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Neutral beam development at the Lawrence Berkeley and Lawrence Livermore Laboratories

Description: The Lawrence Berkeley and Livermore Laboratories Neutral Beam Development Group's work proceeds along two lines. The first is required for the near-term applications (e.g., MFTF, TFTR, and DIII), which require injection at energies up to 120 keV, ion currents per module up to 80 A, and pulse lengths greater than or equal to 0.5 s. These systems are based on the acceleration and neutralization of positive ions. The second part of the program is devoted to development for longer-term applications: positive-ion-based systems with 150 to 200-keV/65 to 100-A/10 to 30-s modules and, smewhat later, negative-ion-based systems for injection at 200 keV and higher energies.
Date: June 1, 1980
Creator: Pyle, R.V.
Partner: UNT Libraries Government Documents Department

Neutral beam development at LBL/LLNL

Description: In a joint program LBL and LLNL are developing and testing neutral beam injection systems based on the acceleration of positive ions, for application in the 80- to 160-keV range on MFTF-B, D III, TFTR/TFM, ETF, MNS, etc. A conceptual design of a 160 keV injection system for the German ZEPHYR project is in progress. For applications at energies above about 200 keV, positive-ion-based system efficiencies are unacceptably low for most applications, and so negative-ion-based systems are being developed also.
Date: October 1, 1980
Creator: Pyle, R.V.
Partner: UNT Libraries Government Documents Department

Neutral-beam-injection systems for reactors

Description: Increasing effort is being put into engineering designs of reactors and reactor-like magnetic confinement experiments. A central question concerns the methods of heating, fueling, and maintaining the plasmas, functions that primarily are now performed by neutral beams. Planning in the USA does not include the use of neutral beams on tokamaks in the 1990's and beyond. Tandem mirrors, however, will use energetic beams (sloshing ion beams) in the end plugs to produce electrostatic potentials that will confine plasma ions. These systems will be based on the production, acceleration, transport, and neutralization of negative hydrogen-ion (D/sup -/), multiampere beams with energies of 200-to 500-keV. In addition, lower-energy D and T beams may be used. These systems must operate steady state, with high reliability, and be compatible with radiation from a D-T burning plasma.
Date: June 1, 1983
Creator: Pyle, R.V.
Partner: UNT Libraries Government Documents Department

National negative-ion-based neutral-beam development plan

Description: The plan covers facilities required, program milestones, and decision points. It includes identification of applications, experiments, theoretical research areas, development of specific technologies and reactor development and demonstration facilities required to bring about the successful application of negative-ion-based neutral beams. Particular emphasis is placed on those activities leading to use on existing plasma confinement experiments or their upgrades.
Date: August 1, 1983
Creator: Cooper, W.S. & Pyle, R.V. (eds.)
Partner: UNT Libraries Government Documents Department

Negative lithium emission from a tungsten surface in a plasma

Description: Three possibilities for making Li/sup -/ ions have been considered: electron capture in a suitable gas or vapor, extraction from a lithium plasma, and production on a low work function surface in a plasma. The only quantitative results, so far, have been for electron capture, with the highest yield being about 5% for Li/sup +/ in Cs vapor at 5 keV. Of the other two methods, Leung has seen some Li/sup -/ produced in the volume of a plasma, and we now report the observation of Li/sup -/ from a surface in a He-Li plasma.
Date: October 1, 1984
Creator: Stearns, J.W. & Pyle, R.V.
Partner: UNT Libraries Government Documents Department

Operation of a quasioptical electron cyclotron maser

Description: The electron cyclotron maser or gyrotron concept has been developed to produce sources producing 200 kW at 28 GHz continuously, and higher power outputs and frequencies in pulsed mode. These sources have been useful in electron cyclotron resonance heating (ECRH) in magnetically confined fusion devices. However, higher frequencies and higher power levels will be required in reactor-grade fusion plasmas, with likely requirements of 1.0 MW or more per source at 140 GHz. Conventional gyrotrons follow a trend of decreasing power for increasing frequency. In order to circumvent this problem, the quasioptical electron cyclotron maser was proposed. In this device, the closed resonator of the conventional gyrotron is replaced with an open, Fabry-Perot type resonator. The cavity modes are then the TEM-type modes of an optical laser. The advantage of this configuration is that the cavity size is not a function of frequency, since the length can be any half-integer number of wavelengths. Furthermore, the beam traverses across the cavity transverse to the direction of radiation output, and thus the rf window design is less complicated than in conventional tubes. The rf output, if obtained by diffraction coupling around one of the mirrors, could be in a TEM mode, which would allow for quasioptical transmission of the microwaves into the plasma in fusion devices. 4 references, 1 figure.
Date: December 1, 1984
Creator: Morse, E.C. & Pyle, R.V.
Partner: UNT Libraries Government Documents Department

