges in xenon and show that the resulting plasma is optically thick. Laser transmission data show that such a body is opaque to visible light, as expected from Kirchoff's law of thermal radiation. Nanosecond framing images of the spark absorbing high-power laser light are presented. The sparks are ideal candidates for nanosecond, high-power laser switches.

Gate Driver Circuit of Power Electronic Switches with Reduced Number of Isolated DC/DC Converter for a Switched Reluctance Motor

International Nuclear Information System (INIS)

Memon, A.A.

2013-01-01

This paper presents a gate driver circuit for the switching devices used in the asymmetrical converter for a switched reluctance machine with reduced number of isolated dc/dc converters. Isolation required in the gate driver circuit of switching devices is indispensable. For the purpose of isolation different arrangements may be used such as pulse transformers. The dc/dc converter for isolation and powering the gate drive circuits is suitable, cheaper in cost and simple to implement. It is also significant that required number of isolation converters is much less than the switches used in converter. In addition, a simple logic circuit has been presented for producing the gate signals at correct phase sequence which is compared with the gated signals directly obtained from the encoder of an existing machine. (author)

Experimental demonstration of a Ku-band radial-line relativistic klystron oscillator based on transition radiation

Science.gov (United States)

Dang, Fangchao; Zhang, Xiaoping; Zhang, Jun; Ju, Jinchuan; Zhong, Huihuang

2017-03-01

We report on a radial-line relativistic klystron oscillator (RL-RKO), which is physically designed to generate gigawatt-level high power microwaves (HPMs) at Ku-band. The 3π/4 mode of a four-gap buncher is selected to highly modulate the radially propagating intense relativistic electron beam (IREB). A three-gap extractor operating at the π mode is employed to extract the radio-frequency energy efficiently. The Ku-band RL-RKO is investigated experimentally on an intense-current electron beam accelerator. The radially propagating IREB is well focused with an axial-width of 2 mm by a radial magnetic field of 0.4 T. Microwaves with a frequency of 14.86 GHz and a power of 1.5 GW are generated, corresponding to an efficiency of 24%, which indicates a significant advance for the research of radial-line HPM sources.

Pseudospark switches (PSS) for pulsed power applications

Energy Technology Data Exchange (ETDEWEB)

Heine, F; Prucker, U; Frank, K; Goertler, A; Schwandner, A; Tkotz, R; Hoffmann, D H.H.; Christiansen, J [Univ. of Erlangen (Germany). Physics Dept. I

1997-12-31

Based on the pseudospark discharge, a low pressure gas discharge in a special geometry, fast closing switches for different pulsed power applications have been designed. Medium power PSS ({<=} 30 kA peak current) were used in laser circuits whereas high current PSS are tested successfully in high current pulsed power applications ({<=} 200 kA). For currents of a few kA the discharge is supported by cathode spots on the cold cathode surface. For higher currents, anode activity is observed too. Inserting semiconductor material seems not only to suppress high erosive spot formation but to support diffuse large-area electrode emission. A different approach to solving the problem of lowering the erosion rate is the multichannel PSS (MUPS). In order to distribute the discharge current to more than one single channel, three or more discharge channels are radial or coaxial arranged. With regard to high voltage applications the maximum hold-off voltage was increased by adding an intermediate electrode. (author). 1 figs., 12 refs.

Pseudospark switches

International Nuclear Information System (INIS)

Billault, P.; Riege, H.; Gulik, M. van; Boggasch, E.; Frank, K.

1987-01-01

The pseudospark discharge is bound to a geometrical structure which is particularly well suited for switching high currents and voltages at high power levels. This type of discharge offers the potential for improvement in essentially all areas of switching operation: peak current and current density, current rise, stand-off voltage, reverse current capability, cathode life, and forward drop. The first pseudospark switch was built at CERN at 1981. Since then, the basic switching characteristics of pseudospark chambers have been studied in detail. The main feature of a pseudospark switch is the confinement of the discharge plasma to the device axis. The current transition to the hollow electrodes is spread over a rather large surface area. Another essential feature is the easy and precise triggering of the pseudospark switch from the interior of the hollow electrodes, relatively far from the main discharge gap. Nanosecond delay and jitter values can be achieved with trigger energies of less than 0.1 mJ, although cathode heating is not required. Pseudospark gaps may cover a wide range of high-voltage, high-current, and high-pulse-power switching at repetition rates of many kilohertz. This report reviews the basic researh on pseudospark switches which has been going on at CERN. So far, applications have been developed in the range of thyratron-like medium-power switches at typically 20 to 40 kV and 0.5 to 10 kA. High-current pseudospark switches have been built for a high-power 20 kJ pulse generator which is being used for long-term tests of plasma lenses developed for the future CERN Antiproton Collector (ACOL). The high-current switches have operated for several hundred thousand shots, with 20 to 50 ns jitter at 16 kV charging voltage and more than 100 kA peak current amplitude. (orig.)

