| Research Abstract |
Purpose of the project is production of a super high energy density plasma(>10^4 J/cm^3) and elucidation of the mechanism of the highly intense soft X-ray generation in a plasma. We investigated the plasma developing diagnostic tools for non-contact and 2-dimensional imaging methods with high spatial and temporal resolution. They are ; (1) A multichannel (including infra red, visible and soft X-rays) imaging system built by a new concept without using an image converter tube. The system enables to record a pulsed soft X-ray image in streak and framing mode simultaneously. (2) A geted pinhole camera system based on an MCP for successive four framing images of 200 ps in exposure time, 2.5 ns in interframe lime and 0.1 mm in spatial resolution. (3) A soft X-ray imaging spectrometer with a convex crystal (RbAP, r = 12.5 mm).
Using the plasma focus facility with the gas puff, puffed neon, argon and krypton are strongly compressed by the discharge current. The electron temperature and the electron density were -2 keV and -10 ^<22>/cm^3 (energy density >3 x 10 ^4 J/cm^4), respectively. The life time of the plasma column was several times longer than that of an ordinary (gas embedded) plasma focus. For a puffed gas with a lower atomic number like neon, the soft X-rays were emitted before disruption of the pinched column by a growth of macroscopic instability seemed to be m=0 type. On the contrary, the soft X-ray emission occurred after disruption of the pisma column when argon or krypton is puffed. This coincided to generation of the ion and electron beam which were accelerated by a high voltage induced by disruption of the plasma column. The facts suggest that the plasma is sufficiently heated only by the compression to the temperature to radiate the K-shall lines in neon. However, in argon and kripton heating is not sufficient by compression, and the beam plasma interaction is indispensable for K-shall radiation.
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