High Power Operations of LEDA

TL;DR

This paper reports on the successful high-power continuous wave operation of the LEDA RFQ, achieving 100-mA proton beam acceleration to 6.7 MeV with high transmission and operational stability.

Contribution

It demonstrates the first high-power CW operation of the LEDA RFQ, including operational parameters, challenges, and solutions for high-current proton acceleration.

Findings

Achieved 111 hours of CW beam operation with at least 90 mA current.

Operated RFQ at 10% above design field levels to maintain high transmission.

Dissipated 1.5 MW RF power during high-current operation.

Abstract

The LEDA RFQ, a 350-MHz continuous wave (CW) radio-frequency quadrupole (RFQ), successfully accelerated a 100-mA CW proton beam from 75 keV to 6.7 MeV. We have accumulated 111 hr of beam on time with at least 90 mA of CW output beam current. The 8-m-long RFQ accelerates a dc, 75-keV, ~106-mA H+ beam from the LEDA injector with ~94% transmission. When operating the RFQ at the RF power level for which it was designed, the peak electrical field on the vane tips is 33 MV/m. However, to maintain the high transmission quoted above with the CW beam, it was necessary to operate the RFQ with field levels ~10% higher than design. The RFQ dissipates 1.5 MW of RF power when operating with this field. Three klystrons provide the 2.2 MW of RF power required by the RFQ to accelerate the 100-mA beam. The beam power is 670 kW. Some of the challenges that were met in accelerating a 100-mA CW proton beam to 6.7 MeV, will be discussed.