The pseudospark switch crowbar unit-high reliability, low cost system

A TD-50k/45, two-gap sealed-off ceramic pseudospark switch operating with pulsed current up to 50 kA and with operating voltage up to 50 kV was used as crowbar switch for high power TV inductive output tube-IOT 7340R produced by EEV (UK). The basic parameters of crowbar system: peak voltage 26-32 kV, storage capacitance 12 /spl mu/F, series resistor-15 /spl Omega/, peak discharge current-2 kA, follow-on current-80-90 A, total charge-6-7 Coulomb, reservoir heater range 6.0 V /spl plusmn/1.0 V (1-1.5 A), trigger energy 0.3 J, delay time of TD-50k/45-110 ns, delay time of crowbar unit-less 2.5-3 /spl mu/s. Pseudospark crowbar system passed type tests accepted in EEV. This system has been working satisfactorily since August 1998 24 hours a day in the 25 kW television transmitter "Onega-25" (St. Petersburg). Cold cathode thyratrons or pseudospark switches combining the advantages of spark gaps and thyratrons are devoid of their basic imperfections. It allows to expect expansion of spheres of their application.