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U.S. Department of Energy
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Space-charge limits in linear accelerators

Technical Report ·
DOI:https://doi.org/10.2172/6742291· OSTI ID:6742291

This report presents equations that allow an approximate evaluation of the limiting beam current for a large class of radio-frequency linear accelerators, which use quadrupole strong focusing. Included are the Alvarez, the Wideroe, and the radio-frequency quadrupole linacs. The limiting-current formulas are presented for both the longitudinal and the transverse degrees of freedom by assuming that the average space-charge force in the beam bunch arises from a uniformly distributed charge within an azimuthally symmetric three-dimensional ellipsoid. The Mathieu equation is obtained as an approximate, but general, form for the transverse equation of motion. The smooth-approximation method is used to obtain a solution and an expression for the transverse current limit. The form of the current-limit formulas for different linac constraints is discussed.

Research Organization:
Los Alamos Scientific Lab., NM (USA)
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
6742291
Report Number(s):
LA-8388
Country of Publication:
United States
Language:
English