Influence of insulator length on the downstream electron temperature and electron density in the coaxial electrode of plasma focus device

Abstract

We have generated the Ar plasma in the diode chamber based on the established coaxial electrode type and investigated the emitted visible light for emission spectroscopy. It is applied to the input voltage 4.5 kV, and obtained the emission spectrum data for the focused plasma in the diode chamber on the argon pressure 40 mTorr. We observed the nine emission lines of Ar II ; 407.3 nm, 410.6 nm, 422.4 nm, 426.8 nm, 427.9 nm, 435.0 nm, 438.1 nm, 444.5 nm and 488.0 nm. The downstream electron temperature and electron density have been measured by the Boltzmann plot and Stark broadening from assumption of local thermodynamic equilibrium (LTE). The length of Acrylic insulator had been changed, which is covered in the cathode by the 30 mm, 40 mm and 45 mm, respectively, to measure the downstream electron temperature and electron density in the experience. The centered wavelength of Stark broadening was 444.58 nm. This experiment can be shown that the downstream electron temperature will be influenced by the insulator length in argon plasma with coaxial electrode. Our results show that the maximum downstream electron temperature and electron density are 2.5 eV and 1.6×1016 cm−3, respectively for the Our result have been appeared the maximum electron temperature of 2.50 eV and density of 1.6×1016 cm−3 for the plasma focus in coaxial electrode under the insulator length of 40 mm.