EP0968518B1 - Diode a vide a densite de courant de saturation elevee et temps de reponse rapide pour la detection de rayonnements electromagnetiques - Google Patents
Diode a vide a densite de courant de saturation elevee et temps de reponse rapide pour la detection de rayonnements electromagnetiques Download PDFInfo
- Publication number
- EP0968518B1 EP0968518B1 EP98917194A EP98917194A EP0968518B1 EP 0968518 B1 EP0968518 B1 EP 0968518B1 EP 98917194 A EP98917194 A EP 98917194A EP 98917194 A EP98917194 A EP 98917194A EP 0968518 B1 EP0968518 B1 EP 0968518B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- diode
- coaxial cable
- grid
- photocathode
- cathode
- 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.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J40/00—Photoelectric discharge tubes not involving the ionisation of a gas
- H01J40/16—Photoelectric discharge tubes not involving the ionisation of a gas having photo- emissive cathode, e.g. alkaline photoelectric cell
Definitions
- the present invention relates to a vacuum diode to high saturation current density and time of rapid response for radiation detection electromagnetic.
- the invention can be used in a broadband spectrometer, which is used to measure the spectrum of X-radiation emitted by a plasma generated by means of a laser.
- the coax cable mentioned above has a diameter of a few millimeters.
- the known vacuum diodes have electrodes, know a photocathode and a grid ("grid”), which are flat, parallel and placed opposite one of the other.
- the voltage and the distance between the electrodes are set by physical considerations of holding in tension, due to the dielectric strength of a cable coaxial of the kind mentioned above, and vacuum level for the distance between electrodes.
- the voltage is of the order of 1500 V and the distance between the electrodes is of the order of 1 mm, which leads to a limiting current density of the order of 13 A / cm 2 .
- a vacuum diode according to the preamble of claim 1 is described in DE 3,238,387.
- the present invention aims to solve previous problems and to propose a vacuum diode to high saturation current density and in time of rapid response for radiation detection electromagnetic.
- said portion is an end of inner conductor of the coaxial cable.
- the inner radius of the grid may be around equal to the inner radius of the outer conductor of the coaxial cable.
- the inner radius of the grid can be chosen so that the impedance of the diode, when it is placed in the void, equal to the impedance characteristic of the coaxial cable.
- the coaxial structure of the vacuum diode object of the present invention allows him to have better performance, in terms of current density maximum, than the known vacuum diodes.
- the soul is preferably used directly (inner conductor) of a coaxial cable like photocathode and one has, on the outskirts of this coaxial cable, the grid intended to collect the electrons that are generated at the soul level of the coaxial cable, by interaction with the radiation.
- the limiting current density is more than 30 A / cm 2 , the limit current density of a planar diode.
- a cable of 3.58 mm in diameter leads to a charge current density of 50 A / cm 2 and it reaches, for a cable of 1.19 mm diameter, a value of the order of 200 A / cm 2 .
- a diode according to the invention makes it possible “convey" an almost constant current, whatever the diameter of the coaxial cable used, and leads to fewer limitations as regards the density of current, that conventional vacuum diodes whose electrodes are flat.
- the vacuum diode according to the invention which is schematically represented in perspective on the single figure attached, is intended to detect a electromagnetic radiation 2 which is for example a X radiation.
- the grid 6 surrounds the photocathode 4 and has the shape of a cylinder whose axis has the reference X in the figure.
- Photocathode 4 also has the shape of a cylinder whose axis is also the X axis as we see on the figure.
- the diode is formed an end 7 of a coaxial cable 8 for example of type SMA.
- This cable comprises an inner conductor 10 of cylindrical shape and an outer conductor 12 also of cylindrical shape, the conductors 10 and 12 being coaxial.
- the space between the conductors 10 and 12 is filled with a dielectric material 14.
- the coaxial cable also includes a sheath protector that is not shown in the figure.
- the photocathode 4 is constituted by a portion of the inner conductor 10 which protrudes at the end 7 of the coaxial cable.
- Grid 6 is a weak metal blade thickness, pierced with a large number of openings 16.
- This rectangular shaped blade has been curved to have the shape of a cylinder whose height is equal to the height of the photocathode 4 and whose inner radius is approximately equal to the radius inside the outer conductor 12 of the coaxial cable 8.
- the base of the grid 6 is electrically connected to this outer conductor 12.
- the height of the grid 6 (height of the photocathode 4) is noted h
- the radius of the photocathode 4 is noted r
- the inner radius and the outer radius of the outer conductor 12 of the coaxial cable 8 are respectively denoted R1 and R2.
- a suitable measuring device 20 to inner conductor 10 and an outer conductor 12 coaxial cable 8, at the end 22 thereof, opposite to the one where the diode is.
