JP2018036132A - Cold-cathode ionization gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold ionization guage suppressing a non-discharge and an abnormal discharge, suppressing a time delay between the time when a high voltage is applied to a cold-cathode ionization guage and the time when an electric current starts to flow by discharge, and suppressing fluctuation of a measurement pressure value.SOLUTION: A cold-cathode ionization guage 1 includes: an anode bar 52; and a discharge induction member 3 provided on one face side of a pole piece 2. The discharge induction member 3 includes: a main body part 3b formed in a ring shape; and a plurality of protrusions 3a extended in a direction opposite to the pole piece 2 from one end part of the main body part 3b. The cold-cathode ionization guage is positioned on a center O of a virtual circle in which a center line L of the anode bar 52 is formed by top end parts 3a1 of the plurality of protrusions 3a. A gap t is formed between the circumferential surface of the anode bar 52 and the top end parts 3a1 of the plurality of protrusions 3a. Moreover, a top end part 52a of the anode bar 52 is positioned at the pole piece 2 moving from the top end parts 3a1 of the plurality of protrusions 3a.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cold cathode ionization vacuum gauge, for example, a cold cathode ionization vacuum gauge that can suppress a delay at the start of discharge by inducing discharge and can efficiently perform measurement.

In general, a cold cathode ionization vacuum gauge (CCG) is often used as a vacuum gauge for measuring the pressure of gas in a high vacuum state.
Regarding this cold cathode ionization vacuum gauge, the present applicant has already proposed a cold cathode ionization vacuum gauge in Patent Document 1. The cold cathode ionization vacuum gauge proposed in Patent Document 1 is shown in FIG. 14, and the cold cathode ionization vacuum gauge will be described based on FIG. 14. As shown in FIG. A cylindrical cathode 51 having an opening, a rod-like anode 52 disposed in the internal space of the cathode 51, and a magnetic field perpendicular to the electric field between the anode 52 and the cathode 51 is formed. 52 and a magnetic means 53 for causing discharge between the cathode 51 and a pole piece 54 detachably fitted to the opening edge of the cathode 51 and covering the opening.
In addition, the pole piece 54 is formed with a protrusion 55 that faces the tip of the rod-shaped anode 52 with a predetermined gap T (gap).

In this cold cathode ionization vacuum gauge, the projection 55 facing the tip of the rod-shaped anode 52 tends to cause discharge between the projection 55 and the tip of the rod-shaped anode 52, and the cold cathode ionization gauge The time delay between the time when the high voltage is applied to the vacuum gauge 50 and the time when the current starts to flow after discharging becomes small, so that the measurement can be performed efficiently (that is, the protrusion 55 is provided). It functions as a discharge inducing member and can perform measurement efficiently).
Further, by replacing the pole piece 54, the protrusion 55 (protrusion that functions as a discharge inducing member) that is consumed by use is also replaced, so that the discharge inducing member can be easily replaced.

Japanese Patent No. 5,164,952

By the way, in order to ensure the induction of discharge, it is necessary that the protrusion is disposed opposite to the tip of the anode with a predetermined gap (gap).
However, due to problems such as the mounting accuracy of the anode and the mounting accuracy of the protruding portion to the pole piece, the gap between the protruding portion and the tip of the anode is uneven. There has been a technical problem that no discharge occurs even when a high voltage is applied between the anode and the anode. In addition, even if a discharge occurs in the cold cathode ionization gauge, there may be a time delay between the time when a high voltage is applied to the cold cathode ionization gauge and the time when the discharge starts and current starts flowing. there were.

  On the other hand, when the gap between the protrusion and the tip of the anode is small, when a high voltage is applied between the cathode and the anode, abnormal discharge occurs and the measured pressure value varies with time (measured pressure). There is a technical problem that the value fluctuates (shakes) and does not show a constant value).

The inventor conducted further earnest research on a cold cathode ionization vacuum gauge in which a discharge inducing member (protrusion) is formed on a pole piece.
As a result, by attaching a discharge inducing member (projection) having a specific configuration to the pole piece, it is not affected by the mounting accuracy of the anode, the mounting accuracy of the discharge inducing member (projection) to the pole piece, etc. A predetermined gap (gap) can be formed between the protrusion and the tip of the anode, and between the time when the high voltage is applied to the cold cathode ionization vacuum gauge and the time when the electric current starts to flow after discharging Thus, the inventors have found that it is possible to suppress the time delay and further suppress the fluctuation (vibration) of the measured pressure value, and arrived at the present invention.

