JP4876471B2 - Field electron emission source and magnetron and microwave application apparatus using the same - Google Patents

Field electron emission source and magnetron and microwave application apparatus using the same Download PDF

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JP4876471B2
JP4876471B2 JP2005223680A JP2005223680A JP4876471B2 JP 4876471 B2 JP4876471 B2 JP 4876471B2 JP 2005223680 A JP2005223680 A JP 2005223680A JP 2005223680 A JP2005223680 A JP 2005223680A JP 4876471 B2 JP4876471 B2 JP 4876471B2
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敏行 塚田
城弘 米口
正幸 相賀
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Matsushita Electric Industrial Co Ltd
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本発明は、陰極基板の表面に炭素繊維を形成した電界電子放出源の製造方法と、この製造方法により得られた電界電子放出源と、その電界電子放出源を陰極部に用いたマグネトロンに関するものである。   The present invention relates to a method of manufacturing a field electron emission source in which carbon fibers are formed on the surface of a cathode substrate, a field electron emission source obtained by this manufacturing method, and a magnetron using the field electron emission source as a cathode portion. It is.

従来、金属製の陰極基板上に炭素繊維を成長させる方法としては、熱ＣＶＤ法などが良く知られている（例えば、特許文献１参照）。   Conventionally, a thermal CVD method or the like is well known as a method for growing carbon fibers on a metal cathode substrate (see, for example, Patent Document 1).

また、エッジ効果による電界集中が起こりやすい凹凸層を陰極基板の表面に形成するために、陰極基板の表面に導電性の粒子を配置し、その後に炭素繊維膜を形成する方法がある（例えば、特許文献２参照）。   In addition, in order to form a concavo-convex layer on the surface of the cathode substrate where electric field concentration is likely to occur due to the edge effect, there is a method in which conductive particles are arranged on the surface of the cathode substrate and then a carbon fiber film is formed (for example, Patent Document 2).

図６は従来の陰極基板表面に凹凸を付け炭素繊維膜を形成した電界電子放出源の断面図である。   FIG. 6 is a cross-sectional view of a field electron emission source in which a carbon fiber film is formed by providing irregularities on the surface of a conventional cathode substrate.

図において、ニトロセルロースなどを用いて金属製の陰極基板１上に導電性の粒子２を定着させる。その後、導電性の粒子を付着させた陰極基板１を一酸化炭素と水素の混合ガス中にて、５５０〜６００℃に加熱すると、表面の鉄を触媒として炭素繊維膜３が形成される。炭素繊維膜における炭素繊維４は直径が５０〜１００ｎｍである。
特開２００１−２８８６２５号公報 特開２０００−２６８７０７号公報 In the figure, conductive particles 2 are fixed on a metal cathode substrate 1 using nitrocellulose or the like. Thereafter, when the cathode substrate 1 to which conductive particles are attached is heated to 550 to 600 ° C. in a mixed gas of carbon monoxide and hydrogen, the carbon fiber film 3 is formed using iron on the surface as a catalyst. The carbon fiber 4 in the carbon fiber film has a diameter of 50 to 100 nm.
JP 2001-288625 A JP 2000-268707 A

しかしながら、上記の炭素繊維成膜方法では、炭素繊維の直径は５０〜１００ｎｍであり径が細い故、大電流を放出させるとジュール熱のため容易に焼き切れ、破損する問題があった。   However, in the carbon fiber film forming method described above, the diameter of the carbon fiber is 50 to 100 nm and the diameter is thin.

また、導電性の粒子を陰極基板上に配置して炭素繊維を成膜しても、凹凸形状が炭素繊維膜に埋もれてしまい、狙いの凹凸形状が緩和されてしまう問題があった。   Further, even when conductive particles are arranged on the cathode substrate to form a carbon fiber, the uneven shape is buried in the carbon fiber film, and the target uneven shape is relaxed.

また、上記の炭素繊維成膜方法では、陰極基板の表面に酸化物膜があり安定しているため、炭素繊維の成長速度が遅いという問題があった。   Further, the above carbon fiber film forming method has a problem that the growth rate of carbon fiber is slow because an oxide film is present on the surface of the cathode substrate and is stable.

