JP2019204721A

JP2019204721A - Electron beam source in mass spectrometer

Info

Publication number: JP2019204721A
Application number: JP2018100057A
Authority: JP
Inventors: 康昭嶽石; Yasuaki Takeishi; 幸一森; Koichi Mori; デンプシー，エドワード; Dempsey Edward
Original assignee: LIFT FORCE CO Ltd; TAKEISHI DENKI KK
Current assignee: LIFT FORCE CO Ltd; TAKEISHI DENKI KK
Priority date: 2018-05-24
Filing date: 2018-05-24
Publication date: 2019-11-28
Anticipated expiration: 2038-05-24
Also published as: JP7075567B2

Abstract

To provide an electron beam source in a mass spectrometer that contributes to improvement of the performance of mass spectrometry, can keep a thermal electron emission point constant, and eliminate anxiety factors such as filament breakage or the like that may occur during analysis while reducing deterioration due to corrosive gas, or the like.SOLUTION: In an electron beam emitting material, one ends of a pair of supporting and conductive members (41, 42) are fixed to the opposing portions of the outer surface of a chip-shaped electron beam emitting material (40) that is sintered by impregnating a sintered metal with a low work function material or containing a low work function substance in the metal, and the other ends of the pair of supporting and conductive members are fixed to a pair of electrodes (31a, 31b), and the chip-shaped electron beam emitting material is energized from the electrodes through the supporting and conductive member to heat the electron beam emitting material.SELECTED DRAWING: Figure 3

Description

本発明は、イオン化法ならびにイオン乖離法の質量分析計における電子線源に関するものである。 The present invention relates to an electron beam source in a mass spectrometer using an ionization method and an ion dissociation method.

質量分析法は、有機、無機物質を高感度で分析することが可能であり、高真空中に配置された電場、磁場等により物質の質量差をその挙動の違いにより分析する。そのため分析対象物に電荷を与え、イオンの状態を保たなければならない。そのために様々なイオン化法が提案されている。２００２年にノーベル賞を受賞した田中耕一氏の提案に係る「生体高分子の同定および構造解析のための手法の開発」もその一つ、MALDI（マトリクス支援レーザー脱離イオン化）法である。 Mass spectrometry is capable of analyzing organic and inorganic substances with high sensitivity, and analyzes the difference in mass of substances by the electric field, magnetic field, and the like placed in a high vacuum. Therefore, it is necessary to give an electric charge to the analyte and maintain the ion state. For this purpose, various ionization methods have been proposed. One of the “MALDI (Matrix Assisted Laser Desorption / Ionization)” methods is “Development of methods for biopolymer identification and structural analysis” proposed by Koichi Tanaka, who won the Nobel Prize in 2002.

本発明は、様々なイオン化法の中で最も古くから用いられている「電子イオン化法」に関し、図１に該電子イオン化法を実施する質量分析計の概略構成を示す。この装置は、ステンレス等の材料で構成された真空容器１５、ターボ分子ポンプ２１及び容積ポンプ２２を備え、該ターボ分子ポンプ２１及び容積ポンプ２２により、真空容器１５内を１×１０^−３Pa以上の高真空状態に保ち、大気圧下から毛細管、流量制御バルブ２０等により高真空を維持したまま微量の試料１７を真空容器１５内の高真空中に導入する。 The present invention relates to an “electron ionization method” that has been used for a long time among various ionization methods, and FIG. 1 shows a schematic configuration of a mass spectrometer that performs the electron ionization method. This apparatus includes a vacuum vessel 15 made of a material such as stainless steel, a turbo molecular pump 21 and a volume pump 22, and the turbo molecular pump 21 and the volume pump 22 allow the inside of the vacuum vessel 15 to be 1 × 10 ⁻³ Pa or more. The small sample 17 is introduced into the high vacuum in the vacuum vessel 15 while maintaining the high vacuum from the atmospheric pressure by the capillary, the flow rate control valve 20 and the like.

真空容器１５内の高真空中に配置されたイオン化室１４には上下２ヶ所に穴１４a，１４ｂが形成されており、真空容器１５内とイオン化室１４内は連通している。イオン化室１４の上部の穴１４ａの近傍にはフィラメント１２が、下部の穴１４ｂの近傍にはトラップ１８がそれぞれ配置されている。フィラメント１２には大気中に配置されている電源（図示せず）から端子１３ａ，１３ｂを経由して電流（フィラメント電流）が供給される。フィラメント１２には、フィラメント電流を流すための上記電源とイオン化室１４との間に電位差を与えている。これをイオン化電圧といい、フィラメント１２側に陰電圧（通常−１０〜−１００Ｖ程度）を印加している。このイオン化電圧を印加することにより、熱せられたフィラメント１２からイオン化室１４に向けて熱電子が放出される。一般的には熱電子の進行する方向に永久磁石により磁束を与え、熱電子同士が反発して発散しないような構造を採用することが多い。 Holes 14a and 14b are formed in two locations at the top and bottom of the ionization chamber 14 disposed in a high vacuum in the vacuum vessel 15, and the inside of the vacuum vessel 15 and the ionization chamber 14 are in communication. A filament 12 is disposed in the vicinity of the upper hole 14a of the ionization chamber 14, and a trap 18 is disposed in the vicinity of the lower hole 14b. A current (filament current) is supplied to the filament 12 from a power source (not shown) arranged in the atmosphere via the terminals 13a and 13b. A potential difference is applied to the filament 12 between the power source for supplying a filament current and the ionization chamber 14. This is called an ionization voltage, and a negative voltage (usually about −10 to −100 V) is applied to the filament 12 side. By applying this ionization voltage, thermoelectrons are emitted from the heated filament 12 toward the ionization chamber 14. In general, a structure is adopted in which a magnetic flux is applied by a permanent magnet in the direction in which the thermoelectrons travel so that the thermoelectrons repel each other and do not diverge.

