The Effect of Nitrogen Diffusion From Surrounding Air on Plasma Bullet Behavior

Photographs obtained from a fast intensified charge-coupled device camera show that the plasma bullet structure depends on the working gas. The plasma bullet appears as donut shape when He is used as working gas. However, the plasma bullet shows a solid disk shape while He is replaced by He/N₂ mixture. Moreover, when the plasma plume is injected into different surrounding gas environment, analysis on the high-speed photographs of the plasma plume with different working gases shows that the diffusion of nitrogen into the working gas flow plays an important role in the acceleration of the plasma bullet.