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Radio-Frequency Quadrupole Accelerating Structure


Design and Manufacture of DTL-RFQ Focusing and Accelerating Structure Prototype for a 3-40 MeV H- Linac of CERN SPL Project

Tech Area / Field

  • PHY-PFA/Particles, Fields and Accelerator Physics/Physics
  • PHY-ANU/Atomic and Nuclear Physics/Physics

8 Project completed

Registration date

Completion date

Senior Project Manager
Malakhov Yu I

Leading Institute
Institute for High Energy Physics (IHEP), Russia, Moscow reg., Protvino

Supporting institutes

  • VNIIEF, Russia, N. Novgorod reg., Sarov


  • CERN, Switzerland, Geneva

Project summary

Goal of this project is to develop and manufacture a prototype of the RFQ-based (radio-frequency quadrupole) accelerating structure for H linac from 3 to 40 MeV as an option for a lower-energy room-temperature part of the CERN SPL Project. A challenging design feature of this linac is its close-to-CW operation mode with a heavy duty-factor of about 20%. Specifically, the “prototype” is understood here as a part (a section, a cavity) of the linac tuned to prescribed RF parameters and intended to examine its serviceability as a part of the entire SPL linac.

The concept itself of the RFQ focusing in linacs was put forward by Ilya Kapchinsky (ITEP, Moscow) and Vladimir Teplyakov (IHEP, Protvino). It is recognized as a major discovery in the field of ion-linac physics and engineering. A structure with a spatially periodic RFQ focusing (alias, a DTL-RFQ), similar to that to be implemented in the prototype, is being successfully employed in the URAL-30 linac which is in service as injector for the booster to U70 proton synchrotron of IHEP for more than 20 years now. The structure in question does not consume a surplus energy for beam focusing, is quite simple in technology, and has smaller geometrical dimensions compared to a conventional Alvarez DTL counterpart.

In the DTL-RFQ structure at issue, measures are foreseen to increase the accelerating rate and lower RF power losses in the cavity walls. Consequently, its effective shunt impedance is expected to surpass this parameter for Alvarez DTL structure almost over the entire energy range from 3 to 40 MeV.

Manufacturing the prototype calls for a vast program of theoretical, experimental, design, and engineering efforts comprising:

1. Computation of beam dynamics and of electro-dynamical properties of the cavities.

2. Manufacturing and testing cold model of the prototype.
3. Study of thermal-physics parameters of the structure and design of the cooling system.
4. Handling the radiation-related problems in the accelerator.
5. Development of the pre-production technological documentation and technical drawings for the prototype.
6. Manufacture of the full-scale working prototype of accelerating structure, its tuning and pre-testing, etc.

The activity aimed at design, manufacturing and pre-testing the prototype of the accelerating structure will be accomplished in IHEP (Protvino) and RFNC-VNIIEF (Sarov).

Linac Dept. of IHEP has a staff of 70 employees. Of these, there are 2 Doctors and 7 Candidates of Sciences. The personnel have gained a long-term experience in R&D and manufacture of the spatially periodic, DTL-RFQ accelerating structures.

RFNC-VNIIEF employs personnel qualified in the field of accelerator physics and technology. The Institution has worked out a reliable engineering approach to ensure safe levels of induced radioactivity of constructive elements. A sound expertise in designing and studying constructions of physical installations with a finite-element method (FEM) has been accumulated. The RFNC-VNIIEF staff has got experience during R&D and construction of a few resonant linacs.


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