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Present and future technology of high voltage systems for neutral beam injections

Description: This paper presents: (1) A brief review of existing neutral beam (NB) power supply technology for operating up to approximately 200 kV, 65 A; (2) Possibilities for using existing systems for next-generation NB sources, and associated problems; (3) A summary of the features of present systems which contribute to a high degree of complexity and/or cost; (4) A plea and proposal for minimizing cost and complexity of future systems operating up to approximately 300 kV; (5) A few comments pertaining to special problems associated with operating in the 300 to 1000-kV range; and (6) A listing of some specific task areas which we believe should receive early R and D effort.
Date: January 27, 1978
Creator: Baker, W.R. & Hopkins, D.B.
Partner: UNT Libraries Government Documents Department

Neutral beam injector research and development work in the USA

Description: This brief review covers the US neutral-beam-injector research and development work carried out at DOE Laboratories: The Brookhaven National Laboratory (BNL), The Lawrence Berkeley and Livermore Laboratories (LBL/LLL), and The Oak Ridge National Laboratory (ORNL).
Date: January 1, 1978
Creator: Pyle, R.V.; Baker, W.R. & Berkner, K.H.
Partner: UNT Libraries Government Documents Department

Positive ion portion of the LBL/LLL Neutral Beam Program

Description: The positive ion portion of the Neutral Beam Development Program at the Lawrence Berkeley (LBL) and Livermore (LLL) Laboratories has two purposes: (a) to carry out general research and development in a timely way to assure that users' needs can be met in principle, and (b) to carry out specific development for users. To meet the first requirement, we have programs to develop sources capable of producing beams with high (85%) atomic fractions, long pulse lengths (10 sec to DC), and at beam energies up to 150 keV. We are also pursuing the development of on-line computer diagnostics and controls, the sophisticated high-power electronics required by neutral beam systems, and energy recovery. To meet the second requirement, we are developing prototype source modules to meet the requirements of the TMX and MFTF experiments at Lawrence Livermore Laboratory, the TFTR experiment at the Princeton Plasma Physics Laboratory, and the Doublet III experiment at General Atomic Co. The Lawrence Laboratories are also constructing and will demonstrate at LBL a complete prototype neutral injection system for TFTR, and are designing a similar system for Doublet III.
Date: June 1, 1978
Creator: Pyle, R.V.; Baker, W.R. & Anderson, O.A.
Partner: UNT Libraries Government Documents Department

Neutral beam injector research and development work in the USA

Description: We describe neutral beam injector research and development at the Brookhaven National Laboratory, Lawrence Berkeley and Lawrence Livermore Laboratories, and Oak Ridge National Laboratory. All neutral beam systems for present and near-term applications are based on the acceleration and neutralization of positive ions. The research and development is carried out at LBL/LLL and ORNL. Present emphasis at LBL/LLL is on 80 to 120 kV systems for the mirror program and for the TFTR and D III tokamaks. Present emphasis at ORNL is on 40 to 80 kV systems for the PLT, ISX, and PDX, and 80 to 200 kV systems for LPTT and TNS tokamaks. Injectors for the future experiments and reactors may operate at energies of 200 keV or higher, especially for mirror machine applications, where positive-ion-based efficiencies will be very low, assuming no energy recovery. Research on negative-ion-based systems with potentially high efficiencies is carried out at BNL and at LBL/LLL and ORNL. The first demonstration of a high-power neutral beam based on negative ions is planned for 1980.
Date: July 1, 1978
Creator: Pyle, R.V.; Baker, W.R. & Barr, W.L.
Partner: UNT Libraries Government Documents Department

