04 Hadron Accelerators

A08 Linear Accelerators

Paper Title Page
TUPLS031 Commissioning of the ISAC-II Heavy Ion Superconducting Linac at TRIUMF 1556
 
  • R.E. Laxdal, W. Andersson, K. Fong, M. Marchetto, A.K. Mitra, W.R. Rawnsley, I. Sekachev, G. Stanford, V.A. Verzilov, V. Zviagintsev
    TRIUMF, Vancouver
  
  A new heavy ion superconducting linac at TRIUMF is being installed to boost the final energy of radioactive beams from ISAC from 1.5MeV/u to above the Coulomb barrier. A first stage of 20MV consisting of five medium beta cryomodules each with four quarter wave bulk niobium cavities and a superconducting solenoid is being commissioned in early 2006. The cavities (Beta0=0.057, 0.071) operate cw at 106MHz with design peak fields of Ep=30MV/m, Bp=60mT while delivering an accelerating voltage of 1.08MV at ~4W power consumption. The report will summarize the commissioning results and early operating experience.  
TUPLS032 Superconducting Driver Linac for the New Spiral 2 Radioactive Ion Beam Facility GANIL 1559
 
  • T. Junquera
    IPN, Orsay
  
  The new Spiral 2 facility will deliver high intensity rare isotope beams for fundamental research in nuclear physics, and high neutron flux for multidisciplinary applications. Based into the ISOL and in-flight isotope production methods this facility will cover broad areas of the nuclide chart. The driver accelerator must deliver CW beams of deuterons (40 MeV, 5 mA) and heavy ions (q/A=1/3, 15 MeV/A, 1 mA). The injector is composed of two ion sources (deuterons and heavy ions) and a common RFQ cavity (88 MHz). The Superconducting Linac is composed of two sections of Quarter Wave Resonators (beta 0.07 and 0.12, frequency 88 MHz) with room temperature focusing devices. After two years of preliminary study, and following the recent decision to launch the construction phase, a complete design of the Driver Accelerator is presently completed. Important results have been obtained during the initial R&D phase, in particular on ion sources, RFQ and superconducting resonators prototypes. Status report on both the design and the prototype performances will be given in this contribution.  
TUPLS033 First Stage of a 40 MeV Proton Deuteron Accelerator Commissioning Results 1562
 
  • C. Piel, K. Dunkel, M. Pekeler, H. Vogel, P. vom Stein
    ACCEL, Bergisch Gladbach
  
  In 2006 the first stage of a 40MeV superconducting linear accelerator for protons and deuterons will be commissioned at SOREQ. This paper will present commissioning of the ECR source after final assembly. First results of the 1.5MeV/u cw RFQ are expected, further test results of the beta=0.09 half wave superconducting resonators are presented, and resonator geometry improvements with respect to electron multipacting behaviour will be discussed. An outlook on the project with respect to achieve the final energy of 40MeV will be given.  
TUPLS034 UNILAC Upgrade Programme for the Heavy Element Research at GSI-SHIP 1565
 
  • W. Barth, L.A. Dahl, S. Hofmann, K. Tinschert
    GSI, Darmstadt
  • U. Ratzinger
    IAP, Frankfurt-am-Main
  
  In the field of heavy-element research using the velocity separator SHIP significant achievements were made at GSI during the last 30 years. The experiences obtained of experiments clearly show that superheavy-element research was always based on efforts to extend the limits of technical possibilities - of these the increase of beam intensity is one of the major contributions. This paper provides for technical information on the already planned upgrades of the present facility, which results in a significant overall increase of the experimental sensitivity. It is foreseen to investigate and to build a sc 28 GHz-ECR ion source, which should increase the primary beam intensities. The beam coming from the new ECR source will be delivered to the GSI-High Charge State Injector by a second LEBT-system. An upgrade program for the rf-amplifiers and the rf-structures is intended to increase the duty factor from 30 % to 50 %. Besides the ECR-source a new RFQ accelerator and the IH structure may alternatively serve as an injector for an new advanced stand alone accelerator providing for 100 % duty factor. Two different linac-layouts will be discussed.  
TUPLS035 The HITRAP Decelerator Project at GSI 1568
 