  The object of the present invention made in the above situation is to suppress undischarge and abnormal discharge, between the time when a high voltage is applied to the cold cathode ionization gauge and the time when the current starts to flow after discharge. An object of the present invention is to provide a cold cathode ionization vacuum gauge that suppresses time delay and suppresses fluctuation of a measured pressure value.

  The cold cathode ionization vacuum gauge according to the present invention made to achieve the above object includes a cylindrical cathode having an opening formed at one end thereof, a rod-like anode disposed in the internal space of the cathode, and the anode. Magnetic means for forming a magnetic field perpendicular to the electric field between the cathode and causing discharge between the anode and the cathode, and a pole piece that is detachably fitted to the opening edge of the cathode and covers the opening And a cold cathode ionization vacuum gauge comprising a discharge inducing member provided on one surface side of a pole piece opposite to the tip of the anode, the discharge inducing member comprises a main body formed in a ring shape, A plurality of protrusions extending from one end of the main body in the opposite direction to the pole piece, and the center line of the anode is on the center of a virtual circle formed by the tips of the plurality of protrusions And the outer peripheral surface of the anode and the composite Gap is formed between the projections of the distal end, further characterized in that the tip portion of the anode is located on the pole piece side of the distal end portion of the plurality of protrusions.

Thus, in the cold cathode ionization vacuum gauge according to the present invention, the discharge inducing member has a plurality of protrusions extending in the direction opposite to the pole piece, and the center line of the anode is the tip of the plurality of protrusions. Is located on the center of the virtual circle formed by.
Therefore, even when the mounting accuracy of the anode (the distance between the tip of the anode and the pole piece) varies, the gap between the projection of the discharge inducing member and the anode can be made to have a certain size (distance). .

  In the cold cathode ionization vacuum gauge according to the present invention, since the tip of the anode is positioned on the pole piece side with respect to the tips of the plurality of projections, both sides (front and back surfaces) of the projection ) Can be placed in the discharge space. As a result, the discharge can be generated reliably and quickly, and the time delay between the time when the high voltage is applied to the cold cathode ionization gauge and the time when the current starts to flow after discharging is suppressed. In addition, the fluctuation (vibration) of the measured pressure value can be suppressed. Incidentally, in the cold cathode ionization vacuum gauge shown in Patent Document 1, one surface of the protruding portion arranged opposite to the tip portion of the anode is arranged in the discharge space.

Here, it is preferable that the gap formed between the outer peripheral surface of the anode and the tips of the plurality of protrusions is 0.8 mm or more and 2.5 mm or less.
When the gap formed between the anode and the tips of the plurality of protrusions is less than 0.8 mm, the gap is small and the electric field strength is large, so abnormal discharge occurs and the measurement pressure value fluctuates ( This is not preferable because of fluctuations).
On the other hand, if the gap formed between the anode and the tips of the plurality of protrusions exceeds 2.5 mm, the gap is large, the electric field strength is reduced, and electric discharge is difficult to occur, which is not preferable. More preferably, it is 2.0 mm or less.
The gap formed between the outer peripheral surface of the anode and the tips of the plurality of protrusions is a line segment perpendicular to the center line of the anode that connects the outer periphery of the anode and the tips of the protrusions. The length of

In addition, two or three protrusions are provided at equal intervals in the circumferential direction of one end of the main body, and the protrusions are at least 55 degrees with respect to one surface of the pole piece in a direction opposite to the pole piece. It is desirable to extend with an angle of 90 degrees or less.
When the angle of the protrusion is obliquely extended with an angle of less than 55 degrees, the cleaning effect by discharge sputtering between the anode rod and the tip of the protrusion is difficult to be exhibited, which is not preferable. This is presumably due to the fact that the oxidation (deterioration) of the tip of the protrusion becomes dominant because only one side of the protrusion is cleaned as the angle of the protrusion becomes smaller.
On the other hand, when the protrusion is extended at an angle exceeding 90 degrees, the distance between the tip of the protrusion and the anode rod becomes long, and the electric field strength becomes weak.
Furthermore, when four or more protrusions are provided at equal intervals in the circumferential direction of the one end of the main body, the electric field strength is dispersed and weakened (sputtering effect is difficult to be exhibited), which is not preferable. .

