RF generation in the DARHT Axis-II beam dump
- Los Alamos National Laboratory
We have occasionally observed radio-frequency (RF) electromagnetic signals in the downstream transport (DST) of the second axis linear induction accelerator (LIA) at the dual-axis radiographic hydrodynamic testing (DARHT) facility. We have identified and eliminated some of the sources by eliminating the offending cavities. However, we still observe strong RF in the range 1 GHz t0 2 GHz occurring late in the {approx}2-{micro}s pulse that can be excited or prevented by varying the downstream tune. The narrow frequency width (<0.5%) and near exponential growth at the dominant frequency is indicative of a beam-cavity interaction, and electro-magnetic simulations of cavity structure show a spectrum rich in resonances in the observed frequency range. However, the source of beam produced RF in the cavity resonance frequency range has not been identified, and it has been the subject of much speculation, ranging from beam-plasma or beam-ion instabilities to unstable cavity coupling.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- DOE/LANL
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1040019
- Report Number(s):
- LA-UR-12-21131; TRN: US1202528
- Country of Publication:
- United States
- Language:
- English
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