Introducing an Inductive Loop Sensor as an Alternative to Record the Phenomena of a Dense Plasma Focus of 400 J

Abstract

Pulsed plasma discharges are of interest for their capability to produce pulsed high energy radiation and particle beams. One of them is the dense plasma focus, a device that has renewed interest for physics research and possible industrial applications. The plasma produced with this device corresponds to the z-pinch phenomena and lasts between 1–10 ns. Electrical quantities such as the voltage across the electrodes of the vacuum chamber where the plasma dynamic takes place and the circuit current are used for the diagnostic of these devices. The short duration of the high density plasma that is produced implies a challenge when choosing a proper sensor. Typically, Rogowski coils wrapped around a conductor are used for measuring the time derivative of the circuit current. The reproducibility of Rogowski coils and variation of its frequency response due to movements can be an issue. An inductive loop sensor was developed as an alternative to measure fast and low amplitude transients of partial discharges. In this work, the use of the inductive loop sensor is proposed as an alternative sensor for the dense plasma focus operation measurement. Simultaneous measurements of both the Rogowski coil and inductive loop sensor were carried out on a low energy dense plasma focus. A comparison between both sensors was made in time and time-frequency domains. Wavelet transform was used in the time-frequency analysis. Further studies regarding the pinch detection were made with correlations between the signal values at this particular instant of the device operation. The results indicated that similar results in the characterization of the dense plasma focus operation can be obtained with the inductive loop sensor. In terms of the frequency response at time of pinch both sensors yielded similar results. A linear tendency between the signal values at time of pinch was found. Future work will be carried out to fully adapt the inductive loop sensor for its application in pulsed power technology.