Gepulste UV-Strahlungsquelle zur Erzeugung eines hoch ionisierten Ausgangsplasmas niedriger Dichte

A 100 kV Z-pinch, pulse-filled with high-density xenon gas, is used as radiation source for photoionizing hydrogen or rare gases at filling pressures of 1–10 mtorr. This produces a homogeneous, magnetic field free, highly ionized (degree of ionization ≈10% in H₂ and ≈ 20% in Ar) plasma suitable for example, for collisionless shock wave experiments. Experimental and theoretical investigations have yielded information on the conversion of the stored electrical energy into radiation energy. As a result of fast magnetic compression and ohmic heating (the relatively low temperature of max. 6 eV due to multiple ionization of the xenon atoms being favourable) the xenon pinch absorbs 30% of the stored electrical energy. Investigation of the matching of the external circuit to theZ-pinch by means of the snowplow model shows that the energy transmission efficiency could be increased about 50% if the current half-cycle is made equal to the compression time. The suitability of the xenon pinch as a radiation source is due on the one hand, to the almost complete conversion of the absorbed energy into radiation and, in particular, to the spectral distribution of the radiation, which is favourable for the ionization of hydrogen. It is found that the radiation is mainly emitted in lines with maximum intensity at the same wavelength λ ≈ 700 Å as the maximum of the photoionization cross section owing to the low temperature of the xenon plasma.