また、陰極基板の表面に導電性の粒子を配置し、その後に炭素繊維を形成する場合、製
造工程が複雑でありコストが高いという問題があった。 Further, when conductive particles are arranged on the surface of the cathode substrate and then carbon fibers are formed, there is a problem that the manufacturing process is complicated and the cost is high.

また、陰極基板の表面に導電性の粒子を配置し、その後に炭素繊維を形成する場合、陰極基板の表面と導電性の粒子との接触抵抗が高く、高電流密度の電子を放出する場合ジュール熱が生じる問題があった。   In addition, when conductive particles are arranged on the surface of the cathode substrate and then carbon fibers are formed, the contact resistance between the surface of the cathode substrate and the conductive particles is high and electrons with a high current density are emitted. There was a problem of heat generation.

本発明は、前記課題に鑑み、容易に凹凸の付いた炭素繊維膜を表面に形成し、製造コストが安く、電流放出特性の優れた電界電子放出源を提供することを目的とする。   In view of the above problems, an object of the present invention is to provide a field electron emission source in which an uneven carbon fiber film is easily formed on the surface, the manufacturing cost is low, and the current emission characteristics are excellent.

上記目的は下記構成により達成される。   The above object is achieved by the following configuration.

前記従来の課題を解決するために、本発明の電界電子放出源は、陰極基板の表面に活性領域と未活性領域とを形成する第１の工程と、前記第１の工程の後に熱ＣＶＤ法を用いて前記陰極基板の表面に炭素繊維膜を形成する第２の工程とを有することを特徴とする電界電子放出源の製造方法にて表面を活性化した前記陰極基板の表面の粗さが、ＪＩＳ Ｂ０６０１の規格により定義される評価方法において十点平均粗さ（Ｒｚ）が７〜１０μｍ、平均長さ（ＲＳｍ）が１４０〜２００μｍであることを特徴とする。 In order to solve the conventional problems, a field electron emission source according to the present invention includes a first step of forming an active region and an inactive region on the surface of a cathode substrate, and a thermal CVD method after the first step. And a second step of forming a carbon fiber film on the surface of the cathode substrate using a surface roughness of the surface of the cathode substrate activated by the method of manufacturing a field electron emission source. In the evaluation method defined by the standard of JIS B0601, the ten-point average roughness (Rz) is 7 to 10 μm and the average length (RSm) is 140 to 200 μm .

本発明の電界電子放出源によれば、第１の工程において形成された陰極基板の活性領域は、第２の工程において炭素繊維の成長が速く炭素繊維膜が厚く形成され、未活性領域では炭素繊維の成長が遅く炭素繊維膜が薄く形成され、そのために陰極基板の表面に導電性の粒子を配置することなく炭素繊維膜表面に凹凸形状が形成できるので製造工程が簡略化でき、製造コストを安くすることが可能となる。さらには、陰極基板と導電性の粒子との間の接触抵抗がなくなるので、大電流を放出した場合でも接触抵抗によるジュール熱を抑えることが可能となる。また、従来の製造方法より径が太い炭素繊維を成膜することができ、大電流放出に耐え得る電界電子放出源を提供できる。 According to the field electron emission source of the present invention , in the active region of the cathode substrate formed in the first step, the carbon fiber grows quickly and the carbon fiber film is formed thick in the second step. The growth of the fiber is slow and the carbon fiber film is formed thin, so that it is possible to form an uneven shape on the surface of the carbon fiber film without arranging conductive particles on the surface of the cathode substrate, thereby simplifying the manufacturing process and reducing the manufacturing cost. It becomes possible to make it cheaper. Furthermore, since there is no contact resistance between the cathode substrate and the conductive particles, Joule heat due to the contact resistance can be suppressed even when a large current is emitted. Further, a carbon fiber having a larger diameter than that of the conventional manufacturing method can be formed, and a field electron emission source that can withstand large current emission can be provided.

また、炭素繊維膜の凹凸形状が０．１〜０．３ｍｍの大きさに形成され、電界集中効果と最大電子放出量のバランスに好適である。Moreover, the uneven shape of the carbon fiber film is formed in a size of 0.1 to 0.3 mm, which is suitable for the balance between the electric field concentration effect and the maximum electron emission amount.

