| Abstract: | The grid current required to fire a thyratron has been shown to depend theoretically upon the shape of the grid current characteristic before firing as well as upon the grid circuit constants.The three-element FG-17 and the four-element FG-95 and FG-98 thyratrons have been investigated.Anomalies where excessively large grid currents were required to start the arc, occurring below certain values of temperature and plate potential, have been found and are described in some detail.Although the argon-filled FG-98 was found to be free from temperature effects over the operating range, positive shield grid potentials introduced anomalies at low plate potentials.Even though the plate and shield potentials and the temperature were kept within the recommended optimum range, it was found that for minimum grid currents at firing the negative grid impedance of these tubes necessitated a grid resistance of 100 to 1000 megohms. |
