Spectroscopic investigations on a low power atmospheric pressure capacitively coupled helium plasma

An atmospheric pressure helium plasma is characterized based on its optical emission. The plasma is generated at 13.56 MHz (continuous wave) at power levels ranging from 4 to 35 W. It is in contact with a single electrode and is part of a resonant electric circuit. The excitation, vibrational and rotational temperatures are in the range 1880-5660 K, 1960-3150 K and 760-1398 K, respectively. The temperatures are correlated with the plasma power, plasma volume and gas dynamic flow. Atomization and excitation capabilities of the plasma were tested for three easily excitable elements (Zn, Na and Li) introduced in the plasma by pneumatic nebulization from liquid solution.