Ultraviolet fluorescence observation of an e-beam pumped argon-fluoride gas mixture medium on the Heaven-I facility

High-power excimer laser is believed to be an attractive driver of inertial confinement fusion energy (IFE) due to some unique advantages of short wavelength, wide bandwidth, high efficiency and capability of repetition operation. As fusion ignition achieved on NIF, the laser drivers for fusion energy are evolving in a direction characterized by shorter wavelength, higher energy and efficiency. In comparison to the electron beam-pumped krypton fluoride laser at the wavelength of 248 nm, the argon fluoride laser with a wavelength of 193 nm exhibits several advantageous characteristics, including a wider bandwidth (~10 THz), a higher fluorescence efficiency (16%) and a beam-target coupling efficiency (> 90%). Therefore, it is a promising contender for the next generation of IFE drivers. In this paper, we present an attempt to pump an argon fluoride laser with a high current electron beam facility of Heaven-I. The fluorescence of ArF at 193.5 nm with a full width at half maximum (FWHM) of 1.8 nm was successfully observed from the electron beam (E-beam) pumped Ar-F2 mixture, which indicates that the waveband is close to 15 THz. The relationships between gas mixture, diode voltage and fluorescence intensity of ArF excimer have been obtained. It is found that the poor deposition efficiency of electron beams in fluorine-argon gas mixtures is responsible for the large gap between the achieved and the desired energy output .The work will be helpful to develop the next-generation high-power excimer laser driver in China.