The RF source of the 60-MeV Linac for the KEK/JAERI Joint Project

TL;DR

This paper details the development and testing of a 3 MW RF source using five klystrons for the 60-MeV KEK/JAERI proton linac, including analysis of oscillation issues and system specifications.

Contribution

It presents the design, manufacturing, and testing of a prototype RF source with novel analysis of oscillation phenomena in high-power klystrons for proton accelerators.

Findings

Achieved nearly 3 MW output power in tests.

Identified and analyzed oscillations caused by back-going electrons.

Successfully tested the DTL hot-model structure.

Abstract

The construction of the 60-MeV proton linac has started as a low-energy front of the KEK/JAERI Joint Project for a high-intensity proton accelerator facility at KEK. The accelerating frequency is 324 MHz. Five UHF klystrons are used as an rf source; their ratings have a maximum power of 3 MW, a beam pulse width of a 700 micro-sec (an rf pulse width is 650 micro-sec) and a repetition rate of 50 pps. We have manufactured a proto-type rf source (a power-supply system with a modulating-anode pulse modulator and prototype klystrons). In this paper, the specifications and developments of the rf source, including the WR-2300 waveguide system, are summarized. During the manufacturing process, strong oscillations due to back-going electrons from the collector were observed. This phenomenon was analyzed both experimentally and theoretically. We have tested up to an output power of nearly 3 MW, and succeeded to test the DTL hot-model structure.