Study of high-density helicon-plasma generation and measurement of the plasma parameters by using a frequency-compensated Langmuir probe

The present work is an experimental study of the various parameters of a high density plasma produced by using helicon waves in a toroidal structure using ordinary Langmuir probe and an RF compensated Langmuir probe. Helicon breakdown and the parameters were investigated in the toroidal vessel was observed with a right helical antenna (m = +1) at a frequency of 32 MHz. During the experiment, transition from a capacitive mode to a helicon mode of discharge was observed. This work also takes a step toward a realization of the necessity for a compensated Langmuir probe in the study of an RF plasma, especially in the frequency range of tens of MHz. A toroidal magnetic field of 600G (max) is applied at the central axis of a toroidal vessel with an aspect ratio equal to 3. The plasma is generated by using a helical antenna to form and sustain a plasma using hydrogen gas. The power is delivered from an RF generator at 32 MHz via an L-Type matching network. A comparative study has been done using compensated and uncompensated Langmuir probes to measure various plasma parameters. A nonlinear increase in the plasma density with input RF power and with the magnetic field is observed.