JPS63198840A - Hot-cathode ionization gauge - Google Patents
Hot-cathode ionization gaugeInfo
- Publication number
- JPS63198840A JPS63198840A JP3084587A JP3084587A JPS63198840A JP S63198840 A JPS63198840 A JP S63198840A JP 3084587 A JP3084587 A JP 3084587A JP 3084587 A JP3084587 A JP 3084587A JP S63198840 A JPS63198840 A JP S63198840A
- Authority
- JP
- Japan
- Prior art keywords
- anode
- collector
- hot cathode
- ion collector
- ion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 150000002500 ions Chemical class 0.000 claims abstract description 81
- 150000001768 cations Chemical class 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 5
- 238000005259 measurement Methods 0.000 abstract description 4
- 230000035945 sensitivity Effects 0.000 description 9
- 238000009530 blood pressure measurement Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000003760 hair shine Effects 0.000 description 1
- 239000002784 hot electron Substances 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- ZCUFMDLYAMJYST-UHFFFAOYSA-N thorium dioxide Chemical compound O=[Th]=O ZCUFMDLYAMJYST-UHFFFAOYSA-N 0.000 description 1
- 229910003452 thorium oxide Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
この発明はイオンコレクターの浴びる軟Ｘ線量を少なく
して、Ｘ線による圧力測定の下限を大幅に向上させた熱
陰極電離真空計に関するものである。[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to a hot cathode ionization vacuum gauge that reduces the amount of soft X-rays exposed to the ion collector and significantly improves the lower limit of pressure measurement using X-rays. be.
（従来の技術及び問題点））
従来、ｔｏ−５ｐａ（約１Ｏ−７Ｔｏｒｒ）以下の超高
真空の圧力測定は、ベアード・アルバート（ＢＡと略称
）型電離真空計が用いられて来た。このＢＡ型電離真空
計は高融点金属線材を円筒状格子に形成した陽極に対し
、陽極の中心軸上に針状イオンコレクターを配置し、陽
極の外側には熱陰極を配置した三極構造となフている。(Prior Art and Problems) Conventionally, a Baird-Albert (abbreviated as BA) type ionization vacuum gauge has been used to measure ultra-high vacuum pressures of to-5 Pa (approximately 1 O-7 Torr) or less. This BA type ionization vacuum gauge has a three-pole structure with an anode made of high-melting point metal wire formed into a cylindrical grid, a needle-shaped ion collector placed on the central axis of the anode, and a hot cathode placed outside the anode. There is a lot of trouble.
この電極構成において、熱陰極と陽極間に電子電流を流
すことにより、電子の一部を陽極を中心に熱陰極とイオ
ンコレクター間で振動させ、この振動電子によって真空
中の残留気体分子を衝撃してイオン化し、生成したイオ
ンをイオンコレクターに捕捉して電流として取り出し、
このイオン電流値より圧力を求める。ところが熱陰極よ
り飛び出した振動電子は振動を繰り返すうちに陽極に衝
突しくこれが前記電子電流に相当する）、この衝突によ
って陽極からはたえず軟Ｘ線が放射される。ところが前
記イオンコレクターがこの軟Ｘ線を浴びると光電子を放
出するため、前記イオン電流と同じ方向の光電子電流が
イオン収集電極に生じることになる。このため圧力が低
くなってイオンコレクターに流入するイオン電流が無く
なったとしても、電流値はこの光電子電流値以下に下ら
ないため、ＢＡ型電離真空計を用いての圧力測定には限
界があった。その限界圧カバｌＯ〜１０ Ｐａ （＝
ｌＯ−” 〜１０−”Ｔｏｒｒ） であフた。In this electrode configuration, by passing an electron current between the hot cathode and the anode, some of the electrons are oscillated between the hot cathode and the ion collector with the anode as the center, and the oscillating electrons bombard residual gas molecules in the vacuum. The generated ions are captured in an ion collector and extracted as an electric current.
The pressure is determined from this ion current value. However, the oscillating electrons ejected from the hot cathode collide with the anode as they repeat their oscillations (this corresponds to the electron current), and due to these collisions, soft X-rays are constantly emitted from the anode. However, when the ion collector is exposed to this soft X-ray, it emits photoelectrons, so a photoelectron current in the same direction as the ion current is generated in the ion collecting electrode. For this reason, even if the pressure becomes low and the ion current flowing into the ion collector disappears, the current value will not fall below this photoelectron current value, so there is a limit to pressure measurement using a BA type ionization vacuum gauge. Its critical pressure is lO ~ 10 Pa (=
The temperature was 10-" to 10-" Torr).
従ってこの圧力測定下限を改善するには、イオンコレク
ターからの光電流を減らさなければならない。光電流を
減らすには針状イオンコレクターの線径および長さを短
くして軟Ｘ線を浴びる表面積を減らすことが考えられる
が、イオンコレクターを小さくするとイオンの収集効率
が小さくなり、真空計としての感度が小さくなる問題が
あった。このため通常用いられるＢＡ型電離真空計の陽
極は直径１０〜２５ｍｍ、長さ４０〜５０ｍｍ位の円筒
格子状に対して、イオンコレクターは、機械的支持強度
限界まで細くしたとしても１００ｐ１位が限度であった
。その結果このＢＡ型電離真空計の軟Ｘ線による圧力測
定の下限は前記のように１０−８〜１Ｏ−９Ｐａ （約
１０” 〜１０−” Ｔｏｒｒ）であった。Therefore, to improve this pressure measurement lower limit, the photocurrent from the ion collector must be reduced. A possible way to reduce the photocurrent is to shorten the wire diameter and length of the needle-shaped ion collector to reduce the surface area exposed to soft There was a problem that the sensitivity was reduced. For this reason, the anode of the commonly used BA type ionization vacuum gauge has a cylindrical lattice shape with a diameter of 10 to 25 mm and a length of about 40 to 50 mm, whereas the ion collector has a limit of about 100p1 even if it is thinned to the mechanical support strength limit. Met. As a result, the lower limit of pressure measurement using soft X-rays of this BA type ionization vacuum gauge was 10-8 to 10-9 Pa (approximately 10'' to 10-'' Torr) as described above.
