Obvious and non-obvious aspects of digital Self-Excited-Loops for SRF cavity control

Fuente: arXiv
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Main Authors: Doolittle, Larry, Murthy, Shreeharshini, Guran, Matei, Reyes, Lennon, Raman, Shrividhyaa Sankar, Varghese, Philip
Format: Preprint
Published: 2025
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author Doolittle, Larry
Murthy, Shreeharshini
Guran, Matei
Reyes, Lennon
Raman, Shrividhyaa Sankar
Varghese, Philip
author_facet Doolittle, Larry
Murthy, Shreeharshini
Guran, Matei
Reyes, Lennon
Raman, Shrividhyaa Sankar
Varghese, Philip
contents In 1978, Delayen showed how Self-Excited Loops (SEL) can be used to great advantage for controlling narrow-band SRF cavities. Its key capability is establishing closed-loop amplitude control early in the setup process, stabilizing Lorentz forces to allow cavity tuning and phase loop setup in a stable environment. As people around the world implement this basic idea with modern FPGA DSP technology, multiple variations and operational scenarios creep in that have both obvious and non-obvious ramifications for latency, feedback stability, and resiliency. This paper will review the key properties of a Delayen-style SEL when set up for open-loop, amplitude stabilized, and phase-stabilized modes. Then the original analog circuit will be compared and contrasted with the known variations of digital CORDIC-based implementations.
format Preprint
id arxiv_https___arxiv_org_abs_2510_14835
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Obvious and non-obvious aspects of digital Self-Excited-Loops for SRF cavity control
Doolittle, Larry
Murthy, Shreeharshini
Guran, Matei
Reyes, Lennon
Raman, Shrividhyaa Sankar
Varghese, Philip
Accelerator Physics
In 1978, Delayen showed how Self-Excited Loops (SEL) can be used to great advantage for controlling narrow-band SRF cavities. Its key capability is establishing closed-loop amplitude control early in the setup process, stabilizing Lorentz forces to allow cavity tuning and phase loop setup in a stable environment. As people around the world implement this basic idea with modern FPGA DSP technology, multiple variations and operational scenarios creep in that have both obvious and non-obvious ramifications for latency, feedback stability, and resiliency. This paper will review the key properties of a Delayen-style SEL when set up for open-loop, amplitude stabilized, and phase-stabilized modes. Then the original analog circuit will be compared and contrasted with the known variations of digital CORDIC-based implementations.
title Obvious and non-obvious aspects of digital Self-Excited-Loops for SRF cavity control
topic Accelerator Physics
url https://arxiv.org/abs/2510.14835