Mobile medium-voltage switching system. Temporary standby power supply in record time; Mobile Mittelspannungsschaltanlage. Vorlaeufige Wiederversorgung in Rekordzeit

Energy Technology Data Exchange (ETDEWEB)

Thiery, Matthias; Schwarz, Stefan [Siemens AG, Mannheim (Germany); Wingerter, Dieter [BASF SE, Ludwigshafen (Germany); Doering, Holger [B. Goebel und Sohn GmbH, Asschaffenburg (Germany). Fahrzeugbau

2011-02-28

BASF SE Ludwigshafen operates more than 100 medium-voltage switching stations for power supply to its plants. The complexity of the production plants and production method make it necessary to have immediate standby power supply in case of interruption of a medium-voltage switching station. For this purpose, a transportable emergency container was acquired that contains a medium-voltage switching system. Power can be supplied at very short notice, simply by plugging the necessary cable connections. No cranes or other tools are required for installation. The emergency container is designed for use at varying voltage levels and can be transported by road to other BASF sites in Europe. The switching station is a gas-insulated medium-voltage switching station 8DA10 by Siemens, designed for operating voltages of 6, 10, 20, and 35 kW.

Recent Upgrade of the Klystron Modulator at SLAC

International Nuclear Information System (INIS)

Nguyen, M.N.; Burkhart, C.P.; Lam, B.K.; Morris, B.

2011-01-01

The SLAC National Accelerator Laboratory employs 244 klystron modulators on its two-mile-long linear accelerator that has been operational since the early days of the SLAC establishment in the sixties. Each of these original modulators was designed to provide 250 kV, 262 A and 3.5 μS at up to 360 pps using an inductance-capacitance resonant charging system, a modified type-E pulse-forming network (PFN), and a pulse transformer. The modulator internal control comprised of large step-start resistor-contactors, vacuum-tube amplifiers, and 120 Vac relays for logical signals. A major, power-component-only upgrade, which began in 1983 to accommodate the required beam energy of the SLAC Linear Collider (SLC) project, raised the modulator peak output capacity to 360 kV, 420 A and 5.0 μS at a reduced pulse repetition rate of 120 pps. In an effort to improve safety, performance, reliability and maintainability of the modulator, this recent upgrade focuses on the remaining three-phase AC power input and modulator controls. The upgrade includes the utilization of primary SCR phase control rectifiers, integrated fault protection and voltage regulation circuitries, and programmable logic controllers (PLC) -- with an emphasis on component physical layouts for safety and maintainability concerns. In this paper, we will describe the design and implementation of each upgraded component in the modulator control system. We will also report the testing and present status of the modified modulators.

6.1-MV, 0.79-MA laser-triggered gas switch for multimodule, multiterawatt pulsed-power accelerators

Directory of Open Access Journals (Sweden)

K. R. LeChien

2010-03-01

Full Text Available A 6.1-MV, 0.79-MA laser-triggered gas switch (LTGS is used to synchronize the 36 modules of the Z machine at Sandia National Laboratories. Each module includes one switch, which serves as the last command-fired switch of the module, and hence is used to determine the time at which each module electrically closes relative to the other modules. The switch is ∼81-cm in length, ∼45-cm in diameter, and is immersed in mineral oil. The outer switch envelope consists of six corrugated monomer-cast acrylic insulators and five contoured stainless-steel rings. The trigger electrodes are fabricated from copper-infused tungsten. The switch is pressurized with several atmospheres of sulfur hexafluoride (SF_{6}, which is turbulently purged within 2 seconds after every shot. Each switch is powered from a 6-MV, 0.78-MJ Marx generator which pulse charges a 24-nF intermediate-store water capacitor in 1.4-μs. Closure of the switch allows power to flow into pulse-forming transmission lines. The power pulse is subsequently compressed by water switches, which results in a total accelerator output power in excess of 70-TW. A previous version of the LTGS performed exceptionally at a 5.4-MV, 0.7-MA level on an engineering test module used for switch development. It exhibited a 1-σ jitter of ∼5  ns, a prefire and flashover rate less than 0.1%, and a lifetime in excess of 150 shots. When installed on the Z accelerator, however, the switch exhibited a prefire probability of ∼3%, a flashover probability of ∼7%, and a 15-ns jitter. The difference in performance is attributed to several factors such as higher total charge transfer, exposure to more debris, and more stressful dynamic mechanical loading upon machine discharge. Under these conditions, the replacement lifetime was less than ten shots. Since refurbishment of Z in October 2007, there have been three LTGS design iterations to improve the performance at 6.1-MV. The most recent design exhibits a

High average power 1314 nm Nd:YLF laser, passively Q-switched with V:YAG

CSIR Research Space (South Africa)

Botha, RC

2013-03-01

Full Text Available A 1314 nm Nd:YLF laser was designed and operated both CW and passively Q-switched. Maximum CW output of 10.4 W resulted from 45.2 Wof incident pump power. Passive Q-switching was obtained by inserting a V:YAG saturable absorber in the cavity...

Thread selection according to predefined power characteristics during context switching on compute nodes

Science.gov (United States)

None, None

2013-06-04

Methods, apparatus, and products are disclosed for thread selection during context switching on a plurality of compute nodes that includes: executing, by a compute node, an application using a plurality of threads of execution, including executing one or more of the threads of execution; selecting, by the compute node from a plurality of available threads of execution for the application, a next thread of execution in dependence upon power characteristics for each of the available threads; determining, by the compute node, whether criteria for a thread context switch are satisfied; and performing, by the compute node, the thread context switch if the criteria for a thread context switch are satisfied, including executing the next thread of execution.

Packet-switched data communication system of the Paks Nuclear Power Plant, Hungary

International Nuclear Information System (INIS)

Szuegyi, M.