このＢＡ型電離真空計のＸ線限界を打破するために開発
された手段の一つとして球状陽極を用いた電離真空計が
ある（特公昭５８−１５０５１号） この電離真空計
は、陽極をメツシュ材を成型して球面状に近似させ、こ
の陽極の外側に熱陰極を配置すると共に、陽極の中心軸
上には針状のイオンコレクターを配置した三極構造を有
する。この電極構成ではイオン化に寄与する電子の軌道
は陽極で囲まれる球状空間の中心に向うため、前記球状
空間の中心部における電子密度およびイオン密度が高く
なりイオン収集効率を高くすることが可能となり、極細
の針状イオンコレクターを用いたとしても、感度の低下
を来たさないというのがその理由である。An ionization vacuum gauge using a spherical anode is one of the means developed to overcome the X-ray limitations of the BA type ionization vacuum gauge (Special Publication No. 15051/1983). It has a three-pole structure in which the material is molded to approximate a spherical shape, a hot cathode is placed outside the anode, and a needle-shaped ion collector is placed on the central axis of the anode. In this electrode configuration, the trajectory of electrons contributing to ionization is directed toward the center of the spherical space surrounded by the anode, so the electron density and ion density at the center of the spherical space are high, making it possible to increase the ion collection efficiency. The reason for this is that even if an ultra-fine needle-shaped ion collector is used, there is no decrease in sensitivity.
しかし、実際、この球状陽極電離真空計において、針状
イオンコレクターの線径を支持強度限界ギリギリの３０
μｓ位のタングステン線に変えて測定を行ってみるとそ
のＸ線限界は１０”Ｔｏｒｒ台で、ＢＡ型電離真空計の
Ｘ線限界を越えないことがわかった。この球状陽極電離
真空計の実際のＸ線限界が、理論通りにならなかったの
は次の理由による。即ち球状陽極は円筒状ＢＡ型陽極に
比べて、縦方向に極端に短いため熱陰極から飛び出して
陽極の内外に振動する電子は、ＢＡ型陽極では円筒の側
面の内外即ち針状イオンコレクターと直角の方向に振動
するのに対し、球状陽極では側面が球面になるが由に電
子を横向きに引き付ける力が弱くなり、電子の撮動は縦
方向に即ち針状イオンコレクターに平行な方向になる。However, in reality, in this spherical anode ionization vacuum gauge, the wire diameter of the needle ion collector was set at 30 mm, which was at the limit of the support strength.
When we changed the measurement to a tungsten wire with a wavelength of approximately μs, we found that its X-ray limit was on the order of 10” Torr, which did not exceed the X-ray limit of the BA type ionization vacuum gauge.The actual use of this spherical anode ionization vacuum gauge The reason why the X-ray limit did not match the theory is as follows: The spherical anode is extremely short in the vertical direction compared to the cylindrical BA-type anode, so it jumps out from the hot cathode and vibrates in and out of the anode. In a BA-type anode, electrons vibrate in and out of the cylindrical side surface, that is, in a direction perpendicular to the needle-shaped ion collector, whereas in a spherical anode, the side surface is spherical, so the force that attracts electrons sideways is weaker, and the electrons The imaging is in the longitudinal direction, that is, in the direction parallel to the needle-like ion collector.