The main body of the discharge inducing member is formed with a plurality of legs extending downward from the main body, and a cylinder for mounting the electric discharge inducing member on one side of the pole piece. It is preferable that the discharge inducing member is attached to the pole piece by forming a portion and fitting the leg portion of the discharge inducing member to the outer peripheral surface of the cylindrical portion.
In this way, by configuring the discharge inducing member so that it can be detachably attached to the pole piece, it is possible to easily attach and replace the protrusion (discharge inducing member) that is consumed by use.

  The discharge inducing member is preferably made of a magnetic material. As described above, since the discharge inducing member is formed of a magnetic material, in addition to the electric field of the anode, it is further affected by the magnetic field by the magnetic means. It becomes easy to generate discharge.

  According to the present invention, undischarged and abnormal discharge is suppressed, and a time delay is suppressed between the time when a high voltage is applied to the cold cathode ionization gauge and the time when electric current starts to flow after discharging. In addition, a cold cathode ionization vacuum gauge that suppresses fluctuations in the measured pressure value can be obtained.

It is a schematic block diagram which shows the cold cathode ionization vacuum gauge concerning embodiment of this invention. It is sectional drawing of the state in which the discharge induction member was mounted | worn with the pole piece of the cold cathode ionization vacuum gauge shown in FIG. It is a top view of the pole piece of the cold cathode ionization vacuum gauge shown in FIG. It is sectional drawing of the discharge induction member shown in FIG. It is a top view of the discharge induction member shown in FIG. FIG. 3 is a perspective view of an attachment member for attaching the discharge inducing member shown in FIG. 2 to a pole piece. It is a top view which shows the modification of a discharge induction member. FIG. 6 is a diagram showing the results of a runout test of Example 1. It is a figure which shows the result of the discharge probability of Example 1. It is a figure which shows the discharge induction member of Example 3, Comprising: (a) is sectional drawing, (b) is a top view. FIG. 6 is a diagram showing the results of a runout test of Example 3. It is a figure which shows the result of the discharge probability of Example 3. It is a figure which shows the result of the discharge probability of Example 4. It is a schematic block diagram which shows the conventional cold cathode ionization vacuum gauge.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6. The same members as those shown in FIG. 14 are denoted by the same reference numerals, and detailed description thereof is omitted.
As shown in FIG. 1, a cold cathode ionization vacuum gauge 1 according to the present invention includes a cylindrical cathode 51 having an opening formed at one end, and a rod-shaped anode 52 disposed in an internal space of the cylindrical cathode 51. And magnetic means (magnets 53a and 53b) for forming a magnetic field substantially orthogonal to the electric field between the anode 52 and the cathode 51 and causing discharge between the anode 52 and the cathode 51.
A pole piece 2 that maintains a discharge state is fitted to the opening edge of the cylindrical cathode 51, and the opening is covered with the pole piece 2. The pole piece 2 can maintain the discharge state even when the pressure is lower than ultra high vacuum.

  The pole piece 2 is detachably provided with a discharge inducing member 3. The discharge inducing member 3 makes it easy for discharge to occur between the tip of the protrusion 3a and the tip of the anode 52, and when the high voltage is applied to the cold cathode ionization gauge 1 The time delay from the time when the current begins to flow is reduced, and the measurement can be performed efficiently.

Hereafter, each structure of this embodiment is demonstrated concretely. First, the configuration of the pole piece 2 and the discharge inducing member 3 will be described.
As shown in FIGS. 1 to 3, the pole piece 2 is formed in a disk shape by stainless steel such as SUS430. The discharge inducing member 3 is detachably attached to one side of the pole piece, that is, one side of the pole piece facing the tip 52a of the anode 52.

