Absolute Spectral Radiation from 200-ns X-pinch Plasma

Summary form only given. X-pinch plasma is a point-like source of radiation emitting in a wide spectral range. X-pinches are known to achieve very high density (n > 10²¹ cm) and temperature (>1 keV) at the same time resulting in energy density, much higher than 105 J/cm³. X-pinch radiation source has been proven to be useful for backlighting diagnostic in the keV range as well. A very compact LC generator (40kV, 200 kA) has been used for driving X-pinches made of 18-25 mum diameter Cu, Mo and W wires with a current rise time of 200 ns. A series of XRD and silicon p-i-n detectors with various filters was used to study their x-ray spectra in the range 20 eV - 10 keV. Complementary information on the multicharged ions dominating in the hot spot was provided by time integrated spectra recorded using flat and curved crystals. Time resolved spectral analysis allows us to characterize some stages of the X-pinch process : (a) The preliminary stage is relatively quiet, with an emission mainly in the spectral region below 200 eV. Its radiating power rises up to ~10s W with a time scale of 100 ns. (b) The tail stage is composed of a few bursts with some background radiation. Its spectrum lies mainly below 400 eV and the total power varies in the interval (1-4) x 108 W with time width of the bursts 2-20 ns, during about 100 ns. (c) In between, at the time of the main peak, the total power yield reaches 1.5 GW with about 35% in the energy range above 1 keV. The extreme ultraviolet part of the spectrum can be fitted by a Plankian function with a temperature 65 -75 eV. The spectral part above 1 keV can be approached by an exponential plot with effective temperature ~ 1100 eV for Mo and ~ 500 eV for Cu. The time duration of the peak bursts depends on the spectral range: from 0.4-0.7 ns above 1 keV up to 2-2.5 ns when the 200-450 eV region is recorded. The total radiated energy is estimated to be between 10 and 30 J.