ここで振動電子が球状陽極の外側から前記陽極に向う方
向は常に求心的であるから、針状イオンコレクターに平
行に振動することは、イオンコレクター近傍にそれだけ
多くのイオンが生成されることになり、イオン収集効率
が高くなり感度が高められることになる。これが球状陽
極電離真空計が高感度となる理由である。しかし反面、
球状陽極の針状イオンコレクターを通す孔附近の格子部
分には、縦方向に振動する電子が非常に沢山衝突するこ
とになり、しいてはこの部分から沢山の軟Ｘ線が発生す
ることになる。ところが前記陽極格子の孔は、イオンコ
レクターに最も近い位置にあるから、ここで発生する軟
Ｘ線はイオンコレクターへの入射確率が高く、イオンコ
レクターの根元附近からの光電子放出は想像以上に多い
。このため例え針状イオンコレクターの線径をＢＡ型針
状イオンコレクターの線径の１／１０以下である１５戸
以下にし、長さも１７６以下にして表面積を１／９０以
下に理論上できると考えても、単位面積当りに放出され
る光電子は１００倍位まで上昇することになり、結果と
して球状陽極型電離真空計は、ＢＡ型電離真空計のＸ線
限界−ｔｏ−１１Ｔｏｒｒを越えることはできなかった
。またこの前記陽極格子の針状イオンコレクターを通す
孔附近の電子衝突の多さは電子′ａ撃撃方ガス加熱時直
接観察することができる。即ち熱陰極からこの球状陽極
へ１００ｍＡ位の電子を５００ｖ位の電圧で加速衝撃し
てやると、球状陽極は赤色に加熱される様子を真空壁の
ガラス窓を通して観察することができる。ところがこの
球状陽極の加熱時の色の付き方は均一でなく、針状イオ
ンコレクターを通る孔附近と、その針の先端の反対側に
当る球状陽極の天頂部分だけが３〜５ｍｍ位のスポット
状に明るく輝くように加熱される。このことはこの陽極
の孔の附近に特別多くの電子か衝突していることを物語
フている。これに対してＢＡ型電離真空計に同じ電子衝
撃を行ってみた場合は、このような均一な加熱のされ方
はしない。Here, since the direction of the oscillating electrons from the outside of the spherical anode toward the anode is always centripetal, the fact that the oscillating electrons oscillate parallel to the needle-shaped ion collector means that more ions are generated near the ion collector. , the ion collection efficiency will be high and the sensitivity will be enhanced. This is the reason why spherical anode ionization gauges have high sensitivity. But on the other hand,
A large number of vertically oscillating electrons collide with the lattice part of the spherical anode near the hole where the acicular ion collector passes, and a large number of soft X-rays are generated from this part. . However, since the holes in the anode lattice are located closest to the ion collector, the soft X-rays generated here have a high probability of entering the ion collector, and photoelectron emission from the vicinity of the base of the ion collector is greater than expected. For this reason, we believe that it is theoretically possible to reduce the surface area to 1/90 or less by reducing the wire diameter of the needle-shaped ion collector to 15 or less, which is 1/10 or less of the wire diameter of the BA-type needle-shaped ion collector, and by making the length 176 or less. However, the number of photoelectrons emitted per unit area increases by about 100 times, and as a result, the spherical anode ionization vacuum gauge cannot exceed the X-ray limit of the BA type ionization vacuum gauge -to-11 Torr. There wasn't. Further, the number of electron collisions near the holes passing through the needle-like ion collector of the anode grid can be directly observed when the electron bombardment gas is heated. That is, when electrons of about 100 mA are accelerated and impacted at a voltage of about 500 V from the hot cathode to this spherical anode, the spherical anode can be observed through the glass window of the vacuum wall as it is heated to a red color. However, the coloration of this spherical anode when heated is not uniform, and only the area near the hole passing through the needle-shaped ion collector and the zenith portion of the spherical anode opposite to the tip of the needle have a spot shape of about 3 to 5 mm. It is heated so that it shines brightly. This suggests that a particularly large number of electrons are colliding near the hole in the anode. On the other hand, when the same electron bombardment is applied to a BA-type ionization vacuum gauge, the heating does not occur as uniformly as this.
以上述べたような理由によって、球状陽極電離真空計は
高感度：小型化を達成できたにもかかわらず、本来目的
としたＸ線限界の改善には計算通りには行かず、従来の
ＢＡ型電離真空計のＸ線限界を越えることはできず、工
業製品として生産されるには至らなかったものである。For the reasons mentioned above, although the spherical anode ionization vacuum gauge achieved high sensitivity and miniaturization, it did not achieve the original goal of improving the X-ray limit as calculated, and the conventional BA type It was not possible to exceed the X-ray limit of ionization vacuum gauges, and it was not produced as an industrial product.
（問題点を解決するための手段）
然るにこの発明は、このような現状を鑑みなされたもの
であって、真空系内に配置した熱陰極および陽極間に電
子電流を流し該電子電流を形成する電子が空間を飛行中
に気体分子を衝撃して作る陽イオンをイオンコレクター
に収集して取り出した電流値から該真空系内のガス圧力
を測定する測定子において、イオンコレクターを点状に
近似せしめて陽極内側に配置すると共に、陽極の外側に
熱陰極を配置したことにより、球状陽極の最大欠点を克
服し、球状陽極の高感度を巧みに生かし、従来のＢＡ型
真空計のＸ線限界を２桁以上も改善することができるよ
うにしたものである。(Means for Solving the Problems) However, the present invention was made in view of the current situation, and involves forming an electron current by flowing an electron current between a hot cathode and an anode arranged in a vacuum system. The ion collector is approximated as a point in a measuring element that measures the gas pressure in the vacuum system from the current value collected by collecting positive ions produced by electrons bombarding gas molecules while flying through space in an ion collector. By arranging the hot cathode inside the anode and the hot cathode outside the anode, the biggest drawback of the spherical anode is overcome, and the high sensitivity of the spherical anode is skillfully utilized to overcome the X-ray limit of the conventional BA type vacuum gauge. This allows for an improvement of more than two orders of magnitude.