質量分析法は、イオン化室１４内に導入される試料１７の量に応じてイオン量が変化することで未知の物質の構造の同定に加え、物質の量も分析可能であるため、試料１７の導入量とイオン量を比例させることが必要となる。この試料１７の導入量とイオン量を比例させるためには、イオン化電流を一定に保つことが最良とされている。よってトラップ１８に流れ込む電流（イオン化電流）を検出し、設定されたイオン化電流値が一定になるようにフィラメント電流をフィードバック制御することでイオン化電流値を一定にし、定量性を確保している。 In mass spectrometry, the amount of ions can be analyzed in addition to identifying the structure of an unknown substance by changing the amount of ions according to the amount of the sample 17 introduced into the ionization chamber 14. It is necessary to make the introduction amount and the ion amount proportional. In order to make the introduction amount of the sample 17 and the ion amount proportional, it is best to keep the ionization current constant. Therefore, the current (ionization current) flowing into the trap 18 is detected, and the filament current is feedback-controlled so that the set ionization current value is constant, thereby making the ionization current value constant and ensuring the quantitativeness.

電子イオン化法の利点は、高感度であり定量性に優れていることが挙げられるが、一方でイオン化室１４内に導入される試料１７によってフィラメント１２が劣化し、短時間でフィラメント１２が切れることもあり、貴重な試料１７の分析時にフィラメント１２が断線してデータが得られないという深刻な事態になることもある。特に半導体のプロセス分析では、腐食性ガスが多く使用されるため、一般的なフィラメント材料であるタングステンやレニウム等は用いず、イリジウムワイヤに酸化イットリウムをコーティングしたフィラメント１２を用いている。このようにイリジウムワイヤに酸化イットリウムをコーティングしたフィラメント１２を用いることにより、フィラメント１２の表面の仕事関数を下げ、低い温度で熱電子を発生させて、フィラメント１２の寿命を延ばしている。 The advantage of the electron ionization method is that it is highly sensitive and excellent in quantitativeness. On the other hand, the filament 12 is deteriorated by the sample 17 introduced into the ionization chamber 14, and the filament 12 is broken in a short time. In some cases, the filament 12 is broken when the valuable sample 17 is analyzed, and data cannot be obtained. Particularly in the process analysis of semiconductors, corrosive gas is often used. Therefore, tungsten, rhenium, etc., which are general filament materials, are not used, but the filament 12 in which iridium wire is coated with yttrium oxide is used. Thus, by using the filament 12 in which the iridium wire is coated with yttrium oxide, the work function of the surface of the filament 12 is lowered, thermionic electrons are generated at a low temperature, and the life of the filament 12 is extended.

一般的にフィラメント１２には、図２（ａ）に示すようにストレートタイプフィラメント１２−１、同図（ｂ）に示すようにコイルタイプフィラメント１２−２、同図（ｃ）に示すようにリボンタイプフィラメント１２−３がある。これらのフィラメント１２はいずれもセラミックスやガラス等の絶縁材からなる絶縁体ブロック３０に所定の間隔で平行に配置固定した一対の導電材料からなる電極３１ａ，３１ｂにその両端部をスポット溶接等で固着され、該電極３１ａ，３１ｂを介して通電されている。 In general, the filament 12 includes a straight type filament 12-1 as shown in FIG. 2A, a coil type filament 12-2 as shown in FIG. 2B, and a ribbon type as shown in FIG. 2C. There is a filament 12-3. Both of these filaments 12 are fixed to a pair of electrodes 31a and 31b made of a conductive material, which are arranged and fixed in parallel at predetermined intervals on an insulator block 30 made of an insulating material such as ceramics or glass, by spot welding or the like. And is energized through the electrodes 31a and 31b.

特開２００５−２９８６０３号公報JP 2005-298603 A

半導体のプロセス分析等で使用される質量分析装置には、一般的に酸化イットリウムをコーティングしたフィラメントが多く使用されているものの、フィラメントに通電する電流のＯＮ／ＯＦＦ等による熱衝撃や機械的衝撃等で酸化イットリウムのコーティングが剥離することがある。また使用中にコーティング膜が薄くなり熱電子の放出量が低減してしまうこともある。 Mass spectrometers used in semiconductor process analysis and the like generally use many filaments coated with yttrium oxide, but thermal shock and mechanical shock due to ON / OFF of the current flowing to the filament, etc. The yttrium oxide coating may peel off. In addition, the coating film may become thin during use, and the amount of emitted thermal electrons may be reduced.

