US3332024A - Heavy particle linear accelerator with continuous variation of output energy - Google Patents

Heavy particle linear accelerator with continuous variation of output energy Download PDF

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US3332024A
US3332024A US294687A US29468763A US3332024A US 3332024 A US3332024 A US 3332024A US 294687 A US294687 A US 294687A US 29468763 A US29468763 A US 29468763A US 3332024 A US3332024 A US 3332024A
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circuit
velocity
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cell
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Leboutet Hubert
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Thales SA
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CSF Compagnie Generale de Telegraphie sans Fil 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
    • H05H9/00—Linear accelerators
    • H05H9/02—Travelling-wave linear accelerators

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  • the present invention relates to linear ion accelerators, and more particularly to the linear ion accelerators of the type with travelling waves in which the particles to be accelerated move parallelly to a delay line and in synchronism with the phase velocity of the wave which propagates within this line, which line has a variable pitch to the extent the velocity of the particles has not attained the relativistic domain.
  • the aim of the present invention is an accelerator of this type which permits a continuous variation, within important limits, of the output energy of the accelerated rons.
  • the accelerated particles are ions, that is, particles having a mass which is several thousand or several tens of thousands times greater than that of the electrons.
  • the velocity of the particles at the output never attains the relativistic do main, and the interaction with the high frequency wave takes place along a circuit whose pitch is variable over the entire length of the accelerator. If in that case one arbitrarily assumes any law of variation of this pitch, and if one attempts to vary the output energy by acting either on the power or on the frequency of the injected wave, one only obtains variations of energy within extremely narrow limits.
  • an accelerator having a variable pitch circuit following an arbitrary law operates only for a predetermined value of power and injected frequency, or within the immediate neighborhoods of this value.
  • Each important deviation from this value has the result that the energy variation of the particles along the circuit ceases to follow continuously the variations of phase velocity of the wave, or that the particles are not, from the beginning, in synchronism with the wave.
  • the accelerator then no longer operates or functions properly outside of the aforementioned narrow band.
  • P z in which 2 is the running coordinate, along the line, between a predetermined homologous point of each cell and a common predetermined point situated in front of the line;
  • A is a coefiicient dependent on the mass of accelerated ions, of the injected high frequency power, and of the frequently utilized.
  • the initial velocity of the particles will be such that the line operates on a predetermined d-ispersive space harmonic.
  • Still another object of the present invention resides in the provision of linear accelerators of the type mentioned hereinabove and operable to accelerate particles of such mass that the particles never attain the relativistic domain, which accelerator permits a continuous control with simple means to change the output energy of the accelerated particles by varying the power of the injected wave and/or the frequency thereof.
  • a further object of the present invention resides in the provision of a delay line for use in linear particle accelerators which is so constructed and arranged that the high frequency field effectively traverses within each cell of the line a constant distance, thereby permitting a continuous variation of the energy output of the accelerated particles.
  • FIGURE 1 is a schematic diagram explanatory of the involved principles of dimension of the delay lines according to the present invention
  • FIGURE 2 is a diagram of distribution of velocity of energy variation along the line in accordance with the present invention.
  • FIGURE 3 is a partial elevational view of a delay line constructed in accordance with the present invention.
  • FIGURE 4 is a modified embodiment of a delay line constructed and dimensioned in accordance with the present invention and incorporated into an ion accelerator.
  • this figure illustrates a chain of cells with variable pitch p, taking in the successive cells the values p p p and it being assumed that the variable pitch is such that it is possible to define within each cell the paths effectively traversed by the high frequency field, this path A, B, C, D, being of meander shape and its length per cell being I. Numerous lines such as meander shaped, interdigital, bent coaxial lines and others are representative examples of such a chain of cells.
  • phase shift per cell may be expressed as follows:
  • k an entire number that may be positive, negative or zero.
  • the first characteristic of the lines utilizable according to the present invention is, therefore, that one dimensions the lines in such a manner that the high frequency field travels effectively within each cell a constant distance.
  • the second characteristic of the lines utilizable according to the present invention is, therefore, that they be utilized on a dispersive harmonic.
