JPS5856953B2 - field emission electron gun - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a field emission electron gun that can supply an extraction voltage and an initial stage acceleration voltage through a single transmission path.

A field emission electron gun that accelerates an electron beam to high energy (for example, an acceleration voltage of 100 KV or more) is usually configured as shown in FIG. 2 anodes (first stage acceleration electrode) P2,
The electrodes of the post-acceleration system P3 are sequentially arranged.

The emitter E is supplied with an acceleration voltage of +30 KV to the final stage ground electrode (not shown) of the rear acceleration system P3 by the acceleration power supply 6.
A variable voltage of about 120 KV is applied, and a voltage obtained by dividing the output of the acceleration power source 6 is applied to other electrodes of the latter stage acceleration system.

On the other hand, a variable output voltage of power supply 1 is applied between emitter E and first anode P1, and regardless of the output of the accelerating power supply, +
Appropriate bowing voltage and pressure of about 5 to +10 KV is applied.

Similarly, the output voltage of the power supply 2 is applied between the emitter and the second anode P2, and when an appropriate electrostatic lens action is applied to the electron beam extracted from the emitter, it is accelerated in the circuit, so that the electron beam is On the other hand, a constant voltage of about +10 KV is applied.

In addition, these power supplies 1 and 2 are each connected to a high frequency oscillator 3, so that the output thereof can be controlled from the ground side regardless of the output of the acceleration power supply 6. It is composed of an isolation transformer 4, a rectifier circuit 5, and the like.

In such a conventional example, each power source is provided individually, which is disadvantageous in terms of cost and increases the size of the device.

The present invention has been made in order to improve these conventional problems, and its purpose is to provide a field emission type electron gun that can supply an extraction voltage and an initial acceleration voltage with a single power source. There is.

The present invention will be explained in detail below using the drawings.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

Components that are the same as those of the conventional example shown in FIG. 1 are given the same symbols or numbers, and their explanation will be omitted.

As shown in FIG. 2, the high frequency generated by the high frequency oscillator 3 is sent to the Kotscroft-Walton circuit 7 via the insulating lance 4.

The Kotscroft-Walton circuit 7 has a two-stage configuration, in which the output voltage v1 of the first stage is applied between the emitter and the first anode, and the output voltage (2) of the second stage is applied between the emitter and the second anode. 8.

Further, a constant voltage element 9 such as a Zener diode is connected between the emitter and the second anode.

Kotscroft-Walton circuit 7 for such a configuration
The second stage output (2) is twice the first stage output V1.

Therefore, in order to vary the beam current, if we change the output of oscillator 3 and change vl in the range of 5KV to 10KV, ■
2 varies in the range of 10KV to 20KV.

However, since the second stage output (2) is supplied to the second anode P2 via a constant voltage circuit consisting of a drop resistor 8 and a constant voltage element 9, a constant voltage (
For example, 10KV) is supplied.

Therefore, both the variable extraction voltage and the constant first stage acceleration voltage can be obtained from a single power supply having a single transmission path.

In the above-described embodiment, an isolation transformer was used as a transmission means between the high-frequency oscillator 3 and the Kotscroft-Walton circuit 7, but this is limited to the high-voltage section (emitter, anode, etc.) and the low-voltage section (high-frequency oscillator 3). ), for example, capacitor coupling may be used as long as it can insulate the two.

Further, in the above embodiment, a two-stage Kotscroft-Walton circuit was used, but the circuit is not limited to this, and a multi-stage structure may be used. In that case, the output of the final stage is sent to the second anode, and
It goes without saying that the anodes may be supplied with the output voltages of appropriate intermediate stages.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional example, and FIG. 2 is a block diagram showing an embodiment of the present invention. 3: High frequency oscillator, 4: Isolation transformer, 7: Kotscroft-Walton circuit, 8 Nitrotube resistor, 9: Constant voltage element, E: Emitter, Pl: First anode, P2: Second anode.

Claims (1)

[Claims] 1 comprising an emitter, a first anode, a second anode, a subsequent acceleration system, a high frequency oscillator, and a multi-stage Kotscroft-Walton circuit to which the high frequency from the oscillator is supplied,
The output voltage of the intermediate stage of the Kotsukcroft-Walton circuit is applied between the emitter and the first anode, and the output voltage of the final stage is applied between the emitter and the second anode via a constant voltage circuit consisting of a drop resistor and a constant voltage element. A field emission type electron gun characterized by applying an electric current.