Effect of Small Focus on Electron Heating and Proton Acceleration in Ultrarelativistic Laser-Solid Interactions

Dover, N. P.; Nishiuchi, Mamiko; Sakaki, H.; Alkhimova, M. A.; Faenov, A. Ya.; Hata, Masayuki; Iwata, N.; Kiriyama, Hiromitsu; Koga, James; Miyahara, Tetsuhiro; Pikuz, T. A.; Pirozhkov, A. S.; Sagisaka, A.; Sentoku, Y.; Watanabe, Yukinobu; Kando, M.; Kondo, K.

doi:10.1103/physrevlett.124.084802

Cited by 42 publications

(24 citation statements)

References 80 publications

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“…In the case of the data shown in Figure 5, unfortunately the laser intensity on target was 20% of the typical intensity during this experiment, giving rise to a lower-than-expected maximum proton energy of 15.2 ± 0.4 MeV from PW laser irradiation of the Ti target without CW laser heating. For a typical laser intensity (I L ) of 5 × 10 21 W/cm 2 , the maximum proton energy (E p ) can be estimated using the spot-size scaling [34] E p ∝ I L 1/4 , which gives E p~2 0 MeV. This calculation is supported by a previous result where a 5 µm steel tape target was irradiated at 5 × 10 21 W/cm 2 without CW laser heating, under laser conditions comparable to the experiment presented here, and the measured maximum proton energy was in excess of 20 MeV [34].…”

Section: Discussionmentioning

confidence: 99%

“…For a typical laser intensity (I L ) of 5 × 10 21 W/cm 2 , the maximum proton energy (E p ) can be estimated using the spot-size scaling [34] E p ∝ I L 1/4 , which gives E p~2 0 MeV. This calculation is supported by a previous result where a 5 µm steel tape target was irradiated at 5 × 10 21 W/cm 2 without CW laser heating, under laser conditions comparable to the experiment presented here, and the measured maximum proton energy was in excess of 20 MeV [34]. Therefore, it is reasonable to assume that PW laser irradiation at 5 × 10 21 W/cm 2 of the Ti target without CW laser heating would generate a maximum proton energy in the region of~20 MeV, corresponding to a sheath potential of~20 MV.…”

Section: Discussionmentioning

confidence: 99%

“…Accelerated kinetic energies and the corresponding potentials Φ for typical ion species with the CW laser heating. The energy and potential for proton without the heating are estimated using the spot-size scaling [34].…”

Section: Discussionmentioning

confidence: 99%

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High-Intensity Laser-Driven Oxygen Source from CW Laser-Heated Titanium Tape Targets

et al. 2020

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The interaction of high-intensity laser pulses with solid targets can be used as a highly charged, energetic heavy ion source. Normally, intrinsic contaminants on the target surface suppress the performance of heavy ion acceleration from a high-intensity laser–target interaction, resulting in preferential proton acceleration. Here, we demonstrate that CW laser heating of 5 µm titanium tape targets can remove contaminant hydrocarbons in order to expose a thin oxide layer on the metal surface, ideal for the generation of energetic oxygen beams. This is demonstrated by irradiating the heated targets with a PW class high-power laser at an intensity of 5 × 1021 W/cm2, showing enhanced acceleration of oxygen ions with a non-thermal-like distribution. Our new scheme using a CW laser-heated Ti tape target is promising for use as a moderate repetition energetic oxygen ion source for future applications.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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High-Intensity Laser-Driven Oxygen Source from CW Laser-Heated Titanium Tape Targets

et al. 2020

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“…More than 50 MeV (Mega electron Volt) protons [49,50] were obtained with a laser intensity of~10 21 W/cm 2 . At the laser intensity of 5 × 10 21 W/cm 2 , the effect of using a small focus spot on electron heating and proton acceleration were investigated [51], and highly charged high-Z ions were accelerated to over GeV (Giga electron Volt) energies. Laser-plasma acceleration has the possibility to downsize conventional large-accelerator systems.…”

Section: Applications With the J-karen-p Laser Systemmentioning

confidence: 99%

Petawatt Femtosecond Laser Pulses from Titanium-Doped Sapphire Crystal

et al. 2020

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Ultra-high intensity femtosecond lasers have now become excellent scientific tools for the study of extreme material states in small-scale laboratory settings. The invention of chirped-pulse amplification (CPA) combined with titanium-doped sapphire (Ti:sapphire) crystals have enabled realization of such lasers. The pursuit of ultra-high intensity science and applications is driving worldwide development of new capabilities. A petawatt (PW = 1015 W), femtosecond (fs = 10−15 s), repetitive (0.1 Hz), high beam quality J-KAREN-P (Japan Kansai Advanced Relativistic ENgineering Petawatt) Ti:sapphire CPA laser has been recently constructed and used for accelerating charged particles (ions and electrons) and generating coherent and incoherent ultra-short-pulse, high-energy photon (X-ray) radiation. Ultra-high intensities of 1022 W/cm2 with high temporal contrast of 10−12 and a minimal number of pre-pulses on target has been demonstrated with the J-KAREN-P laser. Here, worldwide ultra-high intensity laser development is summarized, the output performance and spatiotemporal quality improvement of the J-KAREN-P laser are described, and some experimental results are briefly introduced.

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“…For fixed laser energy and pulse duration, maximizing the intensity by focusing to a near-wavelengthsized focal spot does not, however, necessarily result in higher-energy ions. Recent studies, involving relatively thick foils, have shown that self-generated magnetic fields [27] and unfavorable changes to the temperature and divergence of the energetic electron population injected into the foil [28] can result in lower-energy TNSA ions compared to that expected from intensity scaling laws.…”

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confidence: 99%

Enhanced laser intensity and ion acceleration due to self-focusing in relativistically transparent ultrathin targets

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et al. 2020

Phys. Rev. Research

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Laser-driven proton acceleration from ultrathin foils is investigated experimentally using f /3 and f /1 focusing. Higher energies achieved with f /3 are shown via simulations to result from self-focusing of the laser light in expanding foils that become relativistically transparent, enhancing the intensity. The increase in proton energy is maximized for an optimum initial target thickness, and thus expansion profile, with no enhancement occurring for targets that remain opaque, or with f /1 focusing to close to the laser wavelength. The effect is shown to depend on the drive laser pulse duration.

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Effect of Small Focus on Electron Heating and Proton Acceleration in Ultrarelativistic Laser-Solid Interactions

Cited by 42 publications

References 80 publications

High-Intensity Laser-Driven Oxygen Source from CW Laser-Heated Titanium Tape Targets

High-Intensity Laser-Driven Oxygen Source from CW Laser-Heated Titanium Tape Targets

Petawatt Femtosecond Laser Pulses from Titanium-Doped Sapphire Crystal

Enhanced laser intensity and ion acceleration due to self-focusing in relativistically transparent ultrathin targets

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