1991-01-01

Data communication systems are inherent components of the computer network of nuclear power plants. In the PNPP, Hungary, a new packet-switched network has been installed, based on the X25 protocol. It was developed in the framework of the Information Infrastructure Development project of the country. The most important system and software components of the new packet-switched communication system and computer network installed at PNPP are described. (R.P.) 4 refs.; 1 fig

Improved Switching Characteristics of Fast Power MOSFETs Applying Solder Bump Technology

Directory of Open Access Journals (Sweden)

Sibylle Dieckerhoff

2008-01-01

Full Text Available The impact of a reduced package stray inductance on the switching performance of fast power MOSFETs is discussed applying advanced 3D packaging technologies. Starting from an overview over new packaging approaches, a solder bump technology using a flexible PI substrate is exemplarily chosen for the evaluation. Measurement techniques to determine the stray inductance are discussed and compared with a numerical solution based on the PEEC method. Experimental results show the improvement of the voltage utilization while there is only a slight impact on total switching losses.

Design and RF test result of High Power Hybrid Combiner for Helicon Wave Current Drive in KSTAR Plasmas

Energy Technology Data Exchange (ETDEWEB)

Park, S. Y.; Kim, H. J.; Wi, H. H.; Wang, S. J.; Kwak, J. G. [NFRI, Daejeon (Korea, Republic of)

2016-05-15

200 kW RF power will be injected to plasmas through the traveling wave antenna after combining four klystrons output powers using three hybrid combiners. Each klystron produces 60 kW output at the frequency of 500 MHz. RF power combiners commonly used to divide or combine output powers for various rf and microwave applications. It is divided into several types according to the design type such as Wilkinson combiner, radial and quadrature hybrid combiner. We designed high power hybrid combiners using 6-1/8 inch coaxial line. The power combiner has many advantages such as high isolation, low insertion loss and high power handling capability. In this paper design and rf test results of high power combiners will be described. High power combiners using three coaxial hybrid couplers will be utilized for effectively combining of 500 MHz, 200 kW output powers generated by four klystrons. We have designed, fabricated, and tested a 6-1/8 inch coaxial hybrid combiners at 500 MHz for efficiently off-axis Helicon wave current drive in KSTAR. Simulation and test results of high power coaxial hybrid combiners are good agreement.

Design of a Ku band miniature multiple beam klystron

Energy Technology Data Exchange (ETDEWEB)

Bandyopadhyay, Ayan Kumar, E-mail: ayan.bandyopadhyay@gmail.com; Pal, Debasish; Kant, Deepender [Microwave Tubes Division, CSIR-CEERI, Pilani, Rajasthan-333031 (India); Saini, Anil; Saha, Sukalyan; Joshi, Lalit Mohan

2016-03-09

The design of a miniature multiple beam klystron (MBK) working in the Ku-band frequency range is presented in this article. Starting from the main design parameters, design of the electron gun, the input and output couplers and radio frequency section (RF-section) are presented. The design methodology using state of the art commercial electromagnetic design tools, analytical formulae as well as noncommercial design tools are briefly presented in this article.

A Survey on Modeling and Simulation of MEMS Switches and Its Application in Power Gating Techniques

OpenAIRE

Pramod Kumar M.P; A.S. Augustine Fletcher

2014-01-01

Large numbers of techniques have been developed to reduce the leakage power, including supply voltage scaling, varying threshold voltages, smaller logic banks, etc. Power gating is a technique which is used to reduce the static power when the sleep transistor is in off condition. Micro Electro mechanical System (MEMS) switches have properties that are very close to an ideal switch, with infinite off-resistance due to an air gap and low on-resistance due to the ohmic metal to m...

Electron cyclotron heating/current-drive system using high power tubes for QUEST spherical tokamak

Science.gov (United States)

Onchi, Takumi; Idei, H.; Hasegawa, M.; Nagata, T.; Kuroda, K.; Hanada, K.; Kariya, T.; Kubo, S.; Tsujimura, T. I.; Kobayashi, S.; Quest Team

2017-10-01

Electron cyclotron heating (ECH) is the primary method to ramp up plasma current non-inductively in QUEST spherical tokamak. A 28 GHz gyrotron is employed for short pulses, where the radio frequency (RF) power is about 300 kW. Current ramp-up efficiency of 0.5 A/W has been obtained with focused beam of the second harmonic X-mode. A quasi-optical polarizer unit has been newly installed to avoid arcing events. For steady-state tokamak operation, 8.56 GHz klystron with power of 200 kW is used as the CW-RF source. The high voltage power supply (54 kV/13 A) for the klystron has been built recently, and initial bench test of the CW-ECH system is starting. The array of insulated-gate bipolar transistor works to quickly cut off the input power for protecting the klystron. This work is supported by JSPS KAKENHI (15H04231), NIFS Collaboration Research program (NIFS13KUTR085, NIFS17KUTR128), and through MEXT funding for young scientists associated with active promotion of national university reforms.

A novel excitation assistance switched reluctance wind power generator

DEFF Research Database (Denmark)

Liu, Xiao; Park, Kiwoo; Chen, Zhe

2014-01-01

The high inductance of a general switched reluctance generator (SRG) may prevent the excitation of the magnetic field from being quickly established enough, which may further limit the output power of the SRG. A novel excitation assistance SRG (EASRG) for wind power generation is proposed...... in this paper to solve the above problem. C-shape stator cores are employed in a modular design concept for quick maintenance or replacement, and a ring-shape excitation assistant coil is sandwiched in the space between the modular stator cores. The magnetization and torque characteristics are simulated by 3-D...

