IPAC2021 - List of Keywords (ISAC)

Paper	Title	Other Keywords	Page
TUPAB289	Towards Hysteresis Aware Bayesian Regression and Optimization	experiment, target, controls, operation	2159
	R.J. Roussel University of Chicago, Chicago, Illinois, USA A. Hanuka SLAC, Menlo Park, California, USA
	Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams. Algorithms used today for accelerator optimization assume a simple proportional relationship between an intermediate tuning parameter and the resultant field or mechanism which influences the beam. This neglects the effects of hysteresis, where the magnetic or mechanical response depends not only on the current parameter value, but also on the historical parameter values. This prevents the use of one to one surrogate models, such as Gaussian processes, to assist in optimization when hysteresis effects are not negligible, since identical points in input space no longer correspond to a same point in output space. In this work, we demonstrate how Bayesian inference can be used in conjunction with Gaussian processes to jointly model both the hysteresis cycle of magnetic elements and the beam response. Using this technique we demonstrate how to model the hysteresis cycle of a magnet during accelerator operation in situ by only measuring the beam response, without direct magnetic field measurements. This allows us to quickly build accurate statistical models of the beam response that can be used for rapid tuning of accelerators where hysteresis effects are dominant.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB289
About •	paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 19 August 2021
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THPAB204	End-to-End RMS Envelope Model of the ISAC-I Linac	rfq, linac, simulation, DTL	4183
	O. Shelbaya, R.A. Baartman, O.K. Kester TRIUMF, Vancouver, Canada
	A full end-to-end simulation of the ISAC-I linear accelerator has been built in the first order envelope code TRANSOPTR. This enables the fast tracking of rms sizes and correlations for a 6-dimensional hyperellipsoidal beam distribution defined around a Frenet-Serret reference particle frame, for which the equations guiding envelope evolution are numerically solved through a model of the machine’s electromagnetic potentials. Further, the adopted formalism enables the direct integration of energy gain via time-dependent accelerating potentials, without resorting to transit-time factors.
	Poster THPAB204 [0.627 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB204
About •	paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 31 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB205	On-Line Retuning of ISAC Linac Beam with Quadrupole Scan Tomography	quadrupole, MEBT, rfq, diagnostics	4187
	O. Shelbaya, R.A. Baartman, P.M. Jung, O.K. Kester, S. Kiy, T. Planche, Y.-N. Rao, S.D. Rädel TRIUMF, Vancouver, Canada
	The method of tomographic reconstruction has been in use at TRIUMF and elsewhere for several years, allowing for the beam diagnostic extraction of elements of the beam matrix on-line. One of the more recent applications of the technique at ISAC consists of using the measured density distribution as the input parameters for a real-time tune re-computation. This technique is advantageous since it does not require installation of dedicated emittance meters, but can instead be carried out with existing position monitors. Instead of requiring an operator to manually re-tune quadrupoles in a matching section, which can be time consuming, the technique allows for a fast and reproducible means to precisely control the beam and can be proceduralized for use by operators tuning the machine.
	Poster THPAB205 [0.468 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB205
About •	paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 10 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

TUPAB289

Towards Hysteresis Aware Bayesian Regression and Optimization

experiment, target, controls, operation

2159

R.J. Roussel
University of Chicago, Chicago, Illinois, USA
A. Hanuka
SLAC, Menlo Park, California, USA

Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams.
Algorithms used today for accelerator optimization assume a simple proportional relationship between an intermediate tuning parameter and the resultant field or mechanism which influences the beam. This neglects the effects of hysteresis, where the magnetic or mechanical response depends not only on the current parameter value, but also on the historical parameter values. This prevents the use of one to one surrogate models, such as Gaussian processes, to assist in optimization when hysteresis effects are not negligible, since identical points in input space no longer correspond to a same point in output space. In this work, we demonstrate how Bayesian inference can be used in conjunction with Gaussian processes to jointly model both the hysteresis cycle of magnetic elements and the beam response. Using this technique we demonstrate how to model the hysteresis cycle of a magnet during accelerator operation in situ by only measuring the beam response, without direct magnetic field measurements. This allows us to quickly build accurate statistical models of the beam response that can be used for rapid tuning of accelerators where hysteresis effects are dominant.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB289

About •

paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 19 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB204

End-to-End RMS Envelope Model of the ISAC-I Linac

rfq, linac, simulation, DTL

4183

O. Shelbaya, R.A. Baartman, O.K. Kester
TRIUMF, Vancouver, Canada

A full end-to-end simulation of the ISAC-I linear accelerator has been built in the first order envelope code TRANSOPTR. This enables the fast tracking of rms sizes and correlations for a 6-dimensional hyperellipsoidal beam distribution defined around a Frenet-Serret reference particle frame, for which the equations guiding envelope evolution are numerically solved through a model of the machine’s electromagnetic potentials. Further, the adopted formalism enables the direct integration of energy gain via time-dependent accelerating potentials, without resorting to transit-time factors.

Poster THPAB204 [0.627 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB204

About •

paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 31 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB205

On-Line Retuning of ISAC Linac Beam with Quadrupole Scan Tomography

quadrupole, MEBT, rfq, diagnostics

4187

O. Shelbaya, R.A. Baartman, P.M. Jung, O.K. Kester, S. Kiy, T. Planche, Y.-N. Rao, S.D. Rädel
TRIUMF, Vancouver, Canada

The method of tomographic reconstruction has been in use at TRIUMF and elsewhere for several years, allowing for the beam diagnostic extraction of elements of the beam matrix on-line. One of the more recent applications of the technique at ISAC consists of using the measured density distribution as the input parameters for a real-time tune re-computation. This technique is advantageous since it does not require installation of dedicated emittance meters, but can instead be carried out with existing position monitors. Instead of requiring an operator to manually re-tune quadrupoles in a matching section, which can be time consuming, the technique allows for a fast and reproducible means to precisely control the beam and can be proceduralized for use by operators tuning the machine.

Poster THPAB205 [0.468 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB205

About •

paper received ※ 18 May 2021 paper accepted ※ 08 July 2021 issue date ※ 10 August 2021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)