Digital system for vacuum and gas-filled devices testing

Abstract

Electrical system for measurement of breakdown voltage of vacuum and gas-filled tubes using a dynamic method Rev.A method for measuring the presampled MTF of digital radiographic systems using an edge test device Med.This article describes an improved electrical system aimed at measuring and data acquisition of the breakdown voltage of vacuum and gas-filled devices at low pressures using a discretized dynamic method. The previous system [M. M. Pejovic, C. S. Milosavljevic, and M. M. Pejovic, Rev. Sci. Instrum. 74, 3127 (2002)] included a complex analog circuit for breakdown detection, which did not provide the required reliability. The smallest voltage step which this system could provide was 250 mV. In order to increase the reliability of the breakdown detection, the Keithley model 248 high power supply was added to the system. The breakdown is detected from a monitor output at model 248 rear panel. The disadvantage of this system was the fact that the minimal value of the voltage step in this case is 1 V. An additional Keithley model 2400 Source Meter was introduced as a serial connection with the Keithley model 248 with the aim of decreasing the minimal value of the voltage step, which is in this case 1 mV. PC controls both Keithley models using standard IEEE 488 interface bus. This system provides a minimal voltage step value of 1 mV which results in a high precision in breakdown voltage determination. The proposed system controls a large number of parameters, which makes significantly influences the breakdown voltage value. The system was tested with a neon-filled tube at 6.6 mbar, where two parameters were varied, the relaxation time and the voltage step. The experimental results are in accordance with the literature regarding the influence of these two parameters on the breakdown voltage of gas-filled tubes.

Experimental Investigation of Breakdown Voltage and Electrical Breakdown Time Delay of Commercial Gas Discharge Tubes

“…It should be expected that U b could have a fix value U s , only for very small values of k, theoretically for k ¼ 0. Our previous research for neon-filled tube 19) have shown that U s as a deterministic quantity can be estimated from U b ¼ f ðkÞ dependence, where U b is the mean value of breakdown voltage U b . The estimation is performed in a following way.…”

“…This voltage is increased in steps U p during time intervals t p by Keithley model 2400 until breakdown (see ref. 19 for more details).…”

Modelling of time delay of electrical breakdown for nitrogen-filled tubes at pressures of 6.6 and 13.3 mbar in the increase region of the memory curve

“…It is necessary to perform several measurements of U b , and to use mean values U b (in our experiments U b represents the mean value of 100 measured breakdown voltages U b for each value of k). The breakdown voltage U b was measured by an electronic system described in [27]. The U s value was estimated by fitting the U b = f (k) dependence and finding the intersection of the fitting line with the U b axis (for k = 0).…”

Analysis of statistical nature of electrical breakdown time delay in nitrogen at 6.6 mbar pressure in presence of positive ions and N(4S) atoms

“…increasing voltage in steps until breakdown [17]. The experimental setup for measurements of dynamic breakdown voltage is given in paper [18]. The value of static breakdown voltage U s was estimated by fitting the U b = f (k) dependence (k = U p /t p is the voltage increase rate; U p is the voltage step and t p is the time interval between the two successive voltage steps) and finding the intersection of the fitted line with the U b -axis.…”