Status of POP demonstration of 400 MeV H laser stripping at J-PARC RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Yoneda, Hitoki*; Michine, Yurina*; Sato, Atsushi*; Shibata, Takanori*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.272 - 276, 2023/01

https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/TUP0/TUP003.pdf

Development of laser system for laser stripping injection

Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Kinsho, Michikazu

JPS Conference Proceedings (Internet), 33, p.011026_1 - 011026_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011026

The charge-exchange multi-turn injection by using a carbon stripper foil is adopted in high-intensity proton ring accelerators worldwide. It is a beneficial method to compress the pulsed proton beam with high intensity but there are serious issues for high intensity. First issue is a short lifetime of the foil by deformation or breaking itself. Another issue is high radiation dose corresponding to the scattered particles on the foil. Therefore, a non-destructive stripping injection method is required for higher intensity proton beam. We newly propose a non-destructive method of H stripping by using only laser. The new method is called "laser stripping injection". To establish our method, we are preparing for a POP (Proof-of-Principle) experiment of 400 MeV H- stripping to proton at J-PARC. In our presentation we will present the current status of laser system development for laser stripping injection at J-PARC.

Status of laser development for laser stripping experiment at J-PARC

Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.441 - 445, 2020/09

The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme is destructive-type method by using the foil and can accumulate high intensity proton beam. However, the uncontrolled beam losses by scattering at the foil and the foil breaking by the beam collision are a key issue of high-intensity proton accelerator. In order to realize higher intensity, new injection scheme of non-destructive type is needed instead of the foil. We newly propose laser stripping injection scheme by using laser pulse. We plan proof of principle experiment at J-PARC and are developing the laser system. In my presentation, we introduce the overview of laser stripping injection scheme and report the status of laser development.

Development of two-mirror multi-pass laser system to reduce laser power for laser stripping injection at J-PARC 3-GeV RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Sato, Atsushi*; Yoneda, Hitoki*; Michine, Yurina*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.841 - 845, 2019/07

https://www.pasj.jp/web_publish/pasj2019/proceedings/index.html

Progress status of proof-of-principle demonstration of 400 MeV H laser stripping at J-PARC 3-GeV RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Miura, Akihiko; Yoshimoto, Masahiro; Okabe, Kota; Suganuma, Kazuaki; Yamane, Isao*; Irie, Yoshiro*; Liu, Y.*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.806 - 810, 2018/08

https://www.pasj.jp/web_publish/pasj2018/proceedings/PDF/THP0/THP016.pdf

Zeeman splitting of laser-driven soft X-ray laser line by the enhancement of magnetic field in plasma

Kawachi, Tetsuya; Hasegawa, Noboru; Iwamae, Atsushi*; Yoneda, Hitoki*

Journal of Physics; Conference Series, 548(1), p.012038_1 - 012038_7, 2014/11

https://doi.org/10.1088/1742-6596/548/1/012038

Polarization is a fundamental property of light, and the effective use provides us powerful tools for probing materials and for plasma diagnostics. In plasmas, alignment of emission shows the plasma anisotropy, and Zeeman splitting informs us the magnetic field strength. We took the plasma-based soft X-ray laser as an example and observed the Zeeman splitting under the external magnetic field. A grazing incidence spectrograph, HIREFS, with the resolution of 15000 was used to observe the X-ray laser line. A magnetic coil driven by an electrical pulsed power supply provided the external magnetic field of 1035 T along the direction of the plasma column, and the left-handed and right-handed circular polarization components were obtained separately. The experimental result indicated that the magnetic field was larger by a factor of 4 than that of the applied field, which implied that the magnetic field compression occurred in the dynamics of the intense laser-plasma interaction.

High-resolution spectroscopy of the nickel-like molybdenum X-ray laser toward the generation of circularly polarized X-ray laser

Hasegawa, Noboru; Sasaki, Akira; Yamatani, Hiroshi; Kishimoto, Maki; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kunieda, Yuichi; Kawachi, Tetsuya; Yoneda, Hitoki*; et al.

Journal of the Optical Society of Korea, 13(1), p.60 - 64, 2009/03

https://doi.org/10.3807/JOSK.2009.13.1.060

The precise knowledge about the spectral width of the X-ray laser line is important to generate the circularly polarized X-ray laser. There are three magnetic sub-levels at lower state of the collisional excitation X-ray laser transition of the nickel-like ion X-ray laser medium. The polarization of each transition is circular or linear. Therefore the circularly polarized X-ray laser could be extracted by the influence of the Zeeman effect if the X-ray laser medium was under the external magnetic field. The strength of the magnetic field required for the circularly polarized X-ray laser is determined by the spectral width of the X-ray laser. Only a few measurements of the spectral width of the laser line have been reported, because the spectral width of the X-ray laser is so narrow that the required spectral resolution is quite high. In this study, we took the nickel-like molybdenum X-ray laser as an example and succeeded the measurement of the spectral width of the X-ray laser.

Laser stripping experiment in J-PARC

Harada, Hiroyuki; Saha, P. K.; Yoshimoto, Masahiro; Kinsho, Michikazu; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Shibata, Takanori*

no journal, , 

In high-intensity proton accelerator, H beams are injected with charge exchange into the ring by using a carbon foil. This scheme is destructive-type method and can accumulate high intensity proton beam. However, the uncontrolled beam losses by foil scattering and the foil breaking are a key issue in the world. In the J-PARC, we newly propose a laser stripping injection scheme of nondestructive-type method as an alternative to the foil and are under development for a proof-of-principle experiment of the method. We developed laser system and optical cavity and performed the second trial of the experiment. We were successfully matched laser pulse to ion beam one in time-space dimension. As this experimental result, we realized the charge exchange ratio of 16.8%, which is 30 times higher than first result of 0.57%. We present the experimental results with introducing the scheme.

Development and calibration of Doppler shifted Balmer lines photometry system for 400 MeV atoms generated by laser stripping

Shibata, Takanori*; Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Kinsho, Michikazu

no journal, , 

In order to further increase the intensity of the proton beam at J-PARC, we are planning a laser charge conversion test to convert the proton beam to protons nondestructively instead of the current carbon film. In the laser charge conversion process, we are considering a scenario in which neutral hydrogen is passed through excited . For this experiment, it is necessary to understand the energy levels of and its excitation efficiency. In this study, we are developing a spectroscopic measurement system to spectroscopically detect the light emitted from the excited . In this presentation, we will report on the development of the spectroscopic measurement system, which is important for laser charge conversion.

J-PARC charge exchange experiment with picosecond pulse train laser system

Fuchi, Aoi*; Harada, Hiroyuki; Yoneda, Hitoki*; Michine, Yurina*; Saha, P. K.; Yoshimoto, Masahiro; Kinsho, Michikazu; Shibata, Takanori*

no journal, , 

At the J-PARC, a non-destructive method of "laser charge exchange injection" has been proposed and is under development to replace the carbon foil. In addition, the development of a non-destructive beam profile monitor is also important to stabilize the beam operation. In this study, we developed a laser source and a multi-pass cavity for this purpose, and performed the second experiment. In the development of the laser source, the timing of each of the five laser amplifiers was staggered, and we succeeded in producing a laser with a flat pulse structure. In the development of the multi-pass cavity, we succeeded in focusing 16 pulses of laser simultaneously to the irradiation point. As a result, a charge exchange efficiency of 16.8%, 30 times higher than the previous efficiency of 0.57%, was achieved. In this presentation, we report the results of the laser source development and the multi-pass cavity development.