The BK24 Ignitron as a High Current Switch†

Energy Efficiency Analysis of the Discharge Circuit of Caltech Spheromak Experiment

“…Also, the ignitron resistance was found to be high (∼ 25 mΩ) and relatively independent of the current flowing through the ignitron. Similar estimate for ignitron resistance has been reported earlier [16]. Note that the ignitron resistance is expected to be high (∼20 mΩ) for current pulses with smaller time scales (∼10 μs) and substantially lower (∼ 5 mΩ) for current pulses with longer time scales ( 1 ms) [16].…”

“…Similar estimate for ignitron resistance has been reported earlier [16]. Note that the ignitron resistance is expected to be high (∼20 mΩ) for current pulses with smaller time scales (∼10 μs) and substantially lower (∼ 5 mΩ) for current pulses with longer time scales ( 1 ms) [16]. The damped frequency of oscillations in the current trace from a typical spheromak plasma shot (see Fig.…”

“…The product datasheet [11] lists its approximate inductance to be 20 nH. The inductance measurements of other ignitrons have revealed both very low (∼10 nH) [20] and sometimes higher estimates (∼200 nH) as well [16]. Our analysis estimates the inductance to be high (170-800 nH) for low current regime and low (50 nH) for higher current.…”