InSn plasma penetration through protective single-walled carbon nanotube-based membranes

Abstract

Laser-produced plasma sources of short-wavelength (1–20-nm) radiation are actively used nowadays in numerous applications, including water-window microscopy and extreme ultra-violet lithography. Suppression of laser-plasma debris (responsible for damaging optics) is crucial for the lifetime prolongation of optical systems operated with the short-wavelength radiation. Here, we examine the capability of single-walled carbon nanotube (SWCNT)-based membranes to decrease an InSn plasma flux containing both ions and atoms. Faraday cup measurements show that 40- and 90-nm-thick SWCNT membranes reduce the total charge transition by 20 and 130 times, respectively. The ion analyzer measurements demonstrate that ions pass through the membrane mainly due to the collisionless (ballistic) mechanism. Using scanning electron microscopy, we estimate a decrease in a plasma (ions + atoms) flux to be of 18 and 140 times for 40- and 90-nm-thick SWCNT-based membranes, respectively. The average plasma flux attenuation coefficient of SWCNT membranes is calculated as k = 0.063 nm−1.