第１の発明は、陰極基板の表面に活性領域と未活性領域とを形成する第１の工程と、前記第１の工程の後に熱ＣＶＤ法を用いて前記陰極基板の表面に炭素繊維膜を形成する第２の工程とを有することを特徴とする電界電子放出源の製造方法にて表面を活性化した前記陰極基板の表面の粗さが、ＪＩＳ Ｂ０６０１の規格により定義される評価方法において十点平均粗さ（Ｒｚ）が７〜１０μｍ、平均長さ（ＲＳｍ）が１４０〜２００μｍであることを特徴とする電界電子放出源である。 A first invention is a first step of forming an active region and an inactive region on a surface of a cathode substrate, and a carbon fiber film is formed on the surface of the cathode substrate using a thermal CVD method after the first step. In the evaluation method defined by the standard of JIS B0601, the surface roughness of the cathode substrate whose surface is activated by the method of manufacturing a field electron emission source, characterized in that A field electron emission source characterized in that the point average roughness (Rz) is 7 to 10 μm and the average length (RSm) is 140 to 200 μm .

第２の発明は、第１の発明において、前記陰極基板が、ステンレス材であることを特徴とする電界電子放出源である。A second invention is the field electron emission source according to the first invention, wherein the cathode substrate is made of stainless steel.

第３の発明は、第１または第２の発明において、前記炭素繊維が、カーボンナノチューブ、グラファイトナノファイバーまたはそれらを含むカーボン材料からなる電界電子放出源である。A third invention is a field electron emission source according to the first or second invention, wherein the carbon fibers are made of carbon nanotubes, graphite nanofibers, or a carbon material containing them.

第４の発明は、第３の発明において、前記炭素繊維が、カーボンナノチューブ、グラファイトナノファイバーまたはそれらを含むカーボン材料からなる電界電子放出源である。A fourth invention is the field electron emission source according to the third invention, wherein the carbon fiber is made of carbon nanotubes, graphite nanofibers or a carbon material containing them.

第５の発明は、第１の発明において、前記第１の工程は、前記陰極基板の表面に高速回転するワイヤブラシのグラインダを当接させて機械的に前記陰極基板の表面を粗し、前記陰極基板の表面に活性領域と未活性領域とを形成することを特徴とする電界電子放出源の製造方法。 In a fifth aspect based on the first aspect, in the first step, the surface of the cathode substrate is mechanically roughened by bringing a grinder of a wire brush rotating at a high speed into contact with the surface of the cathode substrate. A method for producing a field electron emission source, comprising forming an active region and an inactive region on a surface of a cathode substrate .

第６の発明は、第１の発明において、前記第１の工程は、前記陰極基板を酸またはアルカリ溶液によってエッチングし、前記陰極基板の表面に活性領域と未活性領域とを形成することを特徴とする電界電子放出源の製造方法である。In a sixth aspect based on the first aspect, in the first step, the cathode substrate is etched with an acid or alkali solution to form an active region and an inactive region on the surface of the cathode substrate. This is a manufacturing method of a field electron emission source.

第７の発明は、第１の発明において、前記第１の工程は、前記陰極基板の表面にダイヤモンドビーズの粒子を高圧で衝突させるブラスト処理を施し、前記陰極基板の表面に活性領域と未活性領域とを形成することを特徴とする電界電子放出源の製造方法である。In a seventh aspect based on the first aspect, in the first aspect, in the first step, a blasting process is performed in which the diamond bead particles collide with the surface of the cathode substrate at a high pressure, and an active region and an inactive state are formed on the surface of the cathode substrate. And a region for forming a field electron emission source.

第８の発明は、第１〜第４の発明のいずれかの電界電子放出源を陰極部に備えていることを特徴とするマグネトロンである。An eighth invention is a magnetron characterized in that the field electron emission source of any one of the first to fourth inventions is provided in a cathode portion.

第９の発明は、第８の発明のマグネトロンを備えたことを特徴とする電子レンジである。A ninth invention is a microwave oven including the magnetron of the eighth invention.

第１０の発明は、第８の発明のマグネトロンを備えたことを特徴とするマイクロ波応用装置である。A tenth invention is a microwave application apparatus comprising the magnetron of the eighth invention.