  • Equation3 In the first place, according to Equation3 one has:
  • Equation 4 the initial velocity of the particle is as follows:
  • the values ofthe pitches p being small in relation to z;, it is not necessary to take as homologous point of each cell the beginning thereof as has been made in the embodiment of FIGURE 1, but one could also define the coordinates Z Z z asgoing from the point 0 to any homologous point of each cell, for example, to its center point or terminal point.
  • the discontinuous law defined by Equation 7 by the law of variation of the pitch along the running coordinate 2 as follows:
  • Equation 9 provides the law of variation of the phase velocity along the circuit as follows:
  • the equation 15 must be interpreted by taking duly into consideration the approximation admitted hereinabove, for, as shows FIGURE 2 of the drawing, in which has been represented graphically the two terms of this equation, the function eV /p is a discontinuous curve in steps whereas the function aW/az is a continuous curve.
  • the exact interpretation of this equation is therefore that within the lines dimensioned and utilized according to the given indications, the velocity of variation of the energy along the circuit coincides with the continuous curve average of the discontinuous curve representing eV /p.
  • the energy therefore increases by a constant quantity eV in each cell, independently of the frequency or the mass of the quantity.
  • Equation 12 the line constructed according to the principles indicated hereinabove remains utilizable as long as the coefiicient A remains constant.
  • the same line is utilizable for the ions of different chemical elements, whereby the variation of the mass m may then be compensated by the variation of one of the parameters V or f or of the two together in such a manner as to maintain the quantity (16) at the same value as with the ions taken as starting point.
  • Equation 14 the energy of the ions, with A constant, varies with V such that the action on V produces the desired energy variation within the limits which are determined only by the band-pass beyond which the frequency j that one causes to vary simultaneously with V must not pass that is, within relatively wide limits.
  • FIGURE 3 shows one embodiment of a delay line according to the present invention, in the form of a coaxial line folded or bent in meander shape, comprising an internal conductor 1 and an external conductor 2. According to the given indications, the folding is made in such a manner that the length of the arcs l remains constant whereas the pitch p 11 p etc. are dimensioned according to the Equations 4 and 7.
  • FIGURE 4 illustrates another embodiment of a line, incorporated into an ion accelerator of which the essential elements are only illustrated schematically since they may be of any conventional construction.
  • This line comprises, within the axis of a parallelepipedic'cavity 3, a series of drift tubes 4, supported by rods 5 secured alternately to the opposite walls of the cavity 3, in the manner of an interdigital line.
  • a conductor 6 bent in meander shape and having its extremities fixed to the end walls of the cavity 3.
  • the dimensions of the arcs l and of the pitches p p p is the same as in FIGURE 3 and conforms to the given indications pointed out hereinabove.
  • the conductor 6, at the places of intersection with the axis of the drift tubes 4, is pierced by orifices 7 for the passage of the beam 11, which enters and leaves the cavity by orifices 8 and 9, provided within the end walls thereof.
  • Such a delay circuit, utilizing drift tubes 4 and a meander-shaped conductor 6, forms part of the copend-ing application Ser. No. 291,337, filed on June 28, 1963, and entitled, Delay Circuit Structure, filed in the name of Hubert Leboutet and Germaine Vincent, assigned to the assignee of the present application, however the particular dimensioning of such delay line in accordance with the present invention is novel to the invention herein.
  • This delay line forms part of the ion accelerator, the ions being supplied by a source 10 of which the ions are concentrated into a beam 11 which is focused by the windings 12.
  • the accelerated beam After having traversed the cavity 3 through the orifices 8 and 9, the accelerated beam enters into the utilization chamber 13 containing, for example, a target 14.
  • the vacuum is maintained within the cavity 3 by a pump 15.
  • the high frequency power is injected into the delay line by means of a generator 16 coupled to the cavity 3 by a loop 17.
  • the power and the frequency of this generator are adjustable by any conventional known means, not shown in detail herein, and indicated only schematically by the control buttons 18 and 19. These regulations and adjustments are eifectuated according to the indications given hereinabove, as a function of the mass of the ions supplied by the source 10 and the desired energy on the target 14.
  • a control member 20 is provided in the source 10 to impart to the particles a velocity such that the interaction takes place with a desired dispersive harmonic mode of the high frequency wave propagating within the line.
