Development and construction of a Laser-Induced Fluorescence (LIF) diagnostics system for a low temperature multidipole plasma device with X-point magnetic configuration, MAXIMUS

A laser-induced fluorescence (LIF) based diagnostics system is being developed to investigate the plasma properties inside a multidipole chamber producing low temperature plasmas. The system utilizes a continuous wave, tunable diode laser for fine modulation of the laser frequency, as well as a lock-in amplifier based measurement system. The implementation of the lock-in amplifier allows the LIF signal to be recovered from overwhelming background emission of the plasma, even at low laser power (~5 mW). The ion velocity distribution functions (IVDF) are measured under various plasma conditions. From the IVDFs, the plasma flow velocities and the ion temperatures are deduced by assuming Maxwellian-shaped distribution function. Present results, capabilities, and limitations of the LIF system are discussed along with future applications on IVDF measurements in an X-point magnetic configuration.