Development of neutral beams for fusion plasma heating

Description: A state-of-the-art account of neutral beam technology at the LBL/LLNL and ORNL facilities is given with emphasis on positive-ion-based systems. The advances made in the last few years are elaborated and problem areas are identified. The ORNL program has successfully completed the neutral injection systems for PLT, ISX-B, and most recently, PDX and the ISX-B upgrade. All of these are high current (60 to 100 A), medium energy (40 to 50 keV) systems. This program is also engaged in the development of a reactor-grade advanced positive ion system (150 to 200 kV/100 A/5 to 10 s) and a multimegawatt, long pulse (30 s) heating system for ISX-C. In a joint program, LBL and LLNL are developing and testing neutral beam injection systems based on the acceleration of positive ions for application in the 80- to 160-keV range on MFTF-B, D-III, TFTR/TFM, ETF, MNS, etc. A conceptual design of a 160-keV injection system for the German ZEPHYR project is in progress at LBL/LLNL and independently at ORNL. The laboratories are also engaged in the development of negative-ion-based systems for future applications at higher energies.
Date: January 1, 1980
Creator: Haselton, H.H. & Pyle, R.V.
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

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

H/sup -/ production from partially cesiated surfaces in the presence of a hydrogen plasma

Description: A large source employing a magnetic bucket geometry with a large curved converter surface focused on a single slit extractor is presently being studied at LBL. In order to understand the relationships among the Cs coverage, the high energy (back-scattered) and low energy (desorbed) H/sup -/ beams and the angular and energy distributions of the beams, we have constructed a small version of the LBL source in which the work function of the converter, which is immersed in the plasma (n < 10/sup 11//cm/sup 3/), can be measured by photo emission while the other parameters are varied. In addition, the converter can be rotated and the H/sup -/ beam collimated and analyzed to give a complete energy and angular spectrum.
Date: November 1, 1983
Creator: Wada, M.; Pyle, R.V. & Stearns, J.W.
Partner: UNT Libraries Government Documents Department

Work function dependence of surface produced H/sup -/ in the presence of a plasma

Description: The maximum H/sup -/ flux from a netatively biased converter cathode occurs at the work function minimum. A cesiated hydrogen plasma produces a partially-cesiated surface at the converter. The cesium coverage can be be controlled by the cesium partial pressure, the bias on the converter and the plasma density, while the work function of the converter surface is measured by the photo-electric effect, using a bright light source and a series of filters. The angular dependence is measured by rotating the converter.
Date: November 1, 1983
Creator: Wada, M.; Pyle, R.V. & Stearns, J.W.
Partner: UNT Libraries Government Documents Department

Performance of a developmental 120-keV, 10-A deuterium (14-A hydrogen) neutral beam system

Description: We have recently operated the LBL 120-keV neutral beam test facility on deuterium. This facility consists of a large (170,000 l) vacuum system, a plasma source, a multiple-aperture electrostatic accelerator structure, an ion sweep magnet, ion and neutral beam dumps, and a computer diagnostic and control system. The total length of the beamline is about 8.5m. Operation of this test facility on deuterium has produced beams with an energy of 120 keV, a total (ion plus neutral) beam current of 10 A, and a pulse length of 0.5 sec. The beam profile at the location of the dump is bi-gaussian, with 1/e halfwidths of about 1.28 and 0.42 degrees. Deuterium operation has been very limited because of the high neutron production rate (about 10/sup 11/ sec/sup -1/ when the beam is on) and the lack of radiation shielding around the facility.
Date: October 1, 1977
Creator: Berkner, K.H.; Cooper, W.S.; Ehlers, K.W. & Pyle, R.V.
Partner: UNT Libraries Government Documents Department

Plasma neutralizers for H/sup -/ or D/sup -/ beams

Description: Plasma neutralizers can produce higher conversion efficiencies than are obtainable with gas neutralizers for the production of high-energy neutral beams from negative hydrogen ions. Little attention has been paid to experimental neutralizer studies because of the more critical problems connected with the development of negative-ion sources. With the prospect of accelerating ampere dc beams from extrapolatable ion sources some time next year, we are re-examining plasma neutralizers. Some basic considerations, two introductory experiments, and a next-step experiment are described.
Date: October 1, 1980
Creator: Berkner, K.H.; Pyle, R.V.; Savas, S.E. & Stalder, K.R.
Partner: UNT Libraries Government Documents Department

Photoelectric work function measurement of a cesiated metal surface and its correlation with the surface-produced H/sup -/ ion flux

Description: For application in plasma heating, fueling, and current drive of magnetic fusion devices, high current negative deuterium ion sources for intense neutral beam injectors are being developed using efficient production of negative hydrogen isotope ions on low work function metal surfaces imbedded in hydrogen plasmas. In order to investigate the correlation between work function and negative hydrogen ion production, photoelectron emission from a cesiated metal surface, which is immersed in a hydrogen plasma with an electron density less than 5 x 10/sup 10//cc, was measured in the photon energy range of 1.3 to 4.1 eV. The work function determination was based on Fowler's analysis, and at the optimum coverage a work function of less than 1.5 eV was observed for a Cs-Cu surface. Measured values of work functions for different Cs coverages were compared to the negative hydrogen currents produced at the metal surface in the discharge; the surface production of negative hydrogen ion current is monotonically increasing with decreasing work function.
Date: September 1, 1982
Creator: Wada, M.; Berkner, K.H.; Pyle, R.V. & Stearns, J.W.
Partner: UNT Libraries Government Documents Department