  • a linear ion accelerator comprising a substantially linearly extending delay circuit, a source of ions provided with means for directing a beam of said ions along the linear extension of said delay circuit, means operable to excite in said circuit a travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction as said beam, and means for adjusting said beam velocity to be synchronous with the phase velocity of a predetermined dispersive space harmonic, said circuit being formed ofa chain of cascade coupled cells, said cells being dimensioned to ensure a substantially constant length of the efiective propagation path of said Wave in each cell, and the size of said cells along-said linear extension increasing substantially in proportion to the cube root of the distance of each 1 respective cell along said linear extension to a predetermined point ahead of said circuit.
  • a linear ion accelerator comprising a substantially linearly extending delay circuit, a source of ions provided with means for directing a beam of said ions along the linear extension of said delay circuit, means operable to excite in said circuita travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction as said beam, and means for adjusting said beam velocity to be synchronous with the phase velocity of a predetermined dispersive space harmonic, said circuit being formed of a chain of cascade coupled cells, said cells being dimensioned to ensure a substantially constant length of the effective propagation path of said wave in each cell, and the'size of said cells along said linear extension increasing substantially in proportion to the cube root of the distance of each respective cell along said linear extension of a predetermined point ahead of said circuit, the dispersive space harmonic being a harmonic of a rank other than the fundamental.
  • a linear ion accelerator comprising a substantially linearly extending delay circuit, a source of ions provided.
  • said circuit' being formed of a chain of cascade coupled cells, said cells being dimensioned to ensure a substantially constant length of the efiective propagation path of said Wave in each cell, and the size of said cells along said linear extension increasing substantially in proportion to cube root of the distance of each respective cell along said linear extension to a predetermined point ahead of said circuit, the said propagation path being arranged to oscillate about an axis which extends substantially in the sense of said linear extension to form arches along said path, the length of each arch of said path between two successive points of intersection thereof with said axis being substantially constant, and the amplitude of said oscillation decreasing successively for each of said arches in the direction of said beam.
  • a linear ion accelerator comprising a substantially linearly extending delay circuit, a source of ions provided wtih means for directing a beam of said ions along the linear extension of said delay circuit, means operable to excite in said circuit a travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction as said beam, and means for adjusting said beam velocity to be synchronous with the phase velocity of a predetermined dispersive space harmonic, said circuit being formed of a chain cascade coupled cells, said cells being dimensioned to ensure a substantially constant length of the effective propagation path of said wave in each cell, and the size of said cells along said linear extension increasing substantially in proportion to the cube root of the distance of each respective cell along said linear extension to a predetermined point ahead of said circuit, and the distance Z between the first of said cells andsaid predetermined point being given by the equation l '1 3 0 f1 A wherein m is the mass of ion, eV is the high frequency power of the exciting means, I is the
  • Z2, Z Z4, z z are the successive distances between each of the respective cells and said pre wherein z is the distance between a given cell and said predetermined point, and A is given by,
  • a linear ion accelerator comprising a substantially linearly extending delay circuit, a source of ions provided with means for directing a beam of said ionsalong the linear extension of said delay circuit, means operable to excite in said circuit a travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction as said'beam, and means for adjusting said beam velocity to be synchronous with the phase velocity of a predetermined, dispersive space harmonic, said circuit being formed of a chain of cascade coupled cells, said cells being dimensioned to ensure a substantially constant length of the effective propagation path of-said wave in each cell, and the size of said cells along said linear extension increasing substantially in pro portion to the cube root of the distance of each respective cell along said linear extension to a predetermined point ahead of said circuit, said delay circuit including a coaxial line undulatorily bent to oscillate about an axis extending substantially in the direction of said linear extension and thereby form arched portions, thelength of each of said arched portions between two successive points ofintersection with
  • a linear ion accelerator comprising a substantially linearily delay circuit, a source of ions provided with means for directing a beam of said ions along the linear extension of said delay circuit, means operable to excite in said circuit a travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction as said beam, and means for adjusting said beam velocity to be synchronous with the phase velocity of a predetermined dispersive space harmonic, said circuit being formed of a' chain of cascade coupled cells, said cells beingdimensionedto ensure a substantially are determined by the constant length of the effective propogation path of said wave in each cell, and the size of said cells along said linear extension increasing substantially in proportion to the cube root of the distance of each respective cell along said linear extension to a predetermined point ahead of said circuit, first adjusting means for adjusting the power of said exciting means and second adjusting means for adjusting the frequency of said traveling wave thereby adjusting over a relatively wide band the output of said ion beam.
