IPAC2011 - Classification: 04 Hadron Accelerators / A14 Advanced Concepts

Paper

Title

Page

Progress of the SPIRAL2 Project

1912

E. Petit
GANIL, Caen, France

The progress of the SPIRAL2 project, the R&D and tests of the key components should be reviewed together with the main challenges for the beam production.

Slides WEYA01 [9.313 MB]

WEOBA02

KEK Digital Accelerator and its Beam Commissioning

1920

K. Takayama, T. Arai, Y. Arakida, M. Hasimoto, T. Iwashita, E. Kadokura, T. Kawakubo, T. Kubo, H. Nakanishi, K. Okamura, H. Someya, A. Takagi, M. Wake
KEK, Ibaraki, Japan
T. Adachi, K.W. Leo
Sokendai, Ibaraki, Japan
K. Okazaki
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan

The digital accelerator (DA), which is a small-scale induction synchrotron no requiring a high-energy injector accelerator and capable of providing a wide variety of ions, has been constructed at KEK*. Since the last winter beam commissioning has been carried out. Preliminary results of the beam commissioning experiment as well as the accelerator itself will be presented at the conference. The KEK-DA consists of a 200 kV high voltage terminal, in which an ECRIS is embedded, 15 m long LEBT, electro-static injection kicker, and a 10 Hz rapid cycle synchrotron, which is the recycle use of the former 500 MeV Booster synchrotron. An ion pulse, which is chopped in 5 μs by the newly developed Marx generator driven chopper**, is guided through the LEBT and injected by the electrostatic kicker, which is turned off before the injected ion pulse completes the first turn. Then the ion pulse is captured with a pair of barrier voltages and accelerated with the induction acceleration voltage through a full acceleration period. Beam commissioning has been started with a He¹⁺ ion beam of 50 micro-ampere. Beam commissioning of other ions such as C, N, O, Ne, and Ar will be expected.
* T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011.
** T.Adachi et al., “A Solid-State Marx Generator Driven Einzel Lens Chopper”, these proceedings.

Slides WEOBA02 [4.268 MB]

THPS012

Simulation of the Generation and Transport of Laser-Accelerated Ion Beams

3445

O. Boine-Frankenheim, V. Kornilov
GSI, Darmstadt, Germany
L. Zsolt
TEMF, TU Darmstadt, Darmstadt, Germany

In the framework of the LIGHT project a dedicated test stand is under preparation at GSI for the transport and focusing of laser accelerated ion beams. The relevant acceleration mechanism for the parameters achievable at the GSI PHELIX laser is the TNSA (Target Normal Sheath Acceleration). The subsequent evolution of the ion beam can be described rather well by the isothermal plasma expansion model. This model assumes an initial dense plasma layer with a 'hot' electron component and 'cold' ions. We will present 1D and 2D simulation results obtained with the VORPAL code on the expansion of the beam and on the cooling down of the neutralizing electrons. The electrons and their temperature can play an important role for the focusing of the beam in a solenoid magnet, as foreseen in the GSI test stand. We will discuss possible controlled de-neutralization schemes using external magnet fields.

THPS013

Radiation Pressure Acceleration of Multi-ion Thin Foil

3448

T.-C. Liu, G. Dudnikova, M.Q. He, C.-S. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su
UMD, College Park, Maryland, USA

Radiation pressure acceleration (RPA) is considered as an efficient way to produce quasi-monoenergetic ions, in which an ultra-thin foil is accelerated by high intensity circularly polarized laser. Our simulation study shows that an important factor limiting this acceleration process is the Rayleigh-Taylor instability, which results in the exponential growth of the foil density perturbation during the acceleration and hence the induced transparency of the foil and broadening of the particle energy spectrum. We will study RPA of multi-ion thin foil made of carbon and hydrogen and investigate the possibility of using abundant electrons supplied from carbon to delay the foil from becoming transparent, enhance the acceleration of protons and therefore improve the energy of quasi-monoenergetic proton beam. We will show the dependence of the energy of quasi-monoenergetic proton and carbon beam on the density and concentration ratio of carbon and hydrogen in the foil as well as foil thickness for RPA.

THPS014

Laser Thin Gas Target Acceleration for Quasi-monoenergetic Proton Generation

3451

M.Q. He, G. Dudnikova, C.-S. Liu, T.-C. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su
UMD, College Park, Maryland, USA
Z.M. Sheng
Shanghai Jiao Tong University, Shanghai, People's Republic of China

We propose a scheme of laser thin gas target acceleration for quasi-monoenergetic proton generation. The scheme uses gas target of thickness about several laser wavelengths with gas density spatial distribution of Guassian or square of sine shape. We performed Particle-In-Cell simulation using circularly polarized laser of normalized maximum amplitude ~5 and hydrogen gas target of thickness ~5 laser wavelength with peak density three times of the critical density. The simulation demonstrates several key physical processes involved in the laser thin gas target acceleration and the observation of quasi-monoenergetic protons. During the early phase of the laser plasma interaction, electron and ion cavities are observed. A compressed plasma layer is formed. The reflected protons in front of the compressed layer are accelerated and thus a bunch of quasi-monoenergetic protons are obtained. The compressed layer is finally destroyed due to Rayleigh-Taylor instability. The acceleration of the quasi-monoenergetic proton then stops with maximum energy about 8 MeV. It is also found that gas target thickness plays an important role for efficient quasi-monoenergetic proton generation.

