tion of Liquid-Metal Jets as the Conductor in a ated, Exploding-Fuse Opening Switc
A repetitive, high-power opening switch technique for use in pulsed power applications using inductive energy storage is presented, along with data which demonstrate performance characteristics. This technique uses jets of a liquid conductor to replace the solid metal fuses in exploding-fuse opening-switch designs. High-power switching characteristics such as interrupt current, holdoff voltage, and resistance change are presented, along with information on how these characteristics change as jet length and circuit parameters are varied. A simulated load is used to demonstrate that exploding liquid-metal jets are feasible replacements for solid-fuse conductors in realistic applications. Likewise, the switching facility has been rep-rated in a two-pulse scenario to show its primary advantage over solid-fuse switches. The use of a highspeed camera to monitor the expansion of the mercury column upon vaporization is also described. Radial expansion velocities have been extracted from the images and are correlated with the electrical data.
Characteristics of a Magnetic Energy Storage System Using Exploding Foils
A capacitor bank operating at 15 kV and 34 kJ is used to energize an inductive system of 40 nH. Interrupting the current of ∼800 kA, by means of an exploding copper foil fuse, produces voltages across the fuse of the order of 80 kV. The opening time of the fuse, as well as the characteristics of the voltage developed across the fuse are examined as a function of the fuse dimensions. If transfer of the current into a matching inductive load is to take place at the time of peak voltage, energy transfer efficiency is of the order of 8% with I's of the order of 2×1012 A/sec.
Long term response stability of a well-type ionization chamber used in calibration of high dose rate brachytherapy sources
Well-type ionization chamber is often used to measure strength of brachytherapy sources. This study aims to check long term response stability of High Dose Rate (HDR)-1000 Plus well-type ionization chamber in terms of reference air kerma rate (RAKR) of a reference 137Cs brachytherapy source and recommend an optimum frequency of recalibration. An HDR-1000 Plus well-type ionization chamber, a reference 137Cs brachytherapy source (CDCSJ5), and a MAX-4000 electrometer were used in this study. The HDR-1000 Plus well-type chamber was calibrated in terms of reference air kerma rate by the Standards Laboratory of the International Atomic Energy Agency (IAEA), Vienna. The response of the chamber was verified at regular intervals over a period of eight years using the reference 137Cs source. All required correction factors were applied in the calculation of the RAKR of the 137Cs source. This study reveals that the response of the HDR-1000 Plus well-type chamber was well within ±0.5% for about three years after calibration/recalibration. However, it shows deviations larger than ±0.5% after three years of calibration/recalibration and the maximum variation in response of the chamber during an eight year period was 1.71%. The optimum frequency of recalibration of a high dose rate well-type chamber should be three years.