  • a source of ions provided with means for directing a beam of said ions along said linearly extending portion of said delay circuit, means for exciting in said circuit a travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction as said beam, and means for adjusting the beam velocity to be synchronous with the phase velocity of a predetermined dispersive space harmonic,
  • the improvement essentially consisting of means in said line to enable adjustment of the energy output of the ion beam over a relatively wide band by selectively varying at least one of the two parameters consisting of the frequency of the travelling wave and the power input of said exciting means.
  • a linear ion accelerator comprising a substantially linearly extending delay circuit, a source of ions provided with means for directing a beam of said ions along the linear extension of said delay circuit, means operable to excite in said circuit a travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction as said beam, and means for adjusting said beam velocity to be synchronous with the phase velocity of a predetermined dispersive space harmonic, said circuit being formed of a chain of cascade coupled cells, said cells being dimensioned to ensure a substantially constant length of the efiective propagation path of said wave in each cell, and the size of said cells along said linear extension increasing substantially in proportion to the cube root of the distance of each respective cell along said linear extension to a predetermined point ahead of said circuit, the dispersive space harmonic being a harmonic of a rank other than the fundamental, first adjusting means for adjusting the power of said exciting means and second adjusting means for adjusting the frequency of said travelling wave thereby adjusting over a relatively wide band the output power of
  • a linear ion accelerator comprising a substantially linearly extending delay circuit portion, a source of ions provided with means for directing a beam of said ions along said delay circuit portion, means for exciting in said circuit portion a travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction a said beam, and means for adjusting said beam velocity to be synchronous with the phase velocity of a predetermined dispersive space harmonic, said circuit portion being formed of a chain of cascade coupled cells, said cells being dimensioned to ensure a substantially constant length of the effective propagation path of said wave in each cell, and the size of said cells along said circuit portion increasing substantially in proportion to the cube root of the distance of each respective cell along said circuit portion with respect to a predetermined point ahead of said circuit, said circuit portion including a cavity resonator bounded by an envelope having at least one axis of symmetry, a series of drift tubes located along said axis, each of said tubes being supported 'by a rod-shaped element, said rodshaped elements being situated in
  • a source of ions provided with means for directing a beam of said ions along said linearly extending portion of said delay circuit, means for exciting in said circuit a travelling wave having at least one space harmonic component propagating with a phase velocity in the same direction as said beam, and means for adjusting the beam velocity to be synchronous with the phase velocity of a predetermined dispersive space harmonic,
  • the improvement essentially consisting of means in said line to enable adjustment of the energy output of the ion beam over a relatively wide band by selectively varying at least one of the two parameters consisting of the frequency of the travelling wave and the power input of said exciting means including means providing a substantially constant length of the effective propagation path for the wave in each cell, and the dimension of said cells along said linearly extending portion increasing approximately in proportion to the cube root of the distance of each respective cell along said linearly extending portion to a predetermined point ahead of said circuit.
  • a delay circuit comprising: a cavity resonator bounded by an envelope having at least one axis of symmetry, a series of drift tubes located along said axis, each of said tubes being supported by a rod-shaped element, said rod-shaped elements being situated in a common plane passing through said axis and being alternately fixed to opposite points of said envelope thereby forming an interdigital structure in an axial plane of said envelope, and a conductor undultaing to and fro between said successive tubes in a plane passing through said axis and having its extremities fixed to said envelope, the length of each arch of said undulation between two successive points of intersection with said axis being substantially constant, the amplitude of said undulation decreasing and the pitch of said undulation increasing successively for each of said arches in the direction of said beam, said increase being substantially in proportion to the cube root of the distance of each respective of said intersection points with respect to a predetermined point on said axis ahead of said circuit.

