A method of real-time monitoring beam output stability of intense pulsed ion beam

Abstract

Intense pulsed ion beam (IPIB) technology has witnessed remarkable advancements in surface modification, mixing, polishing, film deposition, and nano powder synthesis in recent years. However, the surface properties of materials under IPIB irradiation are highly sensitive to beam intensity variations. Deviations from acceptable parameter ranges can result in alterations in surface characteristics and an increased prevalence of defects. Consequently, real-time online monitoring of beam stability during irradiation experiments and prompt identification of pulses exhibiting significant parameter jitter hold paramount importance for accurate result analysis and optimization of surface modification. This study presents a fast-response pulse X-ray diagnostic system employing EJ-200 plastic scintillator, 9266FLB photomultiplier tube, and Tektronic TDS 2024 four-channel oscilloscope. Single particle test demonstrates that the system achieves a time resolution of 6 ns, meeting the temporal response requirements for detecting pulse X-ray signals with a half-width of ~80 ns. By adjusting the insulation magnetic field strength of the ion diode, the IPIB output level is regulated. The diagnostic system successfully captures X-rays emitted by the external magnetic insulated ion diode operating at different output levels. Simultaneously, the ion beam energy density is measured using an infrared camera. To mitigate diagnostic errors stemming from target ablation, the maximum energy density is controlled below 1.32 J/cm<sup>2</sup>. Analysis results establish a positive correlation between X-ray intensity and ion beam energy density. This relationship arises from the influence of the insulating magnetic field adjustment on the diode's operating voltage, which subsequently impacts the bremsstrahlung radiant intensity and ion beam emission intensity. This correlation offers the potential for real-time monitoring of IPIB beam output stability utilizing X-ray signals. To further corroborate the synchronized changes in pulse X-ray intensity and ion beam intensity, Faraday cup are employed as an alternative to infrared imaging methods for measuring ion current density. Results demonstrate that the amplitude of the X-ray signal exhibits a synchronous change to fluctuations in ion current density. Notably, when the beam output intensity deviates significantly (exceeding 10% of the predetermined value), the diagnostic system promptly responds. These findings validate the efficacy of the proposed non-interceptive diagnostic method for real-time monitoring of intense pulsed ion beam output stability.