| 摘要 |
<p>PURPOSE:To shorten the emission rise time of an electron beam by inserting the second heaters having a larger heat capacity in series with cathode heating heaters. CONSTITUTION:The size of core wires and the thickness of insulating materials of the second heaters 7 are made larger as compared with cathode heating heaters 2a-2c to increase its heat capacity. When the rated heater voltage is applied across heater terminal pins 5a, 5b to start the current feed, first the temperature of coil sections of the cathode heating heaters 2a-2c having a small heat capacity rises, then the temperature of the second heaters 7a, 7b having a large heat capacity rises. The tungsten wires of core wires of the second heaters 7a, 7b have a resistance value with the positive temperature coefficient, as a result the temperature of cathode substrates 12a-12c rises quickly, and the emission start time of an electron beam is accelerated.</p> |
