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The guiding of laser ablation plasmas with axial magnetic fields has been used for many applications, since its effectiveness has been proven empirically [L. Gray et al., J. Appl. Phys. 53(10), 6628 (1982); J. Wolowski, Laser Part. Beams 20(01), 113 (2002); M. Okamura et al., Rev. Sci. Instrum. 81, 02A510 (2010); Y. Tsui et al., Appl. Phys. Lett. 70(15), 1953 (1997); C. Pagano and J. Lunney, J. Phys. D: Appl. Phys. 43(30), 305202 (2010)]. For more sophisticated and complicated manipulations of the plasma flow, the behavior of the magnetic field during the interaction and the induced diamagnetic current in the plasma plume needs to be clearly understood. To achieve the first milestone for establishing magnetic plasma manipulation, we measured the spatial and temporal fluctuations of the magnetic field caused by the diamagnetic current. We showed that the small fluctuations of the magnetic field can be detected by using a simple magnetic probe. We observed that the field penetrates to the core of the plasma plume. The diamagnetic current estimated from the magnetic field had temporal and spatial distributions which were confirmed to be correlated with the transformation of the plasma plume. Our results show that the measurement by the magnetic probe is an effective method to observe the temporal and spatial distributions of the magnetic field and diamagnetic current. The systematic measurement of the magnetic field variations is a valuable method to establish the magnetic field manipulation of the laser ablation plasma. [ABSTRACT FROM AUTHOR]

Discharge produced plasma (DPP) is a promising tool to generate effective extreme ultraviolet (EUV) light. A hydrogen-like nitrogen ion emits light at 13.4 nm with an optical allowed atomic transition from n = 3 to 2, where n stands for a principal quantum number. We focus on the properties of population inversion between n =3 and 2 in recombining phase. Population inversion is calculated in the framework of population kinetics, and a gain coefficient G is estimated. In this study, dielectronic-capture ladderlike (DL) processes are included. At high density and low temperature, the DL deexcitations make a large contribution to the population inversion.

We proposed tapered pinch discharge as a measure to conduct laboratory astrophysics experiments. Basic behaviors of the plasma have been characterized using a prototype device. Results show that the plasma flux and velocity depend on initial gas density, discharge current and taper geometry. Those behaviors can be illustrated with a simple model considering the pinching dynamics of the current sheet based on a 1 dimensional (1-D) equation of motion. Achievable value of the tapered pinch plasma is estimated and compared with required plasma parameters based on scaling parameters for laboratory astrophysics.

The investigation of the surface morphology changes for Si surfaces treated with CF4/O2 reveals that the rough Si surfaces can be smoothened and Si trench corners can be rounded using CF4/O2 down-flow etching. Down-flow discharged CF4/O2 gas mixture in high O2 concentration etches the Si surface on which the SiFxOy forms. Fluorine atoms are prevented from reacting with Si by the formation of a thick SiFxOy layer at the concave part of the surface.

For measuring the source profile of proton beams, a method using a Thomson mass spectrometer, which has precise energy resolution and enables the discrimination of ion species, was proposed and applied in an experiment with irradiation of 55-fs, 6.6×1018-W/cm2-laser pulses on a 5-mm-thick copper tape target. The typical measured source size was 150 μm at E=400 keV and 44 μm at E=980 keV in full width at half maximum. [ABSTRACT FROM AUTHOR]

Presents laser initiation of an electrical discharge channel in cesium contained gas. Stages of the laser-initiated breakdown of plasma channels; Confirmation of photoionization; Time lags of laser-initiated discharge.

SUMMARY: A laser‐trigger system has been introduced to a pulse power system composed of counter‐facing plasma focus electrodes in order to make high energy density plasma. Lithium plasmas made by a YAG laser ablation were used for both triggering the plasma focus and supplying the source of the high energy density plasma. Also the supply system of plasma source has been improved for stability and repeatability of the device. Operational principle of the device, details of the configuration, and basic characteristics of the triggering system are shown together with possible applications of the device. [ABSTRACT FROM AUTHOR]