  • L.A. Dahl, W. Barth, M. Kaiser, O.K. Kester, H.J. Kluge, W. Vinzenz
    GSI, Darmstadt
  • B. Hofmann, U. Ratzinger, A.C. Sauer, A. Schempp
    IAP, Frankfurt-am-Main
  
  The heavy ion trap (HITRAP) at GSI is a funded project since 2004. Highly charged ions up to U92+ provided by the GSI accelerator facility will be decelerated and subsequently injected into a Penning trap for further cooling almost to rest. A combination of an IH- and an RFQ-structure decelerates the ions from 4 MeV/u down to 6 keV/u. In front of the decelerator a double-drift-buncher-system provides for phase focusing and a final debuncher integrated in the RFQ-tank reduces the energy spread in order to improve the efficiency for beam capture in the cooler trap. The report gives an overview of the final beam dynamic design of the entire decelerator. Besides the construction status of the cavities, particular beam diagnostic features due to the short pulses of 1 μs and 108 MHz bunch frequency, and the measures for technical and controls integration into the existing GSI accelerator complex are presented. Finally the recent time schedule and considerations for commissioning are shown.  
TUPLS036 Status of the Linac-commissioning for the Heavy Ion Cancer Therapy Facility HIT 1571
 
  • M.T. Maier, R. Baer, W. Barth, L.A. Dahl, C. Dorn, T.G. Fleck, L. Groening, C.M. Kleffner, C. Müller, A. Peters, B. Schlitt, M. Schwickert, K. Tinschert, H. Vormann
    GSI, Darmstadt
  • R. Cee, B. Naas, S. Scheloske, T. Winkelmann
    HIT, Heidelberg
  • U. Ratzinger, A. Schempp
    IAP, Frankfurt-am-Main
  
  A clinical facility for cancer therapy using energetic proton and ion beams (C, He and O) is under construction and will be installed at the Radiologische Universitätsklinik in Heidelberg, Germany. It consists of two ECR ion sources, a 7 MeV/u linac injector and a 6.5 Tm synchrotron to accelerate the ions to final energies of 50-430 MeV/u. The linac comprises a 400 keV/u RFQ and a 7 MeV/u IH-DTL operating at 216.8 MHz. In this contribution the current status of the linear accelerator is reported. After first tests with 1H+ beam of the RFQ at GSI, the commissioning of the accelerator in Heidelberg has already started. The commissioning with beam is performed in three steps for the LEBT, the RFQ and the IH-DTL. For this purpose a versatile beam diagnostic test bench has been designed. It consists of a slit-grid emittance measurement device, transverse pick-ups providing for time of flight energy measurements, SEM-profile grids and different devices for beam current measurements. This paper will provide for a status report of the linac-commissioning.  
TUPLS037 The Frankfurt Funneling Experiment 1574
 
  • U. Bartz, D. Ficek, N. Mueller, A. Schempp, J. Thibus, M. Vossberg
    IAP, Frankfurt-am-Main
  
  The goal of the Frankfurt Funneling Experiment is to multiply beam currents of RFQ accelerators at low energies to avoid problems with space charge. The two beams from the ion sources are injected into two RFQ channels. The last part of the RFQ electrodes have been replaced to achieve a 3d focus at the crossing point of the two beam axis where the funneling deflector as a central peace of the experiment is located. The newly designed multi-cell deflector is adapted to the optimised funneling section. It is mechanically solid, easy to tune in and ready for operation. First measurements will be presented.  
TUPLS038 The MAFF IH-RFQ Test Stand at the IAP Frankfurt 1577
 
  • A. Bechtold, D. Habs
    LMU, München
  • J. Fischbach, U. Ratzinger, J. Rehberg, M. Reichwein, A. Schempp
    IAP, Frankfurt-am-Main
  • J. Haeuser
    NTG Neue Technologien GmbH & Co KG, Gelnhausen
  • O.K. Kester
    GSI, Darmstadt
  
