Thermonuclear Fusion Plasma by Lasers Coupling and Implosion
The current problems of the laser fusion research are to get fundamental understanding of (i) the coupling of laser-plasma due to various interactions and (ii) the implosion process of pellet targets.
To pursue these objectives, the high power laser systems of various wave lengths have been constructed. A glass laser system of 4 beams, “Gekko IV” using a new phosphate glass, LHG-5 has been constructed. The output energy is lkJ in one nanosecond and 300J in 100 picosecond. The focusable size of each beam is 50μm in diameter. An E-beam controlled CO2 laser system, “Lekko I” can deliver 500J in nanosecond. The multiband multiline oscillator is tested to increase the energy extraction. Saturation energy of the laser increases about 60%. The PFN capacitor bank is successfully employed to the main pumping discharge with perfect loading.
As for the laser-plasma coupling, the importance of resonance absorption, its relation to self generated magnetic fields and high energetic ion jet stream, self modulation of the density profile, and the influence of density scale length on the parametric instability related to the Brillouin backscattering are investigated. Using the lasers of 1μm and 10μm in wave length, we can clarify a scaling law of the interaction processes. A model of generation of fast ion jet stream is examined. The neutron yield in plasma focus is enhanced about two times by a strong absorption of the CO2 laser beam.
As for the implosion experiment, various targets with multi-layers have been studied considering the energy flow of radiation. The enhanced transmission of light is found (Ausaka effect). The compression of deuterium filled microballoon is estimated up to 100. The neutron yield is about 105.
KeywordsBlast Wave Phosphate Glass Saturable Absorber Plasma Focus Neutron Yield
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