DEVELOPMENT OF A DIGITAL LOW-LEVEL RF CONTROL SYSTEM FOR THE p-LINAC TEST STAND AT FAIR∗

A test stand for a proton Linac is currently being built at GSI in the context of the FAIR project. Its low-level rf control system will be based on a system that has been developed for the S-DALINAC at TU Darmstadt operating at 3 GHz. This system converts the rf signal coming from the cavity down to the base-band using a hardware I/Q demodulator. The base-band signals are digitized by ADCs and fed into an FPGA executing the control algorithm. The resulting signals are I/Q modulated before they are sent back to the cavity. The rf module has to be adapted to the p-LINAC’s operating frequency of 325 MHz. Moreover, the p-LINAC will run in pulsed operation whereas the S-DALINAC is operated in cw mode. Different characteristics of the cavities and the pulsed operation require a redesign of the control algorithm. We will report on the modifications necessary to adapt the S-DALINAC’s control system to the p-LINAC test stand and on first results obtained from tests with a prototype.