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Discharge characteristics of a plasma generator for SITEX (Surface Ionization with Transverse Extraction) and VITEX (Volume Ionization with Transverse Extraction) ion sources

Description: Surface Ionization with Transverse Extraction (SITEX) and Volume Ionization with Transverse Extraction (VITEX) ion sources are being developed to produce intense beams of light negative ions for neutral particle beam applications. The salient feature of these ion sources is their ability to form intense negative-ion beams. With the objective of improving the performance of these sources, an experimental study of their plasma properties has been conducted. The effects of various electrodes in the plasma generator were investigated. Low electron and ion temperatures (below 1 eV) and positive plasma potential up to +6 V have been measured. The measured distributions of plasma density and potential reveal the existence of multichamber characteristics in the source plasma. The significant discharge characteristics and the plasma properties associated with the performance of SITEX and VITEX ion sources are discussed.
Date: January 1, 1986
Creator: Tsai, C.C.; Dagenhart, W.K.; Stirling, W.L.; Barber, G.C.; Haselton, H.H.; Ryan, P.M. et al.
Partner: UNT Libraries Government Documents Department

Extracted current densities from surface conversion sources of negative ions

Description: The condition for extracting a maximum negative ion current density is found when the product of the radius of the negative ion conversion electrode, the cross-section for negative and positive ion recombination, and the density of positive ions in the ion source equals one. The optimum output is obtained at the highest positive ion density and the smallest electrode radius.
Date: February 10, 1982
Creator: Fink, J.H.
Partner: UNT Libraries Government Documents Department

Considerations involved in the design of negative-ion-based neutral beam systems

Description: We consider the requirements and constraints for negative-ion-based neutral beam injection systems, and show how these are reflected in design considerations. We will attempt to develop a set of guidelines for users and developers to use to see how well (in a qualitative sense, at least) a particular neutral beam system fits a particular proposed need.
Date: November 1, 1983
Creator: Cooper, W.S.
Partner: UNT Libraries Government Documents Department

Pressure limits of negative ion sources based upon gas efficiency and extracted ion-current density

Description: The nature of the electrical discharge has an obvious impact upon the gas efficiency of an ion source and on the current density whch can be drawn from it. However external factors, such as the conductance of the grids and the background pressure along the beamline, also have an effect. Simple approximations based upon these factors show that there is a lower limit to the pressure of an ion source, which can deliver an ion beam of given current density at a specific gas efficiency. Estimates of ion stripping losses in a double gridded structure show that for all practical purposes, there is an upper limit as well.
Date: March 10, 1982
Creator: Fink, J.
Partner: UNT Libraries Government Documents Department

Characteristics of a long-pulse (30-s), high-power (4-MW) ion source for neutral beam injection

Description: A quasi-steady-state ion source has been developed for neutral beam injection applications. It is of the duoPIGatron type designed for delivering 50 A of hydrogen ions at 80 keV for 30-s-long pulses. Ion beams of 40 A at 75 keV were extracted for pulse lengths up to 30 s, maintaining excellent optical quality in the beam for the entire pulse duration. The design features and operational characteristics of the ion source are elaborated.
Date: January 1, 1983
Creator: Menon, M.M.; Barber, G.C.; Combs, S.K.; Dagenhart, W.K.; Gardner, W.L.; Haselton, H.H. et al.
Partner: UNT Libraries Government Documents Department

Neutral-beam development plan, FY 1982-1987

Description: The following chapters are included: (1) status of BNL negative ion source development, (2) source development program plan, (3) status of beam transport and acceleration, (4) accelerator development program plan, (5) neutralizer concepts, (6) neutralization program plan, (7) neutral beam systems, (8) test facilities, (9) program milestones and time schedules, (10) organization and Grumman participation, and (11) funding tables. (MOW)
Date: September 1, 1981
Partner: UNT Libraries Government Documents Department

24-MW neutral-beam injector of 400-keV H/sup 0/

Description: The negative and positive ion systems have both common goals and common problems. In fact, we have identified five items that must be developed before any large, neutral-beam injector, operating continuously or almost so, can be engineered. The five items are: (1) a continuous or almost continuous ion source, with 1A designating a source of positive ions and 1B a direct extraction source of negatives, (2) a recirculating metal-vapor cell, (3) a computer code with which to calculate beam trajectories in three dimensions, (4) a resistive coating to bleed stray charges from the surface of high-voltage vacuum insulators, and (5) an arc suppression technique for large systems. These items are discussed and it is shown how their development is prerequisite to the design of a 24-MW, 400-keV neutral hydrogen injector such as might be required for a fusion power reactor.
Date: November 1, 1979
Creator: Fink, J.H.; Hamilton, G.W. & Erickson, J.L.
Partner: UNT Libraries Government Documents Department

