LINAC2014 - List of Keywords (plasma)

Paper	Title	Other Keywords	Page
MOPP063	Development of a Pepper Pot Emittance Measurement Device for FRANZ	emittance, ion, ion-source, proton	199
	B. Klump, U. Ratzinger, W. Schweizer, K. Volk IAP, Frankfurt am Main, Germany
	Funding: This work is supported by HGS-HIRe Within the FRANZ project [] on the Institute of Applied Physics, University Frankfurt, a robust and simple pepper pot emittance measurement device for high beam power densities is developed. To use the device directly behind the ion source, a high robustness against HV breakdowns is necessary. This paper gives an overview on experimental setup, on the analysis method and on imaging properties of the screen. Furthermore, the implemented software-based evaluation method is shown. It concludes with a preliminary emittance measurement on the high current ion source for FRANZ. [] U. Ratzinger et al., “intense Pulsed Neutron Source FRANZ in the 1-500 keV Range“, Proc. ICANS-XVIII, Dongguan, April 2007, p.210

MOPP086	Ecr Ion Sources Developments at INFN-LNS for the Production of High Brightness Highly Charged Ion Beams	ion, electron, ion-source, ECRIS	254
	D. Mascali, C. Altana, L. Andò, C. Caliri, G. Castro, L. Celona, S. Gammino, L. Neri, F.P. Romano, G. Torrisi INFN/LNS, Catania, Italy G. Sorbello University of Catania, Catania, Italy
	The design of future high-performing ECRIS will require alternative approaches in microwave-to-plasma coupling, in order to maximize the electron density at relatively low frequency and reduce the super-hot electrons formation and their consequences on the beam stability and on source reliability. On these purposes, different activities have been carried out at INFN-LNS in the recent past, including advanced modelling, diagnostics, and studies about alternative methods of plasma heating based on electrostatic-waves generation. A description of these activities will be presented, with special emphasis to the microwave to plasma coupling and to the plasma diagnostics. Some of the already collected results have been a basis for the design of the new AISHa source (for hadrontherapy purposes) and the construction of the innovative prototype named Flexible Plasma Trap: on this machine we will search for advanced schemes of microwave launching, now ongoing thanks to full-wave plus kinetic calculations of the wave-to-plasma interaction mechanism

MOPP115	Plasma Processing of Nb Surfaces for SRF Cavities	SRF, cavity, accelerating-gradient, vacuum	323
	P.V. Tyagi, M. Doleans, S.-H. Kim ORNL, Oak Ridge, Tennessee, USA R. Afanador, C.J. McMahan ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work is supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Field emission is one of the most critical issues to achieve high performances of niobium (Nb) superconducting radio frequency (SRF) cavities. Field emission is mainly related to contaminants present at top surface of SRF cavities that act as electron emitters at high gradient operation and limit the cavity accelerating gradient. An R&D program at the Spallation Neutron Source (SNS) is in place* aiming to develop an in-situ plasma processing technique to remove some of the residual contaminants from inner surfaces of Nb cavities and improve their performance. The plasma processing R&D has first concentrated on removing hydrocarbon contamination from top surface of SRF cavities. Results from the surface studies on plasma processed Nb samples will be presented in this article and showed the removal of hydrocarbons from Nb surfaces as well as improvement of the surface workfuntion (WF). *M. Doleans et al. “Plasma processing R&D for the SNS superconducting linac RF cavities” Proceedings of 2013 SRF workshop, Paris, France
	Slides MOPP115 [1.405 MB]

