EP0136216A2 - Charged particles self-focusing linear accelerating structure - Google Patents

Charged particles self-focusing linear accelerating structure Download PDF

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Publication number
EP0136216A2
EP0136216A2 EP84401699A EP84401699A EP0136216A2 EP 0136216 A2 EP0136216 A2 EP 0136216A2 EP 84401699 A EP84401699 A EP 84401699A EP 84401699 A EP84401699 A EP 84401699A EP 0136216 A2 EP0136216 A2 EP 0136216A2
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cavity
accelerating
length
face
accelerator
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EP0136216A3 (en
EP0136216B1 (en
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Dominique Tronc
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CGR MEV SA
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CGR MEV SA
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
    • H05H7/14—Vacuum chambers
    • H05H7/18—Cavities; Resonators

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  • the invention relates to a self-focusing linear accelerating structure of charged particles, intended to equip a linear electron accelerator.
  • Linear accelerators of charged particles are used in many fields such as, scientific, medical, and even industrial. Depending on their application, these accelerators produce beams of particles, of electrons for example, having energies often between one and several tens of MeV.
  • Linear electron accelerating structures are generally formed by a succession of resonant cavities, the dimensions of which are related to the frequency of an electromagnetic wave injected into the structure to accelerate the electrons, and to the speed of the electrons.
  • the accelerating structures are optimized as regards the longitudinal dynamics: one chooses the lengths of the resonant cavities, which constitute accelerating cavities, so as to constantly accelerate in each of them the electrons.
  • the accelerating part of the electromagnetic wave is at most equal to its half period, and to benefit from a maximum mum of energy given up by this wave to the electrons, that is to say a high value of the so-called "transit angle" coefficient, these cavities commonly have a length 1 substantially equal to the product of a quarter to a third of the length ⁇ o of the electromagnetic wave by the relative speed ⁇ of the electrons, according to the following relation: where / 3 is the quotient of the average speed V of the electrons by the speed C of light ( ), and n is between 3 and 4. This length, defined within the framework of the calculation of a conventional cavity, is called accelerating length.
  • This defocusing of the beam is generally compensated for by adding solenoids arranged concentrically around the accelerating structure, to create a corrective magnetic field, which increases the cost and the complexity.
  • the present invention relates to an accelerating structure of self-focusing charged particles, in which the defocusing effect of the beam is avoided by the cancellation of one of its causes, unlike structures according to the prior art where this effect is only compensated.
  • the accelerating structure according to the invention is obtained thanks to a simple and inexpensive arrangement of the single or the first accelerating cavity of this structure, and particularly strictly applicable in the case where, in this cavity, the beam exit hole has a diameter less than the previously mentioned accelerating length; this arrangement is remarkable in that it makes it possible, in the latter case, to take account of the fact that the radial component of the electric field in the accelerating cavity constitutes one of the main causes of the divergence of peripheral charged particles of the beam, and that this radial component is located near the entry and exit faces of the cavity and has effects contrary to the entry and exit of this cavity.
  • a self-focusing linear accelerating structure of charged particles comprising a first accelerating cavity of a succession of accelerating cavities, making it possible to accelerate a beam of charged particles under the effect of an electromagnetic wave of given frequency F injected in said structure, said first cavity having an axis coincident with a longitudinal axis of said structure and the axis of said beam, and comprising an inlet face and an outlet face provided respectively with an inlet hole and a exit hole of said beam, is characterized in that the distance between the entry and exit faces of said first cavity is formed by an accelerating length, plus an additional length intended to delay the instant of arrival of the particles at the exit face.
  • the particles are not subjected to the defocusing action of the radial component located near the face output, this radial component being either in the process of disappearing, has even become focusing; the only minor drawback is a slight deceleration of these particles, before they have passed the exit hole.
  • FIG. 1 partially shows a linear accelerating structure 1 in accordance with the invention, comprising a first accelerating cavity CA followed by n accelerating cavities C 1 , ..., C n , n being in the example described equal to 2.
  • n did not include any so-called coupling cells, which constitute conventional elements arranged between the cavities C 1 , ..., C in a known manner.
  • the structure 1 has a longitudinal axis Z, coincident with the axis of the first cavity CA, and which also constitutes the axis of a particle beam (not shown) propagating in the direction of the arrow 2; this particle beam is accelerated by the energy of an electromagnetic wave (not shown in FIG. 1) conventionally injected into the structure 1 by a coupling hole 4.
  • the first cavity CA of cylindrical shape, has an inlet face 3 and an outlet face 5 normal to the axis of the beam Z, and spaced from one another by a distance D; the inlet face 3 is provided with an inlet hole 7, the outlet face 5 is provided with an outlet hole 8, these two holes being centered on the axis Z of the beam.
  • the particle beam coming for example, in a known manner, from an electron gun followed by a sliding element (not shown), enters the first accelerating cavity CA by the inlet hole 7, and emerges from this cavity CA through the outlet hole 8, propagating in the structure 1 in the direction shown by the arrow 2.
  • This relative speed of the electrons is calculated by taking the average between the speed of entry into the first cavity CA, and the maximum speed reached in this cavity at the exit of the accelerating length L 1 . It should be noted that certain electrons are decelerated at the very beginning of their trajectory, which is not taken into account in the approximation of the accelerating length L 1 .
  • these same charged particles having crossed the first accelerating length L 1 do not undergo the influence of this diverging radial component Er 2 , from which they are still separated by an additional length L 2 ; the distance D between the inlet and outlet faces being formed by the addition of these two lengths L 1 + L 2 , and the additional length L 2 being equal to or greater than twice the radius r of the outlet hole 8 ( L 2 ⁇ 2 r).
  • the inlet and outlet holes 7,8 generally have spouts, not shown in FIG. 1 which is schematic, and the radius r represents an approximate mean radius of the outlet hole 8.
  • the additional length L 2 is such that the electromagnetic wave is canceled, or even reversed when these particles have crossed the distance D, they leave the first cavity CA through the outlet hole 8 without diverging; they can even, if the phase of the electromagnetic wave is reversed, undergo a convergent action and a weak deceleration, the radial component then being also reversed. It is noted that this additional length L 2 , of the first cavity CA, also promotes the converging action at the entry of the following accelerating cavity CI which constitutes the second cavity.
  • the distance D 1 between the exit face 5 of the first cavity CA and the entry plane 15 of the second cavity C 1 is less than the accelerating length L 1 , and thus ensures convergence sensitive to the input of this second cavity C 1 , taking into account the phase shift of the electromagnetic wave between cavities CA, C 1 , C 2 .
  • the energy gain is such that the effect of the output from the second cavity C 1 is (almost) negligible.
  • L 2 L 1 .K, where K is a coefficient between 0.5 and 1.
  • the distribution of the electric field being symmetrical with respect to the axis Z of the beam, it is not represented in the lower part of the first cavity CA.
  • This distribution of the electric field in the first accelerating cavity CA corresponds to the existence in the latter of an accelerating field.
  • Figure 2 shows the electromagnetic wave OE of which half a period determines this accelerating field and of which the part of the OE wave comprised on the one hand between an instant to and the instant tl, and on the other hand between an instant t3 and an instant t4 determines a decelerating field; the instant t2 corresponding to the peak value of the half period x where the accelerator field Zo is maximum.
  • this electron undergoes a decelerating field near the input face 3 until time tl when the OE wave reverses and the field becomes accelerator; the action of the radial component Er 1 , located near the entry face 3, is therefore first divergent then convergent when the field becomes accelerator, and its action is globally convergent.
  • This slowed down electron is joined by electrons that entered the CA cavity after it.
  • the arrangement of the first cavity CA of the structure 1 according to the invention makes it possible to avoid the defoca-jisation effect at the output for a wide range of values of arrival phase ⁇ o, for example between - 45 ° and - 190 ° relative to Zo or the instant tl.
  • FIG. 3 illustrates the trajectory of a peripheral electron of the beam, and shows the field components Er, Ez seen at different times, taking into account the finite speed of the electron.
  • the exit face 5 would have occupied the position of the line 11 in dotted lines and, the field to which the electron would then have been subjected at its exit from the first cavity CA is represented in dotted lines by the components Er 2 and Ez; the trajectory of the electron would have been modified according to arrow 12 represented in dotted lines, which tends to diverge from the axis Z of the beam.
  • the accelerating structure 1 according to the invention eliminates the defocusing effect of the charged peripheral particles of the beam, at the exit of an accelerating cavity. This elimination of the divergence effect is obtained by a simple, economical arrangement, which makes it possible to increase the efficiency of a linear accelerator of charged particles.

