JPS6032436B2 - Pulsed field emission electron gun - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a power supply circuit in a field emission type electron gun device that performs pulse operation.

Among the electron guns that use field emission phenomenon, those that heat the emitter are further divided into those that operate with direct current and those that perform pulsed field emission to maintain a balance between changes in the shape of the heated emitter tip. It will be done.

Figure 1 shows a power supply circuit for applying a voltage between an emitter electrode 1 and an extraction electrode 2 for generating a strong electric field at the tip of the emitter electrode in a field emission electron gun that performs pulse operation. The circuit connects its output terminals E and F
FIG. 2 shows an example of the voltage waveform generated. When performing pulse operation, during the pulse (
Balance the shape change at the emitter tip by adjusting the pulse period (about several milliseconds), the pulse peak value (about 10 KV), and the reverse bias voltage (about -chick V) during the pulse pause period. Therefore, as in the circuit shown in FIG. 1, the pulse voltage V and bias voltage V2 are configured to be able to be adjusted independently. That is,
In the device shown in FIG. 1, the output of the pulse voltage V, generated in the secondary coil of the step-up transformer 3 by the input pulse voltage Vo, is applied between the output terminals E and F via the thyratron 4. Since it is in a conductive state, the current due to the bias DC voltage V2 only flows through the resistor 5, diode 6, and thyratron 4, and does not contribute to the voltage generated between the terminals EF. Also, during the pulse rest period, the pulse voltage V,
Thyratron 4, which is controlled by a signal synchronized with “
The bias DC voltage V2 is applied between the terminals EF through the secondary winding of the transformer 3. In such a conventional circuit, the entire circuit is at a high potential corresponding to the accelerating voltage of the electron gun. Therefore, sufficient consideration must be given to the insulation of circuit elements.Also, the Thiratron 4 mentioned above has a short lifespan and must be replaced at regular intervals, so it is difficult to use such circuit elements. There was a major problem in the maintenance of the circuit power supply shown in Figure 1.The main purpose of the present invention is to solve this problem, and it uses circuit elements whose lifespan is not an issue to generate pulsed electric fields. This provides a power supply circuit for an emission type electron gun.

FIG. 3 shows an embodiment of the present invention, in which the thyratron 4 used in the circuit of FIG.
Constant voltage elements such as diodes, Zn〇, SiC, varistors, etc. are used. The bias voltage of the bias diode 7 is larger than the bias DC voltage V2, and the voltage of the transformer 3 is higher than the bias DC voltage V2.
A voltage having a smaller value than the pulse voltage V3 generated in the secondary winding of is used. Further, the difference between the pulse voltage V3 and the Zener voltage Vz becomes the voltage applied between the extraction voltage 2 of the emitter 1. Now, during the pulse period, 2 of transformer 3
The current based on the voltage V3 generated at the next output flows in the order of the diode 8, the resistor 9, and the Zener diode 7, and the voltage Vz of the diode 7 is subtracted from the voltage V3, and the resulting voltage is the voltage across the resistor 9, which is the output. Applied between electrons E and F.

Also, since current flows through the Zener diode 7 during the pulse period, the bias voltage V2 is smaller than the Jenner voltage Vz, so the current based on the voltage V2 does not flow through the Jenner diode 7 and the diode 101, and the output terminal voltage does not contribute at all. On the other hand, during the pulse rest period, no current flows through the Jenner diode 7, so that the DC bias voltage V2 is reduced to the diode 10 and the truss 3.
is applied between the output terminals EF via the secondary winding of the .

As described above, in the circuit of the present invention, the pulse power supply circuit is configured with only circuit elements that are easy to maintain, instead of switching elements such as thyratrons that require a signal synchronized with the pulse voltage and are difficult to maintain. As a result, a circuit with stable performance can be obtained at a lower cost than conventional circuits.

Note that the present invention is not limited to the embodiment shown in FIG. 3; for example, low resistance resistors may be used in place of the diodes 8 and 10 as long as no problem with response speed occurs.
Further, instead of the pulse transformer, a pulse power source or a pulse circuit equivalent to this may be used. Brief Description of the Drawings Figure 1 is a schematic diagram showing the main circuit parts of a conventional pulsed field emission electron gun, Figure 2 is a diagram showing the waveform of the output voltage generated by the circuit in Figure 1, and Figure 3 is a diagram showing the waveform of the output voltage generated by the circuit in Figure 1. 1 is a schematic diagram illustrating an embodiment of the present invention.

1... emitter, 2... extraction electrode, 3... transformer, 4... thyratron, 5, 9... resistor, 6, 8, 10... diode, 7... zener diode.

Ax figure Spear Z■ O3 phantom

Claims (1)

[Claims] 1 A pulsed high voltage is applied between the emitter, an extraction electrode that forms a strong electric field at the tip of the emitter, and the electrode and the emitter, and during the pulse rest period, a DC voltage of opposite polarity to the pulse voltage is applied. In a device equipped with a power source, a constant voltage element 7 and a load resistor 9 are connected in series to a pulse output terminal, and a DC voltage lower than the operating voltage of the constant voltage element 7 is applied between both terminals of the constant voltage element 7. A pulsed field emission type electron gun, characterized in that the power source is configured so as to.