Operational experience with -20 kV, 5 A DC power supply in Indus-2 RF system

International Nuclear Information System (INIS)

Tyagi, R.K.; Tripathi, A.; Upadhyay, R.; Badapanda, M.K.; Lad, M.

2015-01-01

An AC regulator based -20 kV, 5 A DC power supply is employed to bias 60 kW, 505.8 MHz klystron amplifier in Indus-2 RF system. A three terminal triggered spark gap based crowbar along with suitable limiting elements is incorporated at the output of the power supply for protection of sensitive klystron amplifier during load arcing conditions. Wire burn test is carried out on this power supply along with crowbar to ensure that the stored energy dumped into klystron during its arcing is less than 20 Joule. Various protection circuits like over voltage, over current, under voltage, phase failure, thermal overload and transformer oil over temperature protection have been incorporated in this power supply. Preventive maintenance of the power supply is carried out at regular intervals to ensure that it operates satisfactorily during actual operation.This includes checking the breakdown strength of transformer oil, drying of Silica gels in transformer breathers, checking of all electrical connections and cleaning of all high voltage components. The calibration of various meters, checking the setting of various protection-interlock cards and checking the healthiness of crowbar system are also done at regular intervals. During operation, crucial performance parameters of this power supply along with various interlock signals are continuously monitored. Suitable arrangement has been made to operate this supply either in local mode as well as in remote mode. This power supply is operating satisfactorily with klystron amplifier in Indus-2 RF system in round the clock mode for last 15 years and its operational experience are presented in this paper. (author)

Environmental influences contributing to window failure of the SLAC 50 MW klystron

International Nuclear Information System (INIS)

Krienen, F.

1984-03-01

The additional heating of the klystron window is due to the intense x-ray level, produced inside the klystron, illuminating the entrance of the output wave guide. Photo-electric effect, although of low efficiency, produces enough electrons at the right location and right phase to start multipactor, which progresses with increasing intensity towards the window. The intercepted charge and the concomitant x-radiation heat the window, but the heating is not the cause of the breakdown per se. The accumulated charge on the window creates electric stress, which comes in addition to the RF stress. It could therefore be a major cause of electrical breakdown. The coating, which is intended to carry this charge off, should have a relaxation time constant small compared to the pulse duration. Unfortunately the coating can not be made conducting enough because it conflicts with the Joule heating in the RF field

SWITCH MODE PULSE WIDTH MODULATED DC-DC CONVERTER WITH MULTIPLE POWER TRANSFORMERS

DEFF Research Database (Denmark)

2009-01-01

A switch mode pulse width modulated DC-DC power converter comprises at least one first electronic circuit on a input side (1) and a second electronic circuit on a output side (2). The input side (1) and the output side (2) are coupled via at least two power transformers (T1, T2). Each power...... transformer (T1, T2) comprises a first winding (T1a, T2a) arranged in a input side converter stage (3, 4) on the input side (1) and a second winding (T1 b, T2b) arranged in a output side converter stage (5) on the output side (2), and each of the windings (T1a, T1 b, T2a, T2b) has a first end and a second end....... The first electronic circuit comprises terminals (AO, A1) for connecting a source or a load, at least one energy storage inductor (L) coupled in series with at least one of the first windings (T1a, T2a) of the power transformers (T1, T2), and for each power transformer (T1, T2), an arrangement of switches...

Approaches to building single-stage AC/AC conversion switch-mode audio power amplifiers

DEFF Research Database (Denmark)

Ljusev, Petar; Andersen, Michael Andreas E.

2004-01-01

This paper discusses the possible topologies and promising approaches towards direct single-phase AC-AC conversion of the mains voltage for audio applications. When compared to standard Class-D switching audio power amplifiers with a separate power supply, it is expected that direct conversion...

A Hamiltonian viewpoint in the modeling of switching power converters : A systematic modeling procedure of a large class of switching power converters using the Hamiltonian approach

NARCIS (Netherlands)

Escobar, Gerardo; Schaft, Arjan J. van der; Ortega, Romeo

1999-01-01

In this paper we show how, using the Hamiltonian formalism, we can systematically derive mathematical models that describe the behaviour of a large class of switching power converters, including the "Boost", "Buck", "Buck-Boost", "Čuk" and "Flyback" converters. We follow the approach earlier

Characteristics of trap-filled gallium arsenide photoconductive switches used in high gain pulsed power applications

International Nuclear Information System (INIS)

ISLAM, N.E.; SCHAMILOGLU, E.; MAR, ALAN; LOUBRIEL, GUILLERMO M.; ZUTAVERN, FRED J.; JOSHI, R.P.

2000-01-01

The electrical properties of semi-insulating (SI) Gallium Arsenide (GaAs) have been investigated for some time, particularly for its application as a substrate in microelectronics. Of late this material has found a variety of applications other than as an isolation region between devices, or the substrate of an active device. High resistivity SI GaAs is increasingly being used in charged particle detectors and photoconductive semiconductor switches (PCSS). PCSS made from these materials operating in both the linear and non-linear modes have applications such as firing sets, as drivers for lasers, and in high impedance, low current Q-switches or Pockels cells. In the non-linear mode, it has also been used in a system to generate Ultra-Wideband (UWB) High Power Microwaves (HPM). The choice of GaAs over silicon offers the advantage that its material properties allow for fast, repetitive switching action. Furthermore photoconductive switches have advantages over conventional switches such as improved jitter, better impedance matching, compact size, and in some cases, lower laser energy requirement for switching action. The rise time of the PCSS is an important parameter that affects the maximum energy transferred to the load and it depends, in addition to other parameters, on the bias or the average field across the switch. High field operation has been an important goal in PCSS research. Due to surface flashover or premature material breakdown at higher voltages, most PCSS, especially those used in high power operation, need to operate well below the inherent breakdown voltage of the material. The lifetime or the total number of switching operations before breakdown, is another important switch parameter that needs to be considered for operation at high bias conditions. A lifetime of ∼ 10 4 shots has been reported for PCSS's used in UWB-HPM generation [5], while it has exceeded 10 8 shots for electro-optic drivers. Much effort is currently being channeled in the

