A peer-reviewed journal published by K. N. Toosi University of Technology

Vacuum system design and pressure profile calculation for the accelerating tube of a tandem accelerator

Document Type : Research Article

Authors

1 Department of Radiation Application, Faculty of Nuclear Engineering, Shahid Beheshti University, P.O. Box 19839-69411, Tehran, Iran

2 Physic and Accelerators Research School, Nuclear Science and Technology Research Institute, P.O. Box 14395-836, Tehran, Iran

Abstract
In tandem accelerators, charge exchange can be achieved using either foil-based or gas-based methods. This study presents the design of a vacuum system specifically for the gas-based charge exchange method in tandem accelerators, aiming to maintain optimal atomic gas density in the interaction region and minimize gas leakage toward the accelerating tubes. To achieve high charge exchange efficiency, precise design of the Beam Transfer Lines (BTL) is essential. In this study, the impact of length and diameter of the BTL on the pressure profile along the tube was investigated. A geometry was selected that concentrates gas in the interaction region while minimizing leakage into accelerating tubes. Subsequently, gas flow simulations were used to determine the optimal operating window for gas throughput and pumping speed in the charge exchange region, ensuring an atomic gas density of 7.24×1016 cm-2 required for nearly 100% charge exchange efficiency. Keeping the gas injection rate fixed, the effective range of pump speeds on charge exchange section and accelerating tubes was then identified to create a pressure ratio of about 10⁻³ mbar between the charge exchange section and accelerating tubes. Results showed that beyond a certain threshold, increasing pumping speed does not significantly reduce the pressure due to conductance limitations.

Highlights

  • Poor vacuum conditions increase electron production, which lead to enhanced background radiation.
  • Design of vacuum system for the gas-based charge exchange method in tandem accelerators.
  • Determine optimal operating window for gas throughput and pumping speed in charge exchange region.
  • Ensuring atomic gas density of 7.24×1016 cm-2 required for nearly 100% charge exchange efficiency.
  • Effective range of pump speeds on charge exchange section and accelerating tubes was identified.

Keywords


 

Copyright
RPE is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

Conflict of Interest

‎The authors declare no potential conflict of interest regarding the publication of this work‎.

Funding

‎The authors declare that no funds‎, ‎grants‎, ‎or other financial support were received during the preparation of this manuscript‎.

 
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Volume 6, Issue 4
Autumn 2025
Pages 55-64

  • Receive Date 16 July 2025
  • Revise Date 23 August 2025
  • Accept Date 17 September 2025