  The IH-type RFQ for the MAFF project at the LMU in Munich is presently under construction and will be integrated into a beam test stand at the IAP in Frankfurt. It is the second RFQ following the IH resonator concept and the first one that can be directly compared to a very similar 4-rod type machine, namely the REX-ISOLDE RFQ at CERN. The MAFF RFQ has been designed to accelerate rare isotope beams (RIBs) with mass to charge ratios up to 6.3 from 3 keV/u to 300 keV/u at an operating frequency of 101.28 MHz with an electrode voltage of 60 kV. First RF-measurements have already been executed and can be compared to appropriate simulation results. Parts of the test stand are currently under construction, such as the volume ion source for He+ at an extraction voltage of 12 keV and an electrostatic quadruplet for injection with an integrated steering system. These tests and accompanying theoretical investigations will be done with special respect to the applicability of such normal conducting RFQ accelerators to the EURISOL post accelerator.  
TUPLS039 Proposal of a Normal Conducting CW-RFQ for the EURISOL Post-accelerator and a Dedicated Beta-beam Linac Concept 1580
 
  • A. Bechtold, H. Podlech
    IAP, Frankfurt-am-Main
  
  A combination of three superconducting RFQs has been proposed for the EURISOL post accelerator layout. At least the first RFQ of this triplet could be replaced by a normal conducting continuous wave (c.w.) device. Efficient cooling systems have already been designed and applied to existing machines at the IAP in Frankfurt. Preliminary electrode and cavity designs can be presented. Since a parallel use for beta-beam applications was intended, we have optimized the design not only for heavy ion applications with negligible beam currents at c.w. but also for lighter ions with currents up to 7.5 mA at pulsed operation. More recent investigations on beta-beams came up with currents around 50 mA, which then would make a separate linac solution for beta-beams necessary. We worked out some preliminary design suggestions for such a dedicated 100 MeV/u machine.  
TUPLS040 Tuning of a 4-rod CW-mode RFQ Accelerator 1583
 
  • P. Fischer, A. Schempp
    IAP, Frankfurt-am-Main
  
  A four-rod RFQ accelerator has been built which operates in CW mode with a power consumption of 250 kW. The assembly of a high power RFQ structure requires a precise mechanical alignment and field tuning of the electrode field. The field distribution must be very flat to enable a proper operation with few losses. Adjusting of the field distribution is critical in long structures. Simulations and the status of the tuned structure will be discussed.  
TUPLS041 The HITRAP RFQ Decelerator at GSI 1586
 
  • B. Hofmann, A. Schempp
    IAP, Frankfurt-am-Main
  • O.K. Kester
    GSI, Darmstadt
  
  The HITRAP linac at GSI will decelerate ions from 5 MeV/u to 6 keV/u for experiments with the large GSI Penning trap. The ions, provided by the GSI accelerator facility, will be decelerated at first in the existing experimental storage ring (ESR) down to an energy of 5 MeV/u, and injected into a new IH decelerator and decelerated to 5oo keV/u. The following 4- Rod type RFQ will decelerate the ion beam from 5oo keV to 6 keV/u. The RFQ has been designed and will be built at the Institute for Applied Physics in Frankfurt. The properties of the RFQ decelerator and the status of the project will be discussed.  
TUPLS042 First Cryogenic Tests of the Superconducting CH-structure 1588
 
  • H. Podlech, C. Commenda, H. Klein, H. Liebermann, U. Ratzinger, A.C. Sauer
    IAP, Frankfurt-am-Main
  
  The CH-structure is a new multi-cell drift tube structure operated in the TE21-mode and is well suited for the acceleration of low and medium beta ion and proton beams. Due to the mechanical stiffness room temperature as well as superconducting CH-cavities can be realised. A 19-cell, beta=0.1 superconducting CH-prototype cavity has been developed and built. First cryogenic tests have been performed at 4.5 K in Frankfurt successfully. An effective accelerating voltage of 3.6 MV has been achieved so far. This corresponds to an electric peak field of 23 MV/m. Actual measurements aim on a localisation of possible field emission centers, afterwards further surface preparation will take place.  
TUPLS043 Simulations for the Frankfurt Funneling Experiment 1591
 
  • J. Thibus, A. Schempp
    IAP, Frankfurt-am-Main
  
  Beam simulations for the Frankfurt Funneling Experiment are done with RFQSim and FUSIONS. RFQSim is responsible for the beam transport through an RFQ accelerator. Behind the accelerator the particle dynamic program FUSIONS calculates the macro bunches of both beam lines through an r.f. funneling deflector. A new space charge routine has now been included. The status of the development of FUSIONS and the results of the simulations will be presented.  
TUPLS044 The 3D Beam Dynamics with the Space Charge in the Low and Middle Energy Super-conducting Option of HIPPI 1594
 