（実施例）
以下本発明を第１図及び第２図に示した一実施例に基い
て説明すれば、１は陽極であって、該陽極１は線径約０
．１ｍｍの平織りの２０メツシユの金網材を直径約２４
ｍｍの椀型に成型したものを２個突き合わせると共に環
状鍔２を介し両者を一体化することにより、球面に近似
させた陽極構成となっている。そして上記陽極１の環状
鍔２下方には一部膨みを持たせ、２個突き合わせること
によって形成される直径約３ｍｍの小孔３を通して針状
コレクター４及びパイプ状シールド電極５を陽極１内に
臨ませである。パイプ状シールド電極５は外径的２ｍｍ
のタンタル金属パイプの先端を丸めて一旦閉じ、再び中
央に直径約０．７ｍｍの小孔６を開けたもので、その先
端部の該陽Ｖｉ壁からの侵入距離は約１．５ｍｍである
。針状イオンコレクター４は直径約０．１５＋ｎｎ＋の
タングステン金属線を電解腐食法によって先端に向って
順次細くし、その先端部の直径は約０．０３ｍｍで、前
記パイプ状シールド電極５の小孔６から突出距離は約Ｑ
、０５ｍｍに設定されている。そしてこの２つの電極構
成によって、針状イオンコレクター４の先端部が点状に
近似されて陽極内側に突出し、該突出部が点状のイオン
コレクター７となるものである。、８は線径約０．１５
ｍｍの酸化トリウムを含有させたタングステン線の熱陰
ｇ１（フィラメント）で、互いに１８０゛の位置で半円
弧のヘアピン状にした支持棒９に張設し前記陽極１の赤
道上に環状に配置される。尚、針状イオンコレクター４
とパイプ状シールド電極５を取り巻く太いパイプ１０は
、針状イオンコレクター４と同電位（アース電位）に置
かれて同軸真空導入電流端子１１に溶接される。同じく
支持棒９，１２も真空導入電流端子１１に溶接され、本
発明の熱陰極電離真空計を構成する。尚、第１図には新
たな電極としてイオン電流を変調するための変調電極１
３が点状イオンコレクター７から約５ ｍｍｆｌねた位
置に示しである。(Example) The present invention will be described below based on an example shown in FIGS. 1 and 2. Reference numeral 1 represents an anode, and the anode 1 has a wire diameter of approximately
．． A wire mesh material of 20 meshes of 1mm plain weave is approximately 24mm in diameter.
By abutting two mm-sized bowl-shaped pieces and integrating them through an annular flange 2, an anode structure that approximates a spherical surface is obtained. A portion of the annular collar 2 of the anode 1 has a bulge below, and a needle collector 4 and a pipe shield electrode 5 are inserted into the anode 1 through a small hole 3 with a diameter of about 3 mm formed by butting the two pieces together. I'm going to face it. The pipe-shaped shield electrode 5 has an outer diameter of 2 mm.
The tip of the tantalum metal pipe is rounded and closed once again, and a small hole 6 with a diameter of about 0.7 mm is made in the center again, and the penetration distance of the tip from the positive Vi wall is about 1.5 mm. The needle-like ion collector 4 is a tungsten metal wire with a diameter of about 0.15+nn+ made by electrolytic corrosion so that it becomes thinner toward the tip. The protrusion distance is approximately Q
, 05mm. With this two-electrode configuration, the tip of the needle-like ion collector 4 is approximated to a dot-like shape and protrudes inside the anode, and the protrusion becomes a dot-like ion collector 7. , 8 is a wire diameter of approximately 0.15
A hot shade g1 (filament) of tungsten wire containing thorium oxide of mm is stretched over a semicircular hairpin-shaped support rod 9 at positions 180° from each other, and arranged in a ring shape on the equator of the anode 1. Ru. In addition, needle-shaped ion collector 4
A thick pipe 10 surrounding the pipe-shaped shield electrode 5 is placed at the same potential (earth potential) as the needle-shaped ion collector 4 and welded to a coaxial vacuum introduction current terminal 11. Similarly, the support rods 9 and 12 are also welded to the vacuum introduction current terminal 11, and constitute the hot cathode ionization vacuum gauge of the present invention. In addition, FIG. 1 shows a modulation electrode 1 for modulating the ion current as a new electrode.
3 is shown at a position about 5 mm fl away from the point ion collector 7.
さて、上記実施例の熱陰極電離真空計を用いて圧力を測
定するには、熱陰極フィラメント８に加熱電源を接続す
ると共に、熱陰極８と陽極１の間には所定の電子電流が
流れるように電子電流制御回路（図示せず）を接続する
。この場合の陽極１の熱陰極８に対する電位Ｕ９ｆ及び
熱陰極８のアース電位に対する電位Ｕずは、例えばＵ
ｑｆ ＝ １１０ Ｖ及びＵｆ＝２００ Ｖである。ま
たパイプ状シールド電極５の電位は通常熱陰８ｉ８と同
じ電位に置かれる。さらに変調電極１３は通常は陽極電
位に置かれるが、変調を行う場合は変調電極電位をアー
ス電位に切り変える。Now, in order to measure pressure using the hot cathode ionization vacuum gauge of the above embodiment, a heating power source is connected to the hot cathode filament 8, and a predetermined electron current is caused to flow between the hot cathode 8 and the anode 1. An electronic current control circuit (not shown) is connected to. In this case, the potential U9f of the anode 1 with respect to the hot cathode 8 and the potential U of the hot cathode 8 with respect to the ground potential are, for example, U
qf = 110V and Uf = 200V. Further, the potential of the pipe-shaped shield electrode 5 is normally set to the same potential as the heat shade 8i8. Furthermore, although the modulation electrode 13 is normally placed at an anode potential, when modulation is performed, the modulation electrode potential is switched to ground potential.
上記の動作条件において、熱陰極８から陽極１に向って
１ｍ＋八はどの電子電流を流してやると、熱電子の一部
は球面に近似させて形成した陽８ｉｆを境としてその内
外の空間を振動する。この振動によって球面内の残留気
体分子は衝窓され正イオンが生成される。Under the above operating conditions, when an electron current of 1m+8 is passed from the hot cathode 8 to the anode 1, some of the hot electrons oscillate in the space inside and outside the positive 8if, which is formed by approximating a spherical surface. do. Due to this vibration, residual gas molecules within the spherical surface are bombarded and positive ions are generated.
