scholarly journals Generation of pre-formed plasma and its reduction for fast-ignition

2012 ◽  
Vol 30 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Atsushi Sunahara ◽  
Tomoyuki Johzaki ◽  
Hideo Nagatomo ◽  
Kunioki Mima

AbstractWe investigated generation of pre-formed plasma on plates and inside cone targets due to a pre-pulse before the arrival of the main ultra-intense laser pulse in the fast-ignition scheme of the inertial confinement fusion. We estimated the pre-pulse level to be 130 mJ for LFEX laser used in the 2009 FIREX experiment, and the density gradient scale length of the pre-formed plasma inside the cone target to be 27–47 microns between the critical and 1/10 of the critical density, based on the two-dimensional radiation hydrodynamic simulations. In order to reduce the generation of pre-formed plasma, we investigated a thin CH foil pre-pulse absorber, and proposed using a cone target with a pointed tip. We simulated CH plasma expansion to show that the CH foils works as a pre-pulse absorber. We also show the aluminum pointed tip of the cone target can delay the shock arrival time by 20 ps, much longer than the delay for the 10 micron thickness gold tip used in the typical implosion of GXII at Osaka University.

Author(s):  
E. Boella ◽  
R. Bingham ◽  
R. A. Cairns ◽  
P. Norreys ◽  
R. Trines ◽  
...  

Two-dimensional particle-in-cell simulations are used to explore collisionless shock acceleration in the corona plasma surrounding the compressed core of an inertial confinement fusion pellet. We show that an intense laser pulse interacting with the long scale-length plasma corona is able to launch a collisionless shock around the critical density. The nonlinear wave travels up-ramp through the plasma reflecting and accelerating the background ions. Our results suggest that protons with characteristics suitable for ion fast ignition may be achieved in this way. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.


Nukleonika ◽  
2015 ◽  
Vol 60 (2) ◽  
pp. 193-198 ◽  
Author(s):  
John Pasley ◽  
I. A. Bush ◽  
Alexander P. L. Robinson ◽  
P. P. Rajeev ◽  
S. Mondal ◽  
...  

Abstract When intense short-pulse laser beams (I > 1022 W/m2, τ < 20 ps) interact with high density plasmas, strong shock waves are launched. These shock waves may be generated by a range of processes, and the relative significance of the various mechanisms driving the formation of these shock waves is not well understood. It is challenging to obtain experimental data on shock waves near the focus of such intense laser–plasma interactions. The hydrodynamics of such interactions is, however, of great importance to fast ignition based inertial confinement fusion schemes as it places limits upon the time available for depositing energy in the compressed fuel, and thereby directly affects the laser requirements. In this manuscript we present the results of magnetohydrodynamic simulations showing the formation of shock waves under such conditions, driven by the j × B force and the thermal pressure gradient (where j is the current density and B the magnetic field strength). The time it takes for shock waves to form is evaluated over a wide range of material and current densities. It is shown that the formation of intense relativistic electron current driven shock waves and other related hydrodynamic phenomena may be expected over time scales of relevance to intense laser–plasma experiments and the fast ignition approach to inertial confinement fusion. A newly emerging technique for studying such interactions is also discussed. This approach is based upon Doppler spectroscopy and offers promise for investigating early time shock wave hydrodynamics launched by intense laser pulses.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jieru Ren ◽  
Zhigang Deng ◽  
Wei Qi ◽  
Benzheng Chen ◽  
Bubo Ma ◽  
...  

Abstract Intense particle beams generated from the interaction of ultrahigh intensity lasers with sample foils provide options in radiography, high-yield neutron sources, high-energy-density-matter generation, and ion fast ignition. An accurate understanding of beam transportation behavior in dense matter is crucial for all these applications. Here we report the experimental evidence on one order of magnitude enhancement of intense laser-accelerated proton beam stopping in dense ionized matter, in comparison with the current-widely used models describing individual ion stopping in matter. Supported by particle-in-cell (PIC) simulations, we attribute the enhancement to the strong decelerating electric field approaching 1 GV/m that can be created by the beam-driven return current. This collective effect plays the dominant role in the stopping of laser-accelerated intense proton beams in dense ionized matter. This finding is essential for the optimum design of ion driven fast ignition and inertial confinement fusion.


2010 ◽  
Vol 104 (5) ◽  
Author(s):  
A. G. MacPhee ◽  
L. Divol ◽  
A. J. Kemp ◽  
K. U. Akli ◽  
F. N. Beg ◽  
...  

2009 ◽  
Vol 56 (1) ◽  
pp. 401-404 ◽  
Author(s):  
Y. Nakao ◽  
M. Katsube ◽  
T. Ohmura ◽  
Y. Saito ◽  
T. Johzaki ◽  
...  

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