BOUNDARY EFFECTS IN ROTATING-PLASMA EXPERIMENTS

Description: The problem of current continuity and viscous drag at the boundaries in rotating-plasma experiments is discussed. A hypothetical model having a steady state with axial symmetry is emphasized; it is shown that the discharge impedance derived from this model does not agree with many observations. The Homopolar III'' experiment is described in which the flux surfaces were strongly convex and parallel to the toroidal-shaped electrodes. In this way friction at the insulators was reduced. But the structure of the discharge deviated drastically from axial symmetry near the outer surface. Several studies led to the conclusion that the flow pattern probably involved secondary flows. A detailed analysis of this structure was not possible. It was also found that the rotational speed could not be raised above a few cm/ mu sec because the insulators failed in spite of the special design of the experiment. 28 references. (auth)
Date: August 1, 1962
Creator: Kunkel, W.B.; Baker, W.R.; Bratenahl, A. & Halbach, K.
Partner: UNT Libraries Government Documents Department

Power supply for the LBL 40 keV neutral beam source

Description: A 20 keV, 50 Amp, 10 millisec pulse D$sup 0$ Neutral Beam Source at the Lawrence Berkeley Laboratory that serves as the prototype for 12 similar sources now in operation on the 2XIIB Mirror Machine at the Lawrence Livermore Laboratory has been recently upgraded to operate at 40 keV. The system of electronically regulated and controlled power supplies that drive the Source is described. (auth)
Date: November 1, 1975
Creator: Baker, W.R.; Fitzgerald, M.L. & Honey, V.J.
Partner: UNT Libraries Government Documents Department

Long-pulse neutral beam power supply system for LBL 20 kV, 10 A sources

Description: A description is given of the power supplies and control system for the LBL 20 kV, 10 A, 10 sec long-pulse neutral beam source test facility, now in operation. Such sources are used in a number of existing and planned fusion power experiments.
Date: May 1, 1976
Creator: Honey, V. J.; Baker, W. R. & Fitzgerald, M. L.
Partner: UNT Libraries Government Documents Department

Shunt regulator for 150-kV, 20-A, 0. 5-Sec neutral-beam-source power supplies

Description: The Lawrence Berkeley Laboratory (LBL) is now constructing a test facility for the development of neutral beam (NB) sources which will operate up to a level of 150 kV, 20A, 0.5 sec with a 1 percent duty cycle (1). Such sources will provide neutral deuterium beams for injection into large-scale experimental fusion devices. These sources require an accel power supply capable of wide-range variation, voltage regulation of +-1 percent, risetime less than or equal to 20 ..mu..sec, turnoff (crowbar) time of less than or equal to 10 ..mu..sec, repetitive crowbarring and restarting during a 0.5 sec pulse, and low rate of current increase during a short circuit. A shunt regulator system is described which uses existing components and satisfies these requirements with simplicity and relatively low cost.
Date: February 1, 1976
Creator: Hopkins, D. B.; Baker, W. R. & Owren, H. M.
Partner: UNT Libraries Government Documents Department

Effect of capacitive stored energy on neutral-beam-accelerator performance

Description: The results of tests to determine the effects of capacitive stored energy (1/2 CV/sup 2/) on the performance of neutral-beam injectors are reported. Typical fault-current waveforms and methods to limit fault current are presented. Tests indicate that deterioration of performance is not only a function of peak stored energy but is also dependent on peak current and the characteristics of the breakdown.
Date: September 1, 1982
Creator: Owren, H.M.; Baker, W.R.; Berkner, K.H.; Hopkins, D.B. & Massoletti, D.J.
Partner: UNT Libraries Government Documents Department

SCR switched capacitor voltage regulator for 150 kV neutral beam power supply

Description: This paper describes the LBL, MFE Neutral Beam Test Stand III B high voltage regulator system. The regulator is 100% solid state and provides 1% regulation at power levels in excess of 10 MW for 50 msec. Regulation is achieved by switching charged capactors in series with a large main capacitor bank which supplies the bulk of the power.
Date: August 1, 1978
Creator: Milnes, K.A.; Baker, W.R.; Hopkins, D.B. & Owren, H.M.
Partner: UNT Libraries Government Documents Department

Lawrence Berkeley Laboratory power supply system for neutral beam source development

