IPAC2019 - Classification: MC4: Hadron Accelerators / T32 Ion Beam Stripping

Paper	Title	Page
THPMP005	Charge Stripping at High Energy Heavy Ion Linacs	3452
	W.A. Barth, S. Yaramyshev GSI, Darmstadt, Germany W.A. Barth HIM, Mainz, Germany W.A. Barth, T. Kulevoy, S.M. Polozov, S. Yaramyshev MEPhI, Moscow, Russia A.S. Fomichev, L.V. Grigorenko JINR, Dubna, Moscow Region, Russia T. Kulevoy NRC, Moscow, Russia
	For heavy-ion accelerator facilities charge stripping is a key Technology: the stripping charge state, its efficiency to produce ions in the required charge state, and the beam quality after stripping substantially determine the entire accelerator performance. Modern heavy ion accelerator facilities such as the future Facility for Antiproton and Ion Research (FAIR) at GSI provide for high intensity heavy ion beams beyond 200 MeV/u. Heavy ion stripping at a lower energy enables more efficient acceleration up to the final beam energy, compared to acceleration of ions with a low charge state. Due to the high power deposited by the heavy ions in the stripping media and radiation damages if a solid target is used, self-recovering stripper media must be applied. General implementation options for different stripper target media are discussed in this paper, as well as general considerations to optimize the Linac layout through the appropriate choice of stripping medium and stripping energy. The driver Linac for the Dubna Electron-Radioactive Isotope Collider fAcility (DERICA) project, recently initiated by JINR, is foreseen to provide for 100 MeV/u Uranium beam in continuous wave mode. First layout scenarios of a one-step and a two-step DERICA-stripper approach will be also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP005
About •	paper received ※ 22 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPMP006	Study on the Theta Pinch Plasmas for Applied as Ion Stripper	3456
	K. Cistakov, Ph. Christ, M. Fröhlich, M. Iberler, J. Jacoby, L. Manganelli, G. Xu IAP, Frankfurt am Main, Germany R. Gavrilin, A. Khurchiev, S.M. Savin ITEP, Moscow, Russia
	Funding: Work supported by BMBF contr. No. 05P18RFRB1 With regard to the development of new accelerator technologies for high-intensity ion beams and more efficient acceleration, the transfer of radiation ions to higher charged states is a prerequisite for many experiments. However, the recent stripping technologies such as film and gas stripper for heavy ion beams with the desired intensities required great effort or are not suitable. The contribution presents the current state of plasma strippers with fully ionized hydrogen with simultaneously high particle densities in the range of some 10¹⁷ cm^-3 for FAIR. To achieve this high particle density, an inductive discharge plasma is ignited within a stripper cell parallel to the axis of the ion beam and compressed towards the beam axis. The advantage over conventional ion strippers is about 1000 times smaller recombination rate for electrons. This significantly increases the equilibrium charge state of ions. At the same time, the relative fraction of ions on the maximum of charge state distribution increases up to 25%. This should create good conditions for the use of plasma strippers at FAIR. Th.Peter, "Energy loss of heavy ions in dense plasma" **O.Haas, "Simulation Studies of plasma-based charge strippers",Proceedings of IPAC 2015, Richmond, VA, USA
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP006
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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THPMP034	Simulating Matter Interactions of Partially Stripped Ions in BDSIM	3514
	A. Abramov, S.T. Boogert, L.J. Nevay JAI, Egham, Surrey, United Kingdom
	Acceleration and storage of beams of relativistic partially stripped ions is more challenging than in the case of fully stripped ions because the interactions with matter, such as those with residual gas and collimators can strip electrons via ionisation. BDSIM is a code for the simulation of energy deposition and charged particle backgrounds in accelerators that uses the Geant4 physics library. Geant4 includes a broad range of ion elastic and inelastic interactions and allows the definition of partially stripped ion beams. However, no models are currently available to handle in-flight interactions involving the bound electrons. In this paper we present a semi-empirical model of beam ion stripping by material atoms that is implemented in BDSIM as an extension of Geant4’s existing physics processes and is fully integrated into a comprehensive set of matter interactions for partially stripped ions. The stripping cross-section for select cases and results from comprehensive simulations are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP034
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPMP049	Sequential Excitation Scheme for Laser Stripping of Hydrogen Ion Beams	3558
	Y. Liu, A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, A. Rakhman ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Resonant laser excitation of the electron in a hydrogen atom is essential to achieve high-efficiency laser stripping of hydrogen ion (H⁻) beam. In the laser stripping experiments recently carried out at SNS, an ultra-violet (UV) laser was used to excite the electrons in 1-GeV hydrogen atoms from the n=1 state to the n=3 state. In this talk, we propose a sequential resonant excitation scheme by using two laser beams to excite electrons in a sequence of two steps: from the n=1 state to the n=2 state and from the n=2 state to any higher state. The advantages of the sequential resonant excitation scheme include (1) lower laser power requirement due to higher transition probability in the first excitation step and (2) possibility of shifting the stripping laser wavelength from UV regime to longer wavelengths. An application of the sequential resonant excitation scheme in combination with the double-resonance optical cavity technology to the laser stripping of 1.3-GeV H⁻ beam (envisioned in the SNS proton power upgrade project) will be described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP049
About •	paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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Paper

