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- ItemControllable Laser Ion Acceleration(Bristol : IOP Publ., 2016) Kawata, S.; Kamiyama, D.; Ohtake, Y.; Takano, M.; Barada, D.; Kong, Q.; Wang, P.X.; Gu, Y.J.; Wang, W.M.; Limpouch, J.; Andreev, A.; Bulanov, S.V.; Sheng, Z.M.; Klimo, O.; Psikal, J.; Ma, Y.Y.; Li, X.F.; Yu, Q.S.In this paper a future laser ion accelerator is discussed to make the laser-based ion accelerator compact and controllable. Especially a collimation device is focused in this paper. The future laser ion accelerator should have an ion source, ion collimators, ion beam bunchers, and ion post acceleration devices [Laser Therapy 22, 103(2013)]: the ion particle energy and the ion energy spectrum are controlled to meet requirements for a future compact laser ion accelerator for ion cancer therapy or for other purposes. The energy efficiency from the laser to ions is improved by using a solid target with a fine sub-wavelength structure or a near-critical density gas plasma. The ion beam collimation is performed by holes behind the solid target or a multi-layered solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching would be successfully realized by a multistage laser-target interaction.
- ItemX-ray emission from stainless steel foils irradiated by femtosecond petawatt laser pulses(Bristol : IOP Publ., 2018) Alkhimova, M.A.; Faenov, A.Ya.; Pikuz, T.A.; Skobelev, I.Yu.; Pikuz, S.A.; Nishiuchi, M.; Sakaki, H.; Pirozhkov, A.S.; Sagisaka, S.; Dover, N.P.; Kondo, Ko.; Ogura, K.; Fukuda, Y.; Kiriyama, H.; Esirkepov, T.; Bulanov, S V.; Andreev, A.; Kando, M.; Zhidkov, A.; Nishitani, K.; Miyahara, T.; Watanabe, Y.; Kodama, R.; Kondo, K.We report about nonlinear growth of x-ray emission intensity emitted from plasma generated by femtosecond petawatt laser pulses irradiating stainless steel foils. X-ray emission intensity increases as ∼ I 4.5 with laser intensity I on a target. High spectrally resolved x-ray emission from front and rear surfaces of 5 μm thickness stainless steel targets were obtained at the wavelength range 1.7-2.1 Å, for the first time in experiments at femtosecond petawatt laser facility J-KAREN-P. Total intensity of front x-ray spectra three times dominates to rear side spectra for maximum laser intensity I ≈ 3.21021 W/cm2. Growth of x-ray emission is mostly determined by contribution of bremsstrahlung radiation that allowed estimating bulk electron plasma temperature for various magnitude of laser intensity on target.
- ItemX-ray spectroscopy of super-intense laser-produced plasmas for the study of nonlinear processes. Comparison with PIC simulations(Bristol : IOP Publ., 2017) Dalimier, E.; Ya Faenov, A.; Oks, E.; Angelo, P.; Pikuz, T.A.; Fukuda, Y.; Andreev, A.; Koga, J.; Sakaki, H.; Kotaki, H.; Pirozhkov, A.; Hayashi, Y.; Skobelev, I.Yu.; Pikuz, S.A.; Kawachi, T.; Kando, M.; Kondo, K.; Zhidkov, A.; Tubman, E.; Butler, N.M.H.; Dance, R.J.; Alkhimova, M.A.; Booth, N.; Green, J.; Gregory, C.; McKenna, P.; Woolsey, N.; Kodama, R.We present X-ray spectroscopic diagnostics in femto-second laser-driven experiments revealing nonlinear phenomena caused by the strong coupling of the laser radiation with the created plasma. Among those nonlinear phenomena, we found the signatures of the Two Plasmon Decay (TPD) instability in a laser-driven CO2 cluster-based plasma by analyzing the Langmuir dips in the profile of the O VIII Lyϵ line, caused by the Langmuir waves created at the high laser intensity 3 1018Wcm-2. With similar laser intensities, we reveal also the nonlinear phenomenon of the Second Harmonic Generation (SHG) of the laser frequency by analyzing the nonlinear phenomenon of satellites of Lyman δ and ϵ lines of Ar XVII. In the case of relativistic laser-plasma interaction we discovered the Parametric Decay Instability (PDI)-induced ion acoustic turbulence produced simultaneously with Langmuir waves via irradiation of thin Si foils by laser intensities of 1021Wcm-2.