Paper	Title	Page
WEYA01	Progress of the SPIRAL2 Project	1912
	E. Petit GANIL, Caen, France
	The progress of the SPIRAL2 project, the R&D and tests of the key components should be reviewed together with the main challenges for the beam production.
	Slides WEYA01 [9.313 MB]

WEOBA02	KEK Digital Accelerator and its Beam Commissioning	1920
	K. Takayama, T. Arai, Y. Arakida, M. Hasimoto, T. Iwashita, E. Kadokura, T. Kawakubo, T. Kubo, H. Nakanishi, K. Okamura, H. Someya, A. Takagi, M. Wake KEK, Ibaraki, Japan T. Adachi, K.W. Leo Sokendai, Ibaraki, Japan K. Okazaki Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan
	The digital accelerator (DA), which is a small-scale induction synchrotron no requiring a high-energy injector accelerator and capable of providing a wide variety of ions, has been constructed at KEK. Since the last winter beam commissioning has been carried out. Preliminary results of the beam commissioning experiment as well as the accelerator itself will be presented at the conference. The KEK-DA consists of a 200 kV high voltage terminal, in which an ECRIS is embedded, 15 m long LEBT, electro-static injection kicker, and a 10 Hz rapid cycle synchrotron, which is the recycle use of the former 500 MeV Booster synchrotron. An ion pulse, which is chopped in 5 μs by the newly developed Marx generator driven chopper, is guided through the LEBT and injected by the electrostatic kicker, which is turned off before the injected ion pulse completes the first turn. Then the ion pulse is captured with a pair of barrier voltages and accelerated with the induction acceleration voltage through a full acceleration period. Beam commissioning has been started with a He¹⁺ ion beam of 50 micro-ampere. Beam commissioning of other ions such as C, N, O, Ne, and Ar will be expected. T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011. ** T.Adachi et al., “A Solid-State Marx Generator Driven Einzel Lens Chopper”, these proceedings.
	Slides WEOBA02 [4.268 MB]

THPS012	Simulation of the Generation and Transport of Laser-Accelerated Ion Beams	3445
	O. Boine-Frankenheim, V. Kornilov GSI, Darmstadt, Germany L. Zsolt TEMF, TU Darmstadt, Darmstadt, Germany
	In the framework of the LIGHT project a dedicated test stand is under preparation at GSI for the transport and focusing of laser accelerated ion beams. The relevant acceleration mechanism for the parameters achievable at the GSI PHELIX laser is the TNSA (Target Normal Sheath Acceleration). The subsequent evolution of the ion beam can be described rather well by the isothermal plasma expansion model. This model assumes an initial dense plasma layer with a 'hot' electron component and 'cold' ions. We will present 1D and 2D simulation results obtained with the VORPAL code on the expansion of the beam and on the cooling down of the neutralizing electrons. The electrons and their temperature can play an important role for the focusing of the beam in a solenoid magnet, as foreseen in the GSI test stand. We will discuss possible controlled de-neutralization schemes using external magnet fields.

THPS013	Radiation Pressure Acceleration of Multi-ion Thin Foil	3448
	T.-C. Liu, G. Dudnikova, M.Q. He, C.-S. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su UMD, College Park, Maryland, USA
	Radiation pressure acceleration (RPA) is considered as an efficient way to produce quasi-monoenergetic ions, in which an ultra-thin foil is accelerated by high intensity circularly polarized laser. Our simulation study shows that an important factor limiting this acceleration process is the Rayleigh-Taylor instability, which results in the exponential growth of the foil density perturbation during the acceleration and hence the induced transparency of the foil and broadening of the particle energy spectrum. We will study RPA of multi-ion thin foil made of carbon and hydrogen and investigate the possibility of using abundant electrons supplied from carbon to delay the foil from becoming transparent, enhance the acceleration of protons and therefore improve the energy of quasi-monoenergetic proton beam. We will show the dependence of the energy of quasi-monoenergetic proton and carbon beam on the density and concentration ratio of carbon and hydrogen in the foil as well as foil thickness for RPA.

THPS014	Laser Thin Gas Target Acceleration for Quasi-monoenergetic Proton Generation	3451
	M.Q. He, G. Dudnikova, C.-S. Liu, T.-C. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su UMD, College Park, Maryland, USA Z.M. Sheng Shanghai Jiao Tong University, Shanghai, People's Republic of China
	We propose a scheme of laser thin gas target acceleration for quasi-monoenergetic proton generation. The scheme uses gas target of thickness about several laser wavelengths with gas density spatial distribution of Guassian or square of sine shape. We performed Particle-In-Cell simulation using circularly polarized laser of normalized maximum amplitude ~5 and hydrogen gas target of thickness ~5 laser wavelength with peak density three times of the critical density. The simulation demonstrates several key physical processes involved in the laser thin gas target acceleration and the observation of quasi-monoenergetic protons. During the early phase of the laser plasma interaction, electron and ion cavities are observed. A compressed plasma layer is formed. The reflected protons in front of the compressed layer are accelerated and thus a bunch of quasi-monoenergetic protons are obtained. The compressed layer is finally destroyed due to Rayleigh-Taylor instability. The acceleration of the quasi-monoenergetic proton then stops with maximum energy about 8 MeV. It is also found that gas target thickness plays an important role for efficient quasi-monoenergetic proton generation.