Abstract:
In a gridless ion source, there is provided a cathode system having dual thermionic filaments (515, 516). The first filament (515) is operated at an electron emission temperature to provide a source of electrons to the ion source. The state of the first filament is monitored by a control circuit (500) and upon failure of the first filament, the control circuit switches in the second filament (516). In preferred embodiments, the switching of the second filament is latched and is automatically reset to the first filament upon shut down of the ion source.
Abstract:
An adaptive heater voltage algorithm and control system for setting and maintaining a vacuum electron device (VED) heater voltage, such as that of a klystron. An algorithm and control system are disclosed that sets and maintains the VED's cathode at the lowest temperature required for 98% of the beam current that corresponds to a fully space limited (FSCL) operation. VED lifetime is dependent upon cathode temperature, and in general, a cooler cathode will last longer. The optimum heater voltage corresponds to the beam current that is 98% of the beam current during FSCL operation. As the VED ages and the cathode becomes depleted, the heater voltage will need to be gradually increased to maintain 98% FSCL value. There are, therefore, two stages to the adaptive heater voltage algorithm - (1) initial determination of the heater voltage and (2) the determination of the heater voltage during amplifier operation.
Abstract:
The method and apparatus for controlling heater voltages to the heaters of a CRT includes sensing the presence of pulses at an input of the heater control circuit (800). In another embodiment, a DC level change is sensed at an input to the heater control circuit. When pulses are present (e.g., retrace pulses), or the DC is at the appropriate level, the heater control circuit reacts to provide a stable 6.3V to the cathode heaters. When the pulses are not present or the DC level is not appropriate, the circuit reverts to a low-conducting mode where insufficient voltage is provided to the heaters of the CRT for normal operation.
Abstract:
A device for stabilization of the electron beam current comprises a sensor (12) of the deviation of the electron beam current from a preset value, a sawtoothed voltage former (14) which is connected to the high-voltage transformer (2) of an acceleration voltage source and which provides for a periodical sawtoothed voltage the slight slope sections of which are started to be formed at those times when the voltage on the transformer (2) passes through zero-point, an adder (13), one of the inputs of which is connected to the output of the sensor (12) and the other input to the output of the former (14), a threshold element (15) connected to the ouput of the adder (13), a differentiating element (16) connected to the output of the threshold element (15) to ensure the forming of electric driving pulses at the times of intersecting the threshold level of the threshold element (15) by the slight slope sections of the sawtoothed voltage at the output of the adder (13), alight radiation source connected to the output of the differentiating element (16) to ensure the transformation of the electric driving pulses into light ones, and a photothrystor (11) which is controlled by the light impulses and which is connected to the primary winding circuit of a filament transformer (5) supplied from one of the secondary windings of the high-voltage transformer (2).