J. Mizui

XUV radiation transfer through high-Z metal foil in a laser-produced plasma

Abstract Aluminum and gold foils have been irradiated with 1.05-μm, 100-psec laser pulses at an intensity of 3 × 10 14 W/cm 2 . A spatially resolved spectrum of XUV radiation from a rear-side plasma has been observed in the wavelength range from 10 to 100 A. The spectral intensity for the Al foil decays exponentially with foil thickness and goes to zero at 3 μm. The intensity for the Au foil also decays exponentially up to 1 μm but remains almost constant from 1 to 6 μm. This result for the Au foil indicates that radiation heat conduction plays an important role in energy transport through high- Z plasmas.

Effects of Plasma Motions on Transport of High-Voltage Pulse Power through a Slender Self-Magnetically Insulated Transmission Line

Direct electric power input to a pellet may prove to be the simplest method of compression in inertial confinement fusion. One of the crucial questions about this method, however, is how much power can be transported to the pellet through a slender self-magnetically insulated transmission line (MITL) without a large loss. Experimental results show that the transport efficiency of pulse power is determined by the gap closure time caused by plasma expansion from the anode and the cathode surface of the slender MITL. This implies that a shorter voltage pulse width (10~20 ns) is required for a gap length of a few millimeters to attain a high transport efficiency.

Interaction of Laser and Plasma Investigated by Scattering of Light

The scattered light around the wavelength of the incident laser and its second harmonic was observed experimentally from the laser produced plasma. The experimental data can be understood consistently by the following model that the second harmonic is produced at the resonance (cut off) region, while the fundamental light is reflected from the turning (before cut-off) region. In the former region, the parametric process produces the large amplitude ion wave, which induces the Brillouin scattering. In the latter region the spectrum broadening of the reflected light is introduced by the self-phase modulation due to the temporal change of the plasma density.