scholarly journals Volume ignition of laser driven fusion pellets and double layer effects

1988 ◽  
Vol 6 (2) ◽  
pp. 163-182 ◽  
Author(s):  
L. Cicchitelli ◽  
S. Eliezer ◽  
M. P. Goldsworthy ◽  
F. Green ◽  
H. Hora ◽  
...  

The realization of an ideal volume compression of laser-irradiated fusion pellets (by C. Yamanaka) opens the possibility for an alternative to spark ignition proposed for many years for inertial confinement fusion. A re-evaluation of the difficulties of the central spark ignition of laser driven pellets is given. The alternative volume compression theory, together with volume burn and volume ignition (discovered in 1977), have received less attention and are re-evaluated in view of the experimental verification by Yamanaka, generalized fusion gain formulas, and the variation of optimum temperatures derived at self-ignition. Reactor-level DT fusion with MJ-laser pulses and volume compression to 50 times the solid-state density are estimated. Dynamic electric fields and double layers at the surface and in the interior of plasmas result in new phenomena for the acceleration of thermal electrons to suprathermal electrons. Double layers also cause a surface tension which stabilizes against surface wave effects and Rayleigh–Taylor instabilities.

2003 ◽  
Vol 69 (5) ◽  
pp. 413-429 ◽  
Author(s):  
H. HORA ◽  
G. H. MILEY ◽  
F. OSMAN ◽  
P. EVANS ◽  
P. TOUPS ◽  
...  

Compression of plasmas with laser pulses in the 10-kJ range produced densities in the range of 1000 times that of the solid state, where however the temperatures within a few hundred eV were rather low. This induced the fast ignitor scheme for central or peripheral deposition of some 10-kJ ps laser pulses on conventional $n_{\rm s}$-precompressed DT plasma of 3000 times solid-state density. We present results where the ps ignition is avoided and only a single-event conventional compression is used. Following our computations of volume ignition and the excellent agreement with measured highest fusion gains of volume compression, we found conditions where compression to 5000 times that of the solid state and by using laser pulses of 10 MJ produce volume ignition with temperatures between 400 and 800 eV only for high-gain volume ignition.


2008 ◽  
Vol 26 (2) ◽  
pp. 241-248 ◽  
Author(s):  
L. Romagnani ◽  
M. Borghesi ◽  
C.A. Cecchetti ◽  
S. Kar ◽  
P. Antici ◽  
...  

AbstractThe use of laser-accelerated protons as a particle probe for the detection of electric fields in plasmas has led in recent years to a wealth of novel information regarding the ultrafast plasma dynamics following high intensity laser-matter interactions. The high spatial quality and short duration of these beams have been essential to this purpose. We will discuss some of the most recent results obtained with this diagnostic at the Rutherford Appleton Laboratory (UK) and at LULI - Ecole Polytechnique (France), also applied to conditions of interest to conventional Inertial Confinement Fusion. In particular, the technique has been used to measure electric fields responsible for proton acceleration from solid targets irradiated with ps pulses, magnetic fields formed by ns pulse irradiation of solid targets, and electric fields associated with the ponderomotive channelling of ps laser pulses in under-dense plasmas.


1992 ◽  
Vol 10 (1) ◽  
pp. 145-154 ◽  
Author(s):  
P. Pieruschka ◽  
L. Cicchitelli ◽  
R. Khoda-Bakhsh ◽  
E. Kuhn ◽  
G. H. Miley ◽  
...  

Since DT laser fusion with 10-MJ laser pulses for 1000-MJ output now offers the physics solution for an economical fusion energy reactor, the conditions are evaluated assuming that controlled ICF reactions will become possible in the future using clean nuclear fusion fuel such as deuterium-helium(3) or hydrogen-boron(11). Using the transparent physics mechanisms of volume ignition of the fuel capsules, we show that the volume ignition for strong reduction of the optimum initial temperature can be reached for both types of fuels if a compression about 100 times higher than those in present-day laser compression experiments is attained in the future. Helium(3) laser-pulse energies are then in the same range as for DT, but ten times higher energies will be required for hydrogenboron(11).


1996 ◽  
Author(s):  
H. Hora ◽  
S. Eliezer ◽  
J. J. Honrubia ◽  
R. Höpfl ◽  
J. M. Martinez-Val ◽  
...  

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.


2011 ◽  
Vol 18 (5) ◽  
pp. 056308 ◽  
Author(s):  
Peter Amendt ◽  
S. C. Wilks ◽  
C. Bellei ◽  
C. K. Li ◽  
R. D. Petrasso

Author(s):  
J. Zhang ◽  
W. M. Wang ◽  
X. H. Yang ◽  
D. Wu ◽  
Y. Y. Ma ◽  
...  

While major progress has been made in the research of inertial confinement fusion, significant challenges remain in the pursuit of ignition. To tackle the challenges, we propose a double-cone ignition (DCI) scheme, in which two head-on gold cones are used to confine deuterium–tritium (DT) shells imploded by high-power laser pulses. The scheme is composed of four progressive controllable processes: quasi-isentropic compression, acceleration, head-on collision and fast heating of the compressed fuel. The quasi-isentropic compression is performed inside two head-on cones. At the later stage of the compression, the DT shells in the cones are accelerated to forward velocities of hundreds of km s –1 . The head-on collision of the compressed and accelerated fuels from the cone tips transfer the forward kinetic energy to the thermal energy of the colliding fuel with an increased density. The preheated high-density fuel can keep its status for a period of approximately 200 ps. Within this period, MeV electrons generated by ps heating laser pulses, guided by a ns laser-produced strong magnetic field further heat the fuel efficiently. Our simulations show that the implosion inside the head-on cones can greatly mitigate the energy requirement for compression; the collision can preheat the compressed fuel of approximately 300 g cm −3 to a temperature above keV. The fuel can then reach an ignition temperature of greater than 5 keV with magnetically assisted heating of MeV electrons generated by the heating laser pulses. Experimental campaigns to demonstrate the scheme have already begun. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.


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