The role of plasma chamber size and fractional ionization in spectroscopically diagnosing Argon plasmas

Optical emission spectroscopy shows promise as a non-perturbative plasma diagnostic, but the use of spectroscopy requires an understanding of the atomic physics within the plasma. Argon plasmas are widely used in low temperature plasma physics applications. This research explores the role of the chamber size and hence plasma dimensions along with the fractional ionization and their impact on the atomic physics of low temperature Argon plasmas due to the presence of metastable states. Results will be shown for the following: a torsatron with a toroidal vacuum chamber diameter of 30 cm, an electron density ranging from 1 x 10¹⁰ to 1 x 10¹² cm^-3, and a pressure of 5 x 10^-5 mTorr; a linear device with a diameter of 10 cm and length of approximately 1.2 m, an electron density ranging from 1 x 10⁸ to 1 x 10¹⁰ cm^-3 and a pressure of 0.5 mTorr; and an octagonal chamber with a height of 6 cm, an electron density ranging from 1 x 10⁸ to 1 x 10¹⁰ cm^-3, and a pressure of 20 mTorr. All plasmas have an electron temperature ranging from 1 to 10 eV. Results show that a smaller chamber results in shorter metastable lifetime, which in turn results in the need for a time dependent approach to atomic modeling.