LINAC2016 - List of Authors (Doebert, S.)

Paper	Title	Page
TUPRC016	S-Band Booster Design and Emittance Preservation for the Awake e-Injector	449
	O. Mete Apsimon, R. Apsimon, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S. Döbert CERN, Geneva, Switzerland G.X. Xia UMAN, Manchester, United Kingdom
	AWAKE is a proton driven plasma wakefield acceleration experiment at CERN which uses the protons from the SPS. It aims to study the self modulation instability of a proton bunch and the acceleration of an externally injected electron beam in the plasma wakefields, during the so called Phase II until the technical stop of LHC and its injector chain (LS2) in 2019. The external electron beam of 0.1 to 1nC charge per bunch will be generated using an S-band photo injector with a high QE semiconducting cathode. A booster linac was designed to allow variable electron energy for the plasma experiments from 16 to 20 MeV. For an RF gun and booster system, emittance control can be highlighted as a challenging transmission task. Once the beam emittance is compensated at the gun exit and the beam is delivered to the booster with an optimum beam envelope, fringing fields and imperfections in the linac become critical for preserving the injection emittance. This paper summarises the rf design studies in order to preserve the initial beam emittance at the entrance of the linac and alternative mitigation schemes in case of emittance growth.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC016
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THOP11	Ultra-Short Bunch Electron Injector for Awake	770
THPLR071	use link to see paper's listing under its alternate paper code
	S. Döbert CERN, Geneva, Switzerland
	The proton driven plasma wake field acceleration experiment AWAKE at CERN will start at the end of this year. In 2017 an S-band electron injector producing bunches of a few ps length will be added to probe the wake fields stimulated by a driving proton beam. In the future this electron injector will have to be upgraded to obtain electron bunches with a length of 100 - 200 fs in order to demonstrate injection into a single bucket of the plasma wave and therefore sustainable acceleration with low energy spread. Target bunch parameters for the study are a bunch charge of 100 pC, 100 fs bunch length, an emittance smaller than 2 mm mrad and a beam energy of 100 MeV. The status of a study to achieve these parameters using X-band accelerator hardware and velocity bunching will be presented.
	Slides THOP11 [2.733 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP11
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THPLR013	LEETCHI: The High Current Electron Source for the CLIC Drive Beam Injector	870
	K. Pepitone, S. Döbert CERN, Geneva, Switzerland B. Cadilhon, B. Cassany, J. Gardelle CEA, LE BARP cedex, France
	LEETCHI is a source which will produce 140 keV, 5 A, 140 μs electron beams at a repetition rate of 50 Hz. The shot to shot and flat top current stability of this drive beam injector for CLIC has to be better than 0.1% and a geometrical emittance of 14 mm mrad is expected. The development of a high voltage modulator, to achieve those requirements, is ongoing. A small test stand has been built which allows to diagnose and dump the beam produced by the thermionic cathode. The thermionic cathode is equipped with a grid which will allow us to control the current and eventually to have a feedback on the flattop shape. The beam dump, made of graphite, has been designed using two different codes, the Monte Carlo code GEANT4 to simulate the energy deposition and ANSYS used to simulate the thermal resistance of the graphite due to the long pulse duration. The geometry has been optimized with the ray tracing code EGUN and the 2D PIC-code MAGIC. All these simulations allowed us to optimize the geometry of the gun and to develop diagnostics which must survive to the heat deposition. Finally, the first electrical measurements of the beam will be presented.
	Poster THPLR013 [19.847 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR013
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Paper

Title

Page

S-Band Booster Design and Emittance Preservation for the Awake e-Injector

449

O. Mete Apsimon, R. Apsimon, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S. Döbert
CERN, Geneva, Switzerland
G.X. Xia
UMAN, Manchester, United Kingdom

AWAKE is a proton driven plasma wakefield acceleration experiment at CERN which uses the protons from the SPS. It aims to study the self modulation instability of a proton bunch and the acceleration of an externally injected electron beam in the plasma wakefields, during the so called Phase II until the technical stop of LHC and its injector chain (LS2) in 2019. The external electron beam of 0.1 to 1nC charge per bunch will be generated using an S-band photo injector with a high QE semiconducting cathode. A booster linac was designed to allow variable electron energy for the plasma experiments from 16 to 20 MeV. For an RF gun and booster system, emittance control can be highlighted as a challenging transmission task. Once the beam emittance is compensated at the gun exit and the beam is delivered to the booster with an optimum beam envelope, fringing fields and imperfections in the linac become critical for preserving the injection emittance. This paper summarises the rf design studies in order to preserve the initial beam emittance at the entrance of the linac and alternative mitigation schemes in case of emittance growth.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC016

Export •

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

THOP11

Ultra-Short Bunch Electron Injector for Awake

770

THPLR071

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

S. Döbert
CERN, Geneva, Switzerland

The proton driven plasma wake field acceleration experiment AWAKE at CERN will start at the end of this year. In 2017 an S-band electron injector producing bunches of a few ps length will be added to probe the wake fields stimulated by a driving proton beam. In the future this electron injector will have to be upgraded to obtain electron bunches with a length of 100 - 200 fs in order to demonstrate injection into a single bucket of the plasma wave and therefore sustainable acceleration with low energy spread. Target bunch parameters for the study are a bunch charge of 100 pC, 100 fs bunch length, an emittance smaller than 2 mm mrad and a beam energy of 100 MeV. The status of a study to achieve these parameters using X-band accelerator hardware and velocity bunching will be presented.

Slides THOP11 [2.733 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP11

Export •

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

THPLR013

LEETCHI: The High Current Electron Source for the CLIC Drive Beam Injector

870

K. Pepitone, S. Döbert
CERN, Geneva, Switzerland
B. Cadilhon, B. Cassany, J. Gardelle
CEA, LE BARP cedex, France

LEETCHI is a source which will produce 140 keV, 5 A, 140 μs electron beams at a repetition rate of 50 Hz. The shot to shot and flat top current stability of this drive beam injector for CLIC has to be better than 0.1% and a geometrical emittance of 14 mm mrad is expected. The development of a high voltage modulator, to achieve those requirements, is ongoing. A small test stand has been built which allows to diagnose and dump the beam produced by the thermionic cathode. The thermionic cathode is equipped with a grid which will allow us to control the current and eventually to have a feedback on the flattop shape. The beam dump, made of graphite, has been designed using two different codes, the Monte Carlo code GEANT4 to simulate the energy deposition and ANSYS used to simulate the thermal resistance of the graphite due to the long pulse duration. The geometry has been optimized with the ray tracing code EGUN and the 2D PIC-code MAGIC. All these simulations allowed us to optimize the geometry of the gun and to develop diagnostics which must survive to the heat deposition. Finally, the first electrical measurements of the beam will be presented.

Poster THPLR013 [19.847 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR013

Export •

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