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 ionizati
on region at the outer plasma radii and leads to uniform plasma production.
Typical plasma densities in the plasma source designed to take advantage o
f this characteristic of the lower hybrid wave are of the order of 10(11) c
m(-3) in the source region for 10 mTorr He and 1 kW radio frequency (rf) po
wer. The radial density profile can be controlled by changing the location
of the lower hybrid resonance by changing the magnetic field B-0. We measur
ed the radial dependence of rf electric and magnetic fields to determine if
lower hybrid wave and helicon wave were present.