Evaluation of the contact switch materials in high voltage power supply for generate of underwater shockwave by electrical discharge

Directory of Open Access Journals (Sweden)

K Higa

2016-10-01

Full Text Available We have developed the high voltage power-supply unit by Cockcroft-Walton circuit for ingenerate high pressure due to underwater shockwave by electrical discharge. This high voltage power supply has the problem of the metal contact switch operation that contact switch stop by melting and bonding due to electrical spark. We have studied the evaluation of materials of contact switch for the reducing electrical energy loss and the problem of contact switch operation. In this research, measurement of discharge voltage and high pressure due to underwater shockwave was carried out using the contact switch made of different materials as brass plate, brass-carbon plate-brass and carbon block. The contact switch made of carbon is effective to reduce energy loss and problem of contactor switch operation.

Power adaptation for joint switched diversity and adaptive modulation schemes in spectrum sharing systems

KAUST Repository

Bouida, Zied

2012-09-01

Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using transmit power adaptation, switched transmit diversity, and adaptive modulation in order to improve the performance of existing switching efficient schemes (SES) and bandwidth efficient schemes (BES). Taking advantage of the channel reciprocity principle, we assume that the channel state information (CSI) of the interference link is available to the secondary transmitter. This information is then used by the secondary transmitter to adapt its transmit power, modulation constellation size, and used transmit branch. The goal of this joint adaptation is to minimize the average number of switched branches and the average system delay given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. We analyze the proposed scheme in terms of the average number of branch switching, average delay, and we provide a closed-form expression of the average bit error rate (BER). We demonstrate through numerical examples that the proposed scheme provides a compromise between the SES and the BES schemes. © 2012 IEEE.

Power adaptation for joint switched diversity and adaptive modulation schemes in spectrum sharing systems

KAUST Repository

Bouida, Zied; Tourki, Kamel; Ghrayeb, Ali A.; Qaraqe, Khalid A.; Alouini, Mohamed-Slim

2012-01-01

Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using transmit power adaptation, switched transmit diversity, and adaptive modulation in order to improve the performance of existing switching efficient schemes (SES) and bandwidth efficient schemes (BES). Taking advantage of the channel reciprocity principle, we assume that the channel state information (CSI) of the interference link is available to the secondary transmitter. This information is then used by the secondary transmitter to adapt its transmit power, modulation constellation size, and used transmit branch. The goal of this joint adaptation is to minimize the average number of switched branches and the average system delay given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. We analyze the proposed scheme in terms of the average number of branch switching, average delay, and we provide a closed-form expression of the average bit error rate (BER). We demonstrate through numerical examples that the proposed scheme provides a compromise between the SES and the BES schemes. © 2012 IEEE.

Model measurements for the switched power linac

International Nuclear Information System (INIS)

Aronson, S.; Caspers, F.; Haseroth, H.; Knott, J.; Willis, W.

1987-01-01

To study some aspects of the structure of the switched power linac (or wakefield transformer), a scaled-up model with 2.4 m diameter has been built. Measurements were performed with real-time and synthetic pulses with spectral components up to 5 GHz. Results are obtained for the achievable transformer ratio as a function of the spectral composition of the pulses and for the influence of discrete feeding at the circumference of the transformer disk. The effects of asymmetric feeding in space and time were also investigated experimentally as well as the influence of the central geometry

State-plane analysis of zero-voltage-switching resonant dc/dc power converters

Science.gov (United States)

Kazimierczuk, Marian K.; Morse, William D.

The state-plane analysis technique for the zero-voltage-switching resonant dc/dc power converter family of topologies, namely the buck, boost, buck-boost, and Cuk converters is established. The state plane provides a compression of information that allows the designer to uniquely examine the nonlinear dynamics of resonant converter operation. Utilizing the state plane, resonant converter modes of operation are examined and the switching frequencies are derived for the boundaries between these modes, including the boundary of energy conversion.

The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

Energy Technology Data Exchange (ETDEWEB)

Guo, Jiquan [Stanford Univ., CA (United States)

2008-12-01

In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

Very high plasma switches. Basic plasma physics and switch technology

International Nuclear Information System (INIS)

Doucet, H.J.; Roche, M.; Buzzi, J.M.