TUPP110	Quasi Nonlinear Plasma Wakefield Acceleration Experiments	electron, focusing, experiment, emittance	680
	S.K. Barber, G. Andonian, B.D. O'Shea, J.B. Rosenzweig, Y. Sakai, O. Williams UCLA, Los Angeles, USA M. Ferrario INFN/LNF, Frascati (Roma), Italy P. Muggli MPI, Muenchen, Germany
	It is generally agreed that the best way forward for beam driven plasma wakefield acceleration (PWFA) is in the nonlinear or blowout regime. In this regime the expulsion of the plasma electrons from the beam occupied region produces a linear transverse focusing effect and position independent longitudinal accelerating fields, which can, in principle, produce high quality beams accelerated over many meters. However, certain aspects of a linear plasma response can be advantageous, such as the possibility for resonant excitation of wakefields through the use of pulse trains. Exploiting advantages of both linear and nonlinear PWFA may be achievable through the use of low emittance and tightly focused beams with relatively small charge. In this case the beam density can be greater than that of the ambient plasma while simultaneously having a smaller total charge than the plasma electrons contained in a cubic plasma skin depth allowing for blowout in the region of the beam while simultaneously maintaining a quasi linear response in the bulk plasma. Recent experiments at BNL have been aimed at probing various salient aspects of this regime and are presented here.

THPP085	The Prototype of the Proton Injector for the European Spallation Source	proton, extraction, emittance, simulation	1044
	L. Celona, L. Andò, G. Castro, S. Gammino, D. Mascali, L. Neri, G. Torrisi INFN/LNS, Catania, Italy
	The update of the design of the PS-ESS source and of its LEBT has been carried out in 2013 and the construction is now ongoing. The Ion Source will be able to provide a proton beam current larger than 70 mA to the 3.6 MeV RFQ. Several innovative solutions have been implemented in the redesign phase in order to cope with high-reliability/high-performance requirements of the ESS project. A flexible magnetic system will allow to investigate alternative configurations for future ion current upgrade of the machine based on the formation of a denser plasma. Innovative set-ups have been also explored for beam extraction, transport and chopping. Calculations have shown that space charge compensation up to 95 % is needed to preserve the low emittance in the low energy beam transfer line (LEBT). In order to obtain the optimal proton beam pulse rise and fall time – that should be 100 ns – we propose a LEBT chopping configuration that permits hundred nanosecond rise times despite the LEBT compensation needs few microseconds. The ongoing development of a 3D PIC code will be also described, that should allow predicting and tuning the beam pulse for different source/LEBT operative configurations.

THPP102	On Nonlinear Dynamics of a Sheet Electron Beam	emittance, electron, electronics, brightness	1090
	H.Y. Barminova MEPhI, Moscow, Russia
	In collisionless approximation the nonlinear dynamics of a charged particle beam is studied. Nonlinear oscillations of the beam radius appear due to external and self-consistent nonlinear forces. To study such oscillations the model is applied based on the kinetic distribution function dependent on the particle motion integrals. The 4th-order equation for the beam radius is obtained. The numerical solutions of the equation are analyzed. The cases of strong and weak nonlinearities caused by the own beam fields are discussed. In the case of weak deviation of the beam parameters from equilibrium ones the effective emittance growth isn't observed.

FRIOA06	AWAKE: Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN	proton, electron, laser, experiment	1196
	E. Gschwendtner CERN, Geneva, Switzerland
	Plasma wakefield acceleration is a promising alternative reaching accelerating fields a magnitude of up to 3 higher (GV/m) when compared to conventional RF acceleration. AWAKE, world’s first proton-driven plasma wakefield experiment, was launched at CERN to verify this concept. In this experiment proton bunches at 400 GeV/c will be extracted from the CERN SPS and sent to the plasma cell, where the proton beam drives the plasma wakefields and creates a large accelerating field. This large gradient of ~GV/m can be achieved by relying on the self-modulation instability (SMI) of the proton beam; when seeded by ionization through a short laser pulse, a train of micro-bunches with a period on the order of the plasma wavelength (~mm) develops, which can drive such a large amplitude wake from a long proton bunch (~12 cm). An electron beam will be injected into the plasma to probe the accelerating wakefield. The AWAKE experiment is being installed at CERN in the former CNGS facility, which must be modified to match the AWAKE requirements. First proton beam to the plasma cell is expected by end 2016.
	Slides FRIOA06 [7.276 MB]