また上記したように、フィラメントには図２（ａ）に示すような断面円形状のワイヤーの両端部を２本の電極３１ａ，３１ｂに固定したストレートタイプフィラメント１２−１や、同図（ｂ）に示すようなフィラメントの中央部分をコイル状に形成しその両端部を固定したコイルタイプフィラメント１２−２や、同図（ｃ）に示すような薄板を細くリボン状に切ったフィラメントの両端部を２本の電極３１ａ，３１ｂの間に固定したリボンタイプフィラメント１２−3がある。これらのフィラメント１２は、通電時には２本の電極３１ａ，３１ｂから最も遠い位置、即ちフィラメントの中央部が最も温度が高くなり、最も多くの熱電子が放出されると考えられる。しかしフィラメントワイヤやリボンの断面積の不均一等の要因により、必ずしもフィラメントの機械的中心位置から熱電子がより多く放出されるとは限らず、フィラメントの個体差による熱電子放出分布位置のバラツキにより、質量分析結果として、分解能、感度に悪影響を及ぼすことがある。 As described above, the filament includes a straight type filament 12-1 in which both ends of a wire having a circular cross section as shown in FIG. 2A are fixed to the two electrodes 31a and 31b, and FIG. A coil-type filament 12-2 in which the center part of the filament as shown is formed in a coil shape and both ends thereof are fixed, or both ends of a filament obtained by thinly cutting a thin plate as shown in FIG. There is a ribbon type filament 12-3 fixed between the electrodes 31a and 31b. It is considered that when these filaments 12 are energized, the temperature farthest from the two electrodes 31a and 31b, that is, the central part of the filament has the highest temperature, and the most thermoelectrons are emitted. However, due to factors such as non-uniformity in the cross-sectional area of the filament wire or ribbon, more thermoelectrons are not necessarily emitted from the mechanical center position of the filament, and due to variations in the thermoelectron emission distribution position due to individual differences in the filament. As a result of mass spectrometry, resolution and sensitivity may be adversely affected.

本発明は上述の点に鑑みてなされたもので、一般的に行われている低仕事関数材料のコーティングの効果と同じく、腐食性ガス等によるフィラメントの劣化を軽減させると共に、分析途中で発生するかもしれないフィラメントの断線等の不安要素を解消し、加えて熱電子の放出点を一定に保つことが可能な、質量分析の性能向上に寄与する質量分析計における電子線源を提供することを目的とする。 The present invention has been made in view of the above points, and, like the effect of coating of a low work function material that is generally performed, reduces the deterioration of the filament due to corrosive gas and the like, and occurs during the analysis. To provide an electron beam source in a mass spectrometer that contributes to improving the performance of mass spectrometry, which can eliminate anxiety factors such as filament breakage that may be possible, and can keep the emission point of thermoelectrons constant. Objective.

上記の課題を解決するために本発明は、電子線放射材料と、絶縁体ブロックに所定の間隔を設けて配置された一対の電極とを備え、電子線放射材料を加熱して該電子線放射材料から電子線を放射させる質量分析計の電子線源において、電子線放射材料は焼結金属中に仕事関数の低い材料（以下場合によって「物質」と記す）を含浸させるか又は金属に仕事関数の低い物質を含有させて焼結したチップ状電子線放射材料であり、チップ状電子線放射材料の外表面の対向する部分に一対の支持兼導電部材のそれぞれ一端を固着すると共に、該一対の支持兼導電部材の他端を一対の電極に固着し、電極から支持兼導電部材を通ってチップ状電子線放射材料に通電する電流で直接前記電子線放射材料を加熱することを特徴とする。 In order to solve the above-mentioned problems, the present invention comprises an electron beam emitting material and a pair of electrodes arranged at a predetermined interval on an insulator block, and heating the electron beam emitting material to emit the electron beam. In an electron beam source of a mass spectrometer that emits an electron beam from a material, the electron beam emitting material is obtained by impregnating a sintered metal with a material having a low work function (hereinafter, referred to as “substance”), or the metal has a work function. A chip-shaped electron beam radiation material that contains a low-concentration substance and is sintered, and one end of each of the pair of supporting and conductive members is fixed to the opposing portion of the outer surface of the chip-shaped electron beam radiation material. The other end of the supporting and conductive member is fixed to a pair of electrodes, and the electron beam emitting material is directly heated by a current passing through the supporting and conductive member from the electrode to the chip-shaped electron beam emitting material.

また、本発明は上記質量分析計の電子線源において、支持兼導電部材のチップ状電子線放射材料に固着される一端部は支持兼導電部材の他端部が電極に固着された状態で該電極の長手方向で且つ互いに同一方向又は長手方向で且つ互いに反対方向に折り曲げられていることを特徴とする。 Further, the present invention provides the electron beam source of the mass spectrometer, wherein one end fixed to the chip-shaped electron beam emitting material of the supporting and conductive member is in a state where the other end of the supporting and conductive member is fixed to the electrode. The electrodes are bent in the longitudinal direction and in the same direction or in the longitudinal direction and in opposite directions.

また、本発明は上記質量分析計の電子線源において、支持兼導電部材は板金材からなり、チップ状電子線放射材料に固着する部分の幅が狭く、電極に固着する部分の幅が広くなっていることを特徴とする。 In the electron beam source of the mass spectrometer according to the present invention, the supporting and conductive member is made of a sheet metal material, the width of the portion fixed to the chip-shaped electron beam emitting material is narrow, and the width of the portion fixed to the electrode is wide. It is characterized by.