The pole piece 2 has a projecting portion 2a projecting toward the anode side on one surface side of the anode 52 facing the cylinder 52 and a cylindrical portion 2b projecting further from the projecting portion 2a toward the anode 52 side. The discharge inducing member 3 is attached to the pole piece 2 by fitting the discharge inducing member 3 to the outer peripheral surface of the cylindrical portion 2b.
Although not shown, a recess is formed in a part of the outer peripheral surface of the cylindrical portion 2b, and the lower end portion of at least one leg portion 3c of the leg portion 3c of the discharge inducing member 3 is bent so that the discharge inducing member 3 is poled. You may make it latch on the side wall of the said recessed part of the piece 2. FIG.
A concave portion 2c is formed in the central portion of the cylindrical portion 2b, and a predetermined space is formed between the tip portion 52a of the anode 52 and one surface of the pole piece by the concave portion 2c. This space is provided so that the anode 52 does not come into contact with one surface of the pole piece 2 and is formed in a size and shape that does not affect the electric field strength or the like.

A first flat portion 2d is formed between the protruding portion 2a and the cylindrical portion 2c, and the end portion of the leg portion 3c of the discharge inducing member 3 is placed on the flat surface 2d. In addition, when the lower end part of the leg part 3c is bent, the edge part of the leg part 3c which is not bent is mounted on the plane 2d.
Further, the pole piece 2 includes a plurality of through holes 2f arranged in the second flat surface portion 2e outside the projecting portion 2a (FIG. 3 illustrates four through holes 2f).
The through holes 2f are provided for smooth exhaust characteristics from atmospheric pressure, and the number thereof is appropriately designed.

As shown in FIGS. 4 and 5, the discharge inducing member 3 includes a main body 3b formed in a ring shape, and a plurality of members extending obliquely from the upper end of the main body 3b in the opposite direction to the pole piece 2. And a leg portion 3c extending downward from the main body portion 3b.
The discharge inducing member 3 is formed of a metal, preferably a magnetic material, more preferably a soft magnetic material. Specifically, for example, a stainless steel material such as SUS430, a pure iron material subjected to nickel plating, or the like. Is done. By forming the discharge inducing member 3 from a magnetic material, in addition to the electric field of the anode 52, the discharge inducing member 3 is further influenced by the magnetic field by the magnetic means 53a and 53b. It becomes easy to generate discharge between 52a.

As shown in FIG. 5, two protrusions 3a are formed at equal intervals in the circumferential direction of one end of the main body 3b, and the shape thereof is formed in a triangular shape with the apex (tip portion) 3a1 facing the anode 52. Has been.
Further, as shown in FIGS. 2, 4, and 5, the center O of a virtual circle (a circle having the diameter of the tips of the two protrusions) formed by the tips 3a1 of the plurality of protrusions 3a. And the center line L of the anode 52 is positioned at a gap t (see FIG. 2) between the outer peripheral surface of the anode 52 and the tips 3a1 of the plurality of protrusions 3a. The member 3 is disposed on the pole piece 2.
Therefore, even if the distance between the pole piece 2 and the tip 52a of the anode 52 varies (in the mounting accuracy of the anode), the gap t between the projection 3a and the anode 52 is always kept constant. It is possible to make a discharge reliably.

The gap t is formed between 0.8 mm and 2.5 mm. Preferably, it is formed to 2.0 mm or less.
When the gap t formed between the anode 52 and the tip portions 3a1 of the plurality of protrusions 3a is less than 0.8 mm, the gap t is small and the electric field strength is large, so abnormal discharge occurs. This is not preferable because the measurement pressure value may fluctuate (fluctuate).
On the other hand, if the gap t formed between the anode 52 and the tip portions 3a1 of the plurality of protrusions 3a exceeds 2.5 mm, the gap is large and the electric field strength is small, so there is a possibility that no discharge will occur. This is not preferable. Considering the certainty of discharge, 2.0 mm or less is preferable.

