JPS5991330A - Insulating type ionization gage - Google Patents

Abstract

PURPOSE:To prevent the effect of disturbance and to measure vacuum degree accurately, by providing a tubular electrode for preventing fluctuation in potential, which has the potential that is insulated from a potential of a part attached to a service port of a vacuum device, around an electrode assembly. CONSTITUTION:An attaching flange 1 of an ionization gage is attached to a service or a vacuum container through attaching holes 1a. A circular cylinder shaped electrode 9, which is used for preventing fluctuation in potential in an electrode assembly comprising a filament 2, grids 3-6, and a collector 8, is arranged between the attaching flange 1 and an annular shaped mechanical protecting frame 7. In this constitution, even though a potential E of the attaching flange 1 is fluctuated, the potential of each electrode can be kept unchanged, the effect of disturbance is prevented, and the vacuum degree can be accurately measured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ionization vacuum gauge used to measure the degree of vacuum in devices that handle charged particles or discharge, such as accelerators, plasma devices, Iti, sputtering devices, and the like.

When this type of ionization vacuum gauge is used to measure the degree of vacuum in the above-mentioned equipment, the electric potential of the vacuum vessel rises instantaneously due to the generation of electrical discharge, which causes a current to flow through the walls of the vacuum vessel to the ground. . This potential levitation is caused by a voltage drop due to the electrical resistance of the wall of the vacuum chamber itself, and by a seal part consisting of 6 rings, for example.
This is caused by a potential difference due to contact resistance. The rise in potential in the vacuum vessel disturbs the rise in potential between the electrodes that make up the vacuum gauge, making measurement difficult.

As one method for solving these drawbacks, a method has been proposed in the past in which a single tube in the service/port section of a vacuum apparatus to which a vacuum gauge is attached is insulated with a ceramic seal made of Kovar. However, although this method is effective when the magnetic field strength is weak or the amount of Kovar (ferromagnetic material) used in the ceramic seal is small, there is a risk of deterioration or damage due to electromagnetic force in a strong magnetic field environment. There is.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the various drawbacks described above by electrically blocking the effects of potential fluctuations in the vacuum container in this type of ionization vacuum gauge.

Therefore, in the insulated ionization vacuum gauge according to the present invention, 1
A cylindrical electrode is provided around the electrode assembly forming the vacuum gauge body, and is designed to have a constant potential regardless of fluctuations in the potential of the portion attached to the service seat of the vacuum device.

Thus, according to the present invention, by providing a cylindrical electrode for preventing fluctuations in potential, the potential of the electrode assembly of the vacuum gauge can be brought to a desired level independently of the potential of the mounting flange and therefore the service port of the vacuum device. Since the voltage can be maintained, it is possible to prevent measurement noise caused by fluctuations in the potential of the vacuum container and damage caused by surges.

The present invention will be further described below with reference to the accompanying drawings.

Fig. 1 shows a pentode-type ionization vacuum gauge embodying the present invention, and 1 is a flange that is attached to a service port of a vacuum vessel (not shown) through a mounting hole 1a. It will be done like this. Reference numeral 2 denotes a filament constituting an electron source, which is connected and supported by a terminal 2a inserted into the flange 1, and this filament 2 is located approximately on the central axis of the vacuum gauge. A grid 3, a grid 4, a grid 5, and a grid 6 are arranged concentrically around the filament 2, and each of the grids 3, 4, and 6 is attached to a combined insulating terminal ( (Figure 1 only shows the insulated terminal 3a for the grid 3)
connected and supported. The grid 5 is attached to an annular mechanical protection frame 7 at the tip of the vacuum gauge. Further, a cylindrical ion collecting electrode, that is, a collector 8 that collects generated ions is arranged concentrically outside the grid 6, and the collector 8 is connected to and supported by an insulated terminal 8a. 'On the outside of this collector 8, between the mounting flange 1 and the annular mechanical protection frame 7, there is a cylindrical electrode 9 for preventing potential fluctuations in the electrode assembly consisting of the filament 2, the grids 3 to 6, and the collector 8. As arranged, this electrode 9 can consist of a plate or a mesh and is attached to the mounting 7 flange 1 via a non-magnetic insulating material 10 by means of suitable fasteners 11. Further, the tip of this electrode 9 is in contact with and locked in an annular mechanical protection frame 7. Inside the mechanical protection frame 7, a blind 12 is constructed by concentrically arranging a number of cylindrical bodies having different diameters.
is attached by a stop rod 16. This blind 12 prevents charged particles or heat rays from directly entering the vacuum gauge. In the above configuration, a grid 5, an annular mechanical protection frame 7, a cylindrical electrode, a pole 9 and a blind 1
2 is electrically at the same potential as shown in the equivalent circuit of FIG. 2, and is connected to the power source ground E2 together with one terminal of the filament 2. Furthermore, potentials as shown in FIG. 2 can be applied to the filament 2, the grids 3 to 6, and the collector 8, respectively. In FIG. 2, El represents the potential of the attachment 7 flange 1 and therefore the service +1-) (not shown).

In the conventional structure, in the equivalent circuit shown in Fig. 2, the potential of the grid 5 (which serves as the ground) is set to the same potential as the 7' flange 1 and the service hoard of the vacuum vessel to which it is attached. The grid potential constantly fluctuates and the potential between the electrodes is disturbed.

In contrast, in the present invention, as shown in FIG. 2, the surrounding electrode 9 is provided for the electrode assembly connected to the flange 1 and therefore to the power supply side ground potential E2 independent of the service hoard potential E1. Even if the potential E1 of the flange 1 fluctuates, the service hoard and therefore the mounting can maintain the potential between each electrode unchanged, thereby preventing the influence of disturbances. Furthermore, there is no risk of deterioration or damage due to electromagnetic force, unlike in the case of the conventional method in which the entire sensor is insulated with a ceramic seal to avoid the effects of potential fluctuations. Therefore, the vacuum gauge according to the present invention can accurately measure the degree of vacuum in devices such as accelerators, plasma devices, and snow-capped devices, regardless of potential fluctuations.

Although the illustrated embodiment has been described in terms of a triode type, it can equally be implemented in a triode type, i.e. surrounding an electrode assembly consisting of a filament, a current collecting electrode for accelerating and trapping the electrons, and an ion collecting electrode (collector). By providing an encircling electrode connected to the ground potential on the power supply side, the same functions and effects as in the above case can be obtained. Furthermore, the present invention is equally applicable regardless of the structure of the electrode assembly, whether triode or triode.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an ionization vacuum gauge according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of the ionization vacuum gauge shown in FIG. In the figure, 1: Mounting flange, 2: Filament, 3~
6: grid, 7: annular mechanical protection frame, 8: collector, 9 two cylindrical electrodes.

Claims (1)

[Claims] In ionization vacuum gauges used to measure the degree of vacuum in equipment that handles charged particles or discharges, such as accelerators, plasma equipment, or sputtering equipment, the potential is isolated from the potential of the part attached to the service hoard of the vacuum equipment. An insulated ionization vacuum gauge characterized by having a cylindrical electrode around an electrode assembly to prevent fluctuations in potential.