Nonperturbing plasma-focus measurements in the run-down phase

Simultaneous and nonperturbing measurements using a multislit streak camera, two high-voltage probes, and a Rogowski coil were carried out to enable an equivalent-circuit analysis to be made of a plasma-focus discharge in the run-down phase. A lead current is assumed to flow to the insulator. Calculations show that maximum constant values of diode voltage, V_p≃5.3 kV, and pinch current, I_p≃200 kA, are attained during the run-down phase; the product of these two parameters shows an upper limit in the input power. From the multislit streak camera, a limiting run-down speed, v_z≃9.2 cm/μs, for the plasma sheath is observed, which suggests a constant rate of change of inductance. These observations indicate a steady-state operation of the plasma focus for this duration