Abstract
Reported are the interactions of 0.53 μm laser pulse with millimeter-scale plasmas that are produced with gas-bag target irradiated with 0.35 μm laser pulses. The generated plasmas are characterized with collective Thomson scattering and space- and time-resolved X-ray images. The density of the plasmas is about 0.1 n c corresponding to the 0.53 μm laser beam, and the temperature is about 0.64 keV with a filling gas of C5 H12 . The interaction laser beam can output 1.0 kJ energy within the duration of 1 ns at the wavelength of 0.53 μm, leading to a nominal intensity less than 1.5 × 1015 W/cm2 . The reflectivity of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) is measured with a full aperture backscatter system. The experimental results show than the reflectivity of SBS is less than 5% and that of SRS is less than 1%. It is a positive result with respect to using 0.53 μm lasers as drivers for laser fusion.
Highlights
Blue laser beams with a wavelength of 0.35 m have been extensively used for the experimental research of inertial confinement fusion for more than two decades [1], and are employed to achieve ignition [2] because of their higher inverse bremsstrahlung absorption efficiency and lower level of laserplasma instabilities (LPIs) in comparison with those with longer wavelength [3]
If the LPIs driven by green laser beams could remain at an acceptable level, high-gain capsule may be ignited with green lasers
We present the investigation on the interaction of green laser pulse with millimeterscale plasmas produced by gasbag target
Summary
Blue laser beams with a wavelength of 0.35 m have been extensively used for the experimental research of inertial confinement fusion for more than two decades [1], and are employed to achieve ignition [2] because of their higher inverse bremsstrahlung absorption efficiency and lower level of laserplasma instabilities (LPIs) in comparison with those with longer wavelength [3]. The price of ultraviolet beams is high: rather low frequency conversion efficiency and serious damage problem for the optic components in the final optic assembly, that limit the maximum energy output capability. Due to the higher frequency conversion efficiency and the higher damage threshold on optics, the beam energy of green laser with a wavelength of 0.53 m can exceed the value by the factor of 1.5 in comparison with that of blue laser. There are only a few articles addressing this subject [5,6,7]
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