Development of a Laser Induced Fluorescence Diagnostic System for Hall Thruster Plasmas
Laser Induced Fluorescence (LIF) Diagnostics
LIF System under Preparation
Wonho CHOE1, Holak KIM1, Seunghun LEE1,2, Guentae DOH1, Sung-Young YOON3
1Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea2Korea Institute of Materials Science (KIMS), Republic of Korea3National 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 w
all
Multiply charged ions High energy ions
Plasma instability Plasma wall interaction
Electric Propulsion and KAIST R&DFundamental Physics
Research
𝜆𝜆laser =𝜆𝜆exc
1 − 𝑣𝑣/𝑐𝑐=
834.72331 − 𝑣𝑣/𝑐𝑐
nm
+ 𝑣𝑣 𝜆𝜆laser Tunable Laser
• Plasma characteristics have been investigatedusing various diagnostics (e.g. Faraday, RPA,ExB etc), however, mostly outside the channeldue to high energetic ions.
• LIF is a powerful diagnostics to obtainimportant physics information includingplasma potential and 2-D ion accelerationprofiles, which are related to our recentresearch (wall interaction, high energy ions,multiply charged ions etc).
Xe+
*S. Mazouffre, PSST 22, 013001 (2013)
Ion Velocity Distribution Function Measurement
Window PinholeMount
126.45mm 10.27mm 16.00mm 88.62mm 30.88mm 10.00mm 36.10mm
1st LensMount
2nd LensMount
3rd LensMount
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
DoubletLens
5.5mm 4.7mm
74.72mm 13.68mm
32.20mm
12.50mm
PMTHouse
18.9mm9.50mm
Optics BoardFront
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
b2b1
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 andcomponents 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.