The PFMA1 (Plasma Focus for Medical Applications 1) is a device conceived to deliver the 150kJ energy stored in the capacitor bank to the plasma load at a maximum repetition rate of 1Hz. Its intended purpose is the production of Short Lived Radio Isotopes for medical applications. A representative lumped circuit model was already developed and its results validated with short circuit tests performed to determine the machine total inductance. An analytical solution is presented to predict the behavior of voltage (V) and current (I) ramps and to characterize their typical oscillations during the early stages of the capacitors discharge, before full development of gas breakdown. This solution is compared to numerical simulations. Extending the model by numerical techniques to the post-breakdown phase, when the plasma discharge is switched on, it is also possible investigate the effects of the switching action and of the resistive plasma phase. Then a time-frequency, multi-resolution analysis technique based on wavelet transforms is proposed for the detection of breakdown delay or the possible spark gap misfiring based on the observation of the shifting of higher harmonics in the signal.
S. Mannucci, D. Mostacci, F. Rocchi, M. Sumini, E. Angeli, A. Tartari (2007). A simple model for pre-breakdown over-voltage and methods for analysis of switching diagnosis on early stages of PFMA1 discharge. PISCATAWAY, NJ : IEEE.
A simple model for pre-breakdown over-voltage and methods for analysis of switching diagnosis on early stages of PFMA1 discharge
MOSTACCI, DOMIZIANO;SUMINI, MARCO;
2007
Abstract
The PFMA1 (Plasma Focus for Medical Applications 1) is a device conceived to deliver the 150kJ energy stored in the capacitor bank to the plasma load at a maximum repetition rate of 1Hz. Its intended purpose is the production of Short Lived Radio Isotopes for medical applications. A representative lumped circuit model was already developed and its results validated with short circuit tests performed to determine the machine total inductance. An analytical solution is presented to predict the behavior of voltage (V) and current (I) ramps and to characterize their typical oscillations during the early stages of the capacitors discharge, before full development of gas breakdown. This solution is compared to numerical simulations. Extending the model by numerical techniques to the post-breakdown phase, when the plasma discharge is switched on, it is also possible investigate the effects of the switching action and of the resistive plasma phase. Then a time-frequency, multi-resolution analysis technique based on wavelet transforms is proposed for the detection of breakdown delay or the possible spark gap misfiring based on the observation of the shifting of higher harmonics in the signal.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
