Faculty Profiles - Nakai Mitsuo

Papers - Nakai Mitsuo

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Improvement in the heating efficiency of fast ignition inertial confinement fusion through suppression of the preformed plasma Reviewed

Y. Arikawa, S. Kojima, A. Morace, M. Hata, S. Sakata, S. Fujioka, T. Kawashima, Y. Hironaka, K. Shigemori, Y. Abe, Z. Zhang, X. Vaisseau, S. Lee, T. Gawa, K. Matsuo, K. F. F. Law, Y. Kato, S. Matsubara, S. Tosaki, A. Yogo, H. Nagatomo, S. Tokita, Y. Nakata, T. Jitsuno, N. Miyanaga, J. Kawanaka, Y. Fujimoto, K. Yamanoi, T. Norimatsu, M. Nakai, H. Nishimura, H. Shiraga, H. Azechi, A. Sunahara, T. Johzaki, T. Ozaki, H. Sakagami

NUCLEAR FUSION 57 ( 6 ) 2017.6

The study of fast electron spectrum optimization by suppression of preformed plasma in fast ignition targets is presented in this work. Integrated fast-electron spectra for electron energies below 3 MeV-the energy range responsible for core heating-are compared for different preformed plasma conditions. The pulse contrast (the ratio of peak-to-pedestal laser intensities) is compared for 10(8), 10(9) and 10(11) conditions at constant laser energy (similar to 500 J), pulse duration (2 ps), spot size (30% encircled energy on 50 mu m diameter) and laser intensity (around 1 x 10(19) W cm(-2)). The best electron spectrum optimization, consisting of maximized electron number for energies below 3 MeV was obtained with 14 mu m thick cone targets. The energy coupling efficiency from heating laser to core plasma, assuming typical core plasma parameters, was estimated to be 2%, although 0.37% was obtained with previous conditions with poor pulse contrast and a 7 mu m thick cone target.

High pressure band gap modification of LiCaAlF6 Reviewed

Toshihiko Shimizu, Mui Viet Luong, Marilou Cadatal-Raduban, Melvin John F. Empizo, Kohei Yamanoi, Ren Arita, Yuki Minami, Nobuhiko Sarukura, Nakai Mitsuo, Hiroshi Azechi, Minh Hong Pham, Hung Dai Nguyen, Kouhei Ichiyanagi, Shunsuke Nozawa, Ryo Fukaya, Shin-ichi Adachi, Kazutaka G. Nakamura, Kentaro Fukuda, Yoshiyuki Kawazoe, Krista G. Steenbergen, Peter Schwerdtfeger

APPLIED PHYSICS LETTERS 110 ( 14 ) 2017.4

First-principles density functional calculations together with experimental measurements demonstrate that pressure (uniform and uniaxial) increases the band gap of a perfect lithium hexafluoroaluminate (LiCaAlF6, LiCAF) crystal. As fluoride crystals can be highly transmitting at vacuum ultraviolet wavelengths, crystal modifications that further increase the band gap are highly sought after for future Vacuum ultraviolet applications. Through an extensive series of density functional theory simulations, we demonstrate that the band gap increases monotonically from 12.2 eV to 14.1 eV with the application of uniform pressure. Through joint theoretical and experimental investigation, we explore different uniaxial compressions that can be achieved through cutting-edge laser-shock compression. We find that uniaxial pressure also increases the LiCAF band gap by 0.3 and 0.4 eV for a-and c-axis compressions, respectively. Published by AIP Publishing.

Boosting laser-ion acceleration with multi-picosecond pulses Reviewed

A. Yogo, K. Mima, N. Iwata, S. Tosaki, A. Morace, Y. Arikawa, S. Fujioka, T. Johzaki, Y. Sentoku, H. Nishimura, A. Sagisaka, K. Matsuo, N. Kamitsukasa, S. Kojima, H. Nagatomo, M. Nakai, H. Shiraga, M. Murakami, S. Tokita, J. Kawanaka, N. Miyanaga, K. Yamanoi, T. Norimatsu, H. Sakagami, S. V. Bulanov, K. Kondo, H. Azechi

SCIENTIFIC REPORTS 7 2017.2

Using one of the world most powerful laser facility, we demonstrate for the first time that high-contrast multi-picosecond pulses are advantageous for proton acceleration. By extending the pulse duration from 1.5 to 6 ps with fixed laser intensity of 10(18) W cm(-2), the maximum proton energy is improved more than twice (from 13 to 33 MeV). At the same time, laser-energy conversion efficiency into the MeV protons is enhanced with an order of magnitude, achieving 5% for protons above 6 MeV with the 6 ps pulse duration. The proton energies observed are discussed using a plasma expansion model newly developed that takes the electron temperature evolution beyond the ponderomotive energy in the over picoseconds interaction into account. The present results are quite encouraging for realizing ion-driven fast ignition and novel ion beamlines.

