Diagnostics of inductively coupled chlorine plasmas: Measurement of electron and total positive ion densities

This work is part of a broader study that creates a set of experimentally measured chlorine plasma parameters (electron and gas temperatures, electron energy distribution function, electron density, densities of ion fractions, and total ion density). This set is obtained over a broad range of operating conditions (1–20 mTorr, 5–1000 W) of an inductively coupled plasma. In this part, we present the electron (ne) and total positive ion (ni+=nCl2++nCl+) densities. ne and ni+ were measured with a Langmuir probe across the diameter or in the middle of the reactor. Line integrated values of ne were independently obtained with microwave interferometry, and converted into the spatially resolved data using the Langmuir probe ne profiles. Finally, a method is presented for measuring relative positive ion densities, based on optical emission at 7504 Å from trace amounts of Ar.