Plasma Production and Wave Propagation in a Plasma Source Using Lower Hybrid Waves

The lower hybrid wave, which is in the same frequency range as the helicon wave, is resonant at the lower hybrid frequency and does not penetrate into the higher density side of the plasma. This creates the localized ionization region at the outer plasma radii and leads to uniform plasma production. Typical plasma densities in the plasma source designed to take advantage of this characteristic of the lower hybrid wave are of the order of 1011cm-3 in the source region for 10 mTorr He and 1 kW radio frequency (rf) power. The radial density profile can be controlled by changing the location of the lower hybrid resonance by changing the magnetic field B0. We measured the radial dependence of rf electric and magnetic fields to determine if lower hybrid wave and helicon wave were present.