以下、本発明の実施の形態について、図面を参照しながら説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

（実施の形態１）
図１は本発明の実施の形態１における炭素繊維成膜前の陰極基板の断面図であり、図２は本発明の実施の形態１における炭素繊維成膜後の電界電子放出源の断面図、図３は本発明の実施の形態１における電界電子放出源と従来型電界電子放出源との電界強度に対する電流密度の関係比較グラフ、図４は本発明の実施の形態１における陰極基板の表面の粗さ値Ｒｚ［μｍ］に対する電界電子放出源から放出される電流密度の関係グラフである。 (Embodiment 1)
1 is a cross-sectional view of a cathode substrate before carbon fiber deposition in Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view of a field electron emission source after carbon fiber deposition in Embodiment 1 of the present invention. FIG. 3 is a graph comparing the relationship between the electric field intensity of the field electron emission source according to the first embodiment of the present invention and the conventional field electron emission source, and FIG. It is a relationship graph of the current density emitted from the field electron emission source with respect to the roughness value Rz [μm].

本実施の形態における金属製の陰極基板５は安価であるステンレスであり、表面に安定した酸化クロムの不動態膜がある。   The metallic cathode substrate 5 in the present embodiment is stainless steel, which is inexpensive, and has a stable chromium oxide passive film on the surface.

まず第１の工程において、陰極基板５の表面に高速回転させたステンレスワイヤーブラシのグラインダを数秒間当てると、陰極基板５表面にはステンレスワイヤーが衝突し活性化された活性領域６と、ステンレスワイヤーが衝突せずに酸化クロムの不動態膜が残存した未活性領域７が半々に存在している。   In the first step, when a stainless steel wire brush grinder rotated at high speed is applied to the surface of the cathode substrate 5 for several seconds, the surface of the cathode substrate 5 collides with the activated region 6 activated by the stainless steel wire, and the stainless steel wire. The inactive region 7 in which the passive film of chromium oxide remains without colliding with each other exists in half.

この陰極基板の表面をＪＩＳのＢ０６０１の規格により表面粗さを数値化したところ、十点平均粗さ（Ｒｚ）が７〜１０μｍ、平均長さ（ＲＳｍ）が１４０〜２００μｍであった。   When the surface roughness of the surface of this cathode substrate was quantified according to the standard of JIS B0601, the 10-point average roughness (Rz) was 7 to 10 μm and the average length (RSm) was 140 to 200 μm.

次に、第２の工程として、上記第１の工程による処理を施した陰極基板５を熱ＣＶＤ装置（図示せず）のチャンバー内に配置し、一酸化炭素と水素を体積比１：１で混合したガス雰囲気１気圧中において、底面からのヒーターで５５０℃に加熱、２５分間炭素繊維を気相成長させ電界電子放出源１１を形成した。   Next, as a second step, the cathode substrate 5 subjected to the treatment in the first step is placed in a chamber of a thermal CVD apparatus (not shown), and carbon monoxide and hydrogen are mixed at a volume ratio of 1: 1. In a mixed gas atmosphere at 1 atm, a field electron emission source 11 was formed by heating to 550 ° C. with a heater from the bottom and vapor growing carbon fiber for 25 minutes.

その際、陰極基板５にステンレスワイヤーが衝突した活性領域６は、金属が活性化され、かつ表面の不動態膜が除去されているのでステンレスワイヤーが衝突せずに不動態膜が
残存した未活性領域７より一酸化炭素と良く反応する。そして、陰極基板５内の鉄原子（Ｆｅ）が一酸化炭素中の炭素（Ｃ）と結合し炭化鉄（２ＦｅＣ）となる。炭化鉄はさらに炭素と結合する。その際の反応式は以下である。 At that time, in the active region 6 where the stainless steel wire collides with the cathode substrate 5, the metal is activated and the passive film on the surface is removed, so that the passive film remains without colliding with the stainless steel wire. It reacts better with carbon monoxide than region 7. And the iron atom (Fe) in the cathode substrate 5 couple | bonds with the carbon (C) in carbon monoxide, and turns into iron carbide (2FeC). Iron carbide further bonds with carbon. The reaction formula at that time is as follows.

２Ｆｅ ＋ ２ＣＯ → ２ＦｅＣ ＋Ｏ２
２ＦｅＣｎ ＋ ２ＣＯ → ２ＦｅＣｎ＋１ ＋Ｏ２
炭素と結合しながら炭化鉄は膨張し、やがて過飽和状態になり、これを核として炭素繊維が成長する。 2Fe + 2CO → 2FeC + O 2
2FeC n + 2CO → 2FeC n + 1 + O 2
Iron carbide expands while bonded to carbon, and eventually becomes supersaturated, and carbon fiber grows using this as a core.