- the measuring apparatus 20 is intended to establish a suitable electrical voltage between these outer and inner conductors, and therefore between the photocathode 4 and the gate 6 of the diode, and to measure the current supplied by the gate 6 when the diode is placed in the vacuum (very low pressure, of the order of 10 -5 Pa to 13 -3 Pa according to the experiments to be performed) and that the radiation 2 that is to be studied is sent to the diode.
- the inner radius of the grid may be greater than the outside radius of the driver outside 12 of the coaxial cable 8 and it is then brought to provide an adaptation piece (not shown) enabling the establishment of an electrical connection between the grid 6 and the outer conductor 12.
- This table also indicates the value of parameter ⁇ 2 for the coaxial cables considered.
- the diodes according to the invention with a structure coaxial, have a low capacity per unit of length (less than 0.1 pF / cm), which leads to RC response time constants less than one dozen picoseconds and therefore to resolutions in accordance with the needs of the measures.
- These diodes according to the invention are usable in areas of current densities and temporal responses that are inaccessible with the vacuum diodes known.
- the present invention is capable of many applications, particularly in the field of laser metrology.
- D 1 (mm) 5,309 2,985 1,676 0,940 d (mm) 1,628 .9195 0.511 0.287 Vm (V) 3000 1900 1500 1000 ⁇ 2 0.557 0.557 0.557 0.557 S (cm 2 ) 0.51 0.29 0.16 0.09 J 1 (A / cm) 16.3 14.6 18.2 17.3 J 2 (A / cm) 20 18 21.5 21 j 1 (A / cm 2 ) 32 51 113 196 j 2 (A / cm 2 ) 39 62 134 233
Landscapes
- Measurement Of Radiation (AREA)
Description
- d'une part de disposer du courant de saturation le plus élevé possible, pour pouvoir accepter un flux de photons important, et de placer ce détecteur le plus près possible du plasma émissif afin de réduire par là-même l'encombrement du spectromètre,
- d'autre part, d'obtenir une meilleure réponse temporelle que celle des détecteurs (diodes à vide) habituellement utilisés dans un tel spectromètre, réponse temporelle qui vaut environ 150 ps.
- J représente cette densité de courant par unité de surface, exprimée en A/cm2,
- V représente la tension entre les électrodes de la diode à vide, exprimée en V, et
- d représente la distance entre ces électrodes, exprimée en cm.
Une diode à vide selon le préambule de la revendication 1 est décrite dans le document DE 3 238 387.
- une photocathode destinée à recevoir le rayonnement, et
- une grille placée en regard de la photocathode, espacée de celle-ci et destinée à collecter les électrons émis par la photocathode lorsque celle-ci reçoit le rayonnement, la grille a la forme d'un cylindre et entoure la photocathode, cette dernière s'étendant suivant l'axe du cylindre, cette diode étant caractérisée en ce que la photocathode comprend une partie du conducteur intérieur d'un câble coaxial, le conducteur extérieur et le matériau électriquement isolant de ce câble coaxial étant éliminés en regard de cette partie, et en ce que la grille est électriquement reliée au conducteur extérieur de ce câble coaxial, les conducteurs intérieur et extérieur étant coaxiaux.
- J représente cette densité de courant par unité de longueur de cathode (cette longueur étant exprimée en cm), J étant exprimé en A/cm,
- V représente la tension entre l'anode et la cathode (exprimée en V),
- r représente le rayon du cylindre de l'anode (exprimé en cm), et
- β-2 est un terme correctif (sans dimension) qui tend vers 1 lorsque le rapport du rayon de la cathode (supposée cylindrique) au rayon de l'anode tend vers 0.
- une photocathode 4 qui est destinée à recevoir le rayonnement 2, et
- une grille 6 qui est placée en regard de la photocathode 4 et espacée de cette photocathode et qui est destinée à collecter les électrons émis par cette photocathode 4 lorsque celle-ci reçoit le rayonnement.
D2 (mm) | 6,35 | 3,58 | 2,2 | 1,19 |
D1 (mm) | 5,309 | 2,985 | 1,676 | 0,940 |
d (mm) | 1,628 | 0,9195 | 0,511 | 0,287 |
Vm (V) | 3000 | 1900 | 1500 | 1000 |
β2 | 0,557 | 0,557 | 0,557 | 0,557 |
S (cm2) | 0,51 | 0,29 | 0,16 | 0,09 |
J1 (A/cm) | 16,3 | 14,6 | 18,2 | 17,3 |
J2 (A/cm) | 20 | 18 | 21,5 | 21 |
j1 (A/cm2) | 32 | 51 | 113 | 196 |
j2 (A/cm2) | 39 | 62 | 134 | 233 |
Claims (4)
- Diode à vide, pour la détection d'un rayonnement électromagnétique (2), cette diode comprenant :une photocathode (4) destinée à recevoir le rayonnement, etune grille (6) placée en regard de la photocathode, espacée de celle-ci et destinée à collecter les électrons émis par la photocathode lorsque celle-ci reçoit le rayonnement, la grille (6) a la forme d'un cylindre et entoure la photocathode (4), cette dernière s'étendant suivant l'axe (X) du cylindre, cette diode étant caractérisée en ce que la photocathode comprend une partie (4) du conducteur intérieur (10) d'un câble coaxial (8), le conducteur extérieur et le matériau électriquement isolant (14) de ce câble coaxial étant éliminés en regard de cette partie, et en ce que la grille (6) est électriquement reliée au conducteur extérieur (12) de ce câble coaxial, les conducteurs intérieur et extérieur étant coaxiaux.