Description: The Lawrence Berkeley Laboratory has developed and constructed a 20-kV, 20-A test facility for the development of multi-megawatt neutral atomic beam sources. This facility has been in service for approximately two years and routinely operated at 120-kV, 20-A, 0.5-sec pulses since April 1977. The accelerator power supply system consists of four 50-kV, 20-A, 0.5-sec power modules which may be connected in a variety of series and parallel combinations. The primaries are controlled with ignitron contractors and induction voltage regulators. The high voltage output is shunt regulated with two DP-15-type triodes connected in parallel. A special varistor plate load is used to limit the anode voltage to 60 kV. High voltage switching is done with series connected silicon controlled rectifiers (SCR's). Solid state power supplies of 15 V dc at 2200 A, and 125 V at 2500 A are provided for the source filament and arc power.
Date: October 1, 1977
Creator: Owren, H.M.; Baker, W.R.; Hopkins, D.B. & Acker, R.C.
Partner: UNT Libraries Government Documents Department

Linear Pinch Work in Berkeley

Description: The following report discusses the data of the Z-field pick-up loop, an effective diagnostic tool introduced to help experiments with the linear pinch.
Date: July 1956
Creator: Anderson, O. A. & Baker, W. R.
Partner: UNT Libraries Government Documents Department

Arc Snubbers Neutral Beam Sources

Description: At LBL it has been observed and verified many times that the amount of 1/2 CV{sup 2} energy associated with the accel grid that a neutral beam source can tolerate under sparkdown conditions is quite limited. If this energy exceeds approximately 5-7 Joules, serious degradation of the voltage holding capability of the source occurs. To allow a margin of safety, a 3 Joule maximum has been set as a design goal. It is perhaps relevant to note here that this limitation does not occur in the case of high vacuum modulator tubes where 50 Joules is acceptable and even beneficial. The difference is apparently associated with the few microns of gas present in neutral beam sources. This provides a much faster space charge neutralization capability in the accel gap so that a high current discharge can develop in a few nanoseconds. In a vacuum tube where the neutralizing ions must come from the electrodes, the time is much longer. A study of the latter type of breakdown was made for a switch-tube project at LLL, where this was found to be 1-2 {micro}secs. In a source, the discharge can be much more localized because of the gas and, in fact, may become a 'pinch' type discharge where the magnetic field of the arc column focuses the discharge into a small channel.
Date: January 1, 1979
Creator: Baker, W. R.
Partner: UNT Libraries Government Documents Department

Test facility for the development of 150-keV, multi-megawatt neutral beam systems

Description: The next generation of CTR experiments, such as the Tokamak Fusion Test Reactor (TFTR), will require neutral-beam injection systems that produce multi- megawatt, 120-keV deuterium-beam pulses of 0.5-second duration. Since present injection systems are operating in the 10- to 40-keV range, an intensive development effort is in progress to meet a 150-keV requirement. The vacuum system and power supplies that make up a test facility to be used in the development of these injectors are described. (MOW)
Date: November 1, 1975
Creator: Haughian, W.; Baker, W.R.; Biagi, L.A. & Hopkins, D.B.
Partner: UNT Libraries Government Documents Department

Saturable reactor-controlled power supply system for TCT/TFTR neutral beam sources

Description: Each neutral beam source requires one major power supply, the acceleration supply, and four auxiliary power supplies. The power supplies are designed to permit independent interruption of current to any source and crowbarring within 20 $mu$sec, in the event of a source spark, while not disturbing the normal pulsing of all other adjacent sources. The sources are described. (MOW)
Date: November 1, 1975
Creator: Baker, W.R.; Hopkins, D.B.; Dexter, W.L.; Kuenning, R.W. & Smith, B.J.
Partner: UNT Libraries Government Documents Department