活性領域６と未活性領域７とで成膜速度に差があるため、図２に示されるように炭素繊維膜の厚い領域８と、薄い領域９が生じ、炭素繊維膜に凹凸が生じた。また、炭素繊維膜の成膜後、陰極基板５の表面を電子顕微鏡で確認したところ、従来の炭素繊維膜の形成法によって成長させた炭素繊維の径よりも太い３００〜８００ｎｍの径の炭素繊維１０を確認した。これはグラファイトナノファイバーであった。   Since there is a difference in film formation speed between the active region 6 and the non-active region 7, as shown in FIG. 2, a thick region 8 and a thin region 9 of the carbon fiber film are generated, and irregularities are generated in the carbon fiber film. Moreover, when the surface of the cathode substrate 5 was confirmed with an electron microscope after the carbon fiber film was formed, the carbon fiber having a diameter of 300 to 800 nm thicker than the diameter of the carbon fiber grown by the conventional carbon fiber film forming method. 10 was confirmed. This was a graphite nanofiber.

なお、電界電子放出源として陰極基板の表面に形成された炭素繊維の径による電子放出特性について確認すると、炭素繊維の径が細いと電界が分散してしまうため、電子放出特性が低下することを確認した。また、極端に太いと炭素繊維に電界が集中しないため、やはり電子放出特性が低下することを確認した。   In addition, when the electron emission characteristics due to the diameter of the carbon fiber formed on the surface of the cathode substrate as a field electron emission source are confirmed, the electric field is dispersed if the carbon fiber diameter is small, and the electron emission characteristics are deteriorated. confirmed. In addition, if the thickness is extremely thick, the electric field does not concentrate on the carbon fiber.

また、炭素繊維の中でもカーボンナノチューブ、グラファイトナノファイバーまたはそれらを含むカーボン材料はアスペクト比が特に大きく、優れた電子放出特性が得られることを確認した。   In addition, among carbon fibers, carbon nanotubes, graphite nanofibers, or carbon materials containing them have a particularly large aspect ratio, and it has been confirmed that excellent electron emission characteristics can be obtained.

さらに、本実施の形態による電界電子放出源１１と平板陽極（図示せず）を１ｍｍのギャップで真空内に平行に配置し、両電極間に電圧を徐々に印加して電界電子放出を開始する電圧値を評価したところ、４００Ｖの直流電圧にて１μＡ／ｃｍ２の放出電流密度を確認した。従来の表面を活性化せずに炭素繊維膜を形成した電界電子放出源の場合は、１μＡ／ｃｍ２の放出電流密度を得るためには１ｋＶの印加電圧が必要であった。また、本実施の形態の電界電子放出源と平板陽極との電極間に３ｋＶの直流電圧を印加すると、本発明は１１７ｍＡ／ｃｍ２の放出電流密度を確認したのに対し、従来の表面を活性化せずに炭素繊維膜を形成した電界電子放出源の放出電流密度は２５ｍＡ／ｃｍ２であった。 Further, the field electron emission source 11 according to the present embodiment and a flat plate anode (not shown) are arranged in parallel in a vacuum with a gap of 1 mm, and a voltage is gradually applied between both electrodes to start field electron emission. When the voltage value was evaluated, an emission current density of 1 μA / cm 2 was confirmed at a DC voltage of 400V. In the case of a field electron emission source in which a carbon fiber film is formed without activating the conventional surface, an applied voltage of 1 kV is required to obtain an emission current density of 1 μA / cm 2 . In addition, when a DC voltage of 3 kV was applied between the field electron emission source of the present embodiment and the plate anode, the present invention confirmed an emission current density of 117 mA / cm 2 whereas the conventional surface was activated. The emission current density of the field electron emission source in which the carbon fiber film was formed without conversion was 25 mA / cm 2 .

グラインダで粗す場合、表面粗さ値ＲＳｍとＲｚの関係は以下にある。   When roughening with a grinder, the relationship between the surface roughness values RSm and Rz is as follows.

