ORCID
https://orcid.org/0000-0003-1752-4807
Abstract
High-performance electron cyclotron resonance ion sources (ECRISs) generate large amounts of bremsstrahlung photons that affect the cryogenic systems due to the extra heat load that is produced. Thus, this study investigates the bremsstrahlung photons energy spectra at various RF powers, presenting some insight about the trends of the electron heating process inside the plasma. Bremsstrahlung photons from a 28 GHz ECRIS were measured at Busan center of Korean Basic Science Institute (KBSI). The gamma-ray detection system consists of three round-type NaI(Tl) scintillation detectors placed 620 mm radially from the beam axis at the extraction side of the ECRIS, and a NaI(Tl) scintillation detector placed at the viewport for monitoring photon intensity along the beam axis. Bremsstrahlung photons energy spectra were measured at various RF powers from 0.5 to 3.0 kW with 0.5 kW interval. Geant4-based Monte Carlo simulations were performed to correct for the system's geometrical acceptance and energy-dependent detection efficiency, accounting for the substantial material non-uniformity of the ECRIS.
The results show that in all three measurement positions, the minimum and maximum points of the integrated photon yields appear at 60∘ (193,615440) for 500 W and at 90° (7,447,523 ± 2729) for 3000 W respectively, suggesting that increasing power leads to the linear increase in the number of counts but saturates the electrons of the spectra since the higher power causes plasma heating. Consequently, this work highlights the necessity for searching optimal RF power operating conditions that will avoid the generation of enormous amounts of bremsstrahlung photons which result in a substantial heat load to the cryostat.
Recommended Citation
Kumwenda, M. J. (2026). Bremsstrahlung Photons Emissions Measured at Different RF Power in 28 GHz ECR Ion Source. Tanzania Journal of Engineering and Technology, 45(1), 60-69. https://doi.org/https://doi.org/10.65085/2619-8789.1060
Publisher Name
University of Dar es Salaam