Carbon ion stripper for NSTRI tandem accelerator

Area of Science:

• Nuclear Physics and Engineering
• Accelerator Science and Technology
• Analytical Chemistry

Background:

• The Nuclear Science and Technology Research Institute (NSTRI) is developing a 1.7 MV tandem accelerator for Accelerator Mass Spectrometry (AMS).
• A critical component for AMS is the stripper section, responsible for optimizing ion charge states.
• This study focuses on the design of a stripper section specifically for carbon ion beams.

Purpose of the Study:

• To design and optimize a stripper section for a carbon ion beam within a 1.7 MV tandem accelerator.
• To achieve efficient charge exchange and equilibrium thickness for various carbon charge states.
• To validate the design through simulations and experimental measurements, considering isotopic mass effects.

Main Methods:

• Derived interaction cross-sections for 14 charge state transitions ((q, q+1) and (q, q-1)).
• Introduced an optimal geometry and calculated charge exchange efficiency based on gas throughput.
• Validated simulation results with experimental pressure measurements and compared charge-state fractions with existing data.

Main Results:

• Achieved an equilibrium thickness of 2.3 × 10¹⁶ cm^-2 at 9 SCCM gas throughput.
• Reported ¹⁴C/¹²C stripping ratios of 1.22, 1.01, and 0.89 for charge states 1+, 2+, and 3+ respectively.
• Demonstrated close agreement between simulated and experimental results, validating the optimized stripper design.

Conclusions:

• The optimized stripper section geometry ensures efficient charge exchange equilibrium for carbon ions.
• The design accounts for isotopic mass effects, crucial for accurate AMS-based radiocarbon measurements.
• The compact design reduces overall length by approximately two-thirds compared to conventional strippers, enhancing practicality.