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  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)

Abstract

L'invention concerne une structure accélératrice linéaire autofocalisante de particules chargées dans laquelle est évité un effet de défocalisation radiale du faisceau de particules, notamment à la sortie d'une première cavité accélératrice (CA) que comporte cette structure (1). La première cavité accélératrice (CA) comporte une face d'entrée (3) et une face de sortie (5) dont l'écartement (D) est formé d'une longueur accélératrice (Li) plus une longueur supplémentaire (L2), destinée à retarder l'arrivée des particules à la face de sortie (5). Une structure selon l'invention permet d'augmenter le rendement d'un accélérateur linéaire de particules chargées, grâce à un agencement simple et peu coûteux de la première cavité (CA) de cette structure.

Figure imgaf001
The invention relates to a self-focusing linear accelerating structure of charged particles in which a radial defocusing effect of the particle beam is avoided, in particular at the outlet of a first accelerating cavity (CA) which this structure (1) comprises. The first accelerating cavity (CA) comprises an inlet face (3) and an outlet face (5) whose spacing (D) is formed by an accelerating length (Li) plus an additional length (L 2 ), intended to delay the arrival of particles at the outlet face (5). A structure according to the invention makes it possible to increase the efficiency of a linear accelerator of charged particles, thanks to a simple and inexpensive arrangement of the first cavity (CA) of this structure.
Figure imgaf001

Description

L'invention concerne une structure accélératrice linéaire autofocalisante de particules chargées, destinée à équiper un accélérateur linéaire d'électrons.The invention relates to a self-focusing linear accelerating structure of charged particles, intended to equip a linear electron accelerator.

Des accélérateurs linéaires de particules chargées sont utilisés dans de nombreux domaines tels que, scientifiques, médicaux, et même industriels. Selon leur application, ces accélérateurs produisent des faisceaux de particules, d'électrons par exemple, ayant des énergies souvent comprises entre un et plusieurs dizaines de MeV.Linear accelerators of charged particles are used in many fields such as, scientific, medical, and even industrial. Depending on their application, these accelerators produce beams of particles, of electrons for example, having energies often between one and several tens of MeV.

La puissance électrique consommée par ces accélérateurs est considérable, elle peut atteindre par exemple 130 Kw dont seulement 20 Kw se retrouvent dans le faisceau accéléré ; aussi le rendement global d'un tel accélérateur a une répercussion directe et importante sur le coût d'utilisation de cet accélérateur, et une amélioration de son rendement par l'optimisation des éléments qui le constitue, est un souci constant des spécialistes, l'amélioration du rendement étant également souvent liée à l'amélioration des qualités du faisceau obtenu.The electrical power consumed by these accelerators is considerable, it can reach for example 130 Kw of which only 20 Kw are found in the accelerated beam; also the overall performance of such an accelerator has a direct and significant impact on the cost of using this accelerator, and an improvement in its performance by optimizing the elements which constitute it, is a constant concern of specialists, the improvement in efficiency is also often linked to improvement in the qualities of the beam obtained.

