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Beam injection in the TMX-U central cell

Description: Results pertaining to the recently modified beam-injection arrangement in the central cell of TMX-U are presented here. These modifications followed our observation that beam atoms injected perpendicular to the magnetic axis between the first two magnet-coil gaps give rise to trapped ions with midplane pitch angles lying in the intervals 68/sup 0/ < theta < 78/sup 0/ and 59/sup 0/ < theta < 65/sup 0/. These pitch-angle intervals are similar in value to the earlier arrangement of beams injected at the midplane at pitch angles of 58 and 70/sup 0/. Normal injection at an off-midplane position has two advantages when compared with off-normal injection at the midplane. First, the unattenuated beam can be dumped in the first-injector region rather than in the plasma region. Second, the beams can be oriented with their long dimension horizontal rather than vertical. The first point al
Date: June 15, 1984
Creator: Turner, W.C.
Partner: UNT Libraries Government Documents Department

Optical telemetry control and data transfer system

Description: A multichannel telemetry system has been designed and constructed to control and monitor duoPIGatron ion sources. With the exception of the accelerating and decelerating power supplies, all other power supplies and H/sub 2/ gas control that operate the ion source are elevated to accelerating potential. The telemetry system operates and monitors the isolated power supplies and transmits data across the high voltage gap. The transmission medium is infrared light pulsed through 10 ft-long, /sup 1///sub 8/ in-diam fiber optics, one end at high potential and the other end at ground potential. Conversion is accomplished by digitizing analog signals before transmitting through the optical system and demodulating at the terminating end. A maximum conversion rate of 100 kHz provides adequate resolution to operate the ion source. The output data is documented and stored in a PDP-11 computer. Although the control input is computer compatible, no attempt has been made for closed loop feedback control of the ion source.
Date: January 1, 1977
Creator: Wright, R.E.
Partner: UNT Libraries Government Documents Department

Fuel design considerations for the Mirror Hybrid Reactor

Description: Fuel design considerations for a conceptual design of a commercial mirror hybrid reactor, optimized for breeding /sup 239/Pu, are briefly discussed. /sup 238/U/sub 3/Si fuel and lithium hydride breeding material are proposed, along with helium gas cooling. Selection of materials for the blanket follows conventional fission reactor practice. A table of reactor parameters is presented. The Mirror Hybrid Reactor offers potential economical production of fissile material. (RME)
Date: January 1, 1977
Creator: Bender, D.J.; Lee, J.D. & Schultz, K.R.
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

Development of rf plasma generators for neutral beams

Description: The development of low frequency (1-2 MHz) rf plasma generators for high power neutral beam applications is summarized. Immersed couplers from one to three turns were used. Acceptable plasma profiles, less than or equal to 15% max/min, were obtained in a variety of field-free magnetic bucket and magnetic filter-bucket sources, with 10 x 10 cm or 10 x 40 cm extraction areas. Hydrogen beam properties were measured with a 7 x 10 cm accelerator operated at 80 kV. Atomic fraction and power efficiency were at least as high as with arc plasmas in similar chambers. The potential advantages of an rf plasma source are: ease of operation; reliability; and extended service lifetime.
Date: October 1, 1984
Creator: Vella, M.C.; Ehlers, K.W.; Kippenhan, D.; Pincosy, P.A.; Pyle, R.V.; DiVergilio, W.F. et al.
Partner: UNT Libraries Government Documents Department

Interaction of impurity ions with a weakly non-Maxwellian simple hydrogenic plasma. [None]

Description: The average acceleration of an ensemble of /open quotes/test particles/close quotes/ in a plasma is called the /open quotes/dynamical friction/close quotes/; the average rate at which their velocity vectors spread out in velocity-space diffusion-rate tensor. These quantities are derived for impurity ions intereacting with a weakly non-Maxwellian simple hydrogenic plasma. The distribution functions for the plasma ions and electrons are written explicitly.
Date: March 1, 1988
Creator: Terry, W.K.
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

Very-high-level neutral-beam control system

Description: As increasing numbers of neutral beams are added to fusion machines, their operation can consume a significant fraction of a facility's total resources. LBL has developed a very high level control system that allows a neutral beam injector to be treated as a black box with just 2 controls: one to set the beam power and one to set the pulse duration. This 2 knob view allows simple operation and provides a natural base for implementing even higher level controls such as automatic source conditioning.
Date: October 1, 1981
Creator: Elischer, V.; Jacobson, V. & Theil, E.
Partner: UNT Libraries Government Documents Department

Focussing of an ion beam from a reflex triode

Description: The method employs the use of electrostatic space charge fields to accelerate, focus, and tailor the arrival times of the ions on a target. Some of the test results are briefly described. (MOW)
Date: November 1, 1977
Creator: Kaye, R.J.; Johnson, G.B. & Verdeyen, J.T.
Partner: UNT Libraries Government Documents Department