Paper

Title

Other Keywords

Page

MOPP063

Development of a Pepper Pot Emittance Measurement Device for FRANZ

emittance, ion, ion-source, proton

199

B. Klump, U. Ratzinger, W. Schweizer, K. Volk
IAP, Frankfurt am Main, Germany

Funding: This work is supported by HGS-HIRe
Within the FRANZ project [*] on the Institute of Applied Physics, University Frankfurt, a robust and simple pepper pot emittance measurement device for high beam power densities is developed. To use the device directly behind the ion source, a high robustness against HV breakdowns is necessary. This paper gives an overview on experimental setup, on the analysis method and on imaging properties of the screen. Furthermore, the implemented software-based evaluation method is shown. It concludes with a preliminary emittance measurement on the high current ion source for FRANZ.
[*] U. Ratzinger et al., “intense Pulsed Neutron Source FRANZ in the 1-500 keV Range“, Proc. ICANS-XVIII, Dongguan, April 2007, p.210

MOPP086

Ecr Ion Sources Developments at INFN-LNS for the Production of High Brightness Highly Charged Ion Beams

ion, electron, ion-source, ECRIS

254

D. Mascali, C. Altana, L. Andò, C. Caliri, G. Castro, L. Celona, S. Gammino, L. Neri, F.P. Romano, G. Torrisi
INFN/LNS, Catania, Italy
G. Sorbello
University of Catania, Catania, Italy

The design of future high-performing ECRIS will require alternative approaches in microwave-to-plasma coupling, in order to maximize the electron density at relatively low frequency and reduce the super-hot electrons formation and their consequences on the beam stability and on source reliability. On these purposes, different activities have been carried out at INFN-LNS in the recent past, including advanced modelling, diagnostics, and studies about alternative methods of plasma heating based on electrostatic-waves generation. A description of these activities will be presented, with special emphasis to the microwave to plasma coupling and to the plasma diagnostics. Some of the already collected results have been a basis for the design of the new AISHa source (for hadrontherapy purposes) and the construction of the innovative prototype named Flexible Plasma Trap: on this machine we will search for advanced schemes of microwave launching, now ongoing thanks to full-wave plus kinetic calculations of the wave-to-plasma interaction mechanism

MOPP115

Plasma Processing of Nb Surfaces for SRF Cavities

SRF, cavity, accelerating-gradient, vacuum

323

P.V. Tyagi, M. Doleans, S.-H. Kim
ORNL, Oak Ridge, Tennessee, USA
R. Afanador, C.J. McMahan
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work is supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Field emission is one of the most critical issues to achieve high performances of niobium (Nb) superconducting radio frequency (SRF) cavities. Field emission is mainly related to contaminants present at top surface of SRF cavities that act as electron emitters at high gradient operation and limit the cavity accelerating gradient. An R&D program at the Spallation Neutron Source (SNS) is in place* aiming to develop an in-situ plasma processing technique to remove some of the residual contaminants from inner surfaces of Nb cavities and improve their performance. The plasma processing R&D has first concentrated on removing hydrocarbon contamination from top surface of SRF cavities. Results from the surface studies on plasma processed Nb samples will be presented in this article and showed the removal of hydrocarbons from Nb surfaces as well as improvement of the surface workfuntion (WF).
*M. Doleans et al. “Plasma processing R&D for the SNS superconducting linac RF cavities” Proceedings of 2013 SRF workshop, Paris, France

Slides MOPP115 [1.405 MB]

TUPP110

Quasi Nonlinear Plasma Wakefield Acceleration Experiments

electron, focusing, experiment, emittance

680

S.K. Barber, G. Andonian, B.D. O'Shea, J.B. Rosenzweig, Y. Sakai, O. Williams
UCLA, Los Angeles, USA
M. Ferrario
INFN/LNF, Frascati (Roma), Italy
P. Muggli
MPI, Muenchen, Germany