  • N.E. Vasyukhin, R. Maier, Y. Senichev, R. Tölle
    FZJ, Jülich
  
  For the low and middle energy of the High Intensity Proton Pulse Injector (HIPPI), a superconducting option is considered.The 3D beam dynamics simulation results in the slot and the finger-slot sections covering the energy range from 3 to 160 MeV are presented. The optimization aim is the increase of beam current together with the reduction of emittance growth, beam losses and costs. The slot structure is compared with the conventional spoke structure.  
TUPLS045 Completion of the Commissioning of the Superconducting Heavy Ion Injector PIAVE at INFN-LNL 1597
 
  • G. Bisoffi, G. Bassato, A. Battistella, l. Boscagli, A. Calore, S. Canella, D. Carlucci, M. Cavenago, F. Chiurlotto, M. Comunian, M. De Lazzari, A. Facco, E. Fagotti, A. Galatà, P. Modanese, M.F. Moisio, A. Pisent, M. Poggi, A.M. Porcellato, P.A. Posocco, C. Roncolato, E. Sattin, S. Stark
    INFN/LNL, Legnaro, Padova
  • N. Schiccheri
    CNAO Foundation, Milan
  
  At INFN-LNL the commissioning of the injector PIAVE, based on superconducting RFQs, has been completed. All the superconducting cavities (two RFQs and 8 quarter wave resonators - QWR) have shown very satisfactory stability with respect to changes of the liquid helium pressure and microphonics. Beam parameters are very close to the nominal values. The commissioning was completed by accelerating the pilot beam 16O3+ with the PIAVE injector and the booster linac ALPI (summer 2005). Since December 2005, a number of test beams were accelerated (mainly noble gas species) with PIAVE and ALPI and delivered to user experimental stations. Regular operation will be scheduled from Fall 2006 onwards.  
TUPLS047 An Analysis of Lumped Circuit Equation for Side Coupled Linac (SCL) 1600
 
  • V.G. Vaccaro, A. D'Elia
    Naples University Federico II and INFN, Napoli
  • M.R. Masullo
    INFN-Napoli, Napoli
  
  The behaviour of a SCL module is generally described by resorting to an equation system borrowed from lumped circuit theories. This description holds for a narrow frequency band (mono-modal cavity behaviour). A milestone in this field is represented by the classical analysis made by Knapp & alii where the equations allow for the resonant frequencies of the cavities and the first and second order coupling constants. Eigenvalues and eigenvectors (resonant frequencies of the system and relevant current amplitudes) are also given. We show that the system is not correct in the second and last but one equations for the case of half cell termination and non zero second order coupling constants. Due to the relevance of this formulation and of the case treated, we pay a particular attention to find the missing terms in the above mentioned equation. We suggest a correction term, having in addition a deep meaning from electromagnetic point of view. By means of this term we may justify the analytical solution given by the authors. Some numerical examples are also given showing that a discrepancy appears comparing the new equations with the results of the non-correct formulation.  
TUPLS048 Optimization Design of a Side Coupled Linac (SCL) for Protontherapy: a New Feeding Solution 1603
 
  • V.G. Vaccaro, A. D'Elia
    Naples University Federico II and INFN, Napoli
  • T. Clauser, A.C. Rainò
    Bari University, Science Faculty, Bari
  • C. De Martinis, D. Giove, M. Mauri
    INFN/LASA, Segrate (MI)
  • S. Lanzone
    CERN, Geneva
  • M.R. Masullo
    INFN-Napoli, Napoli
  • R.J. Rush
    e2v technologies, Chelmsford, Essex
  • V. Variale
    INFN-Bari, Bari
  
  It is proposed to use an SCL, starting at 30MeV, up to 230MeV. The linac consists of 25 modules (two tanks each). Twelve, 3GHz power generators, feed two modules in parallel, with the last power generator feeding the last module. The SCL is designed, assuming a mean accelerating field in the cavities of 16,5MV/m. The longitudinal and transverse beam dynamics has been studied, assuming that the input parameters (emittance, energy spread and mean current) are those of commercial 30MeV cyclotrons. The characteristics of the ejected beam were analysed: the transmittance value is largely sufficient to deliver a correct dose for therapy; the beam line activation is kept largely below allowed levels; the output energy spread is sufficiently small. The first prototype module is under construction and a second one is under design. Contacts with e2v have been established for defining an agreement, which proposes to use magnetrons as feeders for the acceleration tests. Attention was therefore paid to phase locking constraints between feeders. Theoretical studies suggest that transmittance stays constant if de-phasing is kept into values that seem attainable with magnetrons.  
TUPLS049 A Rationale to Design Side Coupled Linac (SCL): a Faster and More Reliable Tool 1606
 