Title

Page

Charge Stripping at High Energy Heavy Ion Linacs

3452

W.A. Barth, S. Yaramyshev
GSI, Darmstadt, Germany
W.A. Barth
HIM, Mainz, Germany
W.A. Barth, T. Kulevoy, S.M. Polozov, S. Yaramyshev
MEPhI, Moscow, Russia
A.S. Fomichev, L.V. Grigorenko
JINR, Dubna, Moscow Region, Russia
T. Kulevoy
NRC, Moscow, Russia

For heavy-ion accelerator facilities charge stripping is a key Technology: the stripping charge state, its efficiency to produce ions in the required charge state, and the beam quality after stripping substantially determine the entire accelerator performance. Modern heavy ion accelerator facilities such as the future Facility for Antiproton and Ion Research (FAIR) at GSI provide for high intensity heavy ion beams beyond 200 MeV/u. Heavy ion stripping at a lower energy enables more efficient acceleration up to the final beam energy, compared to acceleration of ions with a low charge state. Due to the high power deposited by the heavy ions in the stripping media and radiation damages if a solid target is used, self-recovering stripper media must be applied. General implementation options for different stripper target media are discussed in this paper, as well as general considerations to optimize the Linac layout through the appropriate choice of stripping medium and stripping energy. The driver Linac for the Dubna Electron-Radioactive Isotope Collider fAcility (DERICA) project, recently initiated by JINR, is foreseen to provide for 100 MeV/u Uranium beam in continuous wave mode. First layout scenarios of a one-step and a two-step DERICA-stripper approach will be also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP005

About •

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

Export •

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

THPMP006

Study on the Theta Pinch Plasmas for Applied as Ion Stripper

3456

K. Cistakov, Ph. Christ, M. Fröhlich, M. Iberler, J. Jacoby, L. Manganelli, G. Xu
IAP, Frankfurt am Main, Germany
R. Gavrilin, A. Khurchiev, S.M. Savin
ITEP, Moscow, Russia

Funding: Work supported by BMBF contr. No. 05P18RFRB1
With regard to the development of new accelerator technologies for high-intensity ion beams and more efficient acceleration, the transfer of radiation ions to higher charged states is a prerequisite for many experiments. However, the recent stripping technologies such as film and gas stripper for heavy ion beams with the desired intensities required great effort or are not suitable. The contribution presents the current state of plasma strippers with fully ionized hydrogen with simultaneously high particle densities in the range of some 10¹⁷ cm^-3 for FAIR. To achieve this high particle density, an inductive discharge plasma is ignited within a stripper cell parallel to the axis of the ion beam and compressed towards the beam axis. The advantage over conventional ion strippers is about 1000 times smaller recombination rate for electrons*. This significantly increases the equilibrium charge state of ions. At the same time, the relative fraction of ions on the maximum of charge state distribution increases up to 25%**. This should create good conditions for the use of plasma strippers at FAIR.
*Th.Peter, "Energy loss of heavy ions in dense plasma"
**O.Haas, "Simulation Studies of plasma-based charge strippers",Proceedings of IPAC 2015, Richmond, VA, USA

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP006

About •

paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

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

THPMP034

Simulating Matter Interactions of Partially Stripped Ions in BDSIM

3514

A. Abramov, S.T. Boogert, L.J. Nevay
JAI, Egham, Surrey, United Kingdom

Acceleration and storage of beams of relativistic partially stripped ions is more challenging than in the case of fully stripped ions because the interactions with matter, such as those with residual gas and collimators can strip electrons via ionisation. BDSIM is a code for the simulation of energy deposition and charged particle backgrounds in accelerators that uses the Geant4 physics library. Geant4 includes a broad range of ion elastic and inelastic interactions and allows the definition of partially stripped ion beams. However, no models are currently available to handle in-flight interactions involving the bound electrons. In this paper we present a semi-empirical model of beam ion stripping by material atoms that is implemented in BDSIM as an extension of Geant4’s existing physics processes and is fully integrated into a comprehensive set of matter interactions for partially stripped ions. The stripping cross-section for select cases and results from comprehensive simulations are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP034

About •

paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

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

THPMP049

Sequential Excitation Scheme for Laser Stripping of Hydrogen Ion Beams

3558

Y. Liu, A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, A. Rakhman
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Resonant laser excitation of the electron in a hydrogen atom is essential to achieve high-efficiency laser stripping of hydrogen ion (H⁻) beam. In the laser stripping experiments recently carried out at SNS, an ultra-violet (UV) laser was used to excite the electrons in 1-GeV hydrogen atoms from the n=1 state to the n=3 state. In this talk, we propose a sequential resonant excitation scheme by using two laser beams to excite electrons in a sequence of two steps: from the n=1 state to the n=2 state and from the n=2 state to any higher state. The advantages of the sequential resonant excitation scheme include (1) lower laser power requirement due to higher transition probability in the first excitation step and (2) possibility of shifting the stripping laser wavelength from UV regime to longer wavelengths. An application of the sequential resonant excitation scheme in combination with the double-resonance optical cavity technology to the laser stripping of 1.3-GeV H⁻ beam (envisioned in the SNS proton power upgrade project) will be described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP049

About •

paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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