| 摘要 |
A generator for pulsed electron beams of the type including a vacuum chamber for performing high voltage discharges, cathode and anode electrodes, for irradiating a sample with accelerated charge carriers, provided in the vacuum chamber, and a first high voltage capacitor connected between the cathode and anode electrodes to serve as the voltage source for the high voltage discharge between the electrodes. The generator is further provided with an arrangement for generating an auxiliary discharge which initiates the discharge process between the cathode and the anode electrodes, which arrangement includes a trigger electrode and a second high voltage capacitor which can be connected between the cathode electrode and the trigger electrode as an energy source for the auxiliary discharge; the distance between the cathode electrode and the trigger electrode being such that when the second or trigger capacitor is conductively connected between the trigger and cathode electrodes, a sparkover is produced therebetween, causing a trigger plasma to be formed which initiates the high voltage discharge. Moreover, the cathode electrode is provided with a central bore through which the trigger plasma can exit into the discharge chamber formed between the cathode and anode electrodes; and the anode is a metal network or net which is highly transparent to electrons and through which fly the electrons accelerated by the electric field existing between the cathode and anode electrodes due to the voltage of the first or main capacitor. Preferably the sample carrier, which is disposed on the side of the anode electrode facing away from the cathode electrode, is mounted so that it is adjustable along the axis of the electrode system.
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