  • V.G. Vaccaro, A. D'Elia
    Naples University Federico II and INFN, Napoli
  • M.R. Masullo
    INFN-Napoli, Napoli
  
  A module of an SCL is formed by a cascade of two or more tanks, connected by a Bridge Couplers (BC) with an RF feeder, which realizes a well defined accelerating field configuration in all the coupled cavities. Even resorting to geometrical scaling for the design of the adjacent tanks in the module it is not possible to reproduce the same e-m parameters. In addition to this the BC's for each tanks have a different geometrical design because of phasing constraints. The standard procedure may leads a very slow convergence of the design to the optimum and it is not in general clear if the optimum is reached. In this paper a rationale for designing a module of an SCL will be described and it will be presented its application to PALME first module (30-3???MeV). From a lumped circuit model one may get useful relations between e-m global response of the system and single cell parameters. Therefore it provides a certain number of tools which are used for the designing steps in connection with the standard electromagnetic CAD's, the results of which were used as "measurements".  
TUPLS051 Development of PEFP 20 MeV Proton Accelerator 1609
 
  • Y.-S. Cho, H.M. Choi, S.-H. Han, I.-S. Hong, J.-H. Jang, H. S. Kim, K.Y. Kim, Y.-H. Kim, H.-J. Kwon, K.T. Seol, Y.-G. Song
    KAERI, Daejon
  
  A 20 MeV proton accelerator has been developed as a low energy part of PEFP (Proton Engineering Frontier Project) 100 MeV accelerator. The 20 MeV accelerator consists of ion source, LEBT (Low Energy Beam Transport), 3 MeV RFQ (Radiofrequency Quadrupole) and 20 MeV DTL (Drift Tube Linac). After the field tuning and high power RF conditioning of the accelerating cavities, the first beam test of the 20 MeV accelerator is underway. During the test, the pulsed proton beam was extracted from the ion source by pulsing the high voltage power supply. Two 1.1 MW, 350MHz RF systems were used to drive the 20 MeV accelerator. The current transformers between DTL tanks and Faraday cup at the end of 20 MeV DTL were used to measure the beam current. In this paper, the development of 20MeV accelerator are summarized and the first beam test results are discussed.  
TUPLS052 Beam Dynamics of the PEFP Linac 1612
 
  • J.-H. Jang, Y.-S. Cho, K.Y. Kim, Y.-H. Kim, H.-J. Kwon
    KAERI, Daejon
  
  The PEFP Linac consists of a 50 keV ion source, LEBT, 3 MeV RFQ, 20 MeV DTL called DTL1, MEBT, and 100 MeV DTL called DTL2. The MEBT includes two small DTL tanks, which match the 20 MeV proton beams into the DTL2, and a bending magnet, which extracts the 20 MeV proton beams to the experimental hall. We will present the full beam dynamics study from the entrance of the DTL1 to the end of DTL2 with the initial beam parameters obtained from a simulation study of the RFQ. Our study focuses on the longitudinal beam matching in order to compensate the missing RF effect between every neighboring DTL tanks as well as the full beam matching between DTL1 and DTL2.  
TUPLS053 Beam Dynamics of a High Current IH-DTL Structure for the TWAC Injector 1615
 
  • S. Minaev, T. Kulevoy, B.Y. Sharkov
    ITEP, Moscow
  • U. Ratzinger, R. Tiede
    IAP, Frankfurt-am-Main
  
  A powerful ion injector based on a laser ion source is needed for an efficient operation of the Tera Watt Accumulator (TWAC) complex including a heavy ion synchrotron and a storage ring, which is under progress now at ITEP, Moscow. The Interdigital H-type drift tube linac (IH-DTL) structure operating at 162 MHz is proposed for the second stage of the injector linac behind of a 81 MHz RFQ. Consisting of independently driven sections with inter-tank quadrupole triplet focusing, this structure will accelerate highly stripped ions with charge-to-mass ratios above 1/3 in the energy range from 1.57 MeV/u at the RFQ exit to 7 MeV/u. Beam currents up to 100 mA are expected for medium ions like Carbon or Aluminum. Since the rf frequency is duplicated at the entrance of the IH-DTL in order to reduce size as well as power consumption, space charge effects are dominant at full current. Beam dynamics and structure parameters are discussed in detail.  
TUPLS055 First Section of a 352 MHz Prototype Alvarez DTL Tank for the CERN SPL 1621
 