Les structures accélératrices linéaires d'électrons sont généralement formées par une succession de cavités résonantes, dont les dimensions sont liées à la fréquence d'une onde électromagnétique injectée dans la structure pour accélérer les électrons, et à la vitesse des électrons.Linear electron accelerating structures are generally formed by a succession of resonant cavities, the dimensions of which are related to the frequency of an electromagnetic wave injected into the structure to accelerate the electrons, and to the speed of the electrons.

Traditionnellement, les structures accélératrices sont optimisées en ce qui concerne la dynamique longitudinale : on choisit les longueurs des cavités résonantes, qui constituent des cavités accélératrices, de façon à accélérer constamment dans chacune d'elles les électrons.Traditionally, the accelerating structures are optimized as regards the longitudinal dynamics: one chooses the lengths of the resonant cavities, which constitute accelerating cavities, so as to constantly accelerate in each of them the electrons.

La partie accélératrice de l'onde électromagnétique est au maximum égale à sa demie période, et pour bénéficier d'un maximum d'énergie cédée par cette onde aux électrons, c'est-à-dire d'une valeur élevée du coefficient dit "d'angle de transit", ces cavités ont couramment une longueur 1 sensiblement égale au produit du quart au tiers de la longueur λo de l'onde électromagnétique par la vitesse relative β des électrons, selon la relation suivante :

Figure imgb0001
où /3 est le quotient de la vitesse V moyenne des électrons par la vitesse C de la lumière (
Figure imgb0002
 ), et n est compris entre 3 et 4. Cette longueur, définie dans le cadre du calcul d'une cavité classique, est appelée longueur accélératrice.The accelerating part of the electromagnetic wave is at most equal to its half period, and to benefit from a maximum mum of energy given up by this wave to the electrons, that is to say a high value of the so-called "transit angle" coefficient, these cavities commonly have a length 1 substantially equal to the product of a quarter to a third of the length λo of the electromagnetic wave by the relative speed β of the electrons, according to the following relation:
Figure imgb0001
 where / 3 is the quotient of the average speed V of the electrons by the speed C of light (
Figure imgb0002
 ), and n is between 3 and 4. This length, defined within the framework of the calculation of a conventional cavity, is called accelerating length.

Ainsi par exemple, dans le cas d'une structure accélératrice fonctionnant à 3000 MHZ, soit une longueur d'onde À o égale à 100 mm et pour β = 0,5, les cavités accélératrices ont une longueur de l'ordre de 12 à 16 mm environ, augmentant progressivement pour atteindre 25à33 mm lorsque β =1.Thus, for example, in the case of an accelerating structure operating at 3000 MHz, or a wavelength λ o equal to 100 mm and for β = 0.5, the accelerating cavities have a length of the order of 12 to About 16 mm, gradually increasing to 25 to 33 mm when β = 1.

Cette approche traditionnelle où l'optimisation est limitée à la dynamique longitudinale, est imparfaite notamment par ce qu'elle ne prend pas en compte un effet de défocalisation radiale du faisceau le long de la structure accélératrice, cet effet s'affirmant particulièrement dans la première partie de cette structure où l'énergie des électrons est encore faible.This traditional approach where the optimization is limited to the longitudinal dynamics, is imperfect in particular by that it does not take into account a radial defocusing effect of the beam along the accelerating structure, this effect being particularly affirmed in the first part of this structure where the energy of the electrons is still low.

Cette défocalisation du faisceau est généralement compensée en ajoutant des solénoïdes disposés concentriquement autour de la structure accélératrice, pour créer un champ magnétique correcteur, ce qui augmente le coût et la complexité.This defocusing of the beam is generally compensated for by adding solenoids arranged concentrically around the accelerating structure, to create a corrective magnetic field, which increases the cost and the complexity.

La présente invention concerne une structure accélératrice de particules chargées autofocalisante, dans laquelle l'effet de défocalisation du faisceau est évité par l'annulation de l'une de ses causes, contrairement aux structures selon l'art antérieur où cet effet est seulement compensé.The present invention relates to an accelerating structure of self-focusing charged particles, in which the defocusing effect of the beam is avoided by the cancellation of one of its causes, unlike structures according to the prior art where this effect is only compensated.

Dans la structure accélératrice selon l'invention, ceci est obtenu grâce à un agencement simple et peu coûteux de l'unique ou de la première cavité accélératrice de cette structure, et particulièrement applicable dans le cas où, dans cette cavité, le trou de sortie du faisceau a un diamètre inférieur à la longueur accélératrice précédemment mentionnée ; cet agencement est remarquable en ce qu'il permet, dans ce dernier cas, de tenir compte de ce que la composante radiale du champ électrique dans la cavité accélératrice constitue une des causes principales de la divergence de particules chargées périphériques du faisceau, et que cette composante radiale est localisée à proximité des faces d'entrée et de sortie de la cavité et a des effets contraires à l'entrée et à la sortie de cette cavité.In the accelerating structure according to the invention, this is obtained thanks to a simple and inexpensive arrangement of the single or the first accelerating cavity of this structure, and particularly strictly applicable in the case where, in this cavity, the beam exit hole has a diameter less than the previously mentioned accelerating length; this arrangement is remarkable in that it makes it possible, in the latter case, to take account of the fact that the radial component of the electric field in the accelerating cavity constitutes one of the main causes of the divergence of peripheral charged particles of the beam, and that this radial component is located near the entry and exit faces of the cavity and has effects contrary to the entry and exit of this cavity.

