Classifications

• • 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
  • H05H7/22—Details of linear accelerators, e.g. drift tubes
• • 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

Definitions

• the invention relates to an RF resonator cavity can be accelerated with the ge ⁇ charged particles in the form of a particle beam as they are by the RF resonator cavity Gelei ⁇ tet and when in the RF resonator cavity an RF field to acting on the particle beam and an accelerator with such an RF resonator cavity.
• RF resonator cavities are known in the art.
• the acceleration generated with an RF resonator cavity depends on the strength of the RF electromagnetic field generated in the RF resonator cavity, which acts on the particle beam along the particle path. Since with increasing field strengths of the RF field, the probability increases that it comes to the spark sparkover between the electrodes, the maximum achievable particle energy is limited by the RF resonator cavity.
• an RF resonator cavity for the acceleration of charged particles in which an electromag ⁇ netic RF field can be coupled, which acts in operation on a particle beam which crosses the RF resonator cavity by ⁇ , wherein at least one intermediate electrode to increase electrical Dielectric strength is arranged in the RF resonator cavity along the beam path of the particle ⁇ beam.
• the invention is based on the realization that not necessarily the maximum attainable frequency of the E- affects (in accordance with the criterion Kilpatrik-) as an essential factor field strength in the vacuum, but also the electric ⁇ denabstand d, in a first approximation, given by the cooperation slope E ⁇ l / Vd (for the dielectric strength U, in a first approximation U ⁇ Vd).
• the book "Textbook of High Voltage Technology" G. Lesch, E. Baumann, Springer-Verlag, Berlin / Göttingen / Heidelberg, 1959, on page 155
• This relationship apparently applies universally over a very wide voltage range, equally for DC and AC voltage and for geometrically scaled electrode shapes.
• the choice of Elektrodenma ⁇ terials apparently only affects the proportionality constant.
• the experimental criterion of Kilpatrik E ⁇ Vf does not include any parameter that explicitly takes into account the electrode distance .
• this apparent contradiction to the above relationship, involving electrode spacing is resolved by assuming that the shape of the resonator remains geometrically similar at scaling to match the frequency, thus scaling the electrode spacing with the other dimensions of the resonator. This means a choice of the electrode spacing d in d ⁇ 1 / f, and thus an over ⁇ match between the Kilpatrik criterion E ⁇ Vf with the above established criterion E ⁇ l / Vd.
• the frequency dependence according to the Kilpatrik criterion can be at least partially pre-mirrored by the geometric scaling for resonance tuning.
• the frequency on a larger scale independently of the desired maximum E-field strength of the RF field, so that in principle compact accelerators are possible even at low frequencies, eg for heavy ions.
• this achieves a high electrical breakdown strength and associated high E field strengths by complying with the criterion E ⁇ l / Vd.
• the operating frequency of the RF resonator can be chosen much more flexible and ideally independent of the desired E-field strength, the electrical to be reached Dielectric strength is determined by the inter-electrode ⁇ it enables, and not by the choice of operating frequency.
• the invention is based on the consideration, smaller
• the electrode spacings are first given by the resonator shape, a smaller electrode spacing is achieved here by the introduction of the intermediate electrode (s). The distance between the electrodes is thus divided by the intermediate electrode (s) into smaller distances. The distance requirement with respect to breakdown strength can thus be met largely independently of the resonator size and shape.
• the intermediate electrodes fulfill the purpose, the electrical
• the intermediate electrode can be isolated from the walls of the RF resonator cavity in such a way that the intermediate electrode does not generate an RF field which accelerates the particle beam during the operation of the RF resonator cavity , The insulation does not transmit RF power from the walls to the intermediate electrodes, which would otherwise generate an RF field acting on the particle beam from the intermediate electrodes.
• no RF field is then transferred from the resonator ⁇ torwalln to the intermediate electrode, and in so small extent that that of the intermediate electrode - if any - radiated RF field does not significantly and at best not to accelerate the Contributes particle beam or affects the acceleration.
• ⁇ sondere does not receive any RF currents from the resonator walls to the intermediate electrodes.
• the isolation with respect to the resonator walls does not necessarily have to be complete, it is sufficient to design the coupling of the intermediate electrode with the resonator walls in such a way that the intermediate electrode is in the frequency range of the resonator walls. operating frequency of the RF cavity is largely isolated.
• the intermediate electrode may be coupled via a conductive connection to a wall of the RF resonator cavity such that the conductive connection has a high impedance at the operating frequency of the RF resonator cavity, whereby the desired insulation of the intermediate electrode can be achieved.
• the intermediate electrode is thus largely decoupled from the RF resonator cavity for RF energy.
• the HF resonator cavity is attenuated by the septelektro- in only a small extent.
• the conductive connection can simultaneously take over the function of the charge dissipation by scattering particles.