また、本発明は上記質量分析計の電子線源において、板金材からなる一対の支持兼導電部材のチップ状電子線放射材料に固着する幅が狭い部分は一対の支持兼導電部材の幅が広い部分が電極に固着された状態で互いにその先端部が電極の長手方向に屈曲しており、該先端部と先端部の間にチップ状電子線放射材料が位置するようになっていることを特徴とする。 According to the present invention, in the electron beam source of the mass spectrometer, the pair of support and conductive members of the pair of support and conductive members having a narrow width fixed to the chip-shaped electron beam emitting material has a wide width of the pair of support and conductive members. The tip portions of the electrodes are bent in the longitudinal direction of the electrode while the portions are fixed to the electrode, and a chip-shaped electron beam emitting material is positioned between the tip portion and the tip portion. And

また、電子線放射材料と、絶縁体ブロックに所定の間隔を設けて配置された一対の電極とを備え、電子線放射材料を加熱して該電子線放射材料から電子線を放射させる質量分析計の電子線源において、電子線放射材料は焼結金属中に仕事関数の低い材料を含浸させるか又は金属に仕事関数の低い物質を含有させて焼結したチップ状電子線放射材料であり、長尺の導電発熱体を具備し、チップ状電子線放射材料の外周面に導電発熱体を巻回するか又はチップ状電子線放射材料の少なくとも一部外周面に導電発熱体を固着し、該導電発熱体の両端部をそれぞれ一対の電極に固着し、電極から導電発熱体に通電する電流により該導電発熱体から発する熱で電子線放射材料を加熱することを特徴とする。 Further, a mass spectrometer comprising an electron beam emitting material and a pair of electrodes arranged at a predetermined interval on an insulator block, and heating the electron beam emitting material to emit an electron beam from the electron beam emitting material In the electron beam source, the electron beam emitting material is a chip-shaped electron beam emitting material which is sintered by impregnating a sintered metal with a material having a low work function or containing a material having a low work function in a sintered metal. A conductive heating element is wound around the outer peripheral surface of the chip-shaped electron beam radiation material, or the conductive heating element is fixed to at least a part of the outer peripheral surface of the chip-shaped electron beam radiation material. Both ends of the heating element are fixed to a pair of electrodes, respectively, and the electron beam emitting material is heated by the heat generated from the conductive heating element by the current supplied from the electrodes to the conductive heating element.

本発明に係る質量分析計における電子線源は、上記のように焼結金属中に仕事関数の低い材料を含浸させたチップ状電子線放射材料を採用するので、図２に示すストレートタイプフィラメント１２−１、コイルタイプフィラメント１２−２、リボンタイプフィラメント１２−３のように、フィラメントの断面積の不均一等の要因により必ずしも正確な機械的中心位置から熱電子がより多く放出されるとは限らず、フィラメントの個体差によって熱電子放出分布位置にバラツキがあるという問題が解決でき、小さいチップ状電子線放射材料から均等に熱電子が放出され、質量分析計の質量分析の分解能、感度に優れた結果が得られる。 Since the electron beam source in the mass spectrometer according to the present invention employs a chip-shaped electron beam emitting material obtained by impregnating a sintered metal with a material having a low work function as described above, the straight type filament 12-shown in FIG. 1. More thermoelectrons are not necessarily emitted from an accurate mechanical center position due to factors such as non-uniform cross-sectional area of the filament, such as the coil type filament 12-2 and the ribbon type filament 12-3. The problem of variations in the position of thermionic emission distribution due to individual differences in filaments can be solved. Thermal electrons are evenly emitted from a small chip-shaped electron beam emitting material, and the mass spectrometry resolution and sensitivity of the mass spectrometer are excellent. Results are obtained.

本発明では、電子線放射材料に焼結金属中に仕事関数の低い材料を含浸させたチップ状電子線放射材料を採用することにより、従来一般に行われている低仕事関数材料のコーティング効果と同じく、腐食性ガス等による電子線放射材料の劣化を軽減させると共に、分析途中で発生するかもしれないフィラメントの断線等の不安定要素も解消でき、且つ熱電子の放出部をチップ状電子線放射材料の外表面という一定面に保つことが可能となり、質量分析の性能が向上する。 In the present invention, by adopting a chip-shaped electron beam emitting material in which a sintered metal is impregnated with a material having a low work function in the electron beam emitting material, the coating effect of the low work function material generally performed conventionally is adopted. In addition to reducing deterioration of the electron beam emitting material due to corrosive gas, etc., it is also possible to eliminate unstable elements such as filament breakage that may occur during the analysis, and the thermoelectron emission part is replaced with a chip-shaped electron beam emitting material It is possible to maintain a constant surface such as the outer surface of the material, and the performance of mass spectrometry is improved.

従来の質量分析計における電子イオン化法においては、フィラメントの断線が予知できないため、重要な分析を行っている途中でフィラメントが断線すると測定結果が得られない場合も少なくない。またフィラメントの交換にはイオン化が行われる真空容器内を一度大気圧に開放しなければならず、真空容器内を元の高真空に戻すまでに長い時間を要してしまう問題があるが、本発明に係る電子線源では、フィラメントの断線と言う問題は考えられないから、このような問題は発生しない。 In the electron ionization method in the conventional mass spectrometer, since the breakage of the filament cannot be predicted, there are many cases where the measurement result cannot be obtained if the filament breaks during the important analysis. In addition, when replacing the filament, the inside of the vacuum vessel in which ionization is performed must be opened to atmospheric pressure once, and there is a problem that it takes a long time to return the inside of the vacuum vessel to the original high vacuum. In the electron beam source according to the invention, such a problem does not occur because the problem of filament breakage cannot be considered.