ＲＳｍ ÷ Ｒｚ ≒ ２０
３Ｖ／μｍの電圧強度を印加した際のＲｚと電界電子放出源から放出される電流密度との関係は、図４のグラフに示されるように、Ｒｚが１２μｍ以上では放電し電子放出の動作が不安定であり、Ｒｚが少ないと電界集中効果が得られずに電流密度が低くなる。よって、Ｒｚは７〜１０μｍ、ＲＳｍは上記式より１４０〜２００μｍが最適となる。 RSm ÷ Rz ≒ 20
As shown in the graph of FIG. 4, the relationship between Rz when a voltage intensity of 3 V / μm is applied and the current density emitted from the field electron emission source is as follows. It is unstable, and if Rz is small, the electric field concentration effect cannot be obtained and the current density becomes low. Therefore, Rz is optimally 7 to 10 μm, and RSm is optimally 140 to 200 μm from the above formula.

（実施の形態２）
本発明の実施の形態２における電界電子放出源は、陰極基板５としてステンレスを用い、陰極基板５を硝酸と塩酸の混合液に１０秒ほど浸した後に取り出し水洗いした。陰極基板５の表面には酸によって腐食した活性領域６と、腐食しなかった未活性領域７が混在した。この陰極基板５を実施の形態１と同様に炭素繊維膜を成膜したところ、同じように良好な結果が得られた。また、アルカリ性溶液で表面を腐食しても同様の効果が得られた。 (Embodiment 2)
In the field electron emission source according to Embodiment 2 of the present invention, stainless steel was used as the cathode substrate 5. The cathode substrate 5 was immersed in a mixed solution of nitric acid and hydrochloric acid for about 10 seconds and then taken out and washed with water. On the surface of the cathode substrate 5, an active region 6 corroded by an acid and an inactive region 7 which was not corroded were mixed. When this carbon substrate film was formed on the cathode substrate 5 in the same manner as in the first embodiment, the same good results were obtained. The same effect was obtained even when the surface was corroded with an alkaline solution.

（実施の形態３）
本発明の実施の形態３における電界電子放出源は、陰極基板５としてステンレスを用い
、陰極基板５の表面に直径１０μｍのダイヤモンドビーズを高圧で衝突させるブラスト処理を行った。表面にはダイヤモンドビーズが衝突した活性領域６と、衝突しなかった未活性領域７が混在した。この陰極基板５を実施の形態１と同様に炭素繊維膜を成膜したところ、同じように良好な結果が得られた。 (Embodiment 3)
In the field electron emission source according to Embodiment 3 of the present invention, stainless steel was used as the cathode substrate 5 and blasting was performed by causing diamond beads having a diameter of 10 μm to collide with the surface of the cathode substrate 5 at a high pressure. The active region 6 where the diamond beads collided and the inactive region 7 which did not collide were mixed on the surface. When this carbon substrate film was formed on the cathode substrate 5 in the same manner as in the first embodiment, the same good results were obtained.

（実施の形態４）
図５は本発明における電界電子放出源を用いたマグネトロンの要部を示す縦断面図である。 (Embodiment 4)
FIG. 5 is a longitudinal sectional view showing a main part of a magnetron using the field electron emission source in the present invention.

本実施の形態では、上記実施の形態１における電界電子放出源１１の生成法と同様に、陰極部１２の円筒状の陰極基板１３の外周表面に活性領域と未活性領域とを形成し熱ＣＶＤ法でグラファイトナノファイバー１４を成長させる。そのグラファイトナノファイバー１４薄膜を形成した円筒状の陰極基板１３を上下のエンドハット１５で挟んで陰極部１２を構成した。   In the present embodiment, similarly to the method for generating the field electron emission source 11 in the first embodiment, an active region and an inactive region are formed on the outer peripheral surface of the cylindrical cathode substrate 13 of the cathode portion 12 to perform thermal CVD. Graphite nanofibers 14 are grown by the method. A cylindrical cathode substrate 13 on which the graphite nanofiber 14 thin film was formed was sandwiched between upper and lower end hats 15 to form a cathode portion 12.