The protrusion 3a extends in the opposite direction to the pole piece 2 from the horizontal plane (with respect to one surface of the pole piece 2) with an angle θ of 55 degrees or more and 90 degrees or less.
When the angle of the protrusion is obliquely extended with an angle of less than 55 degrees, the cleaning effect by discharge sputtering between the anode rod and the tip of the protrusion is difficult to be exhibited, which is not preferable. This is presumably due to the fact that as the angle of the protrusion becomes smaller, only one surface of the protrusion is cleaned, and the oxidation (deterioration) of the tip of the protrusion becomes dominant.
On the other hand, when the protrusion is extended at an angle exceeding 90 degrees, the distance between the tip of the protrusion and the anode rod is increased, and the electric field strength is decreased, which is not preferable.

As shown in FIG. 2, the tip 52a of the anode 52 is located on the pole piece 2 side from the tips 3a1 of the plurality of protrusions 3a. That is, the tip 52 a of the anode 52 is located in a space formed by the back surface of the discharge inducing member 3 and one surface of the pole piece 2. Specifically, the tip 52a of the anode 52 penetrates about 1.5 mm to 2.5 mm from the tips 3a1 of the plurality of protrusions 3a to the pole piece 2 side.
Thus, since the tip 52a of the anode 52 is located on the pole piece 2 side from the tip 3a1 of the protrusion 3a, both surfaces (front and back) of the protrusion 3a can be arranged in the discharge space. . As a result, the discharge can be generated reliably and quickly, and the time delay between the time when the high voltage is applied to the cold cathode ionization vacuum gauge 1 and the time when the current starts to flow after discharging is suppressed. In addition, fluctuations (fluctuations) in the measured pressure value can be suppressed.

Further, as shown in FIG. 5, four leg portions 3c are formed at equal intervals in the circumferential direction of one end portion of the main body portion 3b, and the leg portions 3c are fitted to the outer peripheral surface of the cylindrical portion 2c. Is formed. Furthermore, the discharge inducing member 3 is attached (fixed) to the pole piece 2 by attaching the attachment member 4 shown in FIG. 6 to the outside of the leg portion 3c.
As described above, the discharge inducing member 3 is locked to the side wall of the recess of the pole piece 2 by bending the lower end of at least one leg 3c of the leg 3c of the discharge inducing member 3, and further attached. The member 4 may be attached.

The attachment member 4 is made of, for example, stainless steel such as SUS430, and is formed in a ring shape having a notch 4a as shown in FIG. The attachment member 4 is a tightening ring and is attached to the outer peripheral surface of the discharge inducing member 3 attached to the pole piece 2, thereby preventing the discharge inducing member 3 from falling off.
In addition, when removing the discharge induction member 3 from the pole piece 2, it can remove easily by removing the attachment member 4. FIG. In this manner, by configuring the discharge inducing member 3 so as to be detachably attached to the pole piece 2, it is possible to easily attach and replace the protrusion (discharge inducing member) that is consumed by use.

In the above embodiment, the case where two protrusions 3a are formed at equal intervals in the circumferential direction of one end of the main body 3b has been described. However, as shown in FIG. There may be.
However, if a large number of the protrusions 3a are provided, the electric field strength is dispersed (decreased), and good discharge cannot be obtained. Depending on the shape and size, the number of the protrusions 3a is preferably two or three, and when four or more are formed, the electric field strength is dispersed and weakened, which is not preferable.

Next, since the configuration other than the configuration of the pole piece 2 and the discharge inducing member 3 in the cold cathode ionization vacuum gauge 1 according to the present invention is the same as the conventional configuration, it will be briefly described with reference to FIG.
The cylindrical cathode 51 has an opening at one end, a bottom 51a at the other end, and a through hole 51a1 at the axis of the bottom 51a. The bottom 51a is provided with a through hole 51a2 for a Pirani vacuum gauge 5, which will be described later.
In addition, a stepped fitting part 51 b is formed at the opening edge of one end of the cathode 51 and is shaped to fit with the outer peripheral part of the pole piece 2. Then, the pole piece 2 is fitted into the fitting portion 51b, and fixed to the cathode 51 by, for example, a fixing means such as a snap ring.

One end of the anode 52 is attached to the connector 6 and is electrically connected to the connector 6. In addition, the other end (tip portion) of the anode 52 is inserted through a through-hole 51 a 1 in the bottom 51 a of the cathode 51 through the feedthrough (current introduction terminal) 13, and is disposed in a space in the cylinder of the cathode 51.
The other end (tip 52a) of the anode 52 is opposed to the pole piece 2 fitted to the opening end of the cathode 51 in the space of the cathode 51 (enters into the discharge inducing member 3). ing).

