Hot Electron Temperature and Coupling Efficiency Scaling with Prepulse for Cone-Guided Fast Ignition

2012 ◽  
Vol 108 (11) ◽  
Author(s):  
T. Ma ◽  
H. Sawada ◽  
P. K. Patel ◽  
C. D. Chen ◽  
L. Divol ◽  
...  
1990 ◽  
Vol 8 (3) ◽  
pp. 421-426
Author(s):  
V. Palleschi ◽  
D. P. Singh ◽  
M. A. Harith ◽  
M. Vaselli

Coupling of the core with the surrounding corona of hot electrons produced around the plasma critical surface in a spherically symmetric laser-imploded Z-layered plasma target has been analyzed. Considering that the energy equipartition exists between the cold electrons of the core and the hot coronal electrons in the core–corona overlapping region, the analytic expression for core–corona coupling has been derived. The efficiency of heat transfer from the hot corona to the cold core depends on the laser wavelength, mean electron temperature in the ablation region, and the width of the Z-layer in the plasma pellet. Numerical results indicate that short wavelength lasers are favorable for efficient heating of the core by the surrounding hot corona. The core-corona coupling increases primarily with the mean electron temperature up to a certain extent and beyond that further laser flux transfer to the hot corona results in decoupling of the core from the corona. The presence of Z-layer is likely to reduce the electron mean free path in the ablation region and affects the laser wavelength scaling of the core-corona coupling. It is also found to have positive influence on the maximum coupling efficiency of the core with the hot corona.


2009 ◽  
Vol 102 (4) ◽  
Author(s):  
M. G. Haines ◽  
M. S. Wei ◽  
F. N. Beg ◽  
R. B. Stephens

Author(s):  
Laila Andersson ◽  
Christopher Fowler ◽  
Bob Ergun ◽  
Roger Yelle ◽  
Thomas Edward Cravens ◽  
...  

Author(s):  
Hong-bo Cai ◽  
Si-zhong Wu ◽  
Jun-feng Wu ◽  
Mo Chen ◽  
Hua Zhang ◽  
...  

AbstractWe review the present status and future prospects of fast ignition (FI) research of the theoretical group at the IAPCM (Institute of Applied Physics and Computational Mathematics, Beijing) as a part of the inertial confinement fusion project. Since the approval of the FI project at the IAPCM, we have devoted our efforts to improving the integrated codes for FI and designing advanced targets together with the experimental group. Recent FI experiments [K. U. Akli et al., Phys. Rev. E 86, 065402 (2012)] showed that the petawatt laser beam energy was not efficiently converted into the compressed core because of the beam divergence of relativistic electron beams. The coupling efficiency can be improved in three ways: (1) using a cone–wire-in-shell advanced target to enhance the transport efficiency, (2) using external magnetic fields to collimate fast electrons, and (3) reducing the prepulse level of the petawatt laser beam. The integrated codes for FI, named ICFI, including a radiation hydrodynamic code, a particle-in-cell (PIC) simulation code, and a hybrid fluid–PIC code, have been developed to design this advanced target at the IAPCM. The Shenguang-II upgraded laser facility has been constructed for FI research; it consists of eight beams (in total $24~ {\rm kJ}/3\omega $, 3 ns) for implosion compression, and a heating laser beam (0.5–1 kJ, 3–5 ps) for generating the relativistic electron beam. A fully integrated FI experiment is scheduled for the 2014 project.


2020 ◽  
Vol 34 (32) ◽  
pp. 2050322
Author(s):  
A. L. Vartanian ◽  
A. L. Asatryan ◽  
A. G. Stepanyan ◽  
K. A. Vardanyan ◽  
A. A. Kirakosyan

The energy relaxation of hot electrons is proposed based on the spin–orbit (SO) interaction of both Rashba and Dresselhaus types with the effect of hot phonons. A continuum theory of optical phonons in nanowires taking into account the influence of confinement is used to study the hot-electron energy relaxation. The energy relaxation due to both confined (CO) and interface (IO) optical phonon emission on nanowire radius, electrical field strength, parameters of SO couplings and electron temperature is calculated. For considered values of the nanowire radius as well as other system parameters, scattering by IO phonons prevails over scattering by CO phonons. The presence of an electric field leads to the decrease of power loss in transitions between states with the same spin quantum numbers. With the increase of the electric field strength, the influence of the Dresselhaus SO interaction on the energy relaxation rate decreases. The effect of SO interaction does not change the previously obtained increasing dependence of power loss on electron temperature. The sensitivity of energy relaxation to the electric field also through the Rashba parameter allows controlling the rate of energy by electric field.


2013 ◽  
Vol 31 (4) ◽  
pp. 579-582 ◽  
Author(s):  
Yuqiu Gu ◽  
Jinqing Yu ◽  
Weimin Zhou ◽  
Fengjuan Wu ◽  
Jian Wang ◽  
...  

AbstractIn fast ignition of inertial confinement fusion, hot electron beam is considered to be an appropriate energy source for ignition. However, hot electrons are divergent as they are transporting in over-dense plasma. So collimating the hot electrons becomes one of the most important issues in fast ignition. A method to collimate hot electron beam by external magnetic field is proposed in this paper. The external field can be generated by compressing a seed magnetic field at the stage of laser-driven implosion. This method is confirmed by particle-in-cell simulations. The results show that hot electrons are well collimated by external magnetic field from magnetic-flux compression.


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