LINAC2014 - List of Authors (Meusel, O.)

Paper

Title

Page

Investigations of Space-Charge Compensation in Low-Energy Beam Transport (LEBT) Sections Using a Particle-in-Cell Code

205

D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner
IAP, Frankfurt am Main, Germany

Among the advantages of magnetostatic LEBT sections is the possibility for compensation of space charge by electrons in the case of positively charged ion beams. In the past, it has been shown that the distribution of these compensation electrons can lead to unwanted emittance growth. However, the distribution of electrons especially in the presence of the magnetic fields of the focussing lenses is difficult to predict. To improve the understanding of the influence on the beam, models for the relevant processes namely residual gas ionization using realistic cross sections as well as secondary electron production on surfaces have been implemented in a particle-in-cell code. In this contribution, we will present the code used as well as first results for two model systems as an example.

TUPP062

A Rebunching CH Cavity for Intense Proton Beams

566

SUPG011

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

M. Schwarz, C. Claessens, M. Heilmann, O. Hinrichs, D. Koser, O. Meusel, D. Mäder, H. Podlech, U. Ratzinger, A. Seibel
IAP, Frankfurt am Main, Germany

Funding: Project supported by the EU, FP7 MAX, Contract No. 269565
The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is currently under construction at the Goethe-University in Frankfurt am Main (Germany). A 5-Gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination at the end of the LINAC section between two magnetic quadrupole triplets. It will be used for varying the final proton energy as well as for focusing the bunch longitudinally to compensate huge space charge forces at currents up to 200 mA at the final stage of extension. High current beam dynamic simulations have been performed. They include benchmarking of different beam dynamic codes like LORASR and TraceWin, as well as validating the results by measurements. Detailed examination of multipole field impact, due to the cavity’s geometry, together with error tolerance studies and thermal simulations are also performed. Furthermore, this CH rebuncher serves as a prototype for rt CH cavities at MYRRHA (Belgium), an Accelerator Driven System for transmutation of high level nuclear waste. After copper plating the cavity, RF conditioning will start soon.

Poster TUPP062 [6.015 MB]

WEIOB01

Chopping High-Intensity Ion Beams at FRANZ

765

C. Wiesner, M. Droba, O. Meusel, D. Noll, O. Payir, U. Ratzinger, P.P. Schneider
IAP, Frankfurt am Main, Germany

The accelerator-driven Frankfurt Neutron Source FRANZ is under construction at the science campus of Frankfurt University. Its Low-Energy Beam Transport (LEBT) line also serves as test stand for transport and chopping experiments with high-intensity ion beams. The high-current proton source was tested successfully with dc currents above 200 mA . The LEBT section consisting of four solenoids and a 250 kHz, 120 ns chopper was successfully commissioned using a helium test beam at low beam currents. Transport simulations including space-charge compensation and measurements are discussed. Simulations and experimental results of the novel LEBT chopper using a Wien-filter type field array and pulsed electrode voltages of up to ±6kV will be presented.

Slides WEIOB01 [7.925 MB]

THPP070

Alternative Compact LEBT Design for the FAIR Injector Upgrade

1013

K. Schulte, M. Droba, S. Klaproth, O. Meusel, D. Noll, U. Ratzinger
IAP, Frankfurt am Main, Germany
S.G. Yaramyshev
GSI, Darmstadt, Germany

In order to provide high intensity and brightness of the uranium beam for the planned FAIR project, the existing High Current Injector (HSI) at GSI has to be upgraded*. A part of the upgrade program is the design and construction of a compact straight injection line into the 36 MHz Radio Frequency Quadrupole of the HSI. As an alternative to a conventional LEBT design consisting of magnetic systems such as solenoids or quadrupoles, the application of Gabor lenses has been investigated. The focusing force of the Gabor lens is created by the space charge of an electron cloud, confined by crossed magnetic and electric fields inside the lens volume. Therefore, the Gabor lens combines strong, electrostatic focusing with simultaneous space-charge compensation. In previously performed beam transport experiments at GSI a prototype Gabor lens has been tested successfully. Furthermore, the operation and performance of such a device in a real accelerator environment has been studied. In this contribution an alternative LEBT design will be discussed and an improved Gabor lens design will be presented.
*W. Barth et al., “HSI-Frontend Upgrade”, GSI Scientific Report, 2009

