Research

Current Research projects

  • Short-pulse laser matter interaction
  • Inertial confinement fusion, Fast Ignition laser fusion
  • Diagnostic developments for high energy density plasma
  • Numerical studies on high energy density plasma

Short-pulse laser matter interaction
Interaction of an intense, short-pulse laser (> 10^19 W/cm^2) with solids generates a significant number of energetic electrons predominantly by the laser electric fields. The MeV energy electrons play an central role in applications such as hard x-ray generation, charged particle acceleration and heating source for Fast Ignition Laser Fusion. Characterization and optimization of the fast electrons are important to meet the goal of each application, but generation of fast electrons is only broadly understood. Characterization of the fast electrons is the first step to understand the physics of short-pulse laser matter interaction. We perform experiments to determine the electron characteristics with a wide variety of laser conditions at various laser facility around the world including a university scale Leopard laser at Nevada Terawatt Facility, TITAN laser at Lawrence Livermore National Laboratory, OMEGA EP laser at University of Rochester and LFEX laser at Osaka University, Japan.

Ref:
H. Sawada, Y. Sentoku, A. Bass, B. Griffin, R. Pandit, F. Beg, H. Chen, H. Mclean, A.J. Link, P.K. Patel, and Y. Ping, J. Phys. B At. Mol. Opt. Phys. 48, 224008 (2015)


Inertial confinement fusion, Fast Ignition ans Shock Ignition laser fusionscreen-shot-2016-10-22-at-5-29-10-pm
Inertial Confinement fusion (ICF), or known as “Laser fusion”, is a way to create thermonuclear fusion plasma conditions by using high-power lasers. A capsule filled with fusion fuel (Deuterium and Tritium or Deuterium only) is irradiated by lasers or x-rays. The surface of the capsule is quickly heated and ablated away, generating force pushing the shell inward. Convergence of the shell compresses and heats the fuel gas to the ignition temperature, initiating thermonuclear fusions. The key parameters to achieve ignition is the core temperature and cold fuel areal density. In Fast ignition scheme, the compressed core is rapidly heated by energetic charged particles (electrons, protons and/or ions).We study the fuel assembly of direct-drive laser-fusion and Fast ignition type  capsules.

Refs:
H. Sawada, S. Lee, T. Shiroto, H. Nagatomo, Y. Arikawa et al., Appl. Phys. Lett. 108, 254101 (2016).
L.C. Jarrott, M.S. Wei, C. McGuffey, A.A. Solodov, W. Theobald et al., Nat. Phys., 12, 499 (2016).


Diagnostic developments for high energy density plasma
A variety of diagnostics to understand laser-plasma interaction and laser fusion capsules has been developed including visible, UV, x-ray, particle and nuclear products measurements. We have been developing x-ray diagnostics using an intense short-pulse laser. One example is development of monochromatic flash x-ray radiography using a short-pulse laser.

Ref:
H. Sawada, T. Daykin, H.S. McLean, H. Chen, P.K. Patel, Y. Ping, and F. Pérez, Rev. Sci. Instrum. 88, 63502 (2017).
H. Sawada, S. Fujioka, T. Hosoda, Z. Zhang, Y. Arikawa, H. Nagatomo, H. Nishimura, A. Sunahara, W. Theobald, P.K. Patel, and F.N. Beg, J. Phys. Conf. Ser. 717, 12112 (2016).


Numerical studies on high energy density plasma
Numerical simulations play an important role in understanding non-equilibrium plasma created by high-intensity, short-pulse lasers. To simulate fast electron transport and generation of hard x-rays, we perform particle and hybrid particle simulations with implicit particle-in-cell, multi-dimensional hybrid-PIC and Monte Carlo codes in collaboration with Prof. Y. Sentoku. Some of our publications using these simulations are following:

screen-shot-2016-10-22-at-5-27-37-pm

Ref:
H. Sawada and H. Sakagami, Phys. Plasmas (2017)
H. Sawada, D.P. Higginson, A. Link, T. Ma, S.C. Wilks, H.S. McLean, F. Pérez, P.K. Patel, and F.N. Beg, Phys. Plasmas (2012).


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