Operating experience and procedures at the tritium systems test assembly

Description: Operating procedures are important for the safe and efficient operation of the Tritium Systems Test Assembly (TSTA). TSTA has been operating for four years with tritium in a safe and efficient manner. The inventory of tritium in the process loop is 100 grams and several milestone runs have been completed. This paper describes the methods used to operate TSTA. 3 refs., 1 fig.
Date: January 1, 1988
Creator: Carlson, R.V.; Binning, K.E.; Cole, S.P.; Jenkins, E.M.; Wilhelm, R.C. & Cole, S.P.
Partner: UNT Libraries Government Documents Department

Repetitive, small-bore two-stage light gas gun

Description: A repetitive two-stage light gas gun for high-speed pellet injection has been developed at Oak Ridge National Laboratory. In general, applications of the two-stage light gas gun have been limited to only single shots, with a finite time (at least minutes) needed for recovery and preparation for the next shot. The new device overcomes problems associated with repetitive operation, including rapidly evacuating the propellant gases, reloading the gun breech with a new projectile, returning the piston to its initial position, and refilling the first- and second-stage gas volumes to the appropriate pressure levels. In addition, some components are subjected to and must survive severe operating conditions, which include rapid cycling to high pressures and temperatures (up to thousands of bars and thousands of kelvins) and significant mechanical shocks. Small plastic projectiles (4-mm nominal size) and helium gas have been used in the prototype device, which was equipped with a 1-m-long pump tube and a 1-m-long gun barrel, to demonstrate repetitive operation (up to 1 Hz) at relatively high pellet velocities (up to 3000 m/s). The equipment is described, and experimental results are presented. 124 refs., 6 figs., 5 tabs.
Date: January 1, 1991
Creator: Combs, S.K.; Foust, C.R.; Fehling, D.T.; Gouge, M.J. & Milora, S.L.
Partner: UNT Libraries Government Documents Department

Neutral beam requirements for mirror reactors

Description: The neutral beam requirements for mirror reactors as presently envisioned are 200 keV for the Field Reversed Mirror (FRM) and 1200 keV for the Tandem Mirror (TMR). The hybrid version of the Standard Mirror, FRM and TMR require 100 to 120 keV. Due to the energy dependence of atomic processes, negative ions should produce neutrals more efficiently than positive ions above some energy and below this energy, positive ions are probably more efficient. This energy is probably somewhere between 100 and 150 keV for D/sup 0/, and 150 and 225 for T/sup 0/. Thus we conclude that hybrid reactors can use D/sup +/ ions but all of the fusion reactor designs call for D/sup -/ ions to make the neutral beams. Trends in the energy requirements are discussed. The hardening of neutral beams against neutron and gamma radiation is discussed.
Date: December 1, 1977
Creator: Moir, R.W.
Partner: UNT Libraries Government Documents Department

Engineering problems of future neutral beam injectors

Description: Because there is no limit to the energy or power that can be delivered by a neutral-beam injector, its use will be restricted by either its cost, size, or reliability. Studies show that these factors can be improved by the injector design, and several examples, taken from mirror reactor studies, are given.
Date: November 23, 1977
Creator: Fink, J.
Partner: UNT Libraries Government Documents Department

Operation of the TSTA (Tritium Systems Test Assembly) with 100 gram tritium

Description: In March of 1988 full operation of the 4-column isotope separation system (ISS) was realized in runs that approximated the design load of tritium. Previous operations had been fraught with operating difficulties principally due to external systems. This report will examine the recent highly successful 6-day period of operation. During this time the system was cooled from room temperature, loaded with hydrogen isotopes including 109 grams of tritium, integrated with the transfer pumping, impurity injection, and impurity removal systems, as well as the remote computer control system. At the end of the operation 12 grams of tritium having a measured purity of 99.987% (remainder deuterium) were offloaded from the system. Observed profiles in the columns in general agree with computer models. A Height Equivalent to a Theoretical Plate (HETP) of 5.0 cm is confirmed. 3 refs., 5 figs.
Date: January 1, 1988
Creator: Sherman, R.H. & Bartlit, J.R.
Partner: UNT Libraries Government Documents Department

System studies overview

Description: Viewgraphs of the conference presentation on ignition devices are given. Topics which are included are the relationship between the compact ignition device and the TFCX high-performance (HP) copper device, the status of current compact ignition device systems, structural aspects of the TFCX-HP copper device, questions on shielding, peak stress criteria, and major engineering design constraints. 2 figs. (WRF)
Date: January 1, 1985
Creator: Brown, T.G.
Partner: UNT Libraries Government Documents Department