Paper	Title	Page
MOPP065	Investigations of Space-Charge Compensation in Low-Energy Beam Transport (LEBT) Sections Using a Particle-in-Cell Code	205
	D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner IAP, Frankfurt am Main, Germany
	Among the advantages of magnetostatic LEBT sections is the possibility for compensation of space charge by electrons in the case of positively charged ion beams. In the past, it has been shown that the distribution of these compensation electrons can lead to unwanted emittance growth. However, the distribution of electrons especially in the presence of the magnetic fields of the focussing lenses is difficult to predict. To improve the understanding of the influence on the beam, models for the relevant processes namely residual gas ionization using realistic cross sections as well as secondary electron production on surfaces have been implemented in a particle-in-cell code. In this contribution, we will present the code used as well as first results for two model systems as an example.

TUPP062	A Rebunching CH Cavity for Intense Proton Beams	566
SUPG011	use link to see paper's listing under its alternate paper code
	M. Schwarz, C. Claessens, M. Heilmann, O. Hinrichs, D. Koser, O. Meusel, D. Mäder, H. Podlech, U. Ratzinger, A. Seibel IAP, Frankfurt am Main, Germany
	Funding: Project supported by the EU, FP7 MAX, Contract No. 269565 The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is currently under construction at the Goethe-University in Frankfurt am Main (Germany). A 5-Gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination at the end of the LINAC section between two magnetic quadrupole triplets. It will be used for varying the final proton energy as well as for focusing the bunch longitudinally to compensate huge space charge forces at currents up to 200 mA at the final stage of extension. High current beam dynamic simulations have been performed. They include benchmarking of different beam dynamic codes like LORASR and TraceWin, as well as validating the results by measurements. Detailed examination of multipole field impact, due to the cavity’s geometry, together with error tolerance studies and thermal simulations are also performed. Furthermore, this CH rebuncher serves as a prototype for rt CH cavities at MYRRHA (Belgium), an Accelerator Driven System for transmutation of high level nuclear waste. After copper plating the cavity, RF conditioning will start soon.
	Poster TUPP062 [6.015 MB]

WEIOB01	Chopping High-Intensity Ion Beams at FRANZ	765
	C. Wiesner, M. Droba, O. Meusel, D. Noll, O. Payir, U. Ratzinger, P.P. Schneider IAP, Frankfurt am Main, Germany
	The accelerator-driven Frankfurt Neutron Source FRANZ is under construction at the science campus of Frankfurt University. Its Low-Energy Beam Transport (LEBT) line also serves as test stand for transport and chopping experiments with high-intensity ion beams. The high-current proton source was tested successfully with dc currents above 200 mA . The LEBT section consisting of four solenoids and a 250 kHz, 120 ns chopper was successfully commissioned using a helium test beam at low beam currents. Transport simulations including space-charge compensation and measurements are discussed. Simulations and experimental results of the novel LEBT chopper using a Wien-filter type field array and pulsed electrode voltages of up to ±6kV will be presented.
	Slides WEIOB01 [7.925 MB]

THPP070	Alternative Compact LEBT Design for the FAIR Injector Upgrade	1013
	K. Schulte, M. Droba, S. Klaproth, O. Meusel, D. Noll, U. Ratzinger IAP, Frankfurt am Main, Germany S.G. Yaramyshev GSI, Darmstadt, Germany
	In order to provide high intensity and brightness of the uranium beam for the planned FAIR project, the existing High Current Injector (HSI) at GSI has to be upgraded. A part of the upgrade program is the design and construction of a compact straight injection line into the 36 MHz Radio Frequency Quadrupole of the HSI. As an alternative to a conventional LEBT design consisting of magnetic systems such as solenoids or quadrupoles, the application of Gabor lenses has been investigated. The focusing force of the Gabor lens is created by the space charge of an electron cloud, confined by crossed magnetic and electric fields inside the lens volume. Therefore, the Gabor lens combines strong, electrostatic focusing with simultaneous space-charge compensation. In previously performed beam transport experiments at GSI a prototype Gabor lens has been tested successfully. Furthermore, the operation and performance of such a device in a real accelerator environment has been studied. In this contribution an alternative LEBT design will be discussed and an improved Gabor lens design will be presented. W. Barth et al., “HSI-Frontend Upgrade”, GSI Scientific Report, 2009