SRF Seminar: Multi-objective steepest descent optimization of a Quadrupole Resonator under uncertainties surements of Niobium-on-Copper

Thursday 12 May 2022, 15:00 → 16:00 Europe/Zurich

SRF  R&D seminars are seen as a place to discuss subjects and ideas that are interesting, exciting and or novel. The seminars are informal and seen as a place for open discussion, and topics presented can range from first ideas, through work in progress, to presentation of final results.

Naturally, if you have ideas or suggestions for topics (either presented by yourself or by an invited speaker), please do not hesitate to contact the convenor.

15:00 → 15:40 Multi-objective steepest descent optimization of a Quadrupole Resonator under uncertainties..

A calorimetric measurement using a so-called Quadrupole Resonator (QPR) is the most reliable and precise method to identify the RF properties of superconducting materials with an nΩ resolution. However, the procedure is affected by specific systematic measurement errors with various sources of uncertainty. Thereby, variations of geometrical parameters are modeled by the Polynomial Chaos (PC) expansion technique to mimic the manufacturing imperfections. Moreover, since optimal compromises between the conflicting objectives need to be considered, a shape optimization problem with uncertainties is formulated regarding the expected values of suitably chosen figures of merit in the Pareto sense. Additionally, the variance-based sensitivity analysis concept is used to range the contribution of the particular geometrical parameters. This information can be further exploited to modify the steepest descent algorithm in such a way as to reduce significantly the computational load needed to find optimal solutions.

Speakers: Dr Piotr Putek (University of Rostock), Shahnam Gorgi Zadeh (CERN)

15:40 → 15:55 Discussion