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US294687A 1962-09-04 1963-07-12 Heavy particle linear accelerator with continuous variation of output energy Expired - Lifetime US3332024A (en)

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FR908513A FR1340271A (fr) 1962-09-04 1962-09-04 Perfectionnements aux accélérateurs linéaires d'ions

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BE (1) BE636597A (en:Method)
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FR (1) FR1340271A (en:Method)
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3428848A (en) * 1966-09-08 1969-02-18 Us Army Synchronous wave linear accelerator wherein the slow wave circuit couples only to the positive synchronous wave
US3651417A (en) * 1969-02-18 1972-03-21 Alexei Sergeevich Bogomolov Method for linear acceleration of heavy charged particles and device for its realization
US4181894A (en) * 1977-05-05 1980-01-01 Commissariat A L'energie Atomique Heavy ion accelerating structure and its application to a heavy-ion linear accelerator
US4211954A (en) * 1978-06-05 1980-07-08 The United States Of America As Represented By The Department Of Energy Alternating phase focused linacs
US4835446A (en) * 1987-09-23 1989-05-30 Cornell Research Foundation, Inc. High field gradient particle accelerator

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2395936C1 (ru) * 2008-12-16 2010-07-27 Объединенный Институт Ядерных Исследований Способ формирования ускоряющего напряжения в резонансном ускорителе заряженных частиц
RU2395937C1 (ru) * 2009-03-10 2010-07-27 Объединенный Институт Ядерных Исследований Линейный резонансный ускоритель
CN102976155A (zh) * 2012-12-03 2013-03-20 吴江市东飞化纤有限公司 配重张力辊机构

Citations (4)

* 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
US2836759A (en) * 1955-07-22 1958-05-27 Stirling A Colgate Linear accelerator
US3067359A (en) * 1958-05-05 1962-12-04 Commissariat Energie Atomique Structure for linear ion accelerators
US3147396A (en) * 1960-04-27 1964-09-01 David J Goerz Method and apparatus for phasing a linear accelerator

Patent Citations (4)

* 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
US2836759A (en) * 1955-07-22 1958-05-27 Stirling A Colgate Linear accelerator
US3067359A (en) * 1958-05-05 1962-12-04 Commissariat Energie Atomique Structure for linear ion accelerators
US3147396A (en) * 1960-04-27 1964-09-01 David J Goerz Method and apparatus for phasing a linear accelerator

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3428848A (en) * 1966-09-08 1969-02-18 Us Army Synchronous wave linear accelerator wherein the slow wave circuit couples only to the positive synchronous wave
US3651417A (en) * 1969-02-18 1972-03-21 Alexei Sergeevich Bogomolov Method for linear acceleration of heavy charged particles and device for its realization
US4181894A (en) * 1977-05-05 1980-01-01 Commissariat A L'energie Atomique Heavy ion accelerating structure and its application to a heavy-ion linear accelerator
US4211954A (en) * 1978-06-05 1980-07-08 The United States Of America As Represented By The Department Of Energy Alternating phase focused linacs
US4835446A (en) * 1987-09-23 1989-05-30 Cornell Research Foundation, Inc. High field gradient particle accelerator

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NL297417A (en:Method) 1965-11-10
GB986302A (en) 1965-03-17
FR1340271A (fr) 1963-10-18
BE636597A (en:Method) 1963-12-16
DE1181342B (de) 1964-11-12
CH409166A (fr) 1966-03-15

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