Selon l'invention, une structure accélératrice linéaire autofocalisante de particules chargées, comportant une première cavité accélératrice d'une succession de cavités accélératrices, permettant d'accélérer un faisceau de particules chargées sous l'effet d'une onde électromagnétique de fréquence F donnée injectée dans ladite structure, ladite première cavité ayant un axe confondu avec un axe longitudinal de ladite structure et l'axe dudit faisceau, et comportant une face d'entrée et une face de sortie munies respectivement d'un trou d'entrée et d'un trou de sortie dudit faisceau, est caractérisée en ce que la distance entre les faces d'entrée et de sortie de ladite première cavité est formée par une longueur accélératrice, plus une longueur supplémentaire destinée à retarder l'instant d'arrivée des particules à la face de sortie.According to the invention, a self-focusing linear accelerating structure of charged particles, comprising a first accelerating cavity of a succession of accelerating cavities, making it possible to accelerate a beam of charged particles under the effect of an electromagnetic wave of given frequency F injected in said structure, said first cavity having an axis coincident with a longitudinal axis of said structure and the axis of said beam, and comprising an inlet face and an outlet face provided respectively with an inlet hole and a exit hole of said beam, is characterized in that the distance between the entry and exit faces of said first cavity is formed by an accelerating length, plus an additional length intended to delay the instant of arrival of the particles at the exit face.

Nous entendons par longueur accélératrice, une longueur sur laquelle les électrons sont accélérés ainsi qu'il a été expliqué ci- dessus, cette longueur accélératrice étant définie par la relation qui suit :

Figure imgb0003
où : , n -n = 3à4.By accelerator length, we mean a length over which the electrons are accelerated as explained above, this accelerator length being defined by the following relationship:
Figure imgb0003
 where: n = -n 3A4.

Du fait de la longueur supplémentaire entre la face d'entrée et la face de sortie de cette première cavité de la structure accélératrice selon l'invention, les particules ne sont pas soumises à l'action défocalisante de la composante radiale localisée près de la face de sortie, cette composante radiale étant soit en cours de disparition, soit même devenue focalisante ; le seul inconvénient mineur consiste en une légère décélération de ces particules, avant qu'elles n'aient franchi le trou de sortie.Due to the additional length between the entry face and the exit face of this first cavity of the accelerating structure according to the invention, the particles are not subjected to the defocusing action of the radial component located near the face output, this radial component being either in the process of disappearing, has even become focusing; the only minor drawback is a slight deceleration of these particles, before they have passed the exit hole.

L'invention sera mieux comprise à la lumière de la description qui va suivre d'un mode de réalisation d'une structure accélératrice selon son principe, faite en référence aux dessins annexés dans lesquels :

  • - la figure 1 est une vue schématique partielle en coupe de la structure accélératrice selon l'invention ;
  • - la figure 2 illustre l'onde électromagnétique injectée dans cette structure ;
  • - la figure 3 illustre la trajectoire d'un électron accéléré.
The invention will be better understood in the light of the following description of an embodiment of an accelerating structure according to its principle, made with reference to the appended drawings in which:
  • - Figure 1 is a partial schematic sectional view of the accelerator structure according to the invention;
  • - Figure 2 illustrates the electromagnetic wave injected into this structure;
  • - Figure 3 illustrates the trajectory of an accelerated electron.

La figure 1 montre partiellement une structure accélératrice linéaire 1 conforme à l'invention, comportant une première cavité accélératrice CA suivie de n cavités accélératrices C1, ..., Cn, n étant dans l'exemple décrit égal à 2. On n'a pas fait figurer d'éventuelles cellules dites de couplage, lesquelles constituent des éléments classiques disposés entre les cavités C1, ..., C d'une manière connue.FIG. 1 partially shows a linear accelerating structure 1 in accordance with the invention, comprising a first accelerating cavity CA followed by n accelerating cavities C 1 , ..., C n , n being in the example described equal to 2. We n 'did not include any so-called coupling cells, which constitute conventional elements arranged between the cavities C 1 , ..., C in a known manner.

La structure 1 comporte un axe longitudinal Z, confondu avec l'axe de la première cavité CA, et qui constitue également l'axe d'un faisceau de particules (non représenté) se propageant dans le sens de la flèche 2 ; ce faisceau de particules est accéléré grâce à l'énergie d'une onde électromagnétique (non représentée sur la figure 1) injectée de manière classique dans la structure 1 par un trou de couplage 4.The structure 1 has a longitudinal axis Z, coincident with the axis of the first cavity CA, and which also constitutes the axis of a particle beam (not shown) propagating in the direction of the arrow 2; this particle beam is accelerated by the energy of an electromagnetic wave (not shown in FIG. 1) conventionally injected into the structure 1 by a coupling hole 4.

La première cavité CA, de forme cylindrique, comporte une face d'entrée 3 et une face de sortie 5 normales à l'axe du faisceau Z, et écartées l'une de l'autre d'une distance D ; la face d'entrée 3 est munie d'un trou d'entrée 7, la face de sortie 5 est munie d'un trou de sortie 8, ces deux trous étant centrés sur l'axe Z du faisceau. Le faisceau de particules, provenant par exemple, d'une manière connue, d'un canon à électrons suivi d'un élément de glissement (non représentés), pénètre dans la première cavité accélératrice CA par le trou d'entrée 7, et ressort de cette cavité CA par le trou de sortie 8, se propageant dans la structure 1 dans le sens montré par la flèche 2.The first cavity CA, of cylindrical shape, has an inlet face 3 and an outlet face 5 normal to the axis of the beam Z, and spaced from one another by a distance D; the inlet face 3 is provided with an inlet hole 7, the outlet face 5 is provided with an outlet hole 8, these two holes being centered on the axis Z of the beam. The particle beam, coming for example, in a known manner, from an electron gun followed by a sliding element (not shown), enters the first accelerating cavity CA by the inlet hole 7, and emerges from this cavity CA through the outlet hole 8, propagating in the structure 1 in the direction shown by the arrow 2.

