Undergraduate Research at Jefferson Lab

750 MHz Separator Cavity Resonance Control Upgrade

Student: Ocean Armstrong

School: Bridgewater College

Mentored By: Tomasz Plawski

The Continuous Electron Beam uses the fifth pass horizontal separator to propel electrons on either the final pass toward Hall D or to the final set of separators that split electrons into the other three halls. This is achieved using a specific Radio Frequency (RF) exciting the separator cavity. The fifth pass horizontal separator is equipped with a resonance control system in order to maintain the cavity on resonance, hence minimize required RF power. This system operates using a low conductivity water (LCW) electrical heater and valve stepper controller. This is used to heat or cool the cavities to keep them on resonance. Currently the resonance control system runs on Experimental Physics and Industrial Control System (EPICS) software. The focus of my project is to modify and improve the software, firmware, and hardware in order to make this system faster and more reliable. To improve the system's operations for the future, a Field Programmable Gate Array (FPGA) base upgrade is warranted to substitute for the EPICS level software. This replacement will allow the operation to move more swiftly and precisely while allowing flexibility to be reprogrammed to adjust to possible later modifications. Currently, we have been modifying the EPICS software to utilize the newly installed FPGA base stepper controller. The new stepper valve controller was implemented to allow small and precise steps when adjusting the flow of the LCW to prevent the constant overshooting of the detuning angle. After implementation the separator is ready for beam operation in just around sixteen minutes. The results show that the FPGA base operation is the best solution for this system, allowing for a shorter preparation and recovery time.