Large-aperture fast-neutron imaging detector with 10-ns time resolution Reviewed

Y. Arikawa, S. Matsubara, Y. Abe, Y. Kato, H. Kishimoto, A. Yogo, H. Nishimura, M. Nakai, H. Shiraga, S. Fujioka, H. Azechi, Y. Otake, K. Mima, Y. Honda

SELECTED PAPERS FROM THE 31ST INTERNATIONAL CONGRESS ON HIGH-SPEED IMAGING AND PHOTONICS 10328 2017

Fast neutrons, which are neutrons with energies greater than 1 MeV, are expected to be a source of nondestructive inspection for a large-size infrastructure such as a bridge girder because of their mean free path exceeding the meter. A neutron-imaging device with 10-ns time resolution can discriminate pulsed neutrons from X-rays via time of flight. For this purpose, we require a fast-response neutron imager with large aperture and high image resolution.
A neutron-imaging device with time resolution of 10 ns and aperture size of 40 cm x 60 cm was developed. It was filled with fast response liquid scintillator [1] in an aluminum honeycomb plate, which converts neutrons to optical light images. The scintillation light images were relayed using an optical lens and detected using a fast response image intensified CCD. The detector was tested at an electron linear accelerator (LINAC) facility in Osaka University. A short X-ray pulse (30 ps pulse duration) was generated using LINAC, and X-ray radiograph images were obtained with a 10-ns exposure time duration. The radiograph images were well attenuated within 10-ns from the X-ray injection. A high-energy X-ray image and a neutron radiograph image of a 30-cm thick concrete block with iron blocks located behind it were successfully observed. This promising technique could facilitate nondestructive inspection of large concrete constructions.

Ablation-erosion analyses of various fusion material surfaces and developments of surface erosion monitors for notification of fusion chamber maintenance times, as an example: Visible light transparent SiC and up-conversion phosphors applied to plasma facing surface structures, useful for versatile purposes to protect and diagnose fusion chambers and so on Reviewed

K. Kasuya, S. Motokoshi, S. Taniguchi, M. Nakai, K. Tokunaga, K. Kolacek, J. Schmidt, O. Frolov, J. Straus, J. Matejicek, A. Choukourov

XXI INTERNATIONAL SYMPOSIUM ON HIGH POWER LASER SYSTEMS AND APPLICATIONS 2016 10254 2017

Two kinds of pulsed lasers in Japan and Czech Republic were used to irradiate various sample materials to investigate the surface erosion thresholds under very hazardous environments including nuclear fusion chambers. The first was ArF laser in ILT and the second was XUV laser in IPP. These data were in-cooperated with our former data to build up our material strength data for our succeeding applications of various materials to a variety of fields. As an example, we proposed surface erosion monitors to notice the fusion chamber maintenance times with which the facilities can be protected from the collapses under very severe operation conditions. These kinds of monitors are expected to be useful for future different kinds of mechanical structures not only for the fusion chambers but also various chambers for many purposes. Special up-conversion phosphors are also newly proposed to be used as the candidate materials to measure the thermal inputs onto the front surfaces of the armor structures. Optical transparent SiC was also newly tested to enrich our data base for our future diagnostic and protection possibilities.

Radio-chromic Film calibration to diagnose laser accelerated protons Reviewed

Kamitsukasa N., Tosaki S., Yogo A., Tojo S., Takahisa K., Aoi N., Fukuda M., Nakai M., Shiraga H., Azechi H., Morace A., Arikawa Y., Abe Y., Kato H., Gawa T., Matsubara S., Nakajima N., Law F.