球面内の正イオンはパイプ状シールド電８ｉ５の先端に
向ってほぼ直線的に引かれて集められるが、この針状の
先端とパイプ状シールド電極５間には２００Ｖの強い電
界が掛けられているためほとんどのイオンはこの点状コ
レクター７に集束される。この針状イオンコレクター４
には同軸端子１１を介して真空系外に設けられた微小電
流増幅器（図示せず）に接続されており、イオン電流は
増巾され、その値はメータ等によって指示され、これよ
り圧力を求めるものである。Positive ions within the spherical surface are drawn almost linearly toward the tip of the pipe-shaped shield electrode 8i5 and collected, but a strong electric field of 200 V is applied between this needle-shaped tip and the pipe-shaped shield electrode 5. Therefore, most of the ions are focused on this point collector 7. This needle-shaped ion collector 4
is connected to a minute current amplifier (not shown) provided outside the vacuum system via a coaxial terminal 11, the ion current is amplified, and its value is indicated by a meter, etc., and the pressure is determined from this. It is something.
第３図は前記実施例から得られた結果を示すグラフで、
横軸に真空系の実際の圧力を、縦軸に前記実施例から得
られる点状イオンコレクター７のイオン電流値を示した
ものである。FIG. 3 is a graph showing the results obtained from the above example,
The horizontal axis shows the actual pressure of the vacuum system, and the vertical axis shows the ion current value of the point ion collector 7 obtained from the above example.
グラフ上の結果はほぼ４５°の傾きを示す直線であり電
離真空計としての第一の基本特性を満している。The result on the graph is a straight line with an inclination of approximately 45°, which satisfies the first basic characteristic of an ionization vacuum gauge.
他方前記実施例がＸ線限界の改善に本当に役立つかどう
かを調べたのが第４図に示したグラフ群である。このグ
ラフはベアードとアルバートが発明したＢＡ型電離真空
計のＸ線限界が１Ｏ−８Ｐａ（１０−１０Ｔｏｒｒ）附
近にあることを実験的に証明した歴史的方法（第６図の
参考図参照）と同じ方法で５示したものである。即ち横
軸に熱陰極と陽極間の電位差Ｕ９（を取るのに対して縦
軸にはイオンコレクターに流れる電流を取ってやると、
圧力の高いイオン電流が主成分を占でいる時は、グラフ
Ｇ１のようにＬ１９子＝１１０ Ｖに最大の山があり、
それ以上の電圧では右下りになる傾向がある。それに対
し圧力が低くなってイオン電流が少くなり、相対的に光
電子電流の割合が増してくると、光電子電流は電圧の約
２乗倍で増すことが知られているから、グラフはＧ３
、Ｇ４に示したように右上りの傾向が現われてくる。さ
らに良い真空が得られイオン電流がほぼ写となり、光電
子電流だけとなった場合は、破線で示したグラフＧ５の
ような形となる。ところでこのＸ線限界の測定に用いた
真空系の到達圧力は７ ｘ １０ Ｐａ （５ｘ
１０” Ｔｏｒｒ）であフたから、この実施例のＸ線限
界を求めるには不十分である。そこで第１図に示した変
調電極１３を用いてイオン電流を変調することによって
Ｘ線限界を求めた。この変調電極１３は第５図に示した
ような特性を持っている。従ってこの変調電極１３をｔ
Ｊｍ ＝Ｕ ＋ ＋ ｔＪ ９ｆ ＝３１０ Ｖの陽極
電位からＵ、、＝Ｏのアース電位に切り変えてやると、
イオン電流の９５％をこの変調電極１３に取り込んでし
まうことを意味している。On the other hand, the group of graphs shown in FIG. 4 was used to examine whether the above-mentioned embodiment is really useful for improving the X-ray limit. This graph is based on a historical method (see the reference diagram in Figure 6) that experimentally proved that the X-ray limit of the BA type ionization vacuum gauge invented by Baird and Albert was around 10-8 Pa (10-10 Torr). 5 was shown using the same method. That is, if the horizontal axis represents the potential difference U9 between the hot cathode and the anode, and the vertical axis represents the current flowing through the ion collector, then
When the main component is a high-pressure ion current, the maximum peak is at L19 = 110 V, as shown in graph G1.
At higher voltages, there is a tendency for the curve to fall to the right. On the other hand, when the pressure decreases, the ionic current decreases, and the proportion of photoelectron current increases relatively, it is known that the photoelectron current increases at about the square of the voltage, so the graph becomes G3.
, an upward trend to the right appears as shown in G4. If an even better vacuum is obtained and the ion current becomes almost identical, leaving only the photoelectron current, the shape will be as shown in graph G5 shown by the broken line. By the way, the ultimate pressure of the vacuum system used to measure this X-ray limit is 7 x 10 Pa (5x
10" Torr), which is not sufficient to determine the X-ray limit in this example. Therefore, the X-ray limit was determined by modulating the ion current using the modulation electrode 13 shown in FIG. This modulation electrode 13 has the characteristics shown in FIG.
Jm = U + + tJ 9f When switching from the anode potential of = 310 V to the ground potential of U, , = O,
This means that 95% of the ion current is taken into this modulation electrode 13.
