High-density hydrogen plasma production in a simple torus using helicon waves

High-density hydrogen plasma production in a simple torus using helicon waves has been investigated. The measured plasma density versus external magnetic field peaks at a condition close to the lower-hybrid resonance. The measured dispersion relation of helicon waves in the high-density region shows deviation from that of the m = +1 mode derived using the uniform plasma assumption and agrees relatively well with that using the parabolic density profile. The difference in the dispersion relation of the m = +1 mode between the uniform and non-uniform plasma models is explained by adding the vacuum region in the calculation of the boundary condition.