SRF Cavity Emulator for PIP-II LLRF Lab and Field Testing

TL;DR

This paper presents a hardware emulator for SRF cavities used in PIP-II LLRF development, enabling early testing and control system development before actual cavities are available.

Contribution

It introduces a simple analog emulator design capable of meeting bandwidth and detuning requirements for multiple SRF cavity frequencies.

Findings

Emulator successfully replicates cavity bandwidth and detuning effects.

Design meets the bandwidth requirements for all cavity types.

Test results validate the emulator's performance and accuracy.

Abstract

There are many stages in the LLRF and RF system development process for any new accelerator that can take advantage of hardware emulation of the high-power RF system and RF cavities. LLRF development, bench testing, control system development and testing of installed systems must happen well before SRF cavities are available for test. The PIP-II Linac has three frequencies of SRF cavities, 162.5 MHz, 325 MHz and 650 MHz and a simple analog emulator design has been chosen that can meet the cavity bandwidth requirements, provide tuning errors to emulate Lorentz force detuning and microphonics for all cavity types. This emulator design utilizes a quartz crystal with a bandwidth of 65Hz at an IF of ~ 4 MHz, providing a Q of ~ 1.3 x 10^7 at 650MHz. This paper will discuss the design and test results of this emulator.