従って、 ７ ｘ １０”Ｐａの不十分な真空でもこの
変調室８ｉ１３を用いてイオン電流の９５％を除去する
ことにより点状コレクター７からの真の光電子電流の概
略値を知ることができる。第４図に示したグラフＧ４は
前記変調電極１３の電位をＵ□＝０のアース電位にして
得られたものである。これを見るとまだ直線にはなって
おらず、イオン電流成分が未だ残存していることを意味
している。そこでＵ ｑｔ、 ＝ ７００〜８００■以
上ではほぼ直線と見なし逆算によってベアードとアルバ
ードが行った方法のグラフを描いてみたのが０５で示す
破線グラフである。Therefore, even in an insufficient vacuum of 7 x 10"Pa, by removing 95% of the ion current using this modulation chamber 8i13, it is possible to know the approximate value of the true photoelectron current from the point collector 7. Graph G4 shown in Figure 4 was obtained by setting the potential of the modulation electrode 13 to the ground potential of U□=0.As you can see, it is not yet a straight line, and the ionic current component still remains. Therefore, when U qt, = 700 to 800■ or above, it is assumed that it is almost a straight line, and by back calculation, I drew a graph based on the method used by Baird and Alvard, and the broken line graph shown in 05 is.
このグラフＧ５から電子電流１ｅ＝１ｍＡ″ＱＵ！３ｆ
＝１１０Ｖの正常電圧で用いる場合の点状イオンコレク
ター７に流れる電流１ｃは１Ｏ−１４Ａ以下であり、ま
た第３図のグラフからこの実施例の電離真空計の感度は
約０．４ Ｐａ−１（５３Ｔｏｒｒ−１） ｃ）高感度
であるから、
Ｘ線限界Ｐｘは
と概算できる。From this graph G5, electron current 1e=1mA''QU!3f
When used at a normal voltage of =110V, the current 1c flowing through the point ion collector 7 is less than 1O-14A, and from the graph in Figure 3, the sensitivity of the ionization vacuum gauge of this embodiment is about 0.4 Pa-1. (53Torr-1) c) Since it has high sensitivity, the X-ray limit Px can be roughly estimated as.
これに対して従来のＢＡ型電離真空計では第４図の破線
のグラフＧ５の位置はＩ ｃ ＝ １０”〜１０” Ａ
の位置に現われるから、前記実施例のＸ線限界に対する
改善は約２桁向上したことになる。On the other hand, in the conventional BA type ionization vacuum gauge, the position of the broken line graph G5 in FIG. 4 is I c = 10" to 10" A
Therefore, the improvement with respect to the X-ray limit in the above embodiment is approximately two orders of magnitude.
さらに、前記実施例の変調電極１３は電位を陽極１から
アース電位に切り変えた時、点状イオンコレクター７に
流れ込むイオン電流の９５％を変調することができる。Further, the modulating electrode 13 of the embodiment described above can modulate 95% of the ion current flowing into the point-like ion collector 7 when the potential is switched from the anode 1 to the ground potential.
これに対して従来のＢＡ型電離真空計の針状変調電極に
よる変調率は３０〜４０％であるから、前記実施例の変
調電極１３は変調率においても大幅な改善がなされたこ
とになる。On the other hand, since the modulation rate by the needle-shaped modulation electrode of the conventional BA type ionization vacuum gauge is 30 to 40%, the modulation electrode 13 of the above embodiment has a significant improvement in the modulation rate.
さらに特筆すべきことは前記実施例の電離真空計では、
イオンコレクター７が点状であり、また変調電極１３も
非常に短いため、２電極間の静電容量結合が無視でき、
変調に伴ってイオンコレクター回路に変調に伴う話導電
流が発生しないということである。このため速い周波数
での交流連続変調を行うことが可能となり、この変調に
よって、さらに１桁以上の測定限界の改善が可能となり
＝１０”Ｐａまでの圧力測定が可能となる画期的発明と
なったものである。What is further noteworthy is that in the ionization vacuum gauge of the above embodiment,
Since the ion collector 7 is point-shaped and the modulation electrode 13 is also very short, the capacitance coupling between the two electrodes can be ignored.
This means that no conducting current is generated in the ion collector circuit due to modulation. This made it possible to carry out continuous alternating current modulation at a high frequency, and this modulation made it possible to further improve the measurement limit by more than an order of magnitude, making it possible to measure pressures up to 10"Pa, an epoch-making invention. It is something that
このように従来の電離真空計では測定できなかった１０
Ｐａ （１０”Ｔｏｒｒ）以下の圧力を３桁以上も
向上させて＝ １Ｏ−１２Ｐａまでの圧力測定を可能な
らしめたのは、とりもなおさず、イオンコレクターを点
状に近似させて球状に近似させた陽極１内側に配置する
ために、パイプ形状シールド電極５の一端から針状電極
４の先端部の一部だけを突出させ、該針状電極５先端が
見掛は上点状イオンコレクター７を形成せしめると共に
、この点状コレクター７を球面状に近似せしめて形成し
た陽極１の一部開孔から該陽極内側に配置し、該陽極１
の外側には熱陰極フィラメント８を配置して少くとも画
電極構成を基本とする電離真空計を提供したことに外な
らない。In this way, conventional ionization vacuum gauges cannot measure 10
The reason why we were able to improve the pressure below Pa (10”Torr) by more than three orders of magnitude and make it possible to measure pressures up to 10-12Pa is because the ion collector is approximated to a point shape to a sphere shape. In order to dispose the anode 1 inside the anode 1, only a part of the tip of the needle electrode 4 protrudes from one end of the pipe-shaped shield electrode 5, and the tip of the needle electrode 5 appears to be connected to the upper dot-shaped ion collector 7. At the same time, this dot-like collector 7 is placed inside the anode through a partial opening of the anode 1, which is formed by approximating a spherical shape.