1988-01-01

A review of some high power switches recently developed for very high power technology is made with a special attention to the aspects of plasma physics involved in the mechanisms, which determine the limits of the possible switching parameters

Magnetically switched power supply system for lasers

Science.gov (United States)

Pacala, Thomas J. (Inventor)

1987-01-01

A laser power supply system is described in which separate pulses are utilized to avalanche ionize the gas within the laser and then produce a sustained discharge to cause the gas to emit light energy. A pulsed voltage source is used to charge a storage device such as a distributed capacitance. A transmission line or other suitable electrical conductor connects the storage device to the laser. A saturable inductor switch is coupled in the transmission line for containing the energy within the storage device until the voltage level across the storage device reaches a predetermined level, which level is less than that required to avalanche ionize the gas. An avalanche ionization pulse generating circuit is coupled to the laser for generating a high voltage pulse of sufficient amplitude to avalanche ionize the laser gas. Once the laser gas is avalanche ionized, the energy within the storage device is discharged through the saturable inductor switch into the laser to provide the sustained discharge. The avalanche ionization generating circuit may include a separate voltage source which is connected across the laser or may be in the form of a voltage multiplier circuit connected between the storage device and the laser.

Three Phase Six-Switch PWM Buck Rectifier with Power Factor Improvement

DEFF Research Database (Denmark)

Zafar Ullah Khan, M; Mohsin Naveed, M.; Hussain, Dil Muhammad Akbar

2013-01-01

Conventional Phase Controlled Rectifier injects low order current harmonics into the AC mains. Large size filtering components are required to attenuate these harmonics. In this paper, Three Phase Six-Switch PWM Buck Rectifier[1] is presented which operates at nearly unity power factor and provides...

Switch: a planning tool for power systems with large shares of intermittent renewable energy.

Science.gov (United States)

Fripp, Matthias

2012-06-05

Wind and solar power are highly variable, so it is it unclear how large a role they can play in future power systems. This work introduces a new open-source electricity planning model--Switch--that identifies the least-cost strategy for using renewable and conventional generators and transmission in a large power system over a multidecade period. Switch includes an unprecedented amount of spatial and temporal detail, making it possible to address a new type of question about the optimal design and operation of power systems with large amounts of renewable power. A case study of California for 2012-2027 finds that there is no maximum possible penetration of wind and solar power--these resources could potentially be used to reduce emissions 90% or more below 1990 levels without reducing reliability or severely raising the cost of electricity. This work also finds that policies that encourage customers to shift electricity demand to times when renewable power is most abundant (e.g., well-timed charging of electric vehicles) could make it possible to achieve radical emission reductions at moderate costs.

Effects of angular misalignment on optical klystron undulator radiation

Energy Technology Data Exchange (ETDEWEB)

Mishra, G., E-mail: gmishra_dauniv@yahoo.co.in; Prakash, Bramh; Gehlot, Mona

2015-11-21

In this paper ,we analyze the important effects of optical klystron undulator radiation with an angular offset of the relativistic electron beam in the second undulator section. An anlytical expression for the undulator radiation is obtained through a transparent and simple procedure.It is shown that the effects of the angular offset is more severe for longer undulator lengths and with higher dispersive field strengths.Both these effects are less pronounced for undulators with large K values.

New developments in relativistic klystron amplifiers

Energy Technology Data Exchange (ETDEWEB)

Friedman, M; Colombant, D; Fernsler, R; Hubbard, R; Lampe, M; Serlin, V; Slinker, S [Naval Research Lab., Washington, DC (United States). Plasma Physics Div.

1997-12-31

A relativistic klystron amplifier that employed cavities with inductively loaded wide gaps and a novel converter has achieved 50% energy efficiency, a significant advance over the previous state of the art of 20%. The new device was immersed in a 3 kG magnetic field and contained two innovations: (1) Wide gaps which include an inductively loaded return current structure that was opaque to the unmodulated beam space charge but transparent to the RF field. (2) A novel converter that was made of a `leaky` cavity with a radially-converging inductively-loaded structure that was inserted in the output wide-gap. This structure reduced the potential energy residing in the electron beam and maximized RF output energy. (author). 4 figs., 13 refs.

Role of parasitic capacitances in power MOSFET turn-on switching speed limits

DEFF Research Database (Denmark)

Cittanti, Davide; Iannuzzo, Francesco; Hoene, Eckart

2017-01-01

This paper describes the effect of MOSFET internal capacitances on the channel current during the turn-on switching transition: an intrinsic theoretical switching speed limit is found and detailed mathematically. The set of analytical equations is solved and the effect of the displacement currents...... is highlighted with ideal simulated waveforms. A laboratory experiment is thus performed, in order to prove the theoretical predictions: a 25 mΩ SiC CREE power MOSFET is turned on in a no-load condition (zero drain current), starting from different drain-source voltage values. Finally, a LTSpice equivalent...

Direct switching control of DC-DC power electronic converters using hybrid system theory

Energy Technology Data Exchange (ETDEWEB)

Zhao, J.; Lin, F. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wang, C. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wayne State Univ., Detroit, MI (United States). Div. of Engineering Technology

2010-07-01

A direct switching control (DSC) scheme for power electronics converters was described. The system was designed for use in both traditional and renewable energy applications as well as in electric drive vehicles. The proposed control scheme was based on a detailed hybrid system converter model that used model predictive control (MPC), piecewise affine (PWA) approximations and constrained optimal control methods. A DC-DC converter was modelled as a hybrid machine. Switching among different modes of the DC-DC converter were modelled as discrete events controlled by the hybrid controller. The modelling scheme was applied to a Buck converter. The DSC was used to control the switch of the power converter based on a hybrid machine model. Results of the study showed that the method can be used to regulate output voltage and inductor currents. The method also provides fast transient responses and effectively regulates both currents and voltage. The controller can be used to provide immediate responses to dynamic disturbances and output voltage fluctuations. 23 refs., 7 figs.