また、分割陽極である陽極ベイン１６は既存のマグネトロン（１０分割、内径８ｍｍ）のものとし、上記の陰極部１２を陽極ベイン１６と同軸上に配置し、マグネトロン真空管として組み立てた。軸方向に一対の磁石（図示せず）を配置し３５０ｍＴの直流磁界１７を生じさせ、陰極部１２に電圧を−５．０ｋＶ印加した。陽陰極間電圧のため生じる半径方向の電界によって、陰極部１２のグラファイトナノファイバー１４にて電界放出現象が生じ、電子が放出された。   The anode vane 16 that is a divided anode was an existing magnetron (10 divisions, inner diameter 8 mm), and the cathode portion 12 was arranged coaxially with the anode vane 16 and assembled as a magnetron vacuum tube. A pair of magnets (not shown) were arranged in the axial direction to generate a 350 mT DC magnetic field 17, and a voltage of −5.0 kV was applied to the cathode portion 12. A field emission phenomenon occurred in the graphite nanofibers 14 of the cathode portion 12 due to the radial electric field generated due to the voltage between the positive and negative electrodes, and electrons were emitted.

陰極部１２のグラファイトナノファイバー１４にて放出された電子は、作用空間１８内を直流磁界１７によってサイクロイド運動し、陽陰極間に最大１２０ｍＡの電流が流れ、２．４５ＧＨｚにて４２０Ｗの発振を確認できた。   Electrons emitted from the graphite nanofiber 14 in the cathode section 12 are cycloidly moved in the working space 18 by the DC magnetic field 17, and a maximum current of 120 mA flows between the positive and negative electrodes, confirming an oscillation of 420 W at 2.45 GHz. did it.

比較のために従来型の電界電子放出源を用いたマグネトロンにおいては、陰極部に電圧を−６．０ｋＶ印加したときに、５０ｍＡの電流が流れ２．４５ＧＨｚにて２１０Ｗの発振しか得られなかった。   For comparison, in a magnetron using a conventional field electron emission source, when a voltage of -6.0 kV was applied to the cathode portion, a current of 50 mA flowed and only 210 W oscillation was obtained at 2.45 GHz. .

また、本発明における電界電子放出源を用いたマグネトロンを高周波加熱装置である電子レンジに組込み、動作することが確認できた。   It was also confirmed that the magnetron using the field electron emission source according to the present invention was incorporated in a microwave oven as a high-frequency heating device and operated.

本発明の電界電子放出源は安易な構成で大電流を得られるので、フィールドエミッションディスプレイやマグネトロン等に使用することができる。また、その電界電子放出源を用いたマグネトロンはマイクロ波発生装置、及びその装置を用いたマイクロ波応用装置である高周波加熱装置、レーダー、航空機、船舶、宇宙船、ロケット等に使用することができる。   Since the field electron emission source of the present invention can obtain a large current with an easy configuration, it can be used for a field emission display, a magnetron, or the like. Further, the magnetron using the field electron emission source can be used for a microwave generator and a high-frequency heating apparatus, a radar, an aircraft, a ship, a spacecraft, a rocket, etc., which are microwave application apparatuses using the apparatus. .

本発明の実施の形態１における炭素繊維成膜前の陰極基板の断面図Sectional drawing of the cathode substrate before carbon fiber film-forming in Embodiment 1 of this invention 本発明の実施の形態１における炭素繊維成膜後の電界電子放出源の断面図Sectional drawing of the field electron emission source after carbon fiber film-forming in Embodiment 1 of this invention 本発明の実施の形態１における電界電子放出源と従来型電界電子放出源との電界強度に対する電流密度の関係比較グラフComparison graph of current density with respect to electric field strength between field electron emission source and conventional type field electron emission source in Embodiment 1 of the present invention 本発明の実施の形態１における陰極基板の表面の粗さ値に対する電界電子放出源から放出される電流密度の関係グラフFIG. 5 is a graph showing the relationship between the current density emitted from the field electron emission source and the roughness value of the surface of the cathode substrate in the first embodiment of the present invention. 本発明における電界電子放出源を用いたマグネトロンの要部を示す縦断面図The longitudinal cross-sectional view which shows the principal part of the magnetron using the field electron emission source in this invention 従来の陰極基板表面に導電性の粒子で凹凸を付け炭素繊維膜を形成した電界電子放出源の断面図Sectional view of a field electron emission source in which a carbon fiber film is formed by forming irregularities with conductive particles on the surface of a conventional cathode substrate

