JPH0553000A - Electron beam irradiator - Google Patents

Abstract

PURPOSE:To simplify the constitution for supplying electric power to the filament of an acceleration tube. CONSTITUTION:To supply power to the filament transformer 2 connected to a filament 4 of an acceleration tube 3, the output of a high frequency inverter 13 of a variable output type on the low voltage side is supplied by way of a floating capacity C in between a pair of electrodes 8, 9. The control of the power supply to the filament is done by controlling the output of the high frequency inverter 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam irradiation device.

[0002]

2. Description of the Related Art In an electron beam irradiation apparatus, the electron flow is controlled by controlling the electric power supplied to the filament of an accelerating tube. Therefore, as the filament power source in the electron beam irradiation apparatus, one capable of adjusting the output, particularly one capable of fine adjustment is required. Since the filament is located on the high voltage side, it is necessary to insulate it from the ground side.

Conventionally, as one example, an AC output regulator using a thyristor and a structure using an insulating transformer have been used. FIG. 2 shows the configuration, 1 is a DC high-voltage power supply such as a Cockcroft-Walton circuit including a capacitor and a rectifier, 2 is a filament transformer, 3 is an accelerating tube, 4 is its filament, 5 is the above-mentioned AC output adjusting circuit, 6 is its AC input terminal, and 7 is an insulating transformer.

The DC high voltage generated by the DC high voltage power supply 1 is applied to the acceleration tube 3 as an acceleration voltage. The high frequency output generated by the AC output regulator 5 is given to the filament transformer 2 via the insulating transformer 7, where it is transformed into a required heating voltage and supplied to the filament 4. By adjusting the AC output adjusting circuit 5, the electric power supplied to the filament 4 is adjusted and the electron flow is controlled.

However, in the case of such a configuration, when the acceleration voltage becomes high, it becomes difficult to manufacture the insulating transformer, and the shape becomes large. In addition to this structure, there is a structure in which a motor and a generator are used to supply the output of the generator to the filament, but since the rotating part is required, the life is limited.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to simplify the structure for supplying electric power to the filament of the accelerating tube.

[0007]

According to the present invention, a high voltage side electrode is connected to one end of a filament transformer, and a ground side electrode facing this electrode is connected to a secondary side of a step-up transformer in a low voltage section. A variable output type high frequency inverter is connected to the primary side of the step-up transformer, and the secondary output of the step-up transformer is supplied to the filament transformer via a stray capacitance between the electrodes. And

[0008]

Embodiment An embodiment of the present invention will be described with reference to FIG. In addition, the part given the same code as the code shown in FIG. 2 shows the same or corresponding part. According to the present invention, the high voltage side electrode 8 is connected to one end of the filament transformer 2, and the ground side electrode 9 facing the electrode 8 is connected to the secondary coil 11 of the step-up transformer 10 in the low voltage section. Further, a variable output high frequency inverter 13 is connected to the primary coil 12 of the step-up transformer 10. The high frequency inverter 13 is composed of a thyristor or the like, and its output is adjusted by adjusting the firing angle of the thyristor or the like.

The high-frequency output generated by the high-frequency inverter 13 is boosted by the boosting transformer 10, and the secondary output is supplied to the filament transformer 2 via the stray capacitance C between the electrodes 8 and 9. This power supply is possible by adjusting the oscillation output of the high frequency inverter.

According to this structure, the conventional insulating transformer is not required, and the stray capacitance formed by the pair of electrodes is used. Therefore, the structure does not become large. In addition, there is no problem in terms of life and reliability because it does not have a rotating part as in the case of using a motor or a generator.

With the recent development of element technology, it has been possible to manufacture a high-frequency inverter capable of adjusting the output by pulse width modulation in the case of an oscillation output of 15 K to 20 KHz. If the electrodes 8 and 9 are arranged in an insulating gas atmosphere,
Since the insulation distance between them can be shortened sufficiently,
A stray capacitance of about 100 to 200 pF can be obtained.

Therefore, in order to transmit electric power by utilizing this stray capacitance, the voltage may be raised by the step-up transformer 10 so that the impedance of the stray capacitance does not matter.

By the way, assuming that the receiving voltage on the high voltage side is 10 kV and the filament power needs to be 300 W, the load impedance at this portion is approximately 333 kΩ.
Becomes If the stray capacitance between the electrodes 8 and 9 is 100 pF and the output frequency of the high frequency inverter 13 is 20 kHz, the impedance of the stray capacitance is about 79 kΩ. This is a sufficiently small value as compared with the load impedance.

Loss can be reduced by using, as the step-up transformer for stepping up the voltage of 15 kHz to 20 KHz, one using an amorphal core.

[0015]

As described above, according to the present invention, the output of the low frequency side high frequency inverter is supplied to the high voltage side filament transformer via the stray capacitance as means for supplying electric power to the filament of the accelerating tube. Since it is easy to adjust the power supply, the structure can be simplified compared to the conventional structure, and since there are no moving parts, long life and high reliability can be expected. Produce an effect.

[Brief description of drawings]

FIG. 1 is a layout view showing an embodiment of the present invention.

FIG. 2 is a layout diagram of a conventional example.

[Explanation of symbols]

 1 DC high-voltage power supply 2 Filament transformer 3 Accelerator tube 4 Filament 8 High-voltage side electrode 9 Low-voltage side electrode 10 Step-up transformer 13 High-frequency inverter

Claims (1)

[Claims] 1. A high voltage side electrode is connected to one end of a filament transformer for supplying heating power to a filament of an accelerating tube, and another ground side electrode facing the electrode is connected to a booster transformer in a low voltage section. A secondary output is connected to the primary side of the step-up transformer, and a high-frequency inverter of variable output type is connected to the secondary side of the step-up transformer, and the secondary output of the step-up transformer is supplied to the filament transformer via the stray capacitance between the electrodes. The electron beam irradiation device thus obtained.