Meeting Abstracts of the Physical Society of Japan 72 ( 0 ) 924 - 924 2017

Ultrahigh-contrast kilojoule-class petawatt LFEX laser using a plasma mirror Reviewed

Yasunobu Arikawa, Sadaoki Kojima, Alessio Morace, Shohei Sakata, Takayuki Gawa, Yuki Taguchi, Yuki Abe, Zhe Zhang, Xavier Vaisseau, Seung Ho Lee, Kazuki Matsuo, Shota Tosaki, Masayasu Hata, Koji Kawabata, Yuhei Kawakami, Masato Ishida, Koichi Tsuji, Satoshi Matsuo, Noboru Morio, Tetsuji Kawasaki, Shigeki Tokita, Yoshiki Nakata, Takahisa Jitsuno, Noriaki Miyanaga, Junji Kawanaka, Hideo Nagatomo, Akifumi Yogo, Mitsuo Nakai, Hiroaki Nishimura, Hiroyuki Shiraga, Shinsuke Fujioka, Hiroshi Azechi, Atsushi Sunahara, Tomoyuki Johzaki, Tetsuo Ozaki, Hitoshi Sakagami, Akito Sagisaka, Koichi Ogura, Alexander S. Pirozhkov, Masaharu Nishikino, Kiminori Kondo, Shunsuke Inoue, Kensuke Teramoto, Masaki Hashida, Shuji Sakabe

APPLIED OPTICS 55 ( 25 ) 6850 - 6857 2016.9

Laser pulse contrast exceeding 1011 was demonstrated on a kilojoule-class petawatt laser for fast ignition experiments (LFEX) laser system [J. Phys. IV France 133, 81 (2006)] by implementing a 2 in. plasma mirror. Laser beams of up to 1.2 kJ striking the plasma mirror with a pulse duration of 1.5 ps were reflected and focused onto a target without significant distortions in the focal spot. Transmitted light from the plasma mirror reveals that it has a high reflectivity 2 ps before the main peak. The estimated laser pulse contrast at the target was 1011 at 1 ns before the main peak. No preformed plasma was observed with optical interferometry diagnostics, but in the experiment without a plasma mirror a preplasma was clearly observed. The energetic proton was generated from a 0.1 mu m thick CH film showing excellent pulse contrast. This technique constitutes a promising method to enhance the LFEX laser system performance in fast ignition experiments. (C) 2016 Optical Society of America

Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field Reviewed

Shinsuke Fujioka, Yasunobu Arikawa, Sadaoki Kojima, Tomoyuki Johzaki, Hideo Nagatomo, Hiroshi Sawada, Seung Ho Lee, Takashi Shiroto, Naofumi Ohnishi, Alessio Morace, Xavier Vaisseau, Shohei Sakata, Yuki Abe, Kazuki Matsuo, King Fai Farley Law, Shota Tosaki, Akifumi Yogo, Keisuke Shigemori, Yoichiro Hironaka, Zhe Zhang, Atsushi Sunahara, Tetsuo Ozaki, Hitoshi Sakagami, Kunioki Mima, Yasushi Fujimoto, Kohei Yamanoi, Takayoshi Norimatsu, Shigeki Tokita, Yoshiki Nakata, Junji Kawanaka, Takahisa Jitsuno, Noriaki Miyanaga, Mitsuo Nakai, Hiroaki Nishimura, Hiroyuki Shiraga, Kotaro Kondo, Mathieu Bailly-Grandvaux, Claudio Bellei, Joao Jorge Santos, Hiroshi Azechi

