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Title: Application of extremum seeking for time-varying systems to resonance control of RF cavities

A recently developed form of extremum seeking for time-varying systems is implemented in hardware for the resonance control of radio-frequency cavities without phase measurements. Normal conducting RF cavity resonance control is performed via a slug tuner, while superconducting TESLA-type cavity resonance control is performed via piezo actuators. The controller maintains resonance by minimizing reflected power by utilizing model-independent adaptive feedback. Unlike standard phase-measurement-based resonance control, the presented approach is not sensitive to arbitrary phase shifts of the RF signals due to temperature-dependent cable length or phasemeasurement hardware changes. The phase independence of this method removes common slowly varying drifts and required periodic recalibration of phase-based methods. A general overview of the adaptive controller is presented along with the proof of principle experimental results at room temperature. Lastly, this method allows us to both maintain a cavity at a desired resonance frequency and also to dynamically modify its resonance frequency to track the unknown time-varying frequency of an RF source, thereby maintaining maximal cavity field strength, based only on power-level measurements.
Authors:
ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-16-20335
Journal ID: ISSN 1063-6536
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
IEEE Transactions on Control Systems Technology
Additional Journal Information:
Journal Volume: 25; Journal Issue: 4; Journal ID: ISSN 1063-6536
Publisher:
IEEE
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 47 OTHER INSTRUMENTATION; accelerator design; technology and operations; mathematics; adaptive control; uncertain systems; nonlinear systems; particle accelerator; resonance control
OSTI Identifier:
1342856