Multi-gap pre-ionization of long-pulse XeCl excimer lasers

To address the stringent requirements for compactness and long-term operational reliability in medical-grade long-pulse XeCl excimer lasers, this paper proposes a novel excitation scheme integrating a series of multi-gap surface tracking pre-ionization structures with a multiplexed inductor topology. In terms of structural design, a series of pre-ionization structures are innovatively adopted to reduce the number of high-voltage feedthroughs to two, thereby significantly mitigating the risk of gas leakage while ensuring the stability of the surface discharge. Regarding the circuit topology, to resolve the inherent mismatch between energy transfer and pre-ionization timing within the excitation circuit, a passive synchronization mechanism based on a multiplexed inductor is introduced. This topology utilizes dynamic magnetic coupling effects to suppress the premature rise of pre-ionization current, achieving precise synchronization of the dual sequences using only a single thyratron. Experimental results indicate that the optimal pre-ionization delay window lies between 80 and 110 ns, and the designed circuit successfully locks the breakdown timing within this high-efficiency interval. Beam quality measurements reveal that the output beam profile exhibits a uniform quasi-Gaussian distribution, confirming the stability of the glow discharge. Ultimately, the system achieved a maximum output energy of 230 mJ and a long-pulse output of approximately 140 ns (FWHM). The findings demonstrate that this scheme provides a robust and compact solution for high-performance medical excimer laser systems.