  The anode 52 and the cathode 51 are arranged in the enclosure 7. In addition, the enclosure 7 is provided with a flange 8 and a Pirani gauge 5 as an auxiliary pressure sensor attached to the flange 8.

The connector 6 is electrically connected to the connector 10b via circuit boards 9c, 9b, 9a. Further, the connector 10 b is connected to a power source (not shown) that applies a voltage to the anode 52, and the power source is further connected to an ammeter that measures a current flowing through the anode 52.
Furthermore, the enclosure 7 is connected to the substrate 9c via the cathode plate 11 and grounded. The circuit boards 9a, 9b, 9c are held by the board holding member 12 and accommodated in the case 14.

  In addition to the connector 10b, the back surface of the case 14 is provided with a switch 10a and an LED 10c for displaying on / off of the power source. Further, reference numeral 15 in the figure denotes a connector for connecting the circuit boards 9a and 9b, and reference numeral 16 denotes a connector for connecting the circuit boards 9b and 9c.

Using the cold cathode ionization vacuum gauge shown in FIG. 1, a runout test and a deterioration test of measured pressure values were performed.
In the discharge inducing member of Example 1, the number of protrusions was two, the angle θ of the protrusion was 58 degrees, and the gap between the anode and the tip of the protrusion was 1 mm.
Here, in the fluctuation test of the measured pressure value, a measured value (pressure value) that was depressurized with time was obtained, and the fluctuation of the measured value was verified.
Moreover, the deterioration test was judged from the discharge probability in the cumulative deterioration time. The discharge probability during this cumulative deterioration time was determined as follows. First, the pressure was set to 0.1 Pa, the pressure was used for 1 hour, and then the pressure was set to 5 × 10 ⁻⁵ Pa, and the discharge probability at that time was obtained. Thereafter, the pressure was again set to 0.1 Pa and used for 1 hour. Thereafter, the pressure was set to 5 × 10 ⁻⁵ Pa, and the discharge probability at that time was determined. In this way, the usage time was accumulated hour by hour, and the discharge probability at that time was obtained.
The discharge probability is 1 when discharged in less than 1 second, 0.5 when discharged within 1 to 5 seconds, and 0 when discharged from 5 to less than 10 seconds. 2 and 0.1 when discharged from 10 seconds to less than 30 seconds, 0 when discharged for 30 seconds or more, and the time in discharge is converted to the above-mentioned numerical value, and the numerical value in three discharges is The average value was added to the discharge probability. That is, the discharge probability was (the first value + the second value + the third value) / 3, and when the discharge probability was less than 70%, it was determined that the discharge inducing member was deteriorated.

As a result, in Example 1, it was confirmed that the fluctuation of the measured pressure value was small and the fluctuation was suppressed, as is apparent from FIG. Moreover, in Example 1, as shown in FIG. 9, although the discharge probability fell to about 80% in about 60 hours, it returned to 100% again and it has confirmed that it could maintain 100% until 100 hours. That is, in Example 1, undischarge is suppressed, and a time delay is suppressed between the time when a high voltage is applied to the cold cathode ionization gauge and the time when electric current starts to flow after discharging. Confirmed that you can. It was also confirmed that the effect of extending the life could be obtained.
Incidentally, in the case of the cold cathode ionization vacuum gauge shown in FIG. 14, the measured pressure value fluctuated greatly and no discharge occurred in about 1 hour.

  Further, as Example 2, a discharge inducing member as shown in FIG. 7 having three protrusions, an angle θ of the protrusions of 58 degrees, and a gap between the anode and the tip of the protrusion of 1 mm was used. In the same manner as in Example 1, a run test and a degradation test of the measured pressure value were performed. As a result, the results shown in FIG. 8 and FIG.