Energy dissipation on ion-accelerator grids during high-voltage breakdown

Description: The effects of stored energy in the system capacitance across the accelerator grids during high voltage vacuum breakdown are examined. Measurements were made of the current flow and the energy deposition on the grids during breakdown. It is shown that only a portion (less than or equal to 40 J) of the total stored energy (congruent to 100 J) is actually dissipated on the grids. Most of the energy is released during the formation phase of the vacuum arc and is deposited primarily on the most positive grid. Certain abnormal situations led to energy depositions of about 200 J on the grid, but the ion accelerator endured them without exhibiting any deterioration in performance.
Date: January 1, 1981
Creator: Menon, M.M. & Ponte, N.S.
Partner: UNT Libraries Government Documents Department

Collisional depolarization in arbitrary magnetic fields

Description: The effect of arbitrary magnetic confinement geometry on the spin polarization of magnetically confined plasmas is investigated. The plasma is assumed to be in equilibrium so that the dominant depolarization mechanism is decorrelation of the spin-precession phase and the gyrophase by collisions.
Date: August 1, 1985
Creator: Cowley, S.C. & Kulsrud, R.M.
Partner: UNT Libraries Government Documents Department

New concept for a high-power beam dump

Description: A new concept for a dump for the ion and neutral beams used in the controlled nuclear fusion program uses thin sheets of a refractory metal such as tungsten formed into troughs having semi-circular cross sections. High-velocity water flowing circumferentially removes heat by subcooled nucleate boiling. Possible advantages are modular construction, lower water-pumping power, and a lower pressure drop than in conventional beam dumps. An example design calculation is shown for a dump capable of absorbing an incident flux of 10 kW/cm/sup 2/.
Date: April 16, 1980
Creator: Moir, R.W. & Taylor, C.E.
Partner: UNT Libraries Government Documents Department

Rail gun powered by an integral explosive generator

Description: We propose the use of a rail gun powered by an explosive magnetic flux compression generator built into the rail gun itself in which the rails of the gun are driven together behind the projectile by explosives. The magnetic field established between the rails by an initial current supplied by an external source at the breech of the gun is trapped and compressed by the collapsing rails to accelerate the projectile down the bore of the gun.
Date: January 1, 1979
Creator: Peterson, D.R. & Fowler, C.M.
Partner: UNT Libraries Government Documents Department

Collisional pumping for the production of intense spin-polarized neutral beams: target considerations. Revision

Description: Polarized beams at intensity levels heretofore not considered feasible have recently been proposed for heating and fueling fusion plasmas. Polarized-beam fueling could increase fusion rates by 50% as well as allow control of the directionality of the fusion products. A process which we have recently described, and called collisional pumping, promises to produce beams of polarized ions vastly more intense than producible by current methods.
Date: April 1, 1985
Creator: Stearns, J.W.; Burrell, C.F.; Kaplan, S.N.; Pyle, R.V.; Ruby, L. & Schlachter, A.S.
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

Diagnostics for the NBETF actively cooled beamdump

Description: Lawrence Berkeley Laboratory's Neutral Beam Engineering Test Facility is currently testing multi-megawatt beams with pulse durations of up to 30 seconds. For this purpose, an actively cooled beam dump composed of heat-absorbing panels tht dissipate the beam energy via high speed water flow has been installed and tested. The panels are mounted in a complex assembly necessary to accommodate the variety of ion sources to be tested. The beam dump required new diagnostics of two kinds: beam diagnostics that provide graphic and quantitative information about the beam, as inferred from energy transferred to the water, and panel diagnostics that provide graphic and quantitative information about the beam dump itself. In this paper we describe our response to these requirements, including new algorithms for beam profiles, and we compare this work to our earlier results for inertial beam dumps. Principal differences are that the power densities on the water-cooled panels can be only indirectly inferred from measurements of the transferred beam energy, and that the acquisition and preparation of raw data is much more complex.
Date: September 1, 1984
Creator: Theil, E. & Jacobson, V.
Partner: UNT Libraries Government Documents Department

Design, fabrication and operation of the mechanical systems for the Neutral Beam Engineering Test Facility

Description: The Neutral Beam Engineering Test Facility (NBETF) at Lawrence Berkeley Laboratory (LBL) is a National Test Facility used to develop long pulse Neutral Beam Sources. The Facility will test sources up to 120 keV, 50 A, with 30 s beam-on times with a 10% duty factor. For this application, an actively cooled beam dump is required and one has been constructed capable of dissipating a wide range of power density profiles. The flexibility of the design is achieved by utilizing a standard modular panel design which is incorporated into a moveable support structure comprised of eight separately controllable manipulator assemblies. A unique neutralizer design has been installed into the NBETF beamline. This is a gun-drilled moveable brazed assembly which provides continuous armoring of the beamline near the source. The unit penetrates the source mounting valve during operation and retracts to permit the valve to close as needed. The beamline is also equpped with many beam scraper plates of differing detail design and dissipation capabilities.
Date: December 1, 1983
Creator: Paterson, J.A.; Biagi, L.A.; Fong, M.; Koehler, G.W.; Low, W.; Purgalis, P. et al.
Partner: UNT Libraries Government Documents Department