Arc current modulator for neutral beam source

Description: The design of an arc current modulator for a 10 x 40 cm neutral beam source is described. The arc modulator has been designed for the TFTR Neutral Beam Source Test Facility. The purpose of the arc modulator is twofold; first, the arc modulator shapes the current rise during the turn on time of the source arc current so that good beam optics are maintained throughout the rise; second, the arc modulator has the capability of regulating the arc current to compensate for power supply ripple and other acceleration voltage fluctuations during the pulse flat top. The maximum current through the arc modulator is 4000 amps which can be switched from the neutral beam source to a parallel circuit of the modulator in the order of a few microseconds, which is required when sparkdown occurs in the source. The arc modulator design is a fast voltage to current converter. (MOW)
Date: November 1, 1979
Creator: DeVries, G.J.; Arthur, A.A.; Baker, W.R.; Fong, E.; Franck, J.V. & Hopkins, D.B.
Partner: UNT Libraries Government Documents Department

Update on the development of 120-keV multi-megawatt neutral beam source

Description: The next generation of U.S. fusion experiments, which includes TFTR, MFTF, and Doublet III, will utilize neutral-beam injection for plasma heating. TFTR, for example, desires 20 MW of 120-keV deuterium atoms in pulses of 0.5-sec duration at 5-minute intervals from a total of 12 individual neutral-beam modules. A discussion is given of some of the design details of a 15-A, 120-keV, 0.5-sec ion-source module that has recently been built to test design concepts for TFTR sources, and some of the features of the facility where it is presently under test at the Lawrence Berkeley Laboratory.
Date: November 1, 1976
Creator: Haughian, J. M.; Baker, W. R.; Biagi, L. A.; Hopkins, D. B.; Owren, H. M. & Paterson, J. A.
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

Protection and fault detection for Lawrence Berkeley Laboratory neutral beam sources

Description: Testing of TFTR neutral beam (NB) sources has begun at the LBL Neutral Beam System Test Facility (NBSTF). Operation at 120 kV, 65 A, 0.5 sec should be achieved soon. Because NB sources spark down frequently during conditioning, the main accelerating (accel) power supply must be interrupted within a few microseconds to avoid degrading the voltage holding capability, or even the damaging, of the NB source. A variety of improper magnitudes and/or ratios of voltages, currents, and times can occur and must be recognized as fault conditions in order to initiate a prompt interruption of the accel power supply. This paper discusses in detail the key signals which must be monitored and the manner in which they are processed in fault detector circuitry for safe operation of LBL NB sources. The paper also reviews the more standard interlocks and protective features recommended for these sources.
Date: November 1, 1979
Creator: Hopkins, D.B.; Baker, W.R.; Berkner, K.H.; Ehlers, K.W.; Honey, V.J.; Lietzke, A.F. et al.
Partner: UNT Libraries Government Documents Department

Neutral-beam research and development at LBL, Berkeley

Description: The neutral-beam research and development effort at LLL has been concerned mainly with design, construction, and testing of ion sources needed in present and planned experiments, chiefly at LLL. Development of techniques for producing reactor-type neutral beam systems with higher voltage, current, and duty cycle proceeds as resources permit. An important part of this program is the attempt to increase the physics understanding and technology needed for the design of beams with precisely controlled trajectories, e.g., converging beams. (auth)
Date: November 1, 1973
Creator: Baker, W.R.; Berkner, K.H.; Cooper, W.S.; Ehlers, K.W.; Kunkel, W.B.; Pyle, R.V. et al.
Partner: UNT Libraries Government Documents Department

THE ELECTRON-RING ACCELERATOR PROGRAM AT LRL

Description: A progress report is presented on the activities at LRL in connection with electron-ring accelerators. A two-stage compressor unit (employing only low-intensity beams) has been built, and operated with a 4-MeV 100-mA linac as an injector. Electron rings have been formed and compressed from 20 cm radius to 7 cm radius. A three-stage compression unit has been constructed and is now under test with the high intensity (200 A) 3.3-MeV beam of the Astron injector. The apparatus is described. Design work on a magnetic expansion unit is reported.
Date: October 1, 1968
Creator: Allison Jr., R.W.; Avery, R.T.; Baker, W.R.; Chupp, W.W.; Hartwig, E.C.; Hernandez, H.P. et al.
Partner: UNT Libraries Government Documents Department