Compte tenu de la vitesse des particules, elles sont accélérées sur un trajet tel que par exemple la longueur accélératrice L1 qui, dans l'invention correspond à une fraction de la distance D entre la face d'entrée 3 et la face sortie 5 de la première cavité CA ; dans

Figure imgb0004
l'exemple non limitatif décrit, la longueur accélératrice L1 correspond à une longueur sensiblement égale à la relation où : n = 3 à 4, λ o est la longueur d'onde de l'onde électromagnétique, et où/3 correspond à la vitesse relative des électrons. Cette vitesse relative des électrons est calculée en prenant la moyenne entre la vitesse d'entrée dans la première cavité CA, et la vitesse maximum atteinte dans cette cavité à la sortie de la longueur accélératrice L1. Il est à remarquer que certains électrons sont décélérés au tout début de leur trajectoire, ce dont on ne tient pas compte dans l'approximation de la longueur accélératrice L1.Given the speed of the particles, they are accelerated on a path such as for example the accelerating length L 1 which, in the invention corresponds to a fraction of the distance D between the entry face 3 and the exit face 5 of the first cavity CA; in
Figure imgb0004
 the nonlimiting example described, the accelerating length L 1 corresponds to a length substantially equal to the relationship where: n = 3 to 4, λ o is the wavelength of the electromagnetic wave, and where / 3 corresponds to the relative speed of electrons. This relative speed of the electrons is calculated by taking the average between the speed of entry into the first cavity CA, and the maximum speed reached in this cavity at the exit of the accelerating length L 1 . It should be noted that certain electrons are decelerated at the very beginning of their trajectory, which is not taken into account in the approximation of the accelerating length L 1 .

L'onde électromagnétique injectée dans la structure 1 détermine un champ électrique ayant une composante longitudinale Ez et des composantes radiales Erl, Er2, et la distribution et l'intensité de ces composantes radiales est influencée par la dimension des trous d'entrée et de sortie 7,8. Aussi, dans l'exemple non limitatif de la description où les rayons r de ces trous sont égaux, on obtient une localisation des composantes radiales Erl, Er2, le rayon r des trous 7,8 étant suffisamment faible par rapport à la longueur accélératrice L1 pour que le rapport soit

Figure imgb0005
inférieur à 1. De ce fait :

  • - une première composante radiale Er1 est localisée à proximité de la face d'entrée 3 et a une action globalement convergente. Pour certains électrons, elle peut se décomposer en une action divergente suivie d'une action convergente ;
  • - une seconde composante radiale Er2 est localisée à proximité de la face de sortie 5, et a une action divergente sur les électrons.
The electromagnetic wave injected into the structure 1 determines an electric field having a longitudinal component E z and radial components Er l , Er 2 , and the distribution and intensity of these radial components is influenced by the size of the entry holes and output 7.8. Also, in the nonlimiting example of the description where the radii r of these holes are equal, a location of the radial components Er l , Er 2 is obtained, the radius r of the holes 7.8 being sufficiently small compared to the length accelerator L 1 so that the ratio is
Figure imgb0005
 less than 1. Therefore:
  • - A first radial component Er 1 is located near the inlet face 3 and has a generally convergent action. For some electrons, it can decompose into a divergent action followed by a convergent action;
  • - A second radial component Er 2 is located near the outlet face 5, and has a diverging action on the electrons.

Ainsi, en supposant que la distance D entre la face d'entrée 3 et la face de sortie 5 soit uniquement formée par la longueur accélératrice LI, des particules périphériques (non représentées) ayant franchi cette distance D et parvenant à proximité du trou de sortie 8 et de la face de sortie 5, subiraient l'influence défocalisante de la composante radiale Er2 du champ.Thus, assuming that the distance D between the entry face 3 and the exit face 5 is only formed by the length accelerator L I , peripheral particles (not shown) having crossed this distance D and arriving near the exit hole 8 and the exit face 5, would undergo the defocusing influence of the radial component Er 2 of the field.

Au contraire, dans la structure 1 selon l'invention, ces mêmes particules chargées ayant franchi la première longueur accélératrice L1, ne subissent pas l'influence de cette composante radiale Er2 divergente, dont elles sont encore séparées par une longueur supplémentaire L2 ; la distance D entre les faces d'entrée et de sortie étant formées par J'addition de ces deux longueurs L 1 + L2, et la longueur supplémentaire L2 étant égale ou supérieure à deux fois le rayon r du trou de sortie 8 (L2 ≥ 2 r). Il est à noter que les trous d'entrée et de sortie 7,8 comportent en général des becs, non représentés sur la figure 1 qui est schématique, et le rayon r représente un rayon approximatif moyen du trou de sortie 8.On the contrary, in the structure 1 according to the invention, these same charged particles having crossed the first accelerating length L 1 , do not undergo the influence of this diverging radial component Er 2 , from which they are still separated by an additional length L 2 ; the distance D between the inlet and outlet faces being formed by the addition of these two lengths L 1 + L 2 , and the additional length L 2 being equal to or greater than twice the radius r of the outlet hole 8 ( L 2 ≥ 2 r). It should be noted that the inlet and outlet holes 7,8 generally have spouts, not shown in FIG. 1 which is schematic, and the radius r represents an approximate mean radius of the outlet hole 8.