PHYSICS OF PLASMAS 23 ( 5 ) 2016.5

A petawatt laser for fast ignition experiments (LFEX) laser system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 laser beams, has been constructed beside the GEKKO-XII laser facility for demonstrating efficient fast heating of a dense plasma up to the ignition temperature under the auspices of the Fast Ignition Realization EXperiment (FIREX) project [H. Azechi et al., Nucl. Fusion 49, 104024 (2009)]. In the FIREX experiment, a cone is attached to a spherical target containing a fuel to prevent a corona plasma from entering the path of the intense heating LFEX laser beams. The LFEX laser beams are focused at the tip of the cone to generate a relativistic electron beam (REB), which heats a dense fuel core generated by compression of a spherical deuterized plastic target induced by the GEKKO-XII laser beams. Recent studies indicate that the current heating efficiency is only 0.4%, and three requirements to achieve higher efficiency of the fast ignition (FI) scheme with the current GEKKO and LFEX systems have been identified: (i) reduction of the high energy tail of the REB; (ii) formation of a fuel core with high areal density using a limited number (twelve) of GEKKOXII laser beams as well as a limited energy (4 kJ of 0.53-mu m light in a 1.3 ns pulse); (iii) guiding and focusing of the REB to the fuel core. Laser-plasma interactions in a long-scale plasma generate electrons that are too energetic to efficiently heat the fuel core. Three actions were taken to meet the first requirement. First, the intensity contrast of the foot pulses to the main pulses of the LFEX was improved to > 10(9). Second, a 5.5-mm-long cone was introduced to reduce pre-heating of the inner cone wall caused by illumination of the unconverted 1.053-mu m light of implosion beam (GEKKO-XII). Third, the outside of the cone wall was coated with a 40-mu m plastic layer to protect it from the pressure caused by imploding plasma. Following the above improvements, conversion of 13% of the LFEX laser energy to a low energy portion of the REB, whose slope temperature is 0.7 MeV, which is close to the ponderomotive scaling value, was achieved. To meet the second requirement, the compression of a solid spherical ball with a diameter of 200-mu m to form a dense core with an areal density of similar to 0.07 g/cm(2) was induced by a laser-driven spherically converging shock wave. Converging shock compression is more hydrodynamically stable compared to shell implosion, while a hot spot cannot be generated with a solid ball target. Solid ball compression is preferable also for compressing an external magnetic field to collimate the REB to the fuel core, due to the relatively small magnetic Reynolds number of the shock compressed region. To meet the third requirement, we have generated a strong kilo-tesla magnetic field using a laser-driven capacitor-coil target. The strength and time history of the magnetic field were characterized with proton deflectometry and a B-dot probe. Guidance of the REB using a 0.6-kT field in a planar geometry has been demonstrated at the LULI 2000 laser facility. In a realistic FI scenario, a magnetic mirror is formed between the REB generation point and the fuel core. The effects of the strong magnetic field on not only REB transport but also plasma compression were studied using numerical simulations. According to the transport calculations, the heating efficiency can be improved from 0.4% to 4% by the GEKKO and LFEX laser system by meeting the three requirements described above. This efficiency is scalable to 10% of the heating efficiency by increasing the areal density of the fuel core. Published by AIP Publishing.

Development of Compton X-ray spectrometer for high energy resolution single-shot high-flux hard X-ray spectroscopy Reviewed

Sadaoki Kojima, Takahito Ikenouchi, Yasunobu Arikawa, Shohei Sakata, Zhe Zhang, Yuki Abe, Mitsuo Nakai, Hiroaki Nishimura, Hiroyuki Shiraga, Tetsuo Ozaki, Shuji Miyamoto, Masashi Yamaguchi, Akinori Takemoto, Shinsuke Fujioka, Hiroshi Azechi

REVIEW OF SCIENTIFIC INSTRUMENTS 87 ( 4 ) 2016.4

Hard X-ray spectroscopy is an essential diagnostics used to understand physical processes that take place in high energy density plasmas produced by intense laser-plasma interactions. A bundle of hard X-ray detectors, of which the responses have different energy thresholds, is used as a conventional single-shot spectrometer for high-flux (>10(13) photons/shot) hard X-rays. However, high energy resolution (Delta hv/hv < 0.1) is not achievable with a differential energy threshold (DET) X-ray spectrometer because its energy resolution is limited by energy differences between the response thresholds. Experimental demonstration of a Compton X-ray spectrometer has already been performed for obtaining higher energy resolution than that of DET spectrometers. In this paper, we describe design details of the Compton X-ray spectrometer, especially dependence of energy resolution and absolute response on photon-electron converter design and its background reduction scheme, and also its application to the laser-plasma interaction experiment. The developed spectrometer was used for spectroscopy of bremsstrahlung X-rays generated by intense laser-plasma interactions using a 200 mu m thickness SiO2 converter. The X-ray spectrum obtained with the Compton X-ray spectrometer is consistent with that obtained with a DET X-ray spectrometer, furthermore higher certainly of a spectral intensity is obtained with the Compton X-ray spectrometer than that with the DET X-ray spectrometer in the photon energy range above 5 MeV. (C) 2016 AIP Publishing LLC.

21aCB-3 Energy absorption ratio evaluation by back scattering of LFEX for Fast Ignitor experiment

Gawa T., Arikawa Y., Kojima S., Morace Alessio, Sakata S., Abe Y., Matsuo K., Tosaki S., Law Farley King Fai, Yogo A., Fujioka S., Nishimura H., Nakai M., Ozaki T., Azechi H.