It is generally agreed that the best way forward for beam driven plasma wakefield acceleration (PWFA) is in the nonlinear or blowout regime. In this regime the expulsion of the plasma electrons from the beam occupied region produces a linear transverse focusing effect and position independent longitudinal accelerating fields, which can, in principle, produce high quality beams accelerated over many meters. However, certain aspects of a linear plasma response can be advantageous, such as the possibility for resonant excitation of wakefields through the use of pulse trains. Exploiting advantages of both linear and nonlinear PWFA may be achievable through the use of low emittance and tightly focused beams with relatively small charge. In this case the beam density can be greater than that of the ambient plasma while simultaneously having a smaller total charge than the plasma electrons contained in a cubic plasma skin depth allowing for blowout in the region of the beam while simultaneously maintaining a quasi linear response in the bulk plasma. Recent experiments at BNL have been aimed at probing various salient aspects of this regime and are presented here.

THPP085

The Prototype of the Proton Injector for the European Spallation Source

proton, extraction, emittance, simulation

1044

L. Celona, L. Andò, G. Castro, S. Gammino, D. Mascali, L. Neri, G. Torrisi
INFN/LNS, Catania, Italy

The update of the design of the PS-ESS source and of its LEBT has been carried out in 2013 and the construction is now ongoing. The Ion Source will be able to provide a proton beam current larger than 70 mA to the 3.6 MeV RFQ. Several innovative solutions have been implemented in the redesign phase in order to cope with high-reliability/high-performance requirements of the ESS project. A flexible magnetic system will allow to investigate alternative configurations for future ion current upgrade of the machine based on the formation of a denser plasma. Innovative set-ups have been also explored for beam extraction, transport and chopping. Calculations have shown that space charge compensation up to 95 % is needed to preserve the low emittance in the low energy beam transfer line (LEBT). In order to obtain the optimal proton beam pulse rise and fall time – that should be 100 ns – we propose a LEBT chopping configuration that permits hundred nanosecond rise times despite the LEBT compensation needs few microseconds. The ongoing development of a 3D PIC code will be also described, that should allow predicting and tuning the beam pulse for different source/LEBT operative configurations.

THPP102

On Nonlinear Dynamics of a Sheet Electron Beam

emittance, electron, electronics, brightness

1090

H.Y. Barminova
MEPhI, Moscow, Russia

In collisionless approximation the nonlinear dynamics of a charged particle beam is studied. Nonlinear oscillations of the beam radius appear due to external and self-consistent nonlinear forces. To study such oscillations the model is applied based on the kinetic distribution function dependent on the particle motion integrals. The 4th-order equation for the beam radius is obtained. The numerical solutions of the equation are analyzed. The cases of strong and weak nonlinearities caused by the own beam fields are discussed. In the case of weak deviation of the beam parameters from equilibrium ones the effective emittance growth isn't observed.

FRIOA06

AWAKE: Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

proton, electron, laser, experiment

1196

E. Gschwendtner
CERN, Geneva, Switzerland

Plasma wakefield acceleration is a promising alternative reaching accelerating fields a magnitude of up to 3 higher (GV/m) when compared to conventional RF acceleration. AWAKE, world’s first proton-driven plasma wakefield experiment, was launched at CERN to verify this concept. In this experiment proton bunches at 400 GeV/c will be extracted from the CERN SPS and sent to the plasma cell, where the proton beam drives the plasma wakefields and creates a large accelerating field. This large gradient of ~GV/m can be achieved by relying on the self-modulation instability (SMI) of the proton beam; when seeded by ionization through a short laser pulse, a train of micro-bunches with a period on the order of the plasma wavelength (~mm) develops, which can drive such a large amplitude wake from a long proton bunch (~12 cm). An electron beam will be injected into the plasma to probe the accelerating wakefield. The AWAKE experiment is being installed at CERN in the former CNGS facility, which must be modified to match the AWAKE requirements. First proton beam to the plasma cell is expected by end 2016.

Slides FRIOA06 [7.276 MB]