Push-pull converter with energy saving circuit for protecting switching transistors from peak power stress

Science.gov (United States)

Mclyman, W. T. (Inventor)

1981-01-01

In a push-pull converter, switching transistors are protected from peak power stresses by a separate snubber circuit in parallel with each comprising a capacitor and an inductor in series, and a diode in parallel with the inductor. The diode is connected to conduct current of the same polarity as the base-emitter juction of the transistor so that energy stored in the capacitor while the transistor is switched off, to protect it against peak power stress, discharges through the inductor when the transistor is turned on, and after the capacitor is discharges through the diode. To return this energy to the power supply, or to utilize this energy in some external circuit, the inductor may be replaced by a transformer having its secondary winding connected to the power supply or to the external circuit.

High Power RF Test Facility at the SNS

CERN Document Server

Kang, Yoon W; Campisi, Isidoro E; Champion, Mark; Crofford, Mark; Davis, Kirk; Drury, Michael A; Fuja, Ray E; Gurd, Pamela; Kasemir, Kay-Uwe; McCarthy, Michael P; Powers, Tom; Shajedul Hasan, S M; Stirbet, Mircea; Stout, Daniel; Tang, Johnny Y; Vassioutchenko, Alexandre V; Wezensky, Mark

2005-01-01

RF Test Facility has been completed in the SNS project at ORNL to support test and conditioning operation of RF subsystems and components. The system consists of two transmitters for two klystrons powered by a common high voltage pulsed converter modulator that can provide power to two independent RF systems. The waveguides are configured with WR2100 and WR1150 sizes for presently used frequencies: 402.5 MHz and 805 MHz. Both 402.5 MHz and 805 MHz systems have circulator protected klystrons that can be powered by the modulator capable of delivering 11 MW peak and 1 MW average power. The facility has been equipped with computer control for various RF processing and complete dual frequency operation. More than forty 805 MHz fundamental power couplers for the SNS superconducting linac (SCL) cavitites have been RF conditioned in this facility. The facility provides more than 1000 ft2 floor area for various test setups. The facility also has a shielded cave area that can support high power tests of normal conducti...

Low Capacitive Inductors for Fast Switching Devices in Active Power Factor Correction Applications

DEFF Research Database (Denmark)

Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

2014-01-01

This paper examines different winding strategies for reduced capacitance inductors in active power factor correction circuits (PFC). The effect of the parasitic capacitance is analyzed from an electro magnetic compatibility (EMI) and efficiency point of views. The purpose of this work is to inves......This paper examines different winding strategies for reduced capacitance inductors in active power factor correction circuits (PFC). The effect of the parasitic capacitance is analyzed from an electro magnetic compatibility (EMI) and efficiency point of views. The purpose of this work...... is to investigate different winding approaches and identify suitable solutions for high switching frequency/high speed transition PFC designs. A low parasitic capacitance PCB based inductor design is proposed to address the challenges imposed by high switching frequency PFC Boost converters....

Neutron, gamma ray and post-irradiation thermal annealing effects on power semiconductor switches

Science.gov (United States)

Schwarze, G. E.; Frasca, A. J.

1991-01-01

The effects of neutron and gamma rays on the electrical and switching characteristics of power semiconductor switches must be known and understood by the designer of the power conditioning, control, and transmission subsystem of space nuclear power systems. The SP-100 radiation requirements at 25 m from the nuclear source are a neutron fluence of 10(exp 13) n/sq cm and a gamma dose of 0.5 Mrads. Experimental data showing the effects of neutrons and gamma rays on the performance characteristics of power-type NPN Bipolar Junction Transistors (BJTs), Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), and Static Induction Transistors (SITs) are presented. These three types of devices were tested at radiation levels which met or exceeded the SP-100 requirements. For the SP-100 radiation requirements, the BJTs were found to be most sensitive to neutrons, the MOSFETs were most sensitive to gamma rays, and the SITs were only slightly sensitive to neutrons. Post-irradiation thermal anneals at 300 K and up to 425 K were done on these devices and the effectiveness of these anneals are also discussed.

E-beam high voltage switching power supply

Science.gov (United States)

Shimer, Daniel W.; Lange, Arnold C.

1997-01-01

A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360.degree./n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load.

E-beam high voltage switching power supply

International Nuclear Information System (INIS)

Shimer, D.W.; Lange, A.C.

1997-01-01

A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360 degree/n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load. 7 figs

Characteristics Analysis of an Excitation Assistance Switched Reluctance Wind Power Generator

DEFF Research Database (Denmark)

Liu, Xiao; Wang, Chao; Chen, Zhe

2015-01-01

In order to fully analyze the characteristics of an excitation assistance switched reluctance generator (EASRG) applied in wind power generation, a static model and a dynamic model are proposed. The static model is based on the 3-D finite-element method (FEM), which can be used to obtain the stat...

High-Power Plasma Switch for 11.4 GHz Microwave Pulse Compressor

International Nuclear Information System (INIS)

Hirshfield, Jay L.

2010-01-01

Results obtained in several experiments on active RF pulse compression at X-band using a magnicon as the high-power RF source are presented. In these experiments, microwave energy was stored in high-Q TE01 and TE02 modes of two parallel-fed resonators, and then discharged using switches activated with rapidly fired plasma discharge tubes. Designs and high-power tests of several versions of the compressor are described. In these experiments, coherent pulse superposition was demonstrated at a 5-9 MW level of incident power. The compressed pulses observed had powers of 50-70 MW and durations of 40-70 ns. Peak power gains were measured to be in the range of 7:1-11:1 with efficiency in the range of 50-63%.