Meeting Abstracts of the Physical Society of Japan 71 914 - 914 2016

22aCB-6 Laser driven neutron generation experiment by using LFEX

Kato Y., Arikawa Y., Abe Y., Matsubara S., Morace Alessio, Yogo A., Nakai M., Nishimura H., Azechi H.

Meeting Abstracts of the Physical Society of Japan 71 983 - 983 2016

21pAP-5 Energy Distribution and Conversion Efficiency of Fast Electrons Generated with Relativistic Intensity Laser Depending on Pre-plasma Scale II

Kojima Sadaoki, Arikawa Yasunobu, Hata Masayasu, Fujioka Shinsuke, Morace Alessio, Vaisseau Xavier, Pirozhkov Alexander, Zhe Zhang, GEKKO& LFEX Team

Meeting Abstracts of the Physical Society of Japan 71 593 - 593 2016

21aCB-4 Simulation study of inner-irradiation of the shell in the fast ignition scheme

Sunahara A., Abe Y., Ozaki T., Johzaki T., Nagatomo H., Arikawa Y., Fujioka S., Sakagami H., Nakai M., Shiraga H., Norimatsu T., Azechi H.

Meeting Abstracts of the Physical Society of Japan 71 915 - 915 2016

Cool-down performance of the new apparatus for fuel layering demonstrations of FIREX targets Reviewed

A. Iwamoto, T. Norimatsu, M. Nakai, H. Sakagami, H. Shiraga, H. Azechi

8TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2013) 688 2016

FIREX targets have been developed under two layering strategies: foam shell and cone guide laser heating methods. Basic studies have been conducted by the collaboration research between ILE and NIFS. Then the next stage requires the characterization of a layered solid fuel. The present system is at the disadvantage of optical observations. Therefore, a new apparatus is designed to solve it. Glass windows with a wide aperture are installed for an interferometer and a microscope. To isolate the vibration from a cryocooler, active vibration control units are equipped, and flexible thermal conductive links are utilized. Furthermore, a quick target exchange mechanism is applied to deal with different types of FIREX targets. A target holder is detachable from a main vacuum chamber. A metal gasket with not fixing bolts but a load of similar to thousand newtons on ensures GHe leak tightness for target cooling. Eventually, the design temperature of 10.00 K at a target container has been achieved. The cool-down performance indecates that the new apparatus provides a cryogenic environment for fuel layering demonstrations.

Energy distribution of fast electrons accelerated by high intensity laser pulse depending on laser pulse duration Reviewed

Sadaoki Kojima, Yasunobu Arikawa, Alessio Morace, Masayasu Hata, Hideo Nagatomo, Tetsuo Ozaki, Shohei Sakata, Seung Ho Lee, Kazuki Matsuo, King Fai Farley Law, Shota Tosaki, Akifumi Yogo, Tomoyuki Johzaki, Atsushi Sunahara, Hitoshi Sakagami, Mitsuo Nakai, Hiroaki Nishimura, Hiroyuki Shiraga, Shinsuke Fujioka, Hiroshi Azechi

9TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2015) 717 2016

The dependence of high-energy electron generation on the pulse duration of a high intensity LFEX laser was experimentally investigated. The LFEX laser (A = 1.054 and intensity = 2.5 3 x 10(18) W/cm(2)) pulses were focused on a 1 mm(3) gold cubic block after reducing the intensities of the foot pulse and pedestal by using a plasma mirror. The full width at half maximum (FWHM) duration of the intense laser pulse could be set to either 1.2 ps or 4 ps by temporally stacking four beams of the LFEX laser, for which the slope temperature of the high-energy electron distribution was 0.7 MeV and 1.4 MeV, respectively. The slope temperature increment cannot be explained without considering pulse duration effects on fast electron generation.

