 Excitation frequencies in the low-frequency (LF) range, usually around 100 kHz, require several hundred volts to sustain the discharge.These large voltages lead to high-energy ion bombardment of surfaces.High-frequency plasmas are often excited at the standard 13.56 MHz frequency widely available for industrial use; at high frequencies, the displacement current from sheath movement and scattering from the sheath assist in ionization, and thus lower voltages are sufficient to achieve higher plasma densities.