Geometrically focused neutral beam accelerators

Journal Article · Wed Jul 01 00:00:00 EDT 1981 · Rev. Sci. Instrum.; (United States)

DOI:https://doi.org/10.1063/1.1136733· OSTI ID:6458092

Molvik, A W; Munger, R H; Duffy, T J; Correll, D L

A more reliable 40 kV, 65 A power supply drain at 0.4 A/cm/sup 2/, neutral-beam accelerator was developed for the Tandem Mirror Experiment (TMX). Multiple slotted aperture grids of 60% transparency are fabricated from refractory metal wires mounted to form a spherical surface. This geometrically focuses the beam by aiming individual beamlets at the center of curvature of the spherical grid (r = 3.2 m). We attain greater reliability and faster conditioning with geometrical focusing than with the previous technique of electrostatically steering beamlets to a common point. Electrostatic steering, accomplished by offsetting grid wires, is satisfactory if the offset of a beamlet is much less than the distance from the beamlet to the grids. It was found that Pierce Angle entrance grids performed better if sharper edged. A redesigned accelerator grid support structure reduced the number of ceramic-to-metal vacuum joints, and eliminated O rings between precisely aligned parts. The suppressor grid feedthrough is required to withstand a maximum voltage of 15 kV occurring during breakdown, greatly exceeding the operating voltage of 1.5 kV. Convenient fabrication and assembly techniques have been developed. Assembly of accelerators and plasma sources in a clean room appears to reduce the conditioning time. Following the successful testing of the prototype, eight 40 kV accelerators were built for TMX. Furthermore, ten 20 kV versions were built that are modifiable to 40 kV by exchanging the entrance grid.

• Research Organization: Lawrence Livermore National Laboratory, University of California, Livermore, California 94550
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6458092
• Journal Information: Rev. Sci. Instrum.; (United States), Journal Name: Rev. Sci. Instrum.; (United States) Vol. 52:7; ISSN RSINA
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430303* -- Particle Accelerators-- Experimental Facilities & Equipment
ACCELERATORS
BREAKDOWN
CONFIGURATION
ELECTRODES
ELECTRONIC EQUIPMENT
ELEMENTS
EQUIPMENT
FABRICATION
FOCUSING
GEOMETRY
GRIDS
INCIDENCE ANGLE
MAGNETIC MIRRORS
MATHEMATICS
METALS
MFTF DEVICES
NEUTRAL PARTICLES
OPACITY
OPEN PLASMA DEVICES
OPTICAL PROPERTIES
PARTICLES
PHYSICAL PROPERTIES
POWER SUPPLIES
REFRACTORIES
RELIABILITY
SPHERICAL CONFIGURATION
SURFACES
THERMONUCLEAR DEVICES
WIRES