IPAC2021 - List of Authors (Bjorkqvist, O.)

Paper	Title	Page
WEPAB342	Beam Induced Power Deposition in CERN SPS Injection Kickers	3490
	M.J. Barnes, O. Bjorkqvist CERN, Geneva 23, Switzerland K. Kodama KEK, Ibaraki, Japan
	The SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam power deposition was considered an issue and before any advanced tools for analysing beam coupling impedance were available in their current form. These magnets are very lossy from a beam impedance perspective, and the beam induced power deposition is highly non-uniform. This is expected to be an issue during SPS operation with the higher intensity beams needed in the future for HL-LHC. There is an existing design, with serigraphy, that will mitigate the heating issues, which is presently being implemented on a prototype for test and measurement. Models have been developed to aid in predicting the safe operating regions until the upgraded MKPs are installed in the SPS: these are reported herein. A novel measurement technique is also presented to confirm the non-uniform power deposition in the ferrite yoke. Beam coupling impedance, power deposition, field rise time and field uniformity data are also presented for an upgraded, prototype, MKP.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB342
About •	paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB345	Impedance and Thermal Studies of the LHC Injection Kicker Magnet Upgrade	3502
	M.J. Barnes, O. Bjorkqvist, F. Motschmann CERN, Geneva, Switzerland
	The bunch intensities of High Luminosity (HL) LHC are predicted to lead to heating of the ferrite yokes of the LHC injection kicker magnets (MKI), in their current configuration, to their Curie temperature. Hence, the MKIs are being upgraded to meet the requirements of HL-LHC, which is planned to start in the mid-2020s. The upgraded design features an RF damping ferrite loaded structure at the upstream end of each magnet, which will absorb a large portion of the beam induced power deposition of the magnet. The ferrite damper is cooled via a copper sleeve, brazed to the ferrite, and a set of water pipes. The thermal contact conductance (TCC) between ferrite and copper is very important, as are the properties of the ferrite. In this paper, we present measurements of the TCC and ferrite properties. This data is used to predict temperatures during operation of the LHC. In addition, a measurement and prediction is shown for the longitudinal impedance of the magnet. The models developed in this study will be benchmarked during run III of the LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB345
About •	paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB346	Electromagnetic Modelling of Kicker Magnets to Derive Equivalent Circuits	3506
	M.J. Barnes, O. Bjorkqvist CERN, Geneva 23, Switzerland L. Jensen, O.A. Nielsen Aarhus University, Aarhus, Denmark
	An equivalent circuit model of a kicker magnet system is an invaluable tool for predicting the performance, studying possible modifications and for helping to diagnose faults. The frequency content of pulses associated with a ferrite loaded transmission line kicker magnet generally extend up to a few tens of MHz: hence, it is feasible to accurately model such a kicker magnet using lumped elements. This modelling technique is powerful since it in general has a run time several orders of magnitude shorter than a full wave electromagnetic simulation. In this paper, we determine values, including those of parasitic components, using modern simulation tools, for use in the lumped equivalent circuit models. In addition, the paper describes a method to simulate coupling between beam and the electrical circuit of a kicker magnet at relatively low frequencies: this allows one to use circuit analysis tools to study means of mitigating beam induced resonances.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB346
About •	paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Beam Induced Power Deposition in CERN SPS Injection Kickers

3490

M.J. Barnes, O. Bjorkqvist
CERN, Geneva 23, Switzerland
K. Kodama
KEK, Ibaraki, Japan

The SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam power deposition was considered an issue and before any advanced tools for analysing beam coupling impedance were available in their current form. These magnets are very lossy from a beam impedance perspective, and the beam induced power deposition is highly non-uniform. This is expected to be an issue during SPS operation with the higher intensity beams needed in the future for HL-LHC. There is an existing design, with serigraphy, that will mitigate the heating issues, which is presently being implemented on a prototype for test and measurement. Models have been developed to aid in predicting the safe operating regions until the upgraded MKPs are installed in the SPS: these are reported herein. A novel measurement technique is also presented to confirm the non-uniform power deposition in the ferrite yoke. Beam coupling impedance, power deposition, field rise time and field uniformity data are also presented for an upgraded, prototype, MKP.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB342

About •

paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 25 August 2021

Export •

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

WEPAB345

Impedance and Thermal Studies of the LHC Injection Kicker Magnet Upgrade

3502

M.J. Barnes, O. Bjorkqvist, F. Motschmann
CERN, Geneva, Switzerland

The bunch intensities of High Luminosity (HL) LHC are predicted to lead to heating of the ferrite yokes of the LHC injection kicker magnets (MKI), in their current configuration, to their Curie temperature. Hence, the MKIs are being upgraded to meet the requirements of HL-LHC, which is planned to start in the mid-2020s. The upgraded design features an RF damping ferrite loaded structure at the upstream end of each magnet, which will absorb a large portion of the beam induced power deposition of the magnet. The ferrite damper is cooled via a copper sleeve, brazed to the ferrite, and a set of water pipes. The thermal contact conductance (TCC) between ferrite and copper is very important, as are the properties of the ferrite. In this paper, we present measurements of the TCC and ferrite properties. This data is used to predict temperatures during operation of the LHC. In addition, a measurement and prediction is shown for the longitudinal impedance of the magnet. The models developed in this study will be benchmarked during run III of the LHC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB345

About •

paper received ※ 19 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021

Export •

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

WEPAB346

Electromagnetic Modelling of Kicker Magnets to Derive Equivalent Circuits

3506

M.J. Barnes, O. Bjorkqvist
CERN, Geneva 23, Switzerland
L. Jensen, O.A. Nielsen
Aarhus University, Aarhus, Denmark

An equivalent circuit model of a kicker magnet system is an invaluable tool for predicting the performance, studying possible modifications and for helping to diagnose faults. The frequency content of pulses associated with a ferrite loaded transmission line kicker magnet generally extend up to a few tens of MHz: hence, it is feasible to accurately model such a kicker magnet using lumped elements. This modelling technique is powerful since it in general has a run time several orders of magnitude shorter than a full wave electromagnetic simulation. In this paper, we determine values, including those of parasitic components, using modern simulation tools, for use in the lumped equivalent circuit models. In addition, the paper describes a method to simulate coupling between beam and the electrical circuit of a kicker magnet at relatively low frequencies: this allows one to use circuit analysis tools to study means of mitigating beam induced resonances.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB346

About •

paper received ※ 16 May 2021 paper accepted ※ 02 July 2021 issue date ※ 14 August 2021

Export •

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