| 摘要 |
A square wave clock signal is coupled to a transistor, the output of which is transformer coupled to the base of a driver transistor. The conducting of the driver transistor will cause an increase in the current through the primary of a flyback transformer, thereby resulting in a relatively small negative going voltage potential being induced therein. When the driver transistor is caused to go into a non-conducting state, due to the signal on the base, the decrease in current through the primary of the flyback transformer in relation to the change in time is large, thereby inducing a large positive voltage potential across the primary. The induced voltage is stepped-up by the flyback transformer where the negative overring portion is rectified and regulated to supply a potential to the grid of an ion source. The positive voltage pulse is coupled into a voltage multiplier circuit, the output of which is connected between the ion source anode and cathode of an accelerator tube used for producing fast neutrons from the D-T reaction. Additionally, a firing reference signal is coupled from the driver transistor to the radioactivity logging instrument to provide a timing signal used to enable the detecting circuitry therein for measuring radiations returning from the formations as a result of fast neutrons being emitted by the ion source.
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