Development of a Laser Induced Fluorescence Diagnostic System for Hall Thruster Plasmas Laser Induced Fluorescence (LIF) Diagnostics LIF System under Preparation Wonho CHOE 1 , Holak KIM 1 , Seunghun LEE 1,2 , Guentae DOH 1 , Sung-Young YOON 3 1 Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea 2 Korea Institute of Materials Science (KIMS), Republic of Korea 3 National Fusion Research Institute (NFRI), Republic of Korea 3 Korean LEO Satellites in Orbit DubaiSat - 2 Deimos - 2 STSAT - 3 z r Anode Inner wall Outer wall Multiply charged ions High energy ions Plasma instability Plasma wall interaction Electric Propulsion and KAIST R&D Fundamental Physics Research laser = exc 1 − / = 834.7233 1 − / nm + laser Tunable Laser • Plasma characteristics have been investigated using various diagnostics (e.g. Faraday, RPA, ExB etc), however, mostly outside the channel due to high energetic ions. • LIF is a powerful diagnostics to obtain important physics information including plasma potential and 2-D ion acceleration profiles, which are related to our recent research (wall interaction, high energy ions, multiply charged ions etc). Xe + *S. Mazouffre, PSST 22, 013001 (2013) Ion Velocity Distribution Function Measurement Window Pinhole Mount 126.45mm 10.27mm 16.00mm 88.62mm 30.88mm 10.00mm 36.10mm 1 st Lens Mount 2 nd Lens Mount 3 rd Lens Mount 12.70mm 12.70mm 12.70mm 2.0mm 4.0mm 0.04mm 2.5mm 4.0mm 4.0mm 111.16mm 5.79mm 38.10mm 3.96mm 21.0mm 11.7mm 32.60mm 2.5mm Doublet Lens 5.5mm 4.7mm 74.72mm 13.68mm 32.20mm 12.50mm PMT House 18.9mm 9.50mm Optics Board Front 6.0mm 1.62mm Distances between Lens (For Zemax) Distances between Mounts (For Mounting) 26.89mm Focus Point 4.51mm Schematic Diagram Optical Path of Detector ESA Electric Propulsion Space Missions Hayabusa-1 μ-10 thruster Electric Propulsion Applications a b 2 b 1 c d e Alignment of Detector The LIF system consists of a tunable diode laser (834.72 nm, Mode hop free tuning: 50 GHz, 90 mW) and a wavemeter (700-1650 nm, accuracy: 1 pm). Optical path was demonstrated by computer calculation and components were aligned by using a visible laser. Difficulties: - Large focal length (1 m) to get signals outside vacuum Not enough fluorescence (541.9 nm) by the laser - Strong fluorescence (541.9 nm) without laser Hard to distinguish the fluorescence - Using lens with short focal length (< 1 m) and increasing laser power could be an alternative.