1. Updates On THE Optical Emission Spectroscopy AND Thomson Scattering Investigations on the Helicon Plasma Experiment (HPX)*
*Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY13
Presented By:
1/c Omar Duke-Tinson
2/c Jackson Karama

2. ABSTRACT
Now that reproducible plasmas have been created on HPX at the Coast Guard Academy Plasma Laboratory (CGAPL) we have set up spectral probes to help verify plasma mode transitions to the W-mode. These optical probes utilize movable filters, and ccd cameras to gather data at selected spectral frequency bands. Raw data collected will be used to measure the plasma's relative density, temperature, and the plasma’s structure and behavior during experiments. Direct measurements of plasma properties can be determined with modeling and by comparison with the state transition tables, both using Optical Emission Spectroscopy (OES). The spectral probes will take advantage of HPX’s magnetic field structure to define and measure the plasma’s radiation temp as a function of time and space. The spectral probe will add to HPX’s data collection capabilities and be used in conjunction with the particle probes, and Thomson Scattering (TS) device to create a robust picture of the internal and external plasma parameters. TS internal temperature and density data will track HPX plasma transitions through the capacitive and inductive modes as it develops into helicon plasma. Once achieved, the system will be invaluable in making quantitative plasma observations in conjunction with the Optical Emission Spectroscopy (OES) System. Recently CGAPL, has focused on building its laser beam transport and scattered light collection optical systems. The high energy laser (HEL) will be configured to directly enter the side port of the chamber, with collection optics mounted on the top port. HPX has acquired and will employ an Andor ICCD spectrometer in a setup similar to HBTEP at Columbia University, for the spectral analysis of the scattered light. Data collected by the TS system will then be logged in real time by CGAPL's Data Acquisition (DAQ) system with remote access to under LabView. Further additions and progress of the OES probe, TS alignment, installation, and calibration on HPX will be reported.
*Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY13

3. Complete TS Detection System: Radiation Collection
Example Thomson Scattering System in Plasma

4. Collection Optics Allow Light to be Transferred to Spectrometer
Refracted light is absorbed though a set of fiber optic wires per spatial point ~ 4X Magnification
Spectrometer separates the wavelengths of scattered light
Photomultiplier reduces gain loss and transforms photons
Fiber Lenses Diverge Volume
Photomultiplier in photocathode allows for compound to emit electrons into fiber optic, photoelectric effect

5. Incoherent Scattering Requires Probe Collection
Electric Field is used to determine Energy of Scattered Light
Probes Detect Energy Levels via Wavelengths from a distant point
Scattered Light is coherent [directional] when collected by spectrometer
Accuracy is Increased

6. Volume Phase Holographic (VPH) Grating Produces Coherent Signal
Transforms Incoherent Scattering light to Coherent Form
Deflects Unwanted wavelengths and transmits selected wavelengths at desired angles
Dichromated Gelatin Coated on Glass
Up to 6000 lines/mm
Compact Setup to Spec.
Ultrafast Laser – signal amplification

7. Recently Acquired Andor iStar DH334T Image Intensified Charge Coupled (ICCD) Spectrometer
Quality Components are Delicate and Expensive!
Specification
Detail
1024 x 1024
Sensor Resolution
13 μm2
Pixel Size
Near Infra-Red
Photocathode Type
114,800
Electrons / Pixel
380 – 1090 nm
Wavelength Range
Calculating Interference from Noise

8. Electron Energy Distribution Function
Particle in a box wave function.
Determine the eigenvectors to correlate the wave function
Can only determine energy function at a moment in time.
Coherent vs. incoherent results of a relativistic particle

9. Solis Software Package Controls iStar in Real Time
Full Automated Spectrometer Control ~ remote resolution
2D & 3D Models
Data exported to LabView GUI
Input Equations
Most Essential Equation:

10. New Laser

11. HPX Next Steps? NEXT UP: Jackson Presents OES Build Collection Optics
Laser Port Hole
Collection Optics
to Spectrometer Port
Probe Housing
RF Plasma Ignition
Build Collection Optics
Configure / Demo Spectrometer
Assemble
Acquire New Laser
NEXT UP: Jackson
Presents OES

12. Visit CGA PLASMA LAB Online!
Keeping updated on the latest development and research of all things plasma

13. Optical Probes on HPX Verify TS & Particle Probe Data
Helicon Plasma Ignited in Pyrex Tube
Optical Probes Installed
Spectrometers Record Emissions & Send to DAQ

14. OES - Currently Main Data Collection Source
Measures Relative Plasma Density & Temperature
Recorded wave length corresponds to specific energy transitions - ID density and temp

15. Optics Used to Explore Neutrals
Filters change collected wavelength
Fiber optic cable collects & transmits signals to spectrometer
CCS Spectrometer
Courtesy of Thor Labs
Visible – Wide range, low res
range: 200 – 1000 nm
resolution: < 2nm FWHM @633 nm
NIR– Smaller range, Higher resolution
range: 500 – 1000 nm
resolution: < .6 nm FWHM @633 nm

16. Long Term Experimental Goals for OES
1. Measure Plasma Density & Temp to Compare with Thompson scattering
Apply Ar Kinetic Code to HPX
particle properties from energy transitions
Compare Transitions to Get intensity Ratios
Calculate transition probabilities to determine measured ne & Te values

17. Long Term Experimental Goals for OES
1. Measure Plasma Density & Temp to Compare with Thompson scattering
Apply Ar Kinetic Code to HPX
particle properties from energy transitions
Compare Transitions to Get intensity Ratios
Calculate transition probabilities to determine measured ne & Te values
Internal Mode Structure
A) Ar neutrals: create ‘map’ with nm Interference filter
D-alpha: same internal mode investigation, just with D2
Mode structure data from Da emissions on HBT-EP
-Courtesy of Columbia University

18. Cadet Summers