Focusing Procedures for Electrostatic Accelerators

Journal Article · Tue Jan 01 04:00:00 EST 1957 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1715772· OSTI ID:4342404

Johnson, C. H.; Judish, J. P.; Snyder, C. W.

Ion optics for Van de Graaff accelerators are reviewed in elementary terms of geometric optics with particular reference to the Oak Ridge 3-Mv accelerator. This machine produces well-focused beams of over l00 mu a and pulsed peak currents of several hundred mu a. The beam diameter measured at a distance of 2.7 tube lengths from the accelerator tube exit decreased from 0.26 in. at 0.35 Mv to 0.l0 in. at 2.47 Mv. The beam divergence at l.8 tube lengths from the exit is nearly constant, approx equal 2.5 x l0/sup -3/ rad. The svstem is analyzed in terms of five separate lenses: (l) einzel lens, (2) gap lens, (3) accelerator tube, (4) 90degree analyzing magnet, and (5) strong-focusing lens. It is shown that the crossovers formed in the gap lens and near the exit of the analyzing magnet are of fundamental importance. Brief reference is made to the small energy spread, approx equal 0.025%, for the beams obtained from this accelerator in spite of the large control slit spacing demanded by a large crossover.

• Research Organization: Oak Ridge National Lab., Tenn.
• Sponsoring Organization: USDOE
• NSA Number: NSA-12-003339
• OSTI ID: 4342404
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 11 Vol. 28; ISSN 0034-6748; ISSN RSINAK
• Publisher: American Institute of Physics (AIP)
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ANGULAR DISTRIBUTION
CONFIGURATION
CONTROL
CURRENTS
DISTRIBUTION
ENERGY RANGE
ION BEAMS
LENSES
MAGNETS
NUMERICALS
OPTICAL SYSTEMS
PLANNING
PULSES
TUBES
VAN DE GRAAFF ACCELERATORS