また、本発明に係る電子線源では、フィラメント材料の劣化等による断線ということが無いから、チップ状電子線放射材料内に含浸又は含有している仕事関数の低い材料が枯渇するまで安定的に熱電子の放出が得られ、その寿命は設定されたイオン化電流に対するチップ状電子線放射材料に供給される電流値を監視することで把握でき、信頼性の高い安定的な質量分析が可能となる。 Further, in the electron beam source according to the present invention, since there is no disconnection due to deterioration of the filament material or the like, it is stable until the material having a low work function impregnated or contained in the chip-shaped electron beam emitting material is exhausted. Thermionic emission can be obtained, and its lifetime can be grasped by monitoring the current value supplied to the chip-shaped electron beam emitting material with respect to the set ionization current, enabling highly reliable and stable mass spectrometry. .

電子イオン化法を実施する質量分析計の概略構成を示す図である。It is a figure which shows schematic structure of the mass spectrometer which implements an electron ionization method. 従来の質量分析計の電子線源の概略構成を示す図である。It is a figure which shows schematic structure of the electron beam source of the conventional mass spectrometer. 本発明に係る質量分析計の電子線源の概略構成を示す図である。It is a figure which shows schematic structure of the electron beam source of the mass spectrometer which concerns on this invention. 本発明に係る質量分析計の他の電子線源の概略構成を示す図である。It is a figure which shows schematic structure of the other electron beam source of the mass spectrometer which concerns on this invention. 本発明に係る質量分析計の他の電子線源の概略構成を示す図である。It is a figure which shows schematic structure of the other electron beam source of the mass spectrometer which concerns on this invention. 本発明に係る質量分析計の他の電子線源の概略構成を示す図である。It is a figure which shows schematic structure of the other electron beam source of the mass spectrometer which concerns on this invention. 本発明に係る質量分析計の他の電子線源の概略構成を示す図である。It is a figure which shows schematic structure of the other electron beam source of the mass spectrometer which concerns on this invention.

以下、本発明の実施の形態について、図３は本発明に係る質量分析計の電子線源の概略構成を示す図で、同図（ａ）は平面図、同図（ｂ）は正面図〔（ａ）のＡ−Ａ矢視図〕である。図示するように、本電子線源は電子線を放射する電子線放射材料４０を具備する。該電子線放射材料４０は、ここでは照明用フィラメントに使用するタングステンの焼結金属中に仕事関数の低い材料、例えば酸化バリウム等を含浸させたものである。このように仕事関数の低い材料を含浸させた丸棒状に形成した材料を所定の短い寸法に切断してチップ状（一例として径０．５ｍｍ〜２ｍｍ、長さ０．５〜３ｍｍ）の電子線放射材料４０としている。 FIG. 3 is a diagram showing a schematic configuration of an electron beam source of a mass spectrometer according to the present invention. FIG. 3 (a) is a plan view, and FIG. 3 (b) is a front view. It is an AA arrow line view of (a). As shown, the electron beam source includes an electron beam emitting material 40 that emits an electron beam. Here, the electron beam emitting material 40 is obtained by impregnating a sintered metal of tungsten used for an illumination filament with a material having a low work function, such as barium oxide. The material formed in the shape of a round bar impregnated with a material having a low work function in this way is cut into a predetermined short dimension to form a chip-shaped electron beam (diameter 0.5 mm to 2 mm, length 0.5 to 3 mm as an example). The radiation material 40 is used.

なお、焼結金属は、多孔質である必要があり、この多孔に仕事関数の低い物質を含浸させる。ここで、焼結金属材料はタングステンに限らず、モリブデン、タンタル、レニウム、イリジウム等でもよい。また、仕事関数の低い物質としては、酸化バリウムに限らず、酸化ストロンチウム、酸化カルシウム、酸化イットリウム、酸化スカンジウム、酸化ランタン、酸化セリウム、酸化トリウム、酸化ジルコニウム単体あるいは混合物質でもよい。よって電子線放射材料としては、タングステン、モリブデン、タンタル、レニウム、イリジウム等の金属に、上記仕事関数の低い物質を含有させて焼結したものであってもよい。 Note that the sintered metal needs to be porous, and the porous material is impregnated with a substance having a low work function. Here, the sintered metal material is not limited to tungsten, but may be molybdenum, tantalum, rhenium, iridium, or the like. The substance having a low work function is not limited to barium oxide, but may be strontium oxide, calcium oxide, yttrium oxide, scandium oxide, lanthanum oxide, cerium oxide, thorium oxide, zirconium oxide alone or a mixed substance. Therefore, the electron beam emitting material may be a material sintered with a metal having a low work function, such as tungsten, molybdenum, tantalum, rhenium, or iridium.

上記のように、仕事関数の低い材料を含浸させた端面円形状の電子線放射材料４０の直径方向に対向する表面位置に該電子線放射材料４０を支持すると共に、該電子線放射材料４０に電流を導くための支持と導電作用とを兼ね備えた支持兼導電部材４１，４２の端部をスポット溶接等で固着して電子線源組立体４３を構成する。支持兼導電部材４１，４２はそれぞれ丸棒状で電子線放射材料４０に固着する部分を略直角に屈曲させており、該屈曲部分を電子線放射材料４０の直径方向に対向する位置の表面にスポット溶接等で固着している。 As described above, the electron beam emitting material 40 is supported at a surface position opposed to the diameter direction of the electron beam emitting material 40 having a circular end face impregnated with a material having a low work function. The electron beam source assembly 43 is configured by fixing the ends of the support and conductive members 41 and 42 having both the support for conducting current and the conductive action by spot welding or the like. Each of the supporting and conductive members 41 and 42 has a round bar shape, and a portion fixed to the electron beam emitting material 40 is bent at a substantially right angle, and the bent portion is spotted on the surface of the electron beam emitting material 40 at a position facing the diameter direction. It is fixed by welding or the like.