La longueur supplémentaire L2 est telle que l'onde électromagnétique est annulée, voire même inversée quand ces particules ont franchi la distance D, elles sortent de la première cavité CA par le trou de sortie 8 sans diverger ; elles peuvent même, si la phase de l'onde électromagnétique est inversée, subir une action convergente et une faible décélération, la composante radiale étant alors inversée également. On note que cette longueur supplémentaire L2, de la première cavité CA, favorise aussi l'action convergente à l'entrée de la cavité accélératrice suivante CI qui constitue la seconde cavité. Dans l'exemple non limitatif décrit, la distance D1 entre la face de sortie 5 de la première cavité CA et le plan d'entrée 15 de la seconde cavité C1 est inférieure à la longueur accélératrice L1, et assure ainsi une convergence sensible à l'entrée de cette seconde cavité C1, compte tenu du déphasage de l'onde électromagnétique entre cavités CA, C1, C2. Ainsi l'effet combiné de l'entrée de la première cavité CA, de la sortie de cette première cavité et de l'entrée de la seconde cavité C1 est optimisé ; ensuite le gain en énergie est tel que l'effet de la sortie de la seconde cavité C1 est (presque) négligeable. Par souci de simplicité on ne parle pas de cet effet de convergence à l'entrée de la seconde cavité C1 dans ce qui suit.The additional length L 2 is such that the electromagnetic wave is canceled, or even reversed when these particles have crossed the distance D, they leave the first cavity CA through the outlet hole 8 without diverging; they can even, if the phase of the electromagnetic wave is reversed, undergo a convergent action and a weak deceleration, the radial component then being also reversed. It is noted that this additional length L 2 , of the first cavity CA, also promotes the converging action at the entry of the following accelerating cavity CI which constitutes the second cavity. In the nonlimiting example described, the distance D 1 between the exit face 5 of the first cavity CA and the entry plane 15 of the second cavity C 1 is less than the accelerating length L 1 , and thus ensures convergence sensitive to the input of this second cavity C 1 , taking into account the phase shift of the electromagnetic wave between cavities CA, C 1 , C 2 . Thus the combined effect of the entry of the first cavity CA, the exit of this first cavity and the entry of the second cavity C 1 is optimized; then the energy gain is such that the effect of the output from the second cavity C 1 is (almost) negligible. For the sake of simplicity we do not speak of this convergence effect at the entry of the second cavity C 1 in what follows.

La longueur supplémentaire L2 est définie par la relation suivante : L2 = L1.K, où K est un coefficient compris entre 0,5 et 1.The additional length L 2 is defined by the following relation: L 2 = L 1 .K, where K is a coefficient between 0.5 and 1.

Dans une réalisation de la structure accélératrice 1 conforme à l'invention, indiquée à titre d'exemple non limitatif, la première cavité accélératrice CA comporte des dimensions suivantes :

  • - un rayon R de la cavité CA est de 40 mm ;
  • - la distance D entre la face d'entrée 3 et la face sortie 5 est de 25 mm ; cette distance D étant constituée d'une longueur accélératrice L1 de 15 mm, à laquelle s'ajoute la longueur supplémentaire LZ de 10 mm ;
  • - le rayon r du trou de sortie 8 est de 3 mm ;
  • - la différence de potentiel entre la face d'entrée 3 et la face de sortie 5 est dQ l'ordre de 500 KV, et la fréquence de l'onde électromagnétique est de 3000 MHZ.
In an embodiment of the accelerator structure 1 according to the invention, indicated by way of nonlimiting example, the first accelerator cavity CA has the following dimensions:
  • - a radius R of the cavity CA is 40 mm;
  • - the distance D between the inlet face 3 and the outlet face 5 is 25 mm; this distance D being made up of an accelerating length L 1 of 15 mm, to which is added the additional length L Z of 10 mm;
  • - the radius r of the outlet hole 8 is 3 mm;
  • - The potential difference between the input face 3 and the output face 5 is d Q of the order of 500 KV, and the frequency of the electromagnetic wave is 3000 MHZ.

La distribution du champ électrique étant symétrique par rapport à l'axe Z du faisceau, elle n'est pas représentée dans la partie inférieure de la première cavité CA.The distribution of the electric field being symmetrical with respect to the axis Z of the beam, it is not represented in the lower part of the first cavity CA.

Cette distribution du champ électrique dans la première cavité accélératrice CA, correspond à l'existence dans cette dernière d'un champ accélérateur.This distribution of the electric field in the first accelerating cavity CA, corresponds to the existence in the latter of an accelerating field.

La figure 2 montre l'onde électromagnétique OE dont une demie période

Figure imgb0006
détermine ce champ accélérateur et dont la partie de l'onde OE comprise d'une part entre un instant to et l'instant tl, et d'autre part entre un instant t3 et un instant t4 détermine un champ décélérateur ; l'instant t2 correspondant à la valeur crête de la demie période x où le champ accélérateur Zo est maximum.Figure 2 shows the electromagnetic wave OE of which half a period
Figure imgb0006
 determines this accelerating field and of which the part of the OE wave comprised on the one hand between an instant to and the instant tl, and on the other hand between an instant t3 and an instant t4 determines a decelerating field; the instant t2 corresponding to the peak value of the half period x where the accelerator field Zo is maximum.

En prenant comme référence l'instant t2 où le champ accélérateur est maximum (Zo), des électrons peuvent arriver dans la première cavité accélératrice CA avec des phases d'arrivées (Ø o de valeurs quelconques. Mais pour éviter l'effet de défocalisation dû à la composante radiale Er2 localisée près de la face de sortie 5, ces électrons devront franchir la distance D et parvenir à proximité de cette face de sortie, sensiblement à l'instant t3 où le champ accélérateur s'annule, grâce à la longueur supplémentaire L2.By taking as reference the instant t2 when the accelerating field is maximum (Zo), electrons can arrive in the first accelerating cavity CA with phases of arrivals (Ø o of any values. But to avoid the effect of defocusing due at the radial component Er 2 located near the exit face 5, these electrons will have to cross the distance D and reach near this outlet face, substantially at time t3 when the accelerator field is canceled out, thanks to the additional length L 2 .