• the high impedance of the conductive connection can be realized via a helical conductor section.
• the intermediate electrodes are in particular arranged perpendicular to the electric field acting on the particle beam RF electric field. As a result, the smallest possible influence on the functionality of the HF cavity by the intermediate electrodes is achieved.
• the intermediate electrode may, for example, have the shape of an annular disc, with a central hole through which the particle beam is passed.
• the shape of the intermediate electrodes can be adapted to the E-field potential areas that set without intermediate electrodes, such that no significant distortion of the ideal, interelectrode-free E-field profile occurs. With a derarti ⁇ gen shaping of the capacity increase by the additional structures is minimized, a detuning of the resonator and lo ⁇ kale E-field peaks are largely avoided.
• the intermediate electrode is advantageously movable gela ⁇ siege, for example by means of a resilient mounting or suspension.
• the resilient mounting may be formed hairpin-shaped. As a result, the Gêttladungsweg along the surface is optimized or maximized, the probability ⁇ probability that G solvedtladonne occur is minimized.
• the resilient mounting may include a helical conductive portion, whereby an impedance increase of the resilient mounting can be achieved at the operating frequency of the RF resonator cavity.
• Chromium, vanadium, titanium , molybdenum, tantalum, tungsten or an alloy comprising these materials can be used as the material of the intermediate electrode . These materials wei ⁇ sen a high electric field strength. The lower surface conductivity for these materials is tolerable, as occur in the protected regions of high electric field strengths typically only small tangential H fields (and thus wall flow ⁇ dense).
• several ⁇ re intermediate electrodes are arranged in the beam direction behind the other in the RF resonator cavity.
• the plurality of intermediate electrodes may be movably mounted, for example against each other via a resilient suspension. With this the individual distances of the electrodes can be distributed evenly.
• the resilient bearings with which the plurality of intermediate electrodes are connected to each other, may be formed conductive and preferably comprise a helical conductive portion and / or formed hairpin-shaped. Thus, a charge transfer is possible by scattering particles between the intermediate electrodes.
• the accelerator according to the invention comprises at least one of the above-described RF resonator cavity with an intermediate electrode.
• Fig. 1 shows schematically the structure of an RF resonator cavity with inserted intermediate electrodes
• Fig. 1 the RF resonator cavity 11 is shown.
• the RF resonator cavity 11 itself is shown in dashed lines in order to more clearly represent the intermediate electrodes 13, which are located in the interior of the RF resonator cavity 11.
• the RF resonator cavity 11 usually comprises conductive
• the accelerating acting on the part ⁇ chenstrahl 15 RF field in the RF resonator cavity 11 is usually generated by a arranged outside of the RF resonator cavity 11 RF transmitter and reso- nant in the RF resonator cavity 11 initiated. In the RF resonator cavity 11 usually high vacuum prevails.
• the intermediate electrodes 13 are arranged along the beam path in the RF resonator cavity 11.
• the intermediate electrodes 13 are annular with a central hole through which the particle beam passes. Between the intermediate electrodes 13 is vacuum.
• the intermediate electrodes 13 are mounted with a resilient suspension 17 relative to the RF resonator cavity 11 and against each other ge ⁇ .
• FIG. 2 shows a longitudinal section through the RF resonator cavity 11 shown in FIG. 1, different types of suspension of the intermediate electrodes 13 being shown here relative to each other and with respect to the resonator walls.
• a resilient suspension of the intermediate electrodes 13 with hairpin-shaped conductive connections 23 is shown in the upper half 19 of Fig. 2, a resilient suspension of the intermediate electrodes 13 with hairpin-shaped conductive connections 23 is shown.
• the hairpin shape reduces the likelihood of sliding discharge along the suspension.
• the intermediate electrodes 13 are connected with helically guided, conductive resilient connections 25 against each other and with respect to the resonator walls.
• This embodiment has the advantage that the helical guide of the conductive connection 25 represents an impedance which generates the desired isolation of the intermediate electrodes with respect to the resonator walls at the operating frequency of the RF resonator cavity 11 with a corresponding configuration.
• ⁇ by excessive attenuation of the RF resonator cavity 11 by inserting the intermediate electrodes 13 in the RF resonator cavity 11 is avoided.

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

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• 2009
  • 2009-10-06 DE DE102009048400A patent/DE102009048400A1/de not_active Ceased
• 2010
  • 2010-08-25 RU RU2012118819/07A patent/RU2583048C2/ru not_active IP Right Cessation
  • 2010-08-25 CN CN201080044897.8A patent/CN102577634B/zh not_active Expired - Fee Related
  • 2010-08-25 JP JP2012532513A patent/JP5823397B2/ja not_active Expired - Fee Related
  • 2010-08-25 BR BR112012007987A patent/BR112012007987A8/pt not_active Application Discontinuation
  • 2010-08-25 CA CA2776983A patent/CA2776983A1/en not_active Abandoned
  • 2010-08-25 WO PCT/EP2010/062373 patent/WO2011042251A1/de active Application Filing
  • 2010-08-25 EP EP10752746A patent/EP2486779A1/de not_active Withdrawn
  • 2010-08-25 US US13/499,898 patent/US20120194104A1/en not_active Abandoned

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