Soft X-ray emission from the gas-puff Z-pinch plasma produced by an inductive pulsed power generator

An inductive pulsed power generator which has copper wire fuses used as an opening switch has been developed at Kyushu University (Japan) as the power source of a gas-puff Z-pinch. The inductive pulsed power generator has a capacitor of 11 /spl mu/F and 19.8 kJ as a primary energy source and can supply a driving current with a rise time of about 200 ns to the gas-puff Z-pinch plasma. Experiments with fast bank and inductive pulsed power methods are performed to investigate the characteristics of gas-puff Z-pinch plasmas. The obtained results show that the intensity of soft X-rays decreases gradually with a delay time which is the time difference between the beginning of the coil current from a gas-puff actuator and that of generator current in both methods. From the observation of hot spots recorded with two pin-hole cameras arranged at right angles to each other, it is found that the hot spots tend to align on the central axis between electrodes with increase of the rising rate of plasma current. The behavior of imploding cylindrical plasma depend on the rising rate of plasma current. Especially, sausage instability in the pinching plasma along the axis becomes predominant in the case of higher rising rate of current by the inductive pulsed power method, and the faster current leads to spatially-confined distributions of hot spots appearance shot to shot.