上記のように、構成した電子線源組立体４３を、絶縁体ブロック３０に所定の間隔で平行に配置固定した丸棒状の電極３１ａ，３１ｂにそれぞれの支持兼導電部材４１，４２の端部をスポット溶接等で固着することにより、電子線源組立体４３の電子線放射材料４０を電極３１ａと電極３１ｂの中間位置で且つ長さ方向の所定位置に位置するように配置することにより、本発明に係る電子線源となる。ここで、電子線源組立体４３の支持兼導電部材４１と支持兼導電部材４２をその反電子線放射材料４０側の端部をスポット溶接等で電極３１ａ，３１ｂに固着する際、支持兼導電部材４１はその屈曲部分の先端部を絶縁体ブロック３０の反対側に向けると共に、支持兼導電部材４２はその屈曲部分の先端部を絶縁体ブロック３０の側に向ける。 As described above, the end portions of the supporting and conductive members 41 and 42 are attached to the round bar-shaped electrodes 31a and 31b in which the configured electron beam source assembly 43 is arranged and fixed in parallel to the insulator block 30 at a predetermined interval. By fixing it by spot welding or the like, the electron beam emitting material 40 of the electron beam source assembly 43 is arranged so as to be positioned at a predetermined position in the longitudinal direction between the electrode 31a and the electrode 31b. It becomes the electron beam source concerning. Here, when the supporting and conductive member 41 and the supporting and conductive member 42 of the electron beam source assembly 43 are fixed to the electrodes 31a and 31b by spot welding or the like, the supporting and conductive member 42 is supported. The member 41 directs the tip of the bent portion toward the opposite side of the insulator block 30, and the support / conductive member 42 directs the tip of the bent portion toward the insulator block 30.

図３に示す実施例では、支持兼導電部材４１の屈曲部分の先端部を絶縁体ブロック３０の反対側に向け、支持兼導電部材４２の屈曲部分の先端部を絶縁体ブロック３０の側に向けているが、これに限定されるものではなく、図４に示すように、支持兼導電部材４１と支持兼導電部材４２はその屈曲部分の先端部を同一方向、即ち絶縁体ブロック３０の反対側に向くようにしてもよい。図示は省略するが、当然、支持兼導電部材４１と支持兼導電部材４２はその屈曲部分の両先端部を絶縁体ブロック３０側に向くようにしてもよい。なお、図４（ａ）は本電子線源の平面図、同図（ｂ）は正面図〔（ａ）のＢ−Ｂ矢視図〕である。 In the embodiment shown in FIG. 3, the tip of the bent portion of the support / conductive member 41 is directed to the opposite side of the insulator block 30, and the tip of the bent portion of the support / conductive member 42 is directed to the insulator block 30. However, the present invention is not limited to this, and as shown in FIG. 4, the support / conductive member 41 and the support / conductive member 42 are arranged in the same direction, that is, on the opposite side of the insulator block 30. You may make it suitable for. Although illustration is omitted, as a matter of course, the support / conductive member 41 and the support / conductive member 42 may be configured such that both ends of the bent portions thereof face the insulator block 30 side. 4A is a plan view of the electron beam source, and FIG. 4B is a front view (a view taken along the line BB in FIG. 4A).

支持兼導電部材４１，４２は電子線放射材料４０に電流を導くための作用と、電子線放射材料４０を電極３１ａと電極３１ｂの間の所定位置に配置支持する作用を奏するから、フィラメント材料で構成してもよいが、熱電子を放射させる必要がないため、高温にならないよう電気抵抗を小さくするため太目の外径でもよく、これにより高温にならないことから、腐食性ガス中であっても劣化を抑えることができる。また、電子線放射材料４０は熱を発する抵抗体となるが、仕事関数の低い酸化バリウム等を含浸させているため、高温にするために充分に通電しなくとも質量分析に必要な熱電子を充分に放射できる。 Since the supporting and conductive members 41 and 42 have an effect of guiding an electric current to the electron beam emitting material 40 and an effect of arranging and supporting the electron beam emitting material 40 at a predetermined position between the electrodes 31a and 31b. Although it may be configured, it is not necessary to radiate thermionic electrons, so a large outer diameter may be used to reduce the electrical resistance so as not to reach a high temperature. Deterioration can be suppressed. The electron beam emitting material 40 is a resistor that emits heat, but is impregnated with barium oxide or the like having a low work function. It can radiate enough.

また、電子線放射材料４０は熱を発して高温となり熱膨張するが、上記のように支持兼導電部材４１と支持兼導電部材４２の電子線放射材料４０に固着する端部に屈曲部を設けているから、この屈曲部が電子線放射材料４０の熱膨張による変位を吸収し、電子線放射材料４０の電極３１ａと電極３１ｂとの間の変位は極めて小さくなる。特に図４に示すように支持兼導電部材４１と支持兼導電部材４２の屈曲部を大きくすることにより、電子線放射材料４０の熱膨張による変位をよりスムーズに吸収でき、電子線放射材料４０の位置の変位が更に小さくなる。 Further, the electron beam emitting material 40 generates heat and becomes a high temperature and thermally expands. However, as described above, the bent portions are provided at the ends of the support / conductive member 41 and the support / conductive member 42 fixed to the electron beam emitting material 40. Therefore, the bent portion absorbs the displacement due to the thermal expansion of the electron beam emitting material 40, and the displacement between the electrode 31a and the electrode 31b of the electron beam emitting material 40 becomes extremely small. In particular, as shown in FIG. 4, by increasing the bent portions of the support / conductive member 41 and the support / conductive member 42, the displacement due to the thermal expansion of the electron beam emitting material 40 can be absorbed more smoothly. The displacement of the position is further reduced.

