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

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

Complete TS Detection System: Radiation Collection Example Thomson Scattering System in Plasma http://www.aa.washington.edu/research/ZaP/images/Thomson_Schematic.png

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

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 http://www.kosi.com/Holographic_Gratings/vph_ht_overview.php http://www.kosi.com/Holographic_Gratings/vph_ht_overview.php

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 http://www.kosi.com/Holographic_Gratings/vph_ht_overview.php Up to 6000 lines/mm Compact Setup to Spec. Ultrafast Laser – signal amplification http://www.kosi.com/Holographic_Gratings/vph_ht_overview.php

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

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

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:

New Laser

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

Visit CGA PLASMA LAB Online! Keeping updated on the latest development and research of all things plasma http://cgaplasma.wordpress.com/

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

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

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

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

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 694.3 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

Cadet Summers