By arranging the hot cathode filament 8 on the outside of the hot cathode filament 8, we have provided an ionization vacuum gauge based on at least a picture electrode configuration.
尚、各電極の構成、材料及び電極の配置構成は図に示し
た実施例に限定されるものではない。Note that the structure, material, and arrangement of each electrode are not limited to the embodiment shown in the drawings.
即ち点状に近似せしめるための２つの電極は、針状コレ
クターとパイプ形状電極に限られるものではなく、例え
ば線状コレクターとラッパ形状の組み合わせなどでもよ
く、要するにコレクターの一部をシールド電極から露出
させ、該露出部が、陽極１表面から見て点状に近似して
見なせるものならばいかなる組み合わせであワてもよい
。また球面状に近似させた陽極１は実施例の形状に限定
されるものではなく、線材で形成した複数の環体を球の
緯線に沿うように配置（従って異なる直径の環体を準備
する）したものや、同じ形状の複数の環体を球の経線に
沿うように配置して陽極を構成したもの、或いは線材を
スパイラルに巻き、その曲率を順次変化させて球面に近
似させて形成して陽極１を構成したものなど、中空で球
面に沿って格子が形成されているものなどいかなる形状
でもよい。In other words, the two electrodes for approximating a dot shape are not limited to a needle-shaped collector and a pipe-shaped electrode, but may also be a combination of a linear collector and a trumpet-shaped electrode, in other words, a part of the collector is exposed from the shield electrode. Any combination may be used as long as the exposed portions can be viewed from the surface of the anode 1 and can be seen as dots. Furthermore, the anode 1, which is approximated to a spherical shape, is not limited to the shape of the embodiment, but a plurality of rings made of wire are arranged along the latitude of the sphere (thus, rings with different diameters are prepared). The anode is formed by arranging multiple rings of the same shape along the meridian of a sphere, or by winding a wire into a spiral and gradually changing its curvature to approximate a spherical surface. The anode 1 may be of any shape, such as a hollow one in which a lattice is formed along a spherical surface.
また実施例に示した熱陰極８は、イオンコレクター７を
球状陽極１の軸に見たとき、該陽極１の赤道（緯線上）
上に張設しであるが、これもこの構成に限ったものでは
なく、半環状又は環状の熱陰極フィラメント材を単数又
は複数本、球状陽極１の経線又は緯線上に張設して構成
したものでもよい。要するに、熱陰極８は球状陽極１の
表面上から電気的に絶縁されるならばいかなる配置構成
でもよい。特に、半環状、又は環状フィラメントを複数
本球状陽Ｆｉｔの天頂の位置で交叉させて、経線に沿っ
て配置したマルチフィラメントとすれば中心軸上を天頂
から下方の点状イオンコレクター７に向って飛び出す電
子が多くなることから、感度及びＸ線限界の向上にさら
に役立つことが予想される。Further, in the hot cathode 8 shown in the embodiment, when the ion collector 7 is viewed along the axis of the spherical anode 1, the equator (on the latitude line) of the anode 1
However, this is not limited to this configuration, and it can be constructed by stretching one or more semicircular or annular hot cathode filament materials on the meridian or latitude line of the spherical anode 1. It can be anything. In short, the hot cathode 8 may be arranged in any configuration as long as it is electrically insulated from the surface of the spherical anode 1. In particular, if a plurality of semi-annular or annular filaments are crossed at the zenith position of the spherical positive Fit and are arranged along the meridian, the central axis will be directed from the zenith to the point-like ion collector 7 below. Since more electrons are ejected, it is expected that this will further help improve sensitivity and X-ray limits.
第１図はこの発明の一実施例の一部を切欠した斜視図、
第２図は同じく点状に近似させたイオンコレクターを構
成する針状コレクターとパイプ状シールドコレクタ一部
の拡大断面図、第３図は真空の圧力とイオンコレクター
に流れるイオン電流の関係を示す図、第４図は実施のＸ
線限界を求めた電子エネルギーＵ、ｆに対するイオンコ
レクター電流の関係を示すベアード・アルバートのプロ
ット図、第５図は実施例に示した針状シート変調電極の
特性曲線を示す図、第６図はＢＡ型電離真空計のＸ線限
界を示す図である。
１・・・球状陽極、２・・・環状鍔、３・・・小孔、４
・・・針状コレクター、５・・・パイプ状シールド電極
、６・・・小孔、７・・・点状イオンコレクター、８・
・・環状熱陰極フィラメント、９・・・支持棒、１０・
・・イオンコレクタ一部シールドパイプ、１１・・・同
軸真空導入電流端子、１２・・・支持棒、１３・・・針
状変調電極、Ｇ１・・・変調電極電位を陽極電位にセッ
トした場合のイオン電流特性、Ｇ２・・・変調電極電位
をアース電位にセットした場合のイオン電流特性、Ｇ３
・・・変調電極電位を陽極電位にセットした場合のイオ
ン電流と光電子電流の和の特性、Ｇ４・・・変調電極電
位をアース電位にセットした場合のイオン電流と光電子
電流の和の特性、Ｇ５・・・光電子電流だけになった場
合予想される特性（ベアード・アルバート・プロット）
。FIG. 1 is a partially cutaway perspective view of an embodiment of the present invention;
Figure 2 is an enlarged cross-sectional view of a part of the needle collector and pipe-shaped shield collector that make up the ion collector, which are also approximated as dots, and Figure 3 is a diagram showing the relationship between vacuum pressure and ion current flowing through the ion collector. , Figure 4 shows the implementation of X
A Baird-Albert plot showing the relationship between the ion collector current and the electron energy U and f for which the line limit was determined. Figure 5 is a diagram showing the characteristic curve of the acicular sheet modulation electrode shown in the example. Figure 6 is a diagram showing the characteristic curve of the acicular sheet modulation electrode shown in the example. It is a figure which shows the X-ray limit of a BA type ionization vacuum gauge. 1... Spherical anode, 2... Annular collar, 3... Small hole, 4
... Needle-shaped collector, 5... Pipe-shaped shield electrode, 6... Small hole, 7... Point-like ion collector, 8...