電子線放射材料４０は上記例では、ワイヤー等の円柱材材料を輪切りにした形状としているが、これに限定されるものではなく、例えば断面矩形状又は多角形状等の棒材を所定長さで切断したものでも良い。また仕事関数の低い酸化バリウム等が含浸させたタングステンの焼結金属材を切削加工により所定形状に形成したものでもよい。また、支持兼導電部材４１，４２はワイヤー等の円柱材材料以外に、図５に示すように板金材で電子線放射材料４０に固着する部分の幅が狭く、電極３１ａ，３１ｂに固着する部分の幅を広く、電子線放射材料４０及び電極３１ａ，３１ｂに固着する部分を除いた平面形状を三角形状とした支持兼導電部材４５、４６でも良い。また、ここでは支持兼導電部材４５、４６の幅が狭い電子線放射材料４０に固着する部分は、電子線源組立体４３を電極３１ａと電極３１ｂに固着した状態で略直角に下方伸びるように折り曲げている。なお、図５（ａ）は本電子線源の平面図、同図（ｂ）は正面図〔（ａ）のＣ−Ｃ矢視図〕である。 In the above example, the electron beam emitting material 40 has a shape obtained by rounding a cylindrical material such as a wire. However, the electron beam emitting material 40 is not limited to this. For example, a rod having a rectangular shape or a polygonal shape with a predetermined length is used. It may be cut. Alternatively, a tungsten sintered metal material impregnated with barium oxide or the like having a low work function may be formed into a predetermined shape by cutting. In addition to the cylindrical material such as a wire, the supporting and conductive members 41 and 42 are portions that are fixed to the electron beam emitting material 40 with a sheet metal material as shown in FIG. 5, and are fixed to the electrodes 31a and 31b. The supporting and conductive members 45 and 46 having a wide planar shape and a triangular shape excluding portions fixed to the electron beam emitting material 40 and the electrodes 31a and 31b may be used. Further, here, the portions where the supporting and conductive members 45 and 46 are fixed to the electron beam emitting material 40 having a narrow width extend downward substantially at right angles with the electron beam source assembly 43 fixed to the electrodes 31a and 31b. It is bent. 5A is a plan view of the electron beam source, and FIG. 5B is a front view (a CC arrow view of FIG. 5A).

また、図６に示すように支持兼導電部材を板金材で電子線放射材料４０に固着する部分の幅が狭く、電極３１ａ，３１ｂに固着する部分の幅を広く、電子線放射材料４０及び電極３１ａ，３１ｂに固着する部分を除いた平面形状を直角三角形状とした支持兼導電部材４７、４８でも良い。ここで支持兼導電部材４7、４８は電子線源組立体４３に組み立てる前に幅が狭い部分を互いに対向する方向に延長し、この延長部分の電子線放射材料４０に固着する部分を互いに下方に折り曲げる。そしてこの折り曲げた部分を電子線放射材料４０にスポット溶接等で固着し、電子線源組立体４３を電極３１ａ，３１ｂに塔載固着した際、電子線放射材料４０が電極３１ａ，３１ｂの間の中央で且つ電極３１ａ，３１ｂの長さ方向の所定の位置に配置されるようにする。なお、図６（ａ）は本電子線源の平面図、同図（ｂ）は正面図〔（ａ）のＤ−Ｄ矢視図〕である。 Further, as shown in FIG. 6, the width of the portion where the supporting and conductive member is fixed to the electron beam emitting material 40 with a sheet metal material is narrow, and the width of the portion fixed to the electrodes 31a and 31b is wide. Support and conductive members 47 and 48 in which the planar shape excluding the portion fixed to 31a and 31b is a right triangle shape may be used. Here, before assembling the support and conductive members 47 and 48, the narrow portions are extended in a direction facing each other before assembling the electron beam source assembly 43, and the portions of the extended portions fixed to the electron beam emitting material 40 are mutually downward. Bend it. The bent portion is fixed to the electron beam emitting material 40 by spot welding or the like, and when the electron beam source assembly 43 is fixed to the electrodes 31a and 31b, the electron beam emitting material 40 is placed between the electrodes 31a and 31b. It is arranged at the center and at a predetermined position in the length direction of the electrodes 31a and 31b. 6A is a plan view of the electron beam source, and FIG. 6B is a front view (a DD arrow view of FIG. 6A).