Determination of species yield of ion sources used for intense neutral-beam injection

Description: For efficient plasma heating, ion sources of neutral-beam injectors should be capable of producing ion beams with an atomic fraction of 90% or higher. Diagnostic techniques for quantitatively determining source species yield have been developed and evaluated. These include magnetic momentum analysis of the unneutralized ions passing through the neutralizer, energy analysis of the neutral beam by electrostatic separation of ions emanating from a stripping cell, and quantity vs implantation-depth analysis of hydrogen implanted into a crystal by SIMS technique. The operational features and advantages and disadvantages of each technique will be discussed. If the effects of beamlet optics, energy straggling in the accelerator, and neutralizer gas scattering are taken into account, the results of the measurements using the three techniques are shown to be mutually consistent within experimental error.
Date: January 1, 1982
Creator: Tsai, C.C.; Barnett, C.F.; Haselton, H.H.; Langley, R.A. & Stirling, W.L.
Partner: UNT Libraries Government Documents Department

Electrode design and performance of the ORNL positive ion sources

Description: The neutral beam development group at ORNL has designed, constructed, and shipped four 50-kV, 100-A sources to PPPL to be used for neutral beam heating of the confined plasma on the PDX tokamak. These sources have higher current capability than scaled-down sources, and they are required to run for 0.5 s as opposed to the 0.3-s requirement for PLT and ISX-B sources. Due to an innovative electrode design, these higher power sources met these requirements and achieved a higher transmission efficiency - 76% of the total input power on target vs 60% for the original ISX-B and modified PLT sources or 40% for the original PLT sources. As a consequence, a power of 2 MW of neutrals to the torus target was achieved; this is a record for measured neutral power and exceeds that of any other power source expected to be used on such advanced tokamaks as TFTR and D-III. A theoretical consideration of the relevant Poisson-Vlasov equations for ions extracted from a plasma was used to optimize the ion optics. Using the same electrode design with a tetraode accelerating structure and a new, indirectly heated cathode, repeatable long pulse, high energy conditions of 70 kV, 7 A, 8 s and 90 kV, 9 A, 5 s were achieved. Grid deformation calculations and Monte Carlo beam line gas deposition algorithms will be discussed. A direct-magnetic-electron-blocking, direct-recovery device is described, and theoretical considerations of it are discussed.
Date: January 1, 1980
Creator: Whealton, J.H.; Gardner, W.L. & Haselton, H.H.
Partner: UNT Libraries Government Documents Department

Experimental database and design concept for a 1-MW, 200-keV neutral-beam line based on a SITEX negative ion source

Description: Scaling studies for a SITEX negative ion source to produce 200-keV, 10-A, long pulse D/sup -/ beams are under way at Oak Ridge National Laboratory (ORNL). Designs have been restricted to the use of established techniques and reasonably well-demonstrated scaling. The results show that the 1-A SITEX source can be directly scaled to produce 200-keV, 10-A long pulse ion beams with a source power efficiency of less than or equal to 5 kW of total plasma generator power per ampere of D/sup -/ beam generated. Extracted electron-to-D/sup -/ ratios should be less than or equal to 0.06, with all extracted electrons recovered at less than or equal to 10% of the first gap potential energy difference. The close-coupled accelerating structure will be 5 cm long and have five electrodes with 21 slits each, with a 50-kV/cm field in each gap.
Date: January 1, 1983
Creator: Dagenhart, W.K.; Gardner, W.L.; Stirling, W.L. & Whealton, J.H.
Partner: UNT Libraries Government Documents Department

Negative-ion generator

Description: This negative ion generator comprises a magnetically insulated transmission line having at least one hole in the cathode to permit negative ions to escape the transmission line, and a device for removing electrons from the negative ion flow.
Date: February 11, 1982
Creator: Stinnett, R.W.
Partner: UNT Libraries Government Documents Department

Accelerated beam experiments with the ORNL SITEX (Surface Ionization with Transverse Extraction) and VITEX (Volume Ionization with Transverse Extraction) H/sup -//D/sup -/ sources

Description: Beam parameters have been measured for both the Surface Ionization with Transverse Extraction (SITEX) and Volume Ionization with Transverse Extraction (VITEX) H/sup -//D/sup -/ ion sources. Both sources use a reflex discharge to generate the main plasma. Beam energies up to 18 keV were used for pulse lengths up to several seconds. For SITEX, Faraday cup magnetically analyzed D/sup -/ beam currents of 110 mA at extraction densities of 48 mA/cm/sup 2/ and at a source ion temperature of 4 eV have been measured. For the VITEX results, Faraday cup magnetically analyzed beam currents of up to 80 mA at extraction densities of 27 mA/cm/sup 2/ and at a source ion temperature of 0.5 eV have been measured. Virtually all extracted electrons were recovered at an energy of 10 to 30% of the accel beam energy, and there were none in the analyzed beam.
Date: January 1, 1986
Creator: Dagenhart, W.K.; Tsai, C.C.; Stirling, W.L.; Ryan, P.M.; Schechter, D.E.; Whealton, J.H. et al.
Partner: UNT Libraries Government Documents Department