Electron transport estimated from electron spectra using electron spectrometer in LFEX laser target experiments Reviewed

T. Ozaki, M. Hata, K. Matsuo, S. Kojima, Y. Arikawa, S. Fujioka, H. Sakagami, A. Sunahara, H. Nagatomo, T. Johzaki, A. Yogo, A. Morace, Z. Zhang, H. Shiraga, S. Sakata, T. Nagai, Y. Abe, S. Lee, M. Nakai, H. Nishimura, H. Azechi

9TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2015) 717 2016

Hot electrons which are generated from targets irradiated by a high-intense laser are measured by two electron spectrometers (ESMs). However, total electron energy observed by the ESM is only less than 1 %. Hot electrons are confined by self-fields due to the huge current. When an external magnetic field of several hundred Tesla is applied during the laser irradiation on targets, the ESM signals always increase. In the simulation, the same result can be obtained. The reason is that the Alfven limit can be mitigated due to the external longitudinal magnetic field.

Experimental Test of the Polarization Persistence in Inertial Confinement Fusion Reviewed

J. P. Didelez, C. Deutsch, M. Fujiwara, M. Nakai, M. Utsuro

8TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2013) 688 2016

The complete deuteron and triton polarization in the DT fusion increases the reactivity by 50%. For Inertial Confinement Fusion (ICF), due to the dynamics of the fusion reaction process, the fusion rate could even be further increased. It has been argued that the polarization would survive as well in magnetic as in inertial confinements. Recently, we have proposed an experiment to test the persistence of the polarization in a fusion process, using a powerful laser hitting a polarized HD target. The polarized deuterons heated in the plasma induced by the laser can fuse. The corresponding reaction is: D + D -> He-3 + n. The angular distribution of the emitted neutrons and the change in the corresponding total cross section are signatures to estimate the polarization persistency. A proposal to test the persistence of the polarization in ICF has been accepted at ILE: the POLAF project (POlarization in LAser Fusion Process). It uses the polarized HD targets produced at RCNP and the powerful ILE lasers, as well as the neutron detectors existing there. Both institutions are on the same campus at Osaka University. The description of the POLAF experiment and of the corresponding set-up is given.

Mechanical design of experimental apparatus for FIREX cryo-target cooling Reviewed

A. Iwamoto, T. Norimatsu, M. Nakai, H. Sakagami, S. Fujioka, H. Shiraga, H. Azechi

9TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2015) 717 2016

Mechanical design of an experimental apparatus for FIREX cryo-target cooling is described. Gaseous helium (GHe) sealing system at a cryogenic environment is an important issue for laser fusion experiments. The dedicated loading system was designed for a metal gasket. We take U-TIGHTSEAL((R)) (Usui Kokusai Sangyo Kaisha. Ltd.) with an indium plated copper jacket as an example. According to its specification, a linear load of 110 N/m along its circumference is the optimum compression; however a lower load would still maintain helium (He) leak below the required level. Its sealing performance was investigated systematically. Our system demanded 27 N/mm of the load to keep He leak tightness in a cryogenic environment. Once leak tightness was obtained, it could be reduced to 9.5 N/mm.

Mitigation of Laser Imprinting with Diamond Ablator for Direct-Drive Inertial Confinement Fusion Targets Reviewed

K. Shigemori, H. Kato, M. Nakai, R. Hosogi, T. Sakaiya, H. Terasaki, S. Fujioka, A. Sunahara, H. Azechi

8TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2013) 688 2016

We propose a novel scheme to mitigate the initial perturbation imprinting due to irradiation non-uniformity. Diamond was potential candidate for the ablator material for ICF targets due to its stiffness. The stiffness is very important parameter for imprint mitigation because the laser imprint is primary as a function of pressure perturbation due to lase irradiation non-uniformity. We measured the imprint amplitude of diamond foils and plastic (CH) foils. The experimental data suggest the initial imprinting is drastically mitigated for the diamond foils.

Progress Towards a Laser Produced Relativistic Electron-Positron Pair Plasma Reviewed

Hui Chen, J. Bonlie, R. Cauble, F. Fiuza, W. Goldstein, A. Hazi, C. Keane, A. Link, E. Marley, S. R. Nagel, J. Park, R. Shepherd, G. J. Williams, D. D. Meyerhofer, G. Fiksel, D. Barnak, P. Y. Chang, M. Nakai, Y. Arikawa, H. Azechi, S. Fujioka, S. Kojima, N. Miyanaga, T. Morita, T. Nagai, H. Nishimura, T. Ozaki, Y. Sakawa, H. Takabe, Z. Zhang, S. Kerr, R. Fedosejevs, Y. Sentoku, M. P. Hill, D. J. Hoarty, L. M. R. Hobbs, S. F. James

8TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2013) 688 2016

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Papers - Nakai Mitsuo