En prenant pour exemple un électron (non représenté) dont la phase d'arrivée Øo dans la première cavité CA est en avance de 170° par rapport à Zo ou instant t2 : cet électron subit un champ décélérateur à proximité de la face d'entrée 3 jusqu'à l'instant tl où l'onde OE s'inverse et où le champ devient accélérateur ; l'action de la composante radiale Er1, localisée près de la face d'entrée 3, est de ce fait d'abord divergente puis convergente quand le champ devient accélérateur, et son action est globalement convergente. Cet électron ralenti est rejoint par des électrons entrés dans la cavité CA après lui. Aussi l'agencement de la première cavité CA de la structure 1 selon l'invention permet d'éviter l'effet de défoca-Jisation en sortie pour une large gamme de valeurs de phase d'arrivée Øo, par exemple comprises entre - 45° et - 190° par rapport à Zo ou l'instant tl.Taking for example an electron (not shown) whose arrival phase Øo in the first cavity CA is 170 ° ahead of Zo or instant t2: this electron undergoes a decelerating field near the input face 3 until time tl when the OE wave reverses and the field becomes accelerator; the action of the radial component Er 1 , located near the entry face 3, is therefore first divergent then convergent when the field becomes accelerator, and its action is globally convergent. This slowed down electron is joined by electrons that entered the CA cavity after it. Also the arrangement of the first cavity CA of the structure 1 according to the invention makes it possible to avoid the defoca-jisation effect at the output for a wide range of values of arrival phase Øo, for example between - 45 ° and - 190 ° relative to Zo or the instant tl.

La figure 3 illustre la trajectoire d'un électron périphérique du faisceau, et montre les composantes de champ Er, Ez vues à des instants différents, compte tenu de la vitesse finie de l'électron.FIG. 3 illustrates the trajectory of a peripheral electron of the beam, and shows the field components Er, Ez seen at different times, taking into account the finite speed of the electron.

La cavité accélératrice est symbolisée par ses parois d'entrée et de sortie 3, 5. La courbe 10 montre la trajectoire d'un électron pénêtrant dans la première cavité CA avec une phase d'arrivée Øo égale à - 170°, et à une distance d de l'axe Z du faisceau :

  • - à l'instant Øo le champ est décélérateur comme montré par la composante longitudinale Ez' , et la composante radiale Er1 est défocalisante ;
  • - à l'instant Ø 1 le champ est accélérateur (composante longitudinale Ez) et la composante radiale Er1 est focalisante ; il est à remarquer qu'à cet instant la trajectoire 10 est très proche de la face d'entrée 3, l'électron ayant subi préalablement une décélération, et s'est davantage écarté de l'axe Z du faisceau ;
  • - a l'instant Ø3 le champ est nul, l'électron sort de la première cavité CA et tend à converger vers l'axe Z du faisceau.
The accelerating cavity is symbolized by its inlet and outlet walls 3, 5. The curve 10 shows the trajectory of an electron penetrating into the first cavity CA with an arrival phase Øo equal to - 170 °, and to a distance d from the Z axis of the beam:
  • - at time Øo the field is decelerating as shown by the longitudinal component E z ' , and the radial component Er 1 is defocusing;
  • - at time Ø 1 the field is accelerating (longitudinal component E z ) and the radial component Er 1 is focusing; it should be noted that at this instant the trajectory 10 is very close to the input face 3, the electron having previously undergone deceleration, and has moved further away from the axis Z of the beam;
  • - at the instant Ø3 the field is zero, the electron leaves the first cavity CA and tends to converge towards the axis Z of the beam.

En supposant que la distance D entre la face d'entrée 3 et la face de sortie 5 ait été constituée uniquement par la longueur accélératrice LI, la face de sortie 5 aurait occupée la position de la ligne 11 en traits pointillés et, le champ auquel aurait alors été soumis l'électron à sa sortie de la première cavité CA est représenté en traits pointillés par les composantes Er 2 et Ez ; la trajectoire de l'électron aurait été modifiée selon la flèche 12 représentée en traits pointillés, laquelle tend à diverger de l'axe Z du faisceau.Assuming that the distance D between the entry face 3 and the exit face 5 was constituted solely by the accelerating length L I , the exit face 5 would have occupied the position of the line 11 in dotted lines and, the field to which the electron would then have been subjected at its exit from the first cavity CA is represented in dotted lines by the components Er 2 and Ez; the trajectory of the electron would have been modified according to arrow 12 represented in dotted lines, which tends to diverge from the axis Z of the beam.

Cette description montre que la structure accélératrice 1 conforme à l'invention, élimine l'effet de défocalisation des particules chargées périphériques du faisceau, à la sortie d'une cavité accélératrice. Cette élimination de l'effet de divergence est obtenue par un agencement simple, économique, qui permet d'augmenter le rendement d'un accélérateur linéaire de particules chargées.This description shows that the accelerating structure 1 according to the invention eliminates the defocusing effect of the charged peripheral particles of the beam, at the exit of an accelerating cavity. This elimination of the divergence effect is obtained by a simple, economical arrangement, which makes it possible to increase the efficiency of a linear accelerator of charged particles.

Claims (4)