Laser-induced fluorescence of metal-atom impurities in a neutral beam

Description: The need to limit impurities in fusion devices to low levels is well known. We have investigated, by the technique of laser-induced fluorescence, the concentration of heavy-metal atoms in a neutral beam caused by their evaporation from the hot filaments in a conventional high-current multifilament hydrogen-ion source.
Date: October 1, 1984
Creator: Burrell, C.F.; Pyle, R.V.; Sabetimani, Z. & Schlachter, A.S.
Partner: UNT Libraries Government Documents Department

Neutron production in a high-intensity deuterium neutral beam facility

Description: Measurement of d-d neutron yields incidentally produced in multi-megawatt neutral deuterium beam injectors used in magnetic fusion experiments is discussed. Unavoidable neutron production in the neutralizer, ion-beam dump, neutral beam calorimeter and beam collimator sections of an injector is measured to provide data for the design of radiation shielding and beam diagnostic experiments. At 120 kV, 10A, 0.5s pulsed injector operation, neutron yields plateau at an instantaneous yield from the calorimeter of 10/sup 11/ n/s. Beam diagnostic applications of neutron measurements are adjustment of beam source conditions to maximize the full-energy fraction of the neutral beam on target, and measurement of density in the neutralizer. (RME)
Date: June 1, 1977
Creator: Berkner, K.H.; Cooper, W.S.; McCaslin, J.B. & Pyle, R.V.
Partner: UNT Libraries Government Documents Department

Neutron production by neutral beam sources

Description: Neutron yields, from interactions of multiampere 40- to 120-keV deuterium beams with deuterium atoms implanted in copper targets, have been measured in order to provide input data for shielding of neutral-deuterium beam facilities for magnetic fusion experiments.
Date: November 1, 1979
Creator: Berkner, K.H.; Massoletti, D.J.; McCaslin, J.B.; Pyle, R.V. & Ruby, L.
Partner: UNT Libraries Government Documents Department

Negative-hydrogen-ion production by backscattering from alkali-metal targets

Description: Measurements have been made of the total backscattered D/sup -/ and H/sup -/ yields from Cs, Rb, K, Na and Li surfaces bombarded with D/sub 2//sup +/, D/sub 3//sup +/, H/sub 2//sup +/ and H/sub 3//sup +/ in the energy range 0.15 to 4 keV/nucleus. All measurements were made at a background pressure less than 10/sup -9/ Torr and the alkali-metal surfaces were evaporated onto a substrate in situ to minimize contamination of surfaces. For each target, the D/sup -/ and H/sup -/ yields exhibited maxima (as high as 8% per incident deuteron or proton for Cs); the maxima occurred at incident energies between 300 and 1000 eV/nucleus and always occurred at a lower incident energy for H than for D for a given target. Both the H/sup -/ and D/sup -/ yields decreased, at any measured energy, in going from Cs to Li in the order given above. Measurements of the H/sup -/ yield were also made for H/sub 3//sup +/ bombarding a W substrate, as a function of the work function of the target, as Li was deposited on the W. The work function of the target showed a minimum as the Li coverage was increased and the H/sup -/ yield showed a corresponding maximum which was almost two orders of magnitude higher than the H/sup -/ yield for a thick Li target.
Date: November 1, 1979
Creator: Schneider, P.J.; Berkner, K.H.; Graham, W.G.; Pyle, R.V. & Stearns, J.W.
Partner: UNT Libraries Government Documents Department

Neutralization of a fast negative-ion beam

Description: Neutralization of a fast negative-ion beam, primarily H/sup -/, is discussed in terms of competing one- and two-electron detachment processes in a variety of media: gas (vapor), plasma, liquid sheet, solid foil.
Date: January 1, 1986
Creator: Schlachter, A.S.; Mowat, J.R.; Stearns, J.W.; Gohil, P. & Pyle, R.V.
Partner: UNT Libraries Government Documents Department

Report on the engineering test of the LBL 30 second neutral beam source for the MFTF-B project

Description: Positive ion based neutral beam development in the US has centered on the long pulse, Advanced Positive Ion Source (APIS). APIS eventually focused on development of 30 second sources for MFTF-B. The Engineering Test was part of competitive testing of the LBL and ORNL long pulse sources carried out for the MFTF-B Project. The test consisted of 500 beam shots with 80 kV, 30 second deuterium, and was carried out on the Neutral Beam Engineering Test Facility (NBETF). This report summarizes the results of LBL testing, in which the LBL APIS demonstrated that it would meet the requirements for MFTF-B 30 second sources. In part as a result of this test, the LBL design was found to be suitable as the baseline for a Common Long Pulse Source design for MFTF-B, TFTR, and Doublet Upgrade.
Date: August 1, 1984
Creator: Vella, M.C.; Pincosy, P.A.; Hauck, C.A. & Pyle, R.V.
Partner: UNT Libraries Government Documents Department