５，１３ 陰極基板
６ 活性領域
７ 未活性領域
８ 炭素繊維膜の厚い領域
９ 炭素繊維膜の薄い領域
１０ 炭素繊維
１１ 電界電子放出源
１２ 陰極部
１４ グラファイトナノファイバー
１５ エンドハット
１６ 陽極ベイン
１７ 直流磁界
１８ 作用空間 5, 13 Cathode substrate 6 Active area 7 Inactive area 8 Thick area of carbon fiber film 9 Thin area of carbon fiber film 10 Carbon fiber 11 Field electron emission source 12 Cathode part 14 Graphite nanofiber 15 End hat 16 Anode vane 17 DC magnetic field 18 working space

Claims (10)

陰極基板の表面に活性領域と未活性領域とを形成する第１の工程と、前記第１の工程の後に熱ＣＶＤ法を用いて前記陰極基板の表面に炭素繊維膜を形成する第２の工程とを有することを特徴とする電界電子放出源の製造方法にて表面を活性化した前記陰極基板の表面の粗さが、ＪＩＳ Ｂ０６０１の規格により定義される評価方法において十点平均粗さ（Ｒｚ）が７〜１０μｍ、平均長さ（ＲＳｍ）が１４０〜２００μｍであることを特徴とする電界電子放出源。 A first step of forming an active region and an inactive region on the surface of the cathode substrate; and a second step of forming a carbon fiber film on the surface of the cathode substrate using a thermal CVD method after the first step. The surface roughness of the cathode substrate whose surface was activated by the method of manufacturing a field electron emission source characterized by having a ten-point average roughness (Rz) in an evaluation method defined by the standard of JIS B0601 ) Is 7 to 10 μm, and the average length (RSm) is 140 to 200 μm . 前記陰極基板が、ステンレス材であることを特徴とする請求項１に記載の電界電子放出源。 2. The field electron emission source according to claim 1, wherein the cathode substrate is made of stainless steel . 前記炭素繊維が、カーボンナノチューブ、グラファイトナノファイバーまたはそれらを含むカーボン材料からなる請求項１または２に記載の電界電子放出源。 The field electron emission source according to claim 1 or 2 , wherein the carbon fibers are made of carbon nanotubes, graphite nanofibers, or a carbon material containing them . 前記炭素繊維がグラファイトナノファイバーであり、直径が３００〜８００ｎｍであることを特徴とする請求項３に記載の電界電子放出源。 The field electron emission source according to claim 3 , wherein the carbon fibers are graphite nanofibers and have a diameter of 300 to 800 nm . 前記第１の工程は、前記陰極基板の表面に高速回転するワイヤブラシのグラインダを当接させて機械的に前記陰極基板の表面を粗し、前記陰極基板の表面に活性領域と未活性領域とを形成することを特徴とする請求項１に記載の電界電子放出源の製造方法。 In the first step, a surface of the cathode substrate is mechanically roughened by contacting a high-speed rotating wire brush grinder on the surface of the cathode substrate, and an active region and an inactive region are formed on the surface of the cathode substrate. The method of manufacturing a field electron emission source according to claim 1, wherein: 前記第１の工程は、前記陰極基板を酸またはアルカリ溶液によってエッチングし、前記陰極基板の表面に活性領域と未活性領域とを形成することを特徴とする請求項１に記載の電界電子放出源の製造方法。 2. The field electron emission source according to claim 1 , wherein in the first step, the cathode substrate is etched with an acid or an alkali solution to form an active region and an inactive region on a surface of the cathode substrate. Manufacturing method . 前記第１の工程は、前記陰極基板の表面にダイヤモンドビーズの粒子を高圧で衝突させるブラスト処理を施し、前記陰極基板の表面に活性領域と未活性領域とを形成することを特徴とする請求項１に記載の電界電子放出源の製造方法。 The first step is characterized in that an active region and an inactive region are formed on the surface of the cathode substrate by performing a blasting process in which diamond bead particles collide with the surface of the cathode substrate at a high pressure. 2. A method for producing a field electron emission source according to 1 . 請求項１〜４のいずれかに記載の電界電子放出源を陰極部に備えていることを特徴とする
マグネトロン。 The field electron emission source according to claim 1 is provided in a cathode portion.
Magnetron . 請求項８に記載のマグネトロンを備えたことを特徴とする電子レンジ。 A microwave oven comprising the magnetron according to claim 8 . 請求項８に記載のマグネトロンを備えたことを特徴とするマイクロ波応用装置。
 A microwave application apparatus comprising the magnetron according to claim 8 .
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