As Example 3, the number of projections 3A and 3B as shown in FIG. 10 is eight, of which four are alternately arranged as short projections 3B and four are long projections 3A, and each projection 3A, The discharge inducing member 3 having an angle θ of 3B of 45 degrees and a gap between the anode and the tip of the long protrusion 3A of 0.65 mm was used.
And it attached to five cold cathode ionization vacuum gauges, and performed the runout test and the deterioration test of the measured pressure value.
As a result, two of the five units suppressed fluctuations in the measured pressure value as shown in FIG. 8, and the discharge probability in the cumulative deterioration time as shown in FIG. On the other hand, some fluctuations in the measured pressure value were recognized in the remaining three units as shown in FIG. Further, as shown in FIG. 12, the cumulative deterioration time when the discharge probability was less than 70% was about 12 hours.
From these results, when the number of protrusions on the discharge inducing member is two or three, it is possible to obtain a more excellent effect of suppressing the fluctuation of the measured pressure value, which is higher than that of the cold cathode ionization vacuum gauge. It was confirmed that the time delay can be further suppressed between the time when the voltage is applied and the time when the current starts to flow after discharging, and the effect of extending the life can be obtained.

In Example 4, the gap between the outer peripheral surface of the anode and the tip of the protrusion is 2 mm, the number of protrusions is three, the angle θ of the protrusions is 90 degrees, and the discharges are alternately arranged. A runout test and a deterioration test were performed using the members.
As a result, in the shake test, the same result as that in FIG. 8 was obtained, and an excellent shake suppression effect of the measured pressure value was confirmed. In the deterioration test, as shown in FIG. 13, it was confirmed that the effect of extending the life could be obtained.

DESCRIPTION OF SYMBOLS 1 Cold cathode ionization vacuum gauge 2 Pole piece 2a Protrusion part 2b Cylindrical part 2c Recessed part 2d 1st plane part 2e 2nd plane part 2f Through-hole 3 Discharge induction member 3a Protrusion part 3a1 Tip part 3b Body part 3c Leg part 3A Long Projection 3B Short Projection 4 Mounting Member 4a Notch L Anode O Center of the virtual circle connecting the tips of the projections θ Inclination angle of the projection t t The gap between the anode and the tip of the projection

Claims (5)

A cylindrical cathode having an opening at one end;
A rod-shaped anode disposed in the internal space of the cathode;
A magnetic means for forming a magnetic field orthogonal to the electric field between the anode and the cathode and causing a discharge between the anode and the cathode;
A pole piece that is detachably fitted to the opening edge of the cathode and covers the opening;
In a cold cathode ionization vacuum gauge comprising a discharge inducing member provided on one side of a pole piece opposite to the tip of the anode,
The discharge inducing member has a main body formed in a ring shape, and a plurality of protrusions extending in the opposite direction from the pole piece from one end of the main body,
A center line of the anode is formed by the tips of the plurality of protrusions and is located on the center of an imaginary circle, and a gap is formed between the outer peripheral surface of the anode and the tips of the plurality of protrusions,
Furthermore, the cold cathode ionization vacuum gauge is characterized in that the tip of the anode is positioned on the pole piece side with respect to the tips of the plurality of protrusions.   The cold cathode ionization vacuum gauge according to claim 1, wherein the gap formed between the outer peripheral surface of the anode and the tips of the plurality of protrusions is 0.8 mm or more and 2.5 mm or less. .   Two or three protrusions are provided at equal intervals in the circumferential direction of one end of the main body, and the protrusions are in the direction opposite to the pole piece and are 55 degrees or more and 90 degrees with respect to one surface of the pole piece. The cold cathode ionization vacuum gauge according to claim 1 or 2, wherein the cold cathode ionization vacuum gauge is extended at the following angle. The main body portion of the discharge inducing member is formed with a plurality of legs extending downward from the main body portion, and a cylindrical portion for mounting the discharge inducing member is provided on one surface side of the pole piece. Formed,
The said discharge induction member is mounted | worn with the said pole piece by the leg part of the said discharge induction member fitting to the outer peripheral surface of the said cylindrical part, The Claim 1 thru | or 3 characterized by the above-mentioned. Cold cathode ionization vacuum gauge.   The cold cathode ionization vacuum gauge according to any one of claims 1 to 4, wherein the discharge inducing member is made of a magnetic material.

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