  • S.V. Plotnikov, A.P. Durkin, D. Kashinskiy, V.A. Koshelev, T. Kulevoy, S. Minaev, V. Pershin, B.Y. Sharkov, V. Skachkov
    ITEP, Moscow
  • V.F. Basmanov, V.A. Demanov, I.D. Goncharov, E.S. Mikhailov, N.I. Moskvin, S.T. Nazarenko, V.S. Pavlov, V.V. Porkhaev, V.T. Punin, A.V. Telnov, V.N. Yanovsky, N.V. Zavyalov, S.A. Zhelezov
    VNIIEF, Sarov (Nizhnii Gorod)
  
  In the Linac4/SPL projects at CERN, 352 MHz 30 mA DTL Alvarez accelerating structure will be used to accelerate protons between 3 and 40 MeV. The R&D for the development of a prototype structure for the energy range from 3 to 10 MeV is taking place jointly at ITEP and VNIIEF. The design of this 2.7 m Alvarez tank containing 27 drift tubes is described in this document. Results of calculations of the section parameters are presented. One of the main features of the design is the use of permanent magnets made of SmCo5 alloy as quadrupole focusing lenses (PMQ) inside the drift tubes. Details of the experimental PMQ-equipped drift tube are described.  
TUPLS057 Linac4, a New Injector for the CERN PS Booster 1624
 
  • R. Garoby, G. Bellodi, F. Gerigk, K. Hanke, A.M. Lombardi, M. Pasini, C. Rossi, E.Zh. Sargsyan, M. Vretenar
    CERN, Geneva
  
  The first bottle-neck towards higher beam brightness in the LHC injector chain is due to space charge induced tune spread at injection in the CERN PS Booster (PSB). A new injector called Linac4 is proposed to remove this limitation. Using RF cavities at 352 and 704 MHz, it will replace the present 50 MeV proton Linac2, and deliver a 160 MeV, 40 mA H beam. The higher injection energy will reduce space charge effects by a factor of 2, and charge exchange will drastically reduce the beam losses at injection. Operation will be simplified and the beam brightness required for the LHC ultimate luminosity should be obtained at PS ejection. Moreover, for the needs of non-LHC physics experiments like ISOLDE, the number of protons per pulse from the PSB will increase by a significant factor. This new linac constitutes an essential component of any of the envisaged LHC upgrade scenarios, which can also become the low energy part of a future 3.5 GeV, multi-megawatt superconducting linac (SPL). The present design has benefited from the support of the French CEA and IN2P3, of the European Union and of the ISTC (Moscow). The proposed machine and its layout on the CERN site are described.  
TUPLS058 New Prestripping Section of the MILAC Linear Accelerator Designed for Accelerating a High Current Beam of Light Ions 1627
 
  • A.P. Kobets, V.A. Bomko, O.F. Dyachenko, Ye.V. Ivakhno, M.S. Lesnykh, Z.O. Ptukhina, V.N. Reshetnikov, S.S. Tishkin, V.P. Yashin, A.V. Zabotin, B.V. Zajtsev, V.G. Zhuravlev
    NSC/KIPT, Kharkov
  
  In the Kharkov Institute of Physics and Technology, the works on construction of a new prestripping section of the multicharge ion linear accelerator (MILAC) is performed. The task is set to provide acceleration of high current beams of light ions for research works on radiation material engineering and applied investigations. The new prestripping section is designed for accelerating ions with A/q=4 up to the energy of 1 MeV/u; after stripping they will be accelerated in the main section up to the energy of 8.5 MeV/u. Special operational mode will allow to increase noticeably the repetition rate with the same power consumption. The calculation results on beam dynamics in the structure with alternating phase focusing in the version with the stepped change of the synchronous phase, and calculations of electrodynamic characteristics of the accelerating structure of the interdigital type. The peculiarities of the construction of the accelerating structure are described.