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Description: An unsynchronized thyratron relaxation oscillator circuit was developed, whose rate is stabilized through the use of a Schmitt discriminator to determine the thyratron firing point. Drift and jitter in the period are less than 0.1% after warmup. (auth)
Date: August 1, 1962
Creator: Cohn, C.E.
Partner: UNT Libraries Government Documents Department


Description: As one of the most critical system for RHIC operation, the beam abort kicker system has to be highly available, reliable, and stable for the entire operating range. Along with the RHIC commission and operation, consistent efforts have been spend to cope with immediate issues as well as inherited design issues. Major design changes have been implemented to achieve the higher operating voltage, longer high voltage hold-off time, fast retriggering and redundant triggering, and improved system protection, etc. Recent system test has demonstrated for the first time that both blue ring and yellow ring beam abort systems have achieved more than 24 hours hold off time at desired operating voltage. In this paper, we report break down, thyratron reverse arcing, and to build a fast re-trigger system to reduce beam spreading in event of premature discharge.
Date: May 12, 2003
Partner: UNT Libraries Government Documents Department

Final report: Efficient thyratron modulator project

Description: The purpose of this program was to examine methods of increasing the efficiency of producing pulses to drive Klystrons in the 150 MW range. This may include 2 Klystrons in the 75 MW range. Specific methods of interest to improve the pulse efficiency were the use of a circuit to add energy to the tail of the pulse, the use of a bipyrimidal transformer, and the use of gas insulation as a means of improving the pulse shape. These methods were investigated using both thyratron and IGBT switching. The low cost designs developed in this work consisted of low voltage designs which don't require the oil immersion. These designs can be ''hot tuned'' based on the use of simple, tunable inductors.
Date: November 26, 1999
Creator: Adler, R. J.; Richter-Sand, R. J. & Gregg, C. W.
Partner: UNT Libraries Government Documents Department


Description: Beam coupling phenomena have been observed in most fast kicker systems through out Brookhaven Collider-Accelerator complex. With ever-higher beam intensity, the signature of the beam becomes increasingly recognizable. The beam coupling at high intensity produced additional heat dissipation in high voltage modulator, thyratron grids, thyratron driver circuit sufficient to damage some components, and causes trigger instability. In this paper, we will present our observations, basic coupling mode analysis, relevance to the magnet structures, issues related to the existing high voltage modulators, and considerations of the future design of the fast kicker systems.
Date: June 18, 2001
Partner: UNT Libraries Government Documents Department

Design Optimization and Construction of the Thyratron/PFN Based Cost Model Modulator for the NLC

Description: As design studies and various R and D efforts continue on Next Linear Collider (NLC) systems, much R and D work is being done on X-Band klystron development, and development of pulse modulators to drive these X-Band klystrons. A workshop on this subject was held at SLAC in June of 1998, and a follow-up workshop is scheduled at SLAC June 23-25, 1999. At the 1998 workshop, several avenues of R and D were proposed using solid state switching, induction LINAC principles, high voltage hard tubes, and a few more esoteric ideas. An optimized version of the conventional thyratron-PFN-pulse transformer modulator for which there is extensive operating experience is also a strong candidate for use in the NLC. Such a modulator is currently under construction for base line demonstration purposes. The performance of this ''Cost Model'' modulator will be compared to other developing technologies. Important parameters including initial capital cost, operating maintenance cost, reliability, maintainability, power efficiency, in addition to the usual operating parameters of pulse flatness, timing and pulse height jitter, etc. will be considered in the choice of a modulator design for the NLC. This paper updates the progress on this ''Cost Model'' modulator design and construction.
Date: March 15, 1999
Creator: Koontz, Roland F
Partner: UNT Libraries Government Documents Department

A gate drive circuit for gate-turn-off (GTO) devices in series stack.

Description: A gate-turn-off (GTO) switch is under development at the Advanced Photon Source as a replacement for a thyratron switch in high power pulsed application. The high voltage in the application requires multiple GTOs connected in series. One component that is critical to the success of GTO operation is the gate drive circuit. The gate drive circuit has to provide fast high-current pulses to the GTO gate for fast turn-on and turn-off. It also has to be able to operate while floating at high voltage. This paper describes a gate drive circuit that meets these requirements.
Date: April 13, 1999
Creator: Despe, O.
Partner: UNT Libraries Government Documents Department


Description: A gas discharge switch EEV HX3002 is being evaluated at Brookhaven National Laboratory as a possible candidate of RHIC Beam Abort Kicker modulator main switch. At higher beam energy and higher beam intensity, the switch stability becomes very crucial. The hollow anode thyratron used in the existing system is not rated for long reverse current conduction. The reverse voltage arcing caused thyratron hold-off voltage de-rating has been the main limitation of the system operation. To improve the system reliability, a new type of gas discharge switch has been suggested by Marconi Applied Technology for its reverse conducting capability.
Date: June 30, 2002
Partner: UNT Libraries Government Documents Department

The Advanced Photon Source linac modulators PSpice simulation and upgrade.