Neutral-particle-beam production and injection

Description: This paper is divided into two sections: the first is a discussion of the interactions of neutral beams with confined plasmas, the second is concerned with the production and diagnosis of the neutral beams. In general we are dealing with atoms, molecules, and ions of the isotopes of hydrogen, but some heavier elements (for example, oxygen) will be mentioned. The emphasis will be on single-particle collisions; selected atomic processes on surfaces will be included.
Date: July 1, 1982
Creator: Post, D. & Pyle, R.
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 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

Characteristics of a self-extraction negative ion source

Description: A multi-cusp, self-extraction, negative hydrogen ion source has been designed and constructed. Several diagnostic techniques have been applied to study the operating characteristics of this type of source. Negative H/sup -/ and D/sup -/ ions are produced on a negatively biased converter surface, and are self-extracted from the system. With the addition of cesium, the source has been operated at a neutral pressure of 1 x 10/sup -3/ Torr to generate a steady-state H/sup -/ ion current greater than 400 mA. The generation of impurity negative ions has been investigated, as have methods for reducing the presence of background electrons in the ion exit region. Plans for a larger, next-generation device will be discussed.
Date: October 1, 1980
Creator: Ehlers, K.W. & Leung, K.N.
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

BNL neutral beam development group. Progress report, FY 1979

Description: The objective of the BNL Neutral Beam Program is to develop a 250 keV neutral beam system suitable for heating experiments in toroidal or mirror plasma devices. The system will be based on acceleration and neutralization of negative hydrogen ions produced in and directly extracted from a source. The objective of source studies is to develop a unit delivering 10 A of negative ion currents in pulses of 1 s duration or longer, operating with extracted current densities of at least 0.5 A/cm/sup 2/ and having acceptable power and gas efficiencies and good beam optics. The 250 keV accelerator development work covers different structures, including those separated from the source by a bending magnet or a beam transfer system. During FY 1979 substantial progress was achieved toward the objectives of the program; in the same period the BNL program was reviewed by a panel, resulting in suggestions for a better orientation toward prospective users' requirements and in establishment of contacts with Princeton Plasma Physics Laboratory (TFTR Project) and Lawrence Berkeley and Livermore Laboratories (MFTF Project). A cooperative effort with Westinghouse was initiated in the second half of FY 1979 in order to utilize industrial facilities and expertise.
Date: January 15, 1980
Creator: Prelec, K. & Sluyters, T.
Partner: UNT Libraries Government Documents Department

Volume production of negative ions in the reflex-type ion source

Description: The production of negative hydrogen ions is investigated in the reflex-type negative ion source. The extracted negative hydrogen currents of 9.7 mA (100 mA/cm/sup 2/) for H/sup -/ and of 4.1 mA(42 mA/cm/sup 2/) for D/sup -/ are obtained continuously. The impurity is less than 1%. An isotope effect of negative ion production is observed.
Date: June 1, 1982
Creator: Jimbo, K.
Partner: UNT Libraries Government Documents Department

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

High energy negative deuterium beams using double charge-exchange or surface production

Description: Experimental and theoretical research on production of negative ion beams is described. Results from a double charge-exchange experiment include 10 ms pulses of 100 ma of D/sup -/ accelerated to 60 kV. Equilibrium fractions of D/sup -/ in several metal vapors are presented. Mechanisms and measurements of D/sup -/ on surfaces are described, and a scheme is shown for producing high current, high energy beams originating on surfaces.
Date: November 29, 1977
Creator: Hooper, E.B. Jr.; Anderson, O.A.; Orzechowski, T. & Poulsen, P.
Partner: UNT Libraries Government Documents Department

Technology of neutral-beam injection based on positive-ion sources

Description: Advances made in each of the following areas are summarized: (1) long pulse plasma sources, (2) the arc discharge, (3) the atomic species, (4) impurities, (5) accelerator development, (6) beam line components, and (7) the role of positive-ion-based injection systems for reactor-size devices. (MOW)
Date: January 1, 1983
Creator: Menon, M.M.
Partner: UNT Libraries Government Documents Department

Improvement of gas efficiency of negative ion sources

Description: A modification of the currently operating Calutron, magnetron, and modified duoPIGatron negative ion source is proposed. The modification should improve gas efficiency by more than an order of magnitude in the Calutron, by a factor of 5 in the magnetron, and by a factor of 2 in the duoPIGatron.
Date: August 1, 1981
Creator: Whealton, J.H.
Partner: UNT Libraries Government Documents Department