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Description
The 30 MeV Karaj-C30 cyclotron, developed for medical and industrial radioisotope production at the Karaj Research Institute for Agricultural, Medical, and Industrial Studies, accelerates H- ions to 15–30 MeV and D- ions below 15 MeV. The system features a filament-based negative hydrogen multicusp ion source providing 1–2 mA, an injection line with optical elements, a two-sector electromagnet, and an RF resonator. It was observed that after a period of cyclotron operation, the beam current on the target gradually decreased. Examination revealed beam impingement on optical elements, indicating misalignment. A Mylar foil was used to investigate the beam profile. The recorded beam profile on the foil was analyzed through image processing. It was found that the beam was misaligned with respect to the beam transport line. Further investigation revealed that the ground electrode had undergone corrosion, as the magnets within the puller electrode caused deflection of the ion beam, leading to its collision with the ground electrode. Erosion of the ground electrode generated a radial electric field deflecting the beam. After replacing the ground electrode with an identical, non-corroded electrode, the beam profile was re-evaluated under the same operating conditions, and it was observed that the beam had been successfully realigned with the beam transport line.