Review of pulsed rf power generation

International Nuclear Information System (INIS)

Lavine, T.L.

1992-04-01

I am going to talk about pulsed high-power rf generation for normal-conducting electron and positron linacs suitable for applications to high-energy physics in the Next Linear Collider, or NLC. The talk will cover some basic rf system design issues, klystrons and other microwave power sources, rf pulse-compression devices, and test facilities for system-integration studies

Latching micro optical switch

Science.gov (United States)

Garcia, Ernest J; Polosky, Marc A

2013-05-21

An optical switch reliably maintains its on or off state even when subjected to environments where the switch is bumped or otherwise moved. In addition, the optical switch maintains its on or off state indefinitely without requiring external power. External power is used only to transition the switch from one state to the other. The optical switch is configured with a fixed optical fiber and a movable optical fiber. The movable optical fiber is guided by various actuators in conjunction with a latching mechanism that configure the switch in one position that corresponds to the on state and in another position that corresponds to the off state.

A nonlinear theory of relativistic klystrons connected to a coaxial waveguide

International Nuclear Information System (INIS)

Uhm, H.S.; Hendricks, K.J.; Arman, M.J.; Bowers, L.; Hackett, K.E.; Spencer, T.A.; Coleman, P.D.; Lemke, R.W.

1997-01-01

A self-consistent nonlinear theory of current modulation in an electron beam propagating through relativistic klystrons connected to a coaxial waveguide is developed. A theoretical model of the beam-energy increase Δγ near the extraction cavity is also developed, based on the self-potential depression. The potential depression κ can be significantly reduced in the vicinity of the extraction cavity from its value at the injection point. In appropriate system parameters, the kinetic-energy increase can easily be more than 50 keV, thereby eliminating the possibility of virtual cathode in the extraction cavity. Properties of the current modulation in a klystron are also investigated, assuming that a regular cylindrical waveguide is connected to a coaxial waveguide at the propagation distance z=z 1 . Due to proximity of a grounded conductor, the beam close-quote s potential depression κ in the coaxial region is considerably less than that in the regular region. It is shown in the present analysis that amplitude of the current modulation increases drastically as the coaxial inner-conductor approaches the driving cavity. Moreover, the amplitude of the current modulation in the coaxial region changes slowly in comparison with that in the regular region

High Power Q-Switched Dual-End-Pumped Ho:YAG Laser

Energy Technology Data Exchange (ETDEWEB)

Xiao-Ming, Duan; Ying-Jie, Shen; Tong-Yu, Dai; Bao-Quan, Yao; Wang Yue-Zhu, E-mail: xmduan@hit.edu.cn [National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001 (China)

2012-09-15

We report the high power acousto-optically Q-switched operation of a dual-end-pumped Ho:YAG laser at room temperature. For the Q-swithched mode, a maximum pulse energy of 2.4 mJ and a minimum pulse width of 23 ns at the repetition rate of 10 kHz are achieved, resulting in a peak power of 104.3 kW. The beam quality factor of M{sup 2} {approx} 1.5, which is demonstrated by a knife-edge method. In addition, the Ho:YAG laser is employed as a pumping source of ZGP optical parametric oscillator, and its total average output power is 13.2 W at 3.9 {mu}m and 4.4 {mu}m with a slope efficiency of 68.4%.

Preliminary design of high-power wave-guide/transmission system

Indian Academy of Sciences (India)

... CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window.

Development of High-Speed Switched Reluctance Motor for Electric Power Tools

Science.gov (United States)

Nakamura, Kenji; Kumasaka, Yuya; Ichinokura, Osamu

2017-10-01

This paper presents design and experimental evaluation of a switched reluctance (SR) motor used for electric power tools. First, characteristics of a previous designed 6/4-pole SR motor is shown and compared to a permanent magnet (PM) motor used in present electric power tools. Next, to further improve characteristics, a 12/8-pole SR motor is designed and evaluated in experiment. It is proved that the performance of the prototype 12/8-pole SR motor is almost comparable or superior to the present PM motor.

A Transformer-less Partial Power Boost Converter for PV Applications Using a Three-Level Switching Cell

Energy Technology Data Exchange (ETDEWEB)

Agamy, Mohammed; Harfman-Todorovic, Maja; Elasser, Ahmed; Essakiappan, Somasundaram

2013-03-01

Photovoltaic architectures with distributed power electronics provide many advantages in terms of energy yield as well as system level optimization. As the power level of the solar farm increases it becomes more beneficial to increase the dc collection network voltage, which requires the use of power devices with higher voltage ratings, and thus making the design of efficient, low cost, distributed power converters more challenging. In this paper a simple partial power converter topology is proposed. The topology is implemented using a three-level switching cell, which allows the use of semiconductor devices with lower voltage rating; thus improving design and performance and reducing converter cost. This makes the converters suitable for use for medium to high power applications where dc-link voltages of 600V~1kV may be needed without the need for high voltage devices. Converter operation and experimental results are presented for two partial power circuit variants using three-level switching cells.

Design and analysis of a radio frequency extractor in an S-band relativistic klystron amplifier

Energy Technology Data Exchange (ETDEWEB)

Zhang Zehai; Zhang Jun; Shu Ting; Qi Zumin [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China)

2012-09-15