Field stability in two-stem drift-tube linacs
Drift tubes supported by two stems have been considered for cryogenic drift-tube linacs (DTLs) to reduce vibrations and to minimize drift-tube deflections upon cool down. We investigated rf properties of two-stem DTL structures at room temperature and low power. Even apart is inherently more stable against tuning errors than a similar structure with single stems. The increased stability is higher for DTLs with shorter drift tubes. Ordinary quarter-wavelength-long post couplers actually destabilize the two-stem DTL fields; the extra stem raises the post coupler frequency compared to the frequency of the same post coupler extended beyond the tank wall into coaxial stub tuners. Adjustment of the stub lengths tunes the post-coupler frequencies, but post-coupler lengths in the tank have no effect, which suggests a field pattern different from traditional post couplers. The stabilized DTL resembles multiple-stem DTLs in which the angle between stems is varied to achieve stabilization. Adjusting the coaxial stub length is mechanically simpler than changing the stem azimuth angle. 5 refs., 6 figs., 1 tab.
- Publication Date:
- OSTI Identifier:
- Report Number(s):
- LA-UR-88-3262; CONF-881049-26
- DOE Contract Number:
- Resource Type:
- Resource Relation:
- Conference: Linear accelerator conference, Williamsburg, VA, USA, 3 Oct 1988; Other Information: Portions of this document are illegible in microfiche products
- Research Org:
- Los Alamos National Lab., NM (USA)
- Country of Publication:
- United States
- 43 PARTICLE ACCELERATORS; LINEAR ACCELERATORS; STABILIZATION; DESIGN; DRIFT TUBES; MAGNETIC FIELDS; RF SYSTEMS; ACCELERATORS 430100* -- Particle Accelerators-- Design, Development, & Operation
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