Description: The APS linac modulators provide DC pulses to Thales 35/45-MW klystrons. The modulators are pulse forming network (PFN)-type pulsers with EMI 40-kV switch-mode charging supplies. The PFN consists of two 8-cell lines connected in parallel. EEV CX1836A thyratrons are used as discharge switches. The PSpice simulation of the modulators using OrCAD release 9.1 made it possible to find appropriate parameters of RC circuits that reduce high-frequency ringing of the pulse transformer primary voltage. In order to improve pulse top flatness (originally {+-}3%), new coils were built and installed. The coils allow discrete tuning of pulse waveforms by changing the amount of used turns. The advantage of two parallel-line PFN configurations was also used. An equivalent method using a low-voltage generator was used for PFN fine tuning.
Date: June 28, 2002
Creator: Cours, A. & Smith, T.
Partner: UNT Libraries Government Documents Department


Description: Fast-heating electronic systems are becoming increasingly important in military applications. Operational requirements in the range of 10 to 12 seconds must be accomplished with a combination of tube and circuit design. Definitions of tube and system operational time are numerous and interrelated so that selection of an appropriate test depends on the circuit application, ease of measurement, and test equipment capabilities. Circuit designs which minimize differences among tubes will also minimize drift during warm-up so that a stable operating point is reached more quickly. Properties of the vacuum tube classed as detrimental, such as interelectrode leakages, are more critical in fast operational tubes. Gains in operational time are achieved by: (1) reduction of the heated mass, (2) high cathode activation, and (3) reduction of conduction losses. General design considerations of the heater, cathode, and tube assembly are discussed. Six tube types encompassing subminiatures, miniature, hydrogen thyratron, and power triodes were developed and produced which function at 10 seconds in a fast operational system, tube characteristics are given. (auth)
Date: June 1, 1958
Creator: Hardin, K D
Partner: UNT Libraries Government Documents Department

A hybrid anode reactor for the SLAC modulator

Description: The SLAC modulators operate at 150 MW ak outputs at 120 pps with an average power of 87 kW. In an effect to improve modulator performance and reliability, we describe the design of a hybrid anode reactor using ferrite to decrease the ringing of the output pulse, and incidentally reduce thyratron commutation loss. The design uses MnZn ferrite as a saturable lossy element to decrease the ringing in combination with NiZn ferrite as a saturable reactor for reducing the switching loss. The output ringing is product of the PFN stray capacitance and the leakage inductance of the pulse transformer, and if not suppressed causes premature failures of the output cable. The saturable switch aspect then offers the necessary rise time and pulse width recovery. While these two goals seem contrary, our initial performance objectives were met Ringing on the output pulse is decreased by 50%. Switching loss reduction is measured by a thyratron temperature decrease of 15% as measured on the anode with a cathode reference temperature. The reactor packaging is very simple, and it is separated from the thyratron space so not to complicate thyratron replacement or modulator repairs and maintenance.
Date: June 1, 1994
Creator: Donaldson, A. R.
Partner: UNT Libraries Government Documents Department

High Voltage Pulsar For 184-inch Cyclotron Electric Deflector

Description: This paper describes a high voltage pulse generator developed to deflect the beam of the 184-inch cyclotron at Berkeley, California. The apparatus develops a deflecting potential of 200 kilovolts that rises from 10% to 90% of peak value in 0.1 microseconds. The unit employs two similar 100 kilovolt water cooled pulse transformers connected symmetrically about ground to the electric deflector bars. Water-cooled General Electric pulse capacitors are discharged through the two turn primary windings of the pulse transformers by triggering a battery of 16 paralleled Kuthe 5022 hydrogen thyratrons. Output voltages are developed across the 17 turn secondary winding of the pulse transformer. The transformer is mounted in an oil filled lucite case that provides both insulation and compact design.
Date: April 24, 1948
Creator: Kerns, Q. A.; Baker, W. R.; Edwards, R. F. & Farly, G. M.
Partner: UNT Libraries Government Documents Department


Description: The Muon Collider and Neutrino Factory projects require low frequency rf cavities because the size and emittance of the muon beam is much larger than is usual for electron or proton beams. The range of 30 MHz to 200 MHz is of special interest. However, the size of an accelerator with low frequency will be impractically large if it is simply scaled up from usual designs. In addition, to get very high peak power in this range is difficult. Presented in this paper is an alternative structure that employs a quasi-lumped inductance that can significantly reduce the transverse size while keeping high gradient. Also addressed is a power compression scheme with a thyratron. This gives a possible solution to provide very high peak power.
Date: June 18, 2001
Creator: ZHAO, Y.
Partner: UNT Libraries Government Documents Department


Description: The new conceptual design of full turn fast extraction kicker power supply system of the Spallation Neutron Source main ring will be presented in this paper. In this design, the extraction kicker power modulators will be located outside of the tunnel, as requested by the SNS Project. Its purpose is to minimize the components inside of the synchrotron tunnel. The high voltage modulator will use Blumlein pulser and hollow-anode thyratron structure, a parallel termination resistor and two transmission cables. Main advantages include: flexible system configuration for unipolar single drive or push-pull double drive of the kicker magnets, lower charging voltage, lower beam impedance, lower number of high voltage cables, and large design margin for implementation and future upgrade.
Date: June 18, 2001
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: April 10, 1999
Creator: Schein, Jochen; Xu, Xiaoxi; Qi, Niansheng; Gensler, Steven; Prasad, Rahul & Krishnan, Mahadevan
Partner: UNT Libraries Government Documents Department

