IPAC2014 - List of Authors (Mastoridis, T.)

Paper	Title	Page
TUPME028	Flat Bunches in the LHC	1413
	E.N. Shaposhnikova, T. Argyropoulos, P. Baudrenghien, J.F. Esteban Müller, T. Mastoridis, G. Papotti, B. Salvant, H. Timko CERN, Geneva, Switzerland C.M. Bhat, A.V. Burov Fermilab, Batavia, Illinois, USA
	A high-harmonic RF system that could serve multiple purposes was proposed for the LHC. Possible applications of the second harmonic RF system include beam stabilisation in the longitudinal plane in the absence of wide-band longitudinal feedback and reduction of bunch peak line-density. Apart from other useful features, flat bunches are expected to produce less beam-induced heating at frequencies below 1 GHz, the frequency region critical for some LHC equipment. The latter, however, can also be achieved by de-populating the bunch centre. This was demonstrated during the dedicated machine development session in the LHC using RF phase modulation. In this paper the results of tests with single bunches and nominal LHC beams are presented and the possible use of this technique in LHC operation is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME028
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THPME174	High-accuracy Diagnostic Tool for Electron Cloud Observation in the LHC based on Synchronous Phase Measurements	3677
SUSPSNE068	use link to see paper's listing under its alternate paper code
	J.F. Esteban Müller, P. Baudrenghien, T. Mastoridis, E.N. Shaposhnikova, D. Valuch CERN, Geneva, Switzerland
	Electron cloud effects such as heat load in the cryogenic system, pressure rise and beam instabilities are among the main limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was developed to monitor the e-cloud activity and has been successfully used in the LHC during Run 1 (2010-2012). The power loss of each bunch due to the e-cloud can be estimated using very precise bunch-by-bunch measurement of the synchronous phase shift. In order to achieve the required accuracy, corrections for reflection in the cables and some systematic errors need to be applied followed by a post-processing of the measurements. Results show clearly the e-cloud build-up along the bunch trains and its evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield (SEY). The total beam power loss can be computed as a sum of the contributions from all bunches and compared with the heat load deposited in the cryogenic system. The plan to use this method in the LHC operation is also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME174
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Flat Bunches in the LHC

1413

E.N. Shaposhnikova, T. Argyropoulos, P. Baudrenghien, J.F. Esteban Müller, T. Mastoridis, G. Papotti, B. Salvant, H. Timko
CERN, Geneva, Switzerland
C.M. Bhat, A.V. Burov
Fermilab, Batavia, Illinois, USA

A high-harmonic RF system that could serve multiple purposes was proposed for the LHC. Possible applications of the second harmonic RF system include beam stabilisation in the longitudinal plane in the absence of wide-band longitudinal feedback and reduction of bunch peak line-density. Apart from other useful features, flat bunches are expected to produce less beam-induced heating at frequencies below 1 GHz, the frequency region critical for some LHC equipment. The latter, however, can also be achieved by de-populating the bunch centre. This was demonstrated during the dedicated machine development session in the LHC using RF phase modulation. In this paper the results of tests with single bunches and nominal LHC beams are presented and the possible use of this technique in LHC operation is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME028

Export •

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

THPME174

High-accuracy Diagnostic Tool for Electron Cloud Observation in the LHC based on Synchronous Phase Measurements

3677

SUSPSNE068

use link to see paper's listing under its alternate paper code

J.F. Esteban Müller, P. Baudrenghien, T. Mastoridis, E.N. Shaposhnikova, D. Valuch
CERN, Geneva, Switzerland

Electron cloud effects such as heat load in the cryogenic system, pressure rise and beam instabilities are among the main limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was developed to monitor the e-cloud activity and has been successfully used in the LHC during Run 1 (2010-2012). The power loss of each bunch due to the e-cloud can be estimated using very precise bunch-by-bunch measurement of the synchronous phase shift. In order to achieve the required accuracy, corrections for reflection in the cables and some systematic errors need to be applied followed by a post-processing of the measurements. Results show clearly the e-cloud build-up along the bunch trains and its evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield (SEY). The total beam power loss can be computed as a sum of the contributions from all bunches and compared with the heat load deposited in the cryogenic system. The plan to use this method in the LHC operation is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME174

Export •

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