- Diode selon la revendication 1, caractérisée en ce que ladite partie (4) est une extrémité du conducteur intérieur (10) du câble coaxial (8).
- Diode selon l'une quelconque des revendications 1 et 2, caractérisée en ce que le rayon intérieur de la grille (6) est environ égal au rayon intérieur (R1) du conducteur extérieur (12) du câble coaxial (8).
- Diode selon l'une quelconque des revendications 1 et 2, caractérisée en ce que le rayon intérieur de la grille est choisi de façon que l'impédance de la diode, lorsqu'elle est placée dans le vide, soit égale à l'impédance caractéristique du câble coaxial (8).
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9703476 | 1997-03-21 | ||
FR9703476A FR2761195B1 (fr) | 1997-03-21 | 1997-03-21 | Diode a vide a densite de courant de saturation elevee et temps de reponse rapide pour la detection de rayonnements electromagnetiques |
PCT/FR1998/000564 WO1998043275A1 (fr) | 1997-03-21 | 1998-03-20 | Diode a vide a densite de courant de saturation elevee et temps de reponse rapide pour la detection de rayonnements electromagnetiques |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0968518A1 EP0968518A1 (fr) | 2000-01-05 |
EP0968518B1 true EP0968518B1 (fr) | 2005-01-05 |
Family
ID=9505049
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP98917194A Expired - Lifetime EP0968518B1 (fr) | 1997-03-21 | 1998-03-20 | Diode a vide a densite de courant de saturation elevee et temps de reponse rapide pour la detection de rayonnements electromagnetiques |
Country Status (5)
Country | Link |
---|---|
US (1) | US6337537B1 (fr) |
EP (1) | EP0968518B1 (fr) |
DE (1) | DE69828494D1 (fr) |
FR (1) | FR2761195B1 (fr) |
WO (1) | WO1998043275A1 (fr) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101971132A (zh) * | 2008-03-13 | 2011-02-09 | 皇家飞利浦电子股份有限公司 | 用于使得能够从多个项目中选择项目的方法和设备 |
CN112868080A (zh) * | 2018-10-16 | 2021-05-28 | 浜松光子学株式会社 | 放大电路用真空管和使用其的放大电路 |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR699787A (fr) * | 1929-05-28 | 1931-02-19 | Thomson Houston Comp Francaise | Perfectionnements apportés aux cellules photographiques |
US3983437A (en) * | 1968-03-12 | 1976-09-28 | The United States Of America As Represented By The United States Energy Research And Development Administration | Electromagnetic radiation detector |
US4358764A (en) * | 1980-07-28 | 1982-11-09 | Southwest Microwave, Inc. | Coupling unit for coaxial cable including means for radiating wave energy |
DE3238387A1 (de) * | 1982-10-16 | 1984-04-19 | Rudolf 8100 Garmisch-Partenkirchen Leutenbauer | Verfahren zur verwendung einer geschlossenen hochvakuumfotozelle fuer die ermittlung der planckschen konstante h und hochvakuumfotozelle, die zur durchfuehrung des verfahrens besonders geeignet ist |
US5245183A (en) * | 1992-09-10 | 1993-09-14 | The United States Of America As Represented By The Secretary Of The Army | Vibration resistant coaxial infrared diode and integrated circuit board |
RU2120706C1 (ru) * | 1997-01-28 | 1998-10-20 | Институт сильноточной электроники СО РАН | Устройство для генерации импульсного электронного пучка |
-
1997
- 1997-03-21 FR FR9703476A patent/FR2761195B1/fr not_active Expired - Lifetime
-
1998
- 1998-03-20 DE DE69828494T patent/DE69828494D1/de not_active Expired - Lifetime
- 1998-03-20 US US09/381,271 patent/US6337537B1/en not_active Expired - Fee Related
- 1998-03-20 EP EP98917194A patent/EP0968518B1/fr not_active Expired - Lifetime
- 1998-03-20 WO PCT/FR1998/000564 patent/WO1998043275A1/fr active IP Right Grant
Also Published As
Publication number | Publication date |
---|---|
WO1998043275A1 (fr) | 1998-10-01 |
DE69828494D1 (de) | 2005-02-10 |
EP0968518A1 (fr) | 2000-01-05 |
FR2761195B1 (fr) | 2006-12-15 |
FR2761195A1 (fr) | 1998-09-25 |
US6337537B1 (en) | 2002-01-08 |
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