Correction of crosstalk effect in the low energy RHIC electron cooler booster cavity

TL;DR

This paper addresses the crosstalk effect in the RHIC electron cooler booster cavity, modeling, simulating, measuring, and proposing a correction method to meet energy spread requirements.

Contribution

It introduces a novel correction method for crosstalk effects in the SRF booster cavity of LEReC, ensuring energy spread specifications are satisfied.

Findings

Crosstalk causes voltage fluctuations exceeding energy spread limits.

The correction method effectively suppresses voltage fluctuations.

Modeling and measurements validate the correction approach.

Abstract

The Low Energy Relativistic Heavy Ion Collider (RHIC) electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with rms dp/p less than 5e-4. The superconducting radiofrequency (SRF) Booster Cavity is the major accelerating component in LEReC. It is a 0.4 cell cavity operating at 2 K, providing a maximum energy gain of 2.2 MeV. It is modified from an experimental Energy Recovery Linac (ERL) photocathode gun, and thus has fundamental power couplers (FPCs), pickup (PU) couplers (field probes) and HOM coupler close to each other on the same side of the cavity. Direct capacitive coupling between the FPC and PU, called the crosstalk effect, combined with microphonic detuning, can induce closed loop voltage fluctuations that exceed the total energy spread requirement of LEReC. The crosstalk effect in this cavity is modelled, simulated, and measured, and A correction method is proposed and demonstrated to suppress the voltage fluctuation so that energy spread requirement can be met.