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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

Electron collisional detachment processes for a 250 keV D/sup -/ ion beam in a partially ionized hydrogen target

Description: Neutral atom beams with energies above 200 keV may be required for various purposes in magnetic fusion devices following TFTR, JET and MFTF-B. These beams can be produced much more efficiently by electron detachment from negative ion beams than by electron capture by positive ions. We have investigated the efficiency with which such neutral atoms can be produced by electron detachment in partially ionized hydrogen plasma neutralizers.
Date: September 1, 1980
Creator: Savas, S.E.
Partner: UNT Libraries Government Documents Department

Steady state gas efficiency of ion sources for neutral beams

Description: Gas present in the acceleration grids of a neutral beam line is one cause of divergent beam power. A measure of this problem is the gas efficiency (nuclear) of the ion source, epsilon/sub g/ = I/sub b//I/sub g/, where I/sub b/ denotes the extracted current of beam nuclei, and I/sub g/ the total current of nuclei to the source as gas. For a short pulse beam, less than or equal to 0.1 sec, gas transients make epsilon/sub g/ difficult to observe. Using the fraction size Berkeley LPA (nominally 120 keV, 10A), the gas efficiency of a positive ion, hydrogen neutral beam has been studied with pulses from 0.5 to 28 sec at 80 keV, 5.7 A, and 0.5 sec at 120 keV, 10A. The observed gas efficiency, 20% to 40%, is shown to agree with a simple steady state model. The model indicates that gas efficiency is determined by the degree of arc ionization.
Date: September 1, 1981
Creator: Vella, M.C.; Berkner, K.H.; Massoletti, D.J.; Owren, H.M. & Willis, J.E.
Partner: UNT Libraries Government Documents Department

Analysis of particle species evolution in neutral beam injection lines

Description: Analytic solutions to the rate equations describing the species evolution of a multispecies positive ion beam of hydrogen due to charge exchange and molecular dissociation are derived as a function of the background gas (H/sub 2/) line density in the neutralizing gas cell and in the drift tube. Using the solutions, calculations are presented for the relative abundance of each species as a function of the gas cell thickness, the reionization loss rates in the drift tube, and the neutral beam power as a function of the beam energy and the species composition of the original ion beam.
Date: July 1, 1978
Creator: Kim, J. & Haselton, H. H.
Partner: UNT Libraries Government Documents Department

Cross-sections for Balmer-alpha excitation in heavy-particle collisions

Description: Doppler shifted and unshifted Balmer-alpha radiation has been observed in the absolute sense for energetic H/sup +/, H/sub 2//sup +/ and H/sub 3//sup +/ ions incident on molecular hydrogen by the method of decay inside the target within the energy range of 20 keV to 150 keV. Most of the measurements were based on single-collision conditions, but a simple thick-target experiment has been tried for the case of dissociative excitation of the target molecules by H atoms.
Date: August 1, 1982
Creator: Bae, Y.K.
Partner: UNT Libraries Government Documents Department