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Brillouin backscattering from laser-produced plasmas of hydrogen and deuterium has shown an isotope effect in the red-side region of the generated second-harmonic light. This isotope shift is explained by the parametric instability at the cutoff region using the phase-matching condition of the waves. The decrease of the reflectivity appeared when the laser intensity increased up to 1 order of magnitude larger than the threshold of the parametric instability. A broad-band laser showed more effective heating of the plasma than a narrow-band laser.

Characteristics of a high power double discharge TEA CO2 laser are described. The laser output energy is more than 20 J and the laser peak power is more than 0.2GW. The gain coefficient measured at the center of discharge is 4-4.5% cm-1. In this paper, the adding effect of Xylene for the uniform discharge and for the laser peak power is also reported.

As lasers have an ability to deliver a large amount of energy very rapidly to matter, one can produce a plasma of thermonuclear temperature by laser bombardment of matter. We observed a neutron yield from a solid deuterium target irradiated by the beam of a glass laser, which had a power of 20 GW for 2 nsec. The theoretically estimated threshold laser power for anomalous heating owing to the parametric instability was in agreement with the experimental result. Above this threshold, an increase in the electron temperature, the appearance of a fast-ion group, and an anomaly in the reflection of light from the plasma were observed. These phenomena were closely correlated with the neutron yield. At the high-temperature region above a few hundred electron volts, the anomalous heating plays an essential role in reaching the fusion-reaction temperature.

The results are given of investigations of the damage to laser glasses by high-power radiation, the use of liquid lasers as light amplifiers, and the application of high-power lasers in plasma heating. A description is given of a new method for the rapid measurement of the temperature and density of a plasma on the basis of the Thomson scattering of light. A complex structure is reported for the central ion peak in the spectrum of the scattered light. It is also reported that 20 neutrons are emitted from solid targets after irradiation with a single laser pulse.

High power double discharge type TEA CO 2 laser was used to study laser plasma interaction on carbon target plasma. The maximum output power was 0.3 GW and full width at half maximum intensity was 100 ns. We measured the reflectivity of the laser light at 10.6 μm in wavelength from the carbon plasma. The reflectivity showed a maximum (≈56%) at the laser power intensity of about 1.1 x 10 10 W/cm 2 , and at above this value, the reflectivity decreased. The absorption was introduced effectively above this intensity. The electron density and temperature were also measured.

High power double discharge type TEA CO2 laser was used to study laser plasma interaction on carbon target plasma. The output power was 0.3 GW and full with at half maximum was 100ns. We measured the reflectivity of the 10.6, μm laser light from the carbon plasma. From the experimental result, thereflectivity was maximum (≈56%) at the laser power density of about 4.4×1010W/cm2, and at above its power density, the reflectivity was decreased. We found that the absorption was edoccur effectively at this power density region.

By using 10.6 μm infrared CO2 laser radiation, electron density measurement of steady TP-D plasma was carried out with forward (θ=30°) and backward (θ=171°) scattering, and interferometry method. Electron densities measured by both methodS as a function of discharge current of TP-D plasma show fairly good agreement.

Spatial phase modulation of laser beam by plasma is computed by two-dimensional configuration. It is possible to estimate an electron density from experimentally measured refraction of CO 2 laser beam by plasma.