IPAC2019 - List of Authors (Wulff, E.G.T.)

Paper	Title	Page
WEPTS051	Comparison of Electron Cloud Build-Up Simulations Against Heat Load Measurements for the LHC Arcs With Different Beam Configurations	3232
	G. Skripka, G. Iadarola, L. Mether, G. Rumolo, E.G.T. Wulff CERN, Meyrin, Switzerland P. Dijkstal PSI, Villigen PSI, Switzerland
	Electron cloud effects are among the main performance limitations for the operation of the Large Hadron Collider (LHC) with 25 ns bunch spacing. A large number of electrons impacting on the beam screens of the cold magnets induces significant heat load, reaching values close to the full cooling capacity available from the cryogenic system. Interestingly, it is observed that parts of the machine that are by design identical show very different heat loads. We used numerical simulations to investigate the possibility that these differences are induced by different surface properties, in particular maximum Secondary Electron Yield (SEY) for the different cryomagnets. Using the PyECLOUD code, the electron cloud build-up was simulated assuming different values of SEY in the LHC cold magnets. Comparing the measured heat loads to the simulation results for the 25 ns beams at 450 GeV we have identified the SEY values that match the observations in these conditions. These SEY values were found to be in good agreement with the heat loads measured with different beam configurations (changing the bunch pattern, the bunch intensity and the beam energy).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS051
About •	paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Comparison of Electron Cloud Build-Up Simulations Against Heat Load Measurements for the LHC Arcs With Different Beam Configurations

3232

G. Skripka, G. Iadarola, L. Mether, G. Rumolo, E.G.T. Wulff
CERN, Meyrin, Switzerland
P. Dijkstal
PSI, Villigen PSI, Switzerland

Electron cloud effects are among the main performance limitations for the operation of the Large Hadron Collider (LHC) with 25 ns bunch spacing. A large number of electrons impacting on the beam screens of the cold magnets induces significant heat load, reaching values close to the full cooling capacity available from the cryogenic system. Interestingly, it is observed that parts of the machine that are by design identical show very different heat loads. We used numerical simulations to investigate the possibility that these differences are induced by different surface properties, in particular maximum Secondary Electron Yield (SEY) for the different cryomagnets. Using the PyECLOUD code, the electron cloud build-up was simulated assuming different values of SEY in the LHC cold magnets. Comparing the measured heat loads to the simulation results for the 25 ns beams at 450 GeV we have identified the SEY values that match the observations in these conditions. These SEY values were found to be in good agreement with the heat loads measured with different beam configurations (changing the bunch pattern, the bunch intensity and the beam energy).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS051

About •

paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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