Experiments and characterization studies of 1 kW RF Helicon plasma thruster with plasma diagnostics techniques

Helicon Thruster systems are being explored as a potential candidate thruster for the space exploration due to their superior features like dense sources, electrode less operation with longer life and higher specific impulse. Helicon thruster system with 1kW RF source and magnetic field (~1400 G using permanent magnets) with Ar gas is designed, constructed and operated. It is essential to have better understanding of various phenomena like plasma production, magnetic nozzle acceleration and detachment physics for the generation of thrust. To study these phenomena, few diagnostics are employed, such as; Langmuir probes for electron density and temperature, Mach probe for plasma flow velocity and optical emission spectroscopy (OES) for electron temperature measurements. A B-dot probe (3D) was employed to detect the helicon waves in the expansion region. Variation of plasma parameters has been studied with RF power, Ar gas pressure. Langmuir probes estimated the plasma density in range of ~1x10¹² cm³ to 4x10¹³ cm³ in the expansion chamber and electron temperature in range of 1eV to 6eV. Mach probe with up-down configuration was employed and measured flow velocities in range of 4.5 km/s to 7 km/s which correspond to Mach numbers in range of ~ 1.3 to 2.1 indicating supersonic flows. OES was employed near to Helicon antenna and Ar lines intensity was measured in both blue and red regions. Spectral data analysis estimates electron temperature for different set of data in range of ~1-4 eV.