また、図７は本発明に係る質量分析計の電子線源の概略構成を示す図である。本電子線源は、タングステンの焼結金属中に仕事関数の低い材料を含浸させた電子線放射材料４０の外周面に導電発熱線４９を巻き付けるか又は図示するように導電発熱線４９の一部を電子線放射材料４０に密接する形状に形成し、この部分をスポット溶接等により固着し、該電子線源組立体４３を構成する。そしてこの電子線源組立体４３の導電発熱線４９の両端部を電極３１ａ，３１ｂに、電子線放射材料４０が電極３１ａと電極３１ｂの中間位置で且つ電極３１ａ，３１ｂの長さ方向の所定位置に位置するように配置し固着することにより、本発明に係る電子線源とする。そして導電発熱線４９に電流を通電させることにより、導電発熱線４９から発する熱で、電子線放射材料４０を加熱する。これにより電子線放射材料４０から電子を放射させる。なお、図７（ａ）は本電子線源の平面図、同図（ｂ）は正面図〔（ａ）のＥ−Ｅ矢視図〕である。 FIG. 7 is a diagram showing a schematic configuration of the electron beam source of the mass spectrometer according to the present invention. In the present electron beam source, a conductive heating wire 49 is wound around the outer peripheral surface of an electron beam emitting material 40 in which a sintered material of tungsten is impregnated with a material having a low work function, or a part of the conductive heating wire 49 as shown in the figure. Is formed in a shape in close contact with the electron beam emitting material 40, and this portion is fixed by spot welding or the like to constitute the electron beam source assembly 43. Then, both ends of the conductive heating wire 49 of the electron beam source assembly 43 are placed on the electrodes 31a and 31b, and the electron beam emitting material 40 is located between the electrodes 31a and 31b and at a predetermined position in the length direction of the electrodes 31a and 31b. The electron beam source according to the present invention is arranged and fixed so as to be located at the position. Then, by passing a current through the conductive heating wire 49, the electron beam emitting material 40 is heated with heat generated from the conductive heating wire 49. As a result, electrons are emitted from the electron beam emitting material 40. 7A is a plan view of the electron beam source, and FIG. 7B is a front view (a view taken along the line E-E in FIG. 7A).

以上、本願発明の実施形態例を説明したが、本発明は上記実施例に限定されるものではなく、特許請求の範囲、及び明細書と図面に記載された技術的思想の範囲内において種々の変形が可能である。 The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims and the technical idea described in the specification and drawings. Deformation is possible.

１２フィラメント
１２−１ストレートタイプフィラメント
１２−２コイルタイプフィラメント
１２−３リボンタイプフィラメント
１３ａ，１３ｂ端子
１４イオン化室
１４ａ，１４ｂ穴
１５真空容器
１７試料
１８トラップ
２１ターボ分子ポンプ
２０流量制御バルブ
２２容積ポンプ
３０絶縁体ブロック
３１ａ，３１ｂ電極
４０電子線放射材料
４１支持兼導電部材
４２支持兼導電部材
４３電子線源組立体
４５支持兼導電部材
４６支持兼導電部材
４７支持兼導電部材
４８支持兼導電部材
４９導電発熱線 12 Filament 12-1 Straight type filament 12-2 Coil type filament 12-3 Ribbon type filament 13a, 13b Terminal 14 Ionization chamber 14a, 14b Hole 15 Vacuum vessel 17 Sample 18 Trap 21 Turbo molecular pump 20 Flow control valve 22 Volume pump 30 Insulation Body block 31a, 31b Electrode 40 Electron radiation material 41 Support / conductive member 42 Support / conductive member 43 Electron beam source assembly 45 Support / conductive member 46 Support / conductive member 47 Support / conductive member 48 Support / conductive member 49 Conductive heat generation line

Claims

A mass spectrometer comprising: an electron beam emitting material; and a pair of electrodes arranged at predetermined intervals on an insulator block, wherein the electron beam emitting material is heated to emit an electron beam from the electron beam emitting material. In the electron beam source
The electron beam emitting material is a chip-shaped electron beam emitting material that is sintered by impregnating a sintered metal with a material having a low work function or containing a material having a low work function in a metal.
One end of each of the pair of supporting and conductive members is fixed to the opposing portion of the outer surface of the chip-shaped electron beam emitting material, and the other end of the pair of supporting and conductive members is fixed to the pair of electrodes, An electron beam source for a mass spectrometer, wherein the electron beam emitting material is directly heated by a current passing through the supporting and conducting member from the tip to the chip-shaped electron beam emitting material.

The electron beam source of the mass spectrometer according to claim 1,
One end portion of the supporting and conductive member fixed to the chip-shaped electron beam emitting material is in the longitudinal direction of the electrode and the same direction or longitudinal direction as the other end portion of the supporting and conductive member is fixed to the electrode. An electron beam source for a mass spectrometer, wherein the electron beam source is bent in a direction opposite to each other.

The electron beam source of the mass spectrometer according to claim 1,
The support and conductive member is made of a sheet metal material, the width of the portion fixed to the chip-shaped electron beam emitting material is narrow, and the width of the portion fixed to the electrode is wide. Radiation source.

The electron beam source of the mass spectrometer according to claim 3,
The narrow portions of the pair of supporting and conductive members made of the sheet metal material that are fixed to the chip-shaped electron beam emitting material are mutually connected in the state where the wide portions of the pair of supporting and conductive members are fixed to the electrodes. An electron beam source for a mass spectrometer, wherein a tip portion is bent in the longitudinal direction of the electrode, and the tip-shaped electron beam emitting material is positioned between the tip portion and the tip portion .

A mass spectrometer comprising: an electron beam emitting material; and a pair of electrodes arranged at predetermined intervals on an insulator block, wherein the electron beam emitting material is heated to emit an electron beam from the electron beam emitting material. In the electron beam source
The electron beam emitting material is a chip-shaped electron beam emitting material that is sintered by impregnating a sintered metal with a material having a low work function or containing a material having a low work function in a metal.
It has a long conductive heating element,
The conductive heating element is wound around the outer peripheral surface of the chip-shaped electron beam radiation material, or the conductive heating element is fixed to at least a part of the outer peripheral surface of the chip-shaped electron beam radiation material, and both ends of the conductive heating element Are fixed to the pair of electrodes, and the electron beam emitting material is heated by heat generated from the conductive heating element by a current flowing from the electrodes to the conductive heating element. .