Fast SCR Thyratron Driver

Description: As part of an improvement project on the linear accelerator at SLAC, it was necessary to replace the original thyratron trigger generator, which consisted of two chassis, two vacuum tubes, and a small thyratron. All solid-state, fast rise, and high voltage thyratron drivers, therefore, have been developed and built for the 244 klystron modulators. The rack mounted, single chassis driver employs a unique way to control and generate pulses through the use of an asymmetric SCR, a PFN, a fast pulse transformer, and a saturable reactor. The resulting output pulse is 2 kV peak into 50 {Omega} load with pulse duration of 1.5 {mu}s FWHM at 180 Hz. The pulse risetime is less than 40 ns with less than 1 ns jitter. Various techniques are used to protect the SCR from being damaged by high voltage and current transients due to thyratron breakdowns. The end-of-line clipper (EOLC) detection circuit is also integrated into this chassis to interrupt the modulator triggering in the event a high percentage of line reflections occurred.
Date: June 18, 2007
Creator: Nguyen, M.N.
Partner: UNT Libraries Government Documents Department


Description: The design of the RHIC injection systems anticipated the possibility of filling and operating the rings with a 120 bunch pattern, corresponding to 110 bunches after allowing for the abort gap. Beam measurements during the 2002 run confirmed the possibility, although at the expense of severe transverse emittance growth and thus not on an operational basis. An improvement program was initiated with the goal of reducing the kicker rise time from 110 to {approx}95 ns and of minimizing pulse timing jitter and drift. The major components of the injection system are 4 kicker magnets and Blmlein pulsers using thyratron switches. The kicker terminating resistor and operating voltage was increased to reduce the rise time. Timing has been stabilized by using commercial trigger units and extremely stable dc supplies for the thyratron reservoir. A fiber optical connection between control room and the thyratron trigger unit has been provided, thereby allowing the operator to adjust timing individually for each kicker unit. The changes were successfully implemented for use in the RHIC operation.
Date: May 12, 2003
Partner: UNT Libraries Government Documents Department

Analysis of beam loss induced abort kicker instability

Description: Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems and improved stability of the RHIC operation.
Date: May 20, 2012
Creator: W., Zhang; Sandberg, J.; Ahrens, L.; Fischer, W.; Hahn, H.; Mi, J. et al.
Partner: UNT Libraries Government Documents Department

Dual Power Supplies for PEP-II Injection Kickers

Description: Originally the PEP-II injection kickers were powered by one power supply. Since the kicker magnets where not perfectly matched, the stored beam got excited by about 7% of the maximum kicker amplitude. This led to luminosity losses which were especially obvious for trickle injection when the detector is on for data taking. Therefore two independent power supplies with thyratrons in the tunnel next to the kicker magnet were installed. This also reduces the necessary power by about a factor of four since there are no long cables that have to be charged. The kickers are now independently adjustable to eliminate any non-closure of the kicker system and therefore excitation of the stored beam. Setup, commissioning and fine tuning of this system are discussed.
Date: May 25, 2005
Creator: Olszewski, J; Decker, F.-J.; Iverson, R.H.; Kulikov, A.; Pappas, C. & /SLAC
Partner: UNT Libraries Government Documents Department

Evaluation of MOSFETS and IGBTS for Pulsed Power Applications

Description: Single solid-state devices or arrays of solid-state devices are being incorporated into many pulsed power applications as a means of generating fast, high-power, high repetition-rate pulses and ultimately replacing hard tubes and thyratrons. While vendors' data sheets provide a starting point for selecting solid-state devices, most data sheets do not have sufficient information to determine performance in a pulsed application. To obtain this relevant information, MOSFET's and IGBT's from a number of vendors have been tested to determine rise times, fall times and current handling capabilities. The emphasis is on the evaluation of devices that can perform in the range of 100ns pulse widths and the test devices must be capable of switching 1000 volts or greater at a pulsed current of at least 25 amperes. Additionally, some devices were retest with a series magnetic switch to evaluate the effects on switching parameters and specifically rise times. All devices were evaluated under identical conditions and the complete test results are presented.
Date: May 31, 2001
Creator: Hickman, B & Cook, E
Partner: UNT Libraries Government Documents Department


Description: Two beam choppers were constructed which produce an approximately square, 20-ns pulse of 3+-MeV electrons out of the best portion of the 300-ns Astron beam or an 8-{micro}s microwave electron linac beam for injection into the electron-ring accelerator (ERA) compressor. The choppers are impedance-matched traveling-wave devices which deflect the beam with equal strength electric and magnetic forces, and are powered with either three-electrode spark gaps or thyratrons and a 20-ns pulse line. The electron beam is biased out of the beam-transport system with a dc magnetic field, and switched into it with the chopper.
Date: February 7, 1969
Creator: Faltens, Andris & Kerns, Cordon.
Partner: UNT Libraries Government Documents Department