On the plasma extent in an RF inductively coupled, cylindrical, hydrogen discharge

Summary form only given. A cylindrical, inductively coupled plasma driven by a solenoidal antenna varies in length along the axial direction depending on its pressure, power, and composition. The utility of such an RF plasma in materials processing and lighting applications depends on its extent and uniformity, To study the phenomena measurements were made of the axial extent of an inductively coupled, hydrogen plasma within a cylindrical tube excited by a coaxial, single turn antenna strap at 13.6 MHz. The pressure ranged from 1/2 to 2 Torr and the power from 1.5 to 4.5 kW. Data were taken for both a quartz and a slotted metal tube. Two diagnostics were used to quantify the plasma extent along the axial direction: (a) the magnetic flux density and (b) the H, emission line intensity. The observed double peaked profile for the axial-component of the magnetic field is indicative of field exclusion by a conductive plasma. The FWHM of the light profile specifies the extent of excited, dissociated hydrogen. The measurements of the plasma extent as determined by the magnetic field exclusion show a similar size for both the dielectric and metal tubes as a function of power and pressure. However, the plasma extent based on the H, emission is larger in the dielectric than the metal tube. A 2-D numerical plasma model with self-consistent field coupling and multi-species diffusion is used to investigate this apparent difference in plasma extent with an emphasis on the role of hydrogen wall recombination in quartz vs. metal tubes.