1. Structure accélératrice linéaire autofocalisante de particules chargées, comportant une première cavité accélératrice (CA) d'une succession de cavités accélératrices (CA, C1, C2), permettant d'accélérer un faisceau de particules chargées sous l'effet d'une onde électromagnérique (O.E) de fréquence F donnée injectée dans ladite structure (1), ladite première cavité (CA) ayant un axe confondu avec un axe longitudinal (Z) de ladite structure (1) et l'axe dudit faisceau, et comportant une face d'entrée (3) et une face de sortie (5) munies respectivement pour le passage dudit faisceau d'un trou d'entrée (7) et d'un trou de sortie (8) ayant un rayon (r) donné, caractérisée en ce que la distance (D) entre les faces d'entrée et de sortie (3, 5) de ladite première cavité (CA) est formée par une longueur accélératrice (L1), plus une longueur supplémentaire (L2) destinée à retarder l'instant (0 3) d'arrivée des particules à la face de sortie (5).1. Self-focusing linear accelerating structure of charged particles, comprising a first accelerating cavity (CA) of a succession of accelerating cavities (CA, C 1 , C 2 ), making it possible to accelerate a beam of charged particles under the effect of an electromagnetic wave (EO) of given frequency F injected into said structure (1), said first cavity (CA) having an axis coincident with a longitudinal axis (Z) of said structure (1) and the axis of said beam, and comprising an inlet face (3) and an outlet face (5) provided respectively for the passage of said beam with an inlet hole (7) and an outlet hole (8) having a given radius (r) , characterized in that the distance (D) between the inlet and outlet faces (3, 5) of said first cavity (CA) is formed by an accelerating length (L 1 ), plus an additional length (L 2 ) intended to delay the instant (0 3) of arrival of the particles at the exit face (5). 2. Structure accélératrice selon la revendication 1, caractérisée en ce que la longueur supplémentaire (L2) est liée à la longueur accélératrice (L1) par la relation : L2 = L1 x K, K étant un coefficient compris entre 0,5 et 1.2. accelerator structure according to claim 1, characterized in that the additional length (L 2 ) is linked to the accelerator length (L 1 ) by the relation: L 2 = L 1 x K, K being a coefficient between 0, 5 and 1. 3. Structure accélératrice selon la revendication 1, caractérisée en ce que la longueur supplémentaire (L2) est égale ou supérieure à deux rayons (r) du trou de sortie (8) : L2 2 r.3. accelerator structure according to claim 1, characterized in that the additional length (L 2 ) is equal to or greater than two radii (r) of the outlet hole (8): L 2 2 r. 4. Structure accélératrice selon la revendication 1, caractérisée en ce que la première cavité accélératrice (CA) est suivie d'une seconde cavité accélératrice (C1) comportant un plan d'entrée (15) dont la distance (D1) à la face de sortie (5) de la première cavité (CA) est inférieure à la longueur accélératrice (L1).4. accelerator structure according to claim 1, characterized in that the first accelerator cavity (CA) is followed by a second accelerator cavity (C 1 ) comprising an entry plane (15) whose distance (D 1 ) to the exit face (5) of the first cavity (CA) is less than the accelerating length (L 1 ).
EP84401699A 1983-09-02 1984-08-21 Charged particles self-focusing linear accelerating structure Expired EP0136216B1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2587164A1 (en) * 1985-09-10 1987-03-13 Cgr Mev Device for pregrouping and accelerating electrons
EP0336850A1 (en) * 1988-04-08 1989-10-11 Cgr Mev Linear accelerator with self-focalising cavities, with high electron capture rate at low injection voltages

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4782303A (en) * 1987-04-06 1988-11-01 Linlor William I Current guiding system
US4906896A (en) * 1988-10-03 1990-03-06 Science Applications International Corporation Disk and washer linac and method of manufacture
US5014014A (en) * 1989-06-06 1991-05-07 Science Applications International Corporation Plane wave transformer linac structure
FR2679727B1 (en) * 1991-07-23 1997-01-03 Cgr Mev PROTON ACCELERATOR USING MAGNETICALLY COUPLED PROGRESSIVE WAVE.
US6777893B1 (en) 2002-05-02 2004-08-17 Linac Systems, Llc Radio frequency focused interdigital linear accelerator
US7098615B2 (en) * 2002-05-02 2006-08-29 Linac Systems, Llc Radio frequency focused interdigital linear accelerator
US6864633B2 (en) * 2003-04-03 2005-03-08 Varian Medical Systems, Inc. X-ray source employing a compact electron beam accelerator
US10398018B2 (en) * 2017-08-30 2019-08-27 Far-Tech, Inc. Coupling cancellation in electron acceleration systems
DE102020119875B4 (en) * 2020-07-28 2024-06-27 Technische Universität Darmstadt, Körperschaft des öffentlichen Rechts Device and method for guiding charged particles

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2770775A (en) * 1951-12-21 1956-11-13 Westinghouse Air Brake Co Wayside vehicle speed determining means
US4211954A (en) * 1978-06-05 1980-07-08 The United States Of America As Represented By The Department Of Energy Alternating phase focused linacs

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2770755A (en) * 1954-02-05 1956-11-13 Myron L Good Linear accelerator
US2925522A (en) * 1955-09-30 1960-02-16 High Voltage Engineering Corp Microwave linear accelerator circuit
FR2110799A5 (en) * 1970-10-30 1972-06-02 Thomson Csf
FR2374815A1 (en) * 1976-12-14 1978-07-13 Cgr Mev DEVELOPMENT OF LINEAR CHARGED PARTICLE ACCELERATORS
FR2386232A1 (en) * 1977-03-31 1978-10-27 Cgr Mev ACCELERATOR STRUCTURE FOR LINEAR CHARGED PARTICLE ACCELERATOR OPERATING IN STANDING WAVE REGIME
FR2386231A1 (en) * 1977-03-31 1978-10-27 Cgr Mev ACCELERATOR STRUCTURE FOR LINEAR ACCELERATOR OF CHARGED PARTICLES

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2770775A (en) * 1951-12-21 1956-11-13 Westinghouse Air Brake Co Wayside vehicle speed determining means
US4211954A (en) * 1978-06-05 1980-07-08 The United States Of America As Represented By The Department Of Energy Alternating phase focused linacs

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2587164A1 (en) * 1985-09-10 1987-03-13 Cgr Mev Device for pregrouping and accelerating electrons
EP0336850A1 (en) * 1988-04-08 1989-10-11 Cgr Mev Linear accelerator with self-focalising cavities, with high electron capture rate at low injection voltages
FR2629976A1 (en) * 1988-04-08 1989-10-13 Cgr Mev LINEAR ACCELERATOR WITH SELF-COATING CAVITIES WITH HIGH ELECTRONIC CAPTURE RATES FOR MODERN INJECTION VOLTAGES
US4975652A (en) * 1988-04-08 1990-12-04 Cgr Mev Linear accelerator provided with self-focusing cavities having high electron capture efficiency in respect of moderate injection voltages

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