Compact Low-Voltage, High-Power, Multi-beam Klystron for ILC: Initial Test Results

TL;DR

This paper reports initial test results of a low-voltage, high-power multi-beam klystron designed for the ILC, demonstrating promising power output, efficiency, and operational potential for future full-scale development.

Contribution

The paper introduces a novel low-voltage multi-beam klystron with initial test data showing high power and efficiency, simplifying accelerator technology for ILC.

Findings

Achieved up to 2.86 MW output power at 60 kV

Demonstrated high efficiency and 56 dB gain

Indicated potential for 11.5 MW in full version

Abstract

Initial test results of an L-band multi-beam klystron with parameters relevant for ILC are presented. The chief distinction of this tube from MBKs already developed for ILC is its low operating voltage of 60 kV, a virtue that implies considerable technological simplifications in the accelerator complex. To demonstrate the concept underlying the tubes design, a six-beamlet quadrant (a 54 inch high one-quarter portion of the full 1.3 GHz tube) was built and recently underwent initial tests, with main goals of demonstrating rated gun perveance, rated gain, and at least one-quarter of the full 10-MW rated power. Our initial three-day conditioning campaign without RF drive (140 microsec pulses @ 60 Hz) was stopped at 53% of full rated duty because of time-limits at the test-site; no signs appeared that would seem to prevent achieving full duty operation (i.e., 1.6 msec pulses @ 10 Hz). The subsequent tests with 10-15 microsec RF pulses confirmed the rated gain, produced output powers of up to 2.86 MW at 60 kV with high efficiency and 56 dB gain, and showed acceptable beam interception. These results suggest that a full version of the tube should be able to produce up to 11.5 MW. Follow-on tests are planned for later in 2015.