...Annular hot cathode filament, 9...Support rod, 10.
...Ion collector part shield pipe, 11...Coaxial vacuum introduction current terminal, 12...Support rod, 13...Acicular modulation electrode, G1...When modulation electrode potential is set to anode potential Ion current characteristics, G2... Ion current characteristics when the modulation electrode potential is set to ground potential, G3
...Characteristics of the sum of ionic current and photoelectron current when the modulating electrode potential is set to the anode potential, G4...Characteristics of the sum of the ionic current and photoelectron current when the modulating electrode potential is set to the ground potential, G5 ...Characteristics expected when there is only photoelectron current (Baird-Albert plot)
.
Claims (4)
流を流し該電子電流を形成する電子が空間を飛行中に気
体分子を衝撃して作る陽イオンをイオンコレクターに収
集して取り出した電流値から該真空系内のガス圧力を測
定する測定子において、前記イオンコレクターを点状に
近似せしめて陽極内側に配置すると共に、陽極の外側に
熱陰極を配置したことを特徴とする熱陰極電離真空計。(1) An electron current was passed between a hot cathode and an anode placed in a vacuum system, and the electrons forming the electron current bombarded gas molecules while flying in space, and the cations produced were collected in an ion collector and taken out. A hot cathode for measuring gas pressure in the vacuum system from a current value, characterized in that the ion collector is approximated to a dot shape and placed inside the anode, and a hot cathode is placed outside the anode. Ionization vacuum gauge.
状電極の一端から突出させることによって点状に近似せ
しめたことを特徴とする特許請求の範囲第１項記載の熱
陰極電離真空計。(2) The hot cathode ionization vacuum gauge according to claim 1, wherein the ion collector has a tip portion of the needle-like electrode protruding from one end of the pipe-like electrode to approximate a point shape.
る特許請求の範囲第１項記載の熱陰極電離真空計。(3) The hot cathode ionization vacuum gauge according to claim 1, wherein the anode is formed to approximate a spherical surface.
イオン電流を変調するための変調電極を配置したことを
特徴とする熱陰極電離真空計。(4) Near the ion collector approximated as a point,
A hot cathode ionization vacuum gauge characterized by having a modulation electrode arranged to modulate the ion current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3084587A JPS63198840A (en) | 1987-02-13 | 1987-02-13 | Hot-cathode ionization gauge |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3084587A JPS63198840A (en) | 1987-02-13 | 1987-02-13 | Hot-cathode ionization gauge |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63198840A true JPS63198840A (en) | 1988-08-17 |
Family
ID=12315037
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3084587A Pending JPS63198840A (en) | 1987-02-13 | 1987-02-13 | Hot-cathode ionization gauge |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63198840A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04105031A (en) * | 1990-08-24 | 1992-04-07 | Sukegawa Electric Co Ltd | X-ray beam electron stream setoff method and hot cathode type electric dissociate vacuum meter using the method |
| US6854723B2 (en) | 2000-08-04 | 2005-02-15 | Honda Giken Kogyo Kabushiki Kaisha | Elastic bush and method of press-fitting elastic bush |
| CN103762147A (en) * | 2013-12-24 | 2014-04-30 | 兰州空间技术物理研究所 | Anode structure of ionization gauge |
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| JPS5589728A (en) * | 1978-12-27 | 1980-07-07 | Shinku Denshi:Kk | Hot-cathode ionization vacuum meter |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5339173A (en) * | 1976-09-21 | 1978-04-10 | Saburou Nagata | Apparatus for measuring superrhigh vacuum pressure sensor |
| JPS5589728A (en) * | 1978-12-27 | 1980-07-07 | Shinku Denshi:Kk | Hot-cathode ionization vacuum meter |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04105031A (en) * | 1990-08-24 | 1992-04-07 | Sukegawa Electric Co Ltd | X-ray beam electron stream setoff method and hot cathode type electric dissociate vacuum meter using the method |
| US6854723B2 (en) | 2000-08-04 | 2005-02-15 | Honda Giken Kogyo Kabushiki Kaisha | Elastic bush and method of press-fitting elastic bush |
| CN103762147A (en) * | 2013-12-24 | 2014-04-30 | 兰州空间技术物理研究所 | Anode structure of ionization gauge |
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