Asdex Upgrade Seminar IPP Garching, 16th November 2011 Divertor Da-Light Profiles in AUG - First Results of New Strike Point Observation Diagnostics - Arthur Weller IPP Garching Acknowledgments for substantial assistance to: T. Lunt, A. Mayer, P. Bischoff, B. Kurzan, Ch. Veth, and the ASDEX Upgrade Team A. Weller, SPO@AUG, Garching 2011

Introduction Connection Lengths (EMC3/EIRENE) T.Lunt, ASDEX Upgrade Major goals of Strike Point Observation (SPO) diagnostics ● Measure light intensities of Ha(Da) & CIII across divertor plates ● assess particle fluxes of H(D) and C by normalizing measured intensities with data predicted by edge model (e.g. EMC3/Eirene) ● characterize footprints of particle interaction with divertor including effects of ELMs and of ELM RMP coils T.Lunt, ASDEX Upgrade A. Weller, SPO@AUG, Garching 2011

Outline Experimental Setup  Optics, CMOS Camera  Laboratory Measurements, Calibration  Arrangement on AUG Initial Measurements on AUG  Analysis Tool  Camera Images & Intensity Histograms  Da Light Profiles & Time Traces  Effect of ELMs and RMP coils Summary A. Weller, SPO@AUG, Garching 2011

Introduction - diagnostics needed refurbishments (new camera & fibres) - ● 2 fibre arrays monitoring light emission across inner and outer divertor plates ● beams splitted into Da- and CIII components ● measured by fast CCD/CMOS camera old system (until end of 2009) A. Weller, SPO@AUG, Garching 2011

Phantom Miro eX4 (VisionResearch) - some data - resolution [pixel] 800x600 pixel size [mm2] 22x22 sensor size [mm2] 17.6 x 13.2 sensitivity [ASA] mono. 4800 ADC [Bit] 12 (real) frame rate [fps] 1265 f. r. (reduced) [fps] 16100 (512x64) memory (GB) 2 interface (data & control) Ethernet (10/100BASE-T) min. shutter [ms] A. Weller, SPO@AUG, Garching 2011

Phantom Miro 4 vs. Phantom 7.3 - both cameras use 12-bit ADCs - Ha + grey-filter 12 (attenuation 1:1640) Ha + grey-filter 13 (attenuation 1:3610) Intensity Histograms Miro 4 Miro 4 Miro 4 structure due to pixel calibrations ? average over 100 frames Phantom 7.3 Phantom 7.3 Phantom 7.3 A. Weller, SPO@AUG, Garching 2011

Tests and Calibration ● Assembly without filters ● 2 fibre bundles (100 m fibres) ● 85 mm Nikkor object lens towards fibre bundle, 50 mm Nikkor lens on camera  light points fit into 256 x 128 pixel frame ● Homogenous illumination of fibres with calibrated Ulbricht sphere A. Weller, SPO@AUG, Garching 2011

Tests and Calibration ● 2 fibre bundles : - good old bundle (LWL_old) test_spo_lwlalt+lwlneu1-ulb_half+grey13_c3_256x128_8000mues_b2_8_calib-6.cine LWL_old CIII LWL_old Ha + grey LWL_new-1 Ha + grey LWL_new-1 CIII broken fibre ● 2 fibre bundles : - good old bundle (LWL_old) - new bundle (LWL_new-1) but fibres disordered (to be replaced again !) ● SPO optics generates 4 rows of fibre light spots (each bundle split into Ha - and C III - light ● Ha - channel attenuated by additional grey filter ● light profile shows vignetting vignetting effect A. Weller, SPO@AUG, Garching 2011

Vignetting Correction (optional) Low field side divertor Ha profiles (#26840 @ 2.0 s) raw data corrected A. Weller, SPO@AUG, Garching 2011

Calibration of Ha Intensities ● absolutely calibrated Ulbricht sphere used ● transmittance of grey filter, Ha-filter and dichroic beam splitters measured A. Weller, SPO@AUG, Garching 2011

Calibration of Ha Intensities calibration with Ulbricht sphere (distance to fibre head ≈ 20 cm) Ha channel, low field side divertor fibres edge fibres not illuminated A. Weller, SPO@AUG, Garching 2011

Determination of Regions of Interest (ROI) - to be used for online image analysis - low field side high field side + reflexes CIII – channel removed in present setup, but still reflexes from hf-side fibres A. Weller, SPO@AUG, Garching 2011

Experimental Setup - LOS directed to gap between sectors 12 and 13 (f = 270°) - Optical heads mounted underneath lower divertor viewing through gaps ● toroidal alignment of LOS into gap between adjacent tiles to reduce light reflection fibres (100 mm) arranged in 2 bundles (2 x ~65 fibres) A. Weller, SPO@AUG, Garching 2011

Neutral Penetration, Neutral Decay Length - neutral density across divertor gap ? - according to Goldston, Plasma Physics (including e--impact ionization and CX) ● no significant change of neutral density expected across gap A. Weller, SPO@AUG, Garching 2011

Neutral Penetration, Ha Emissivities - Te and ne dependency - neutral profiles according to Goldston, Plasma Physics ● line of sight integrated intensity only weak dependence on Te ● Expected Ha intensity roughly consistent with measured values A. Weller, SPO@AUG, Garching 2011

Experimental Setup - Line of Sight Geometry - Div II d Light Spots from Fibre Illumination inner divertor target plate TPi TPic ● spatial resolution ~ 3-4 mm ● S-coordinate of spots measured (backward illumination) ● R-z coordinates of spots calculated A. Weller, SPO@AUG, Garching 2011

New SPO Line of Sight Geometry - S-coordinates and R-z coordinates - A. Weller, SPO@AUG, Garching 2011

axial tilt angle adjustment Experimental Setup - assembly of adjustable support & magnetic shielding - axial tilt angle adjustment for optics & camera horiz. & vert. camera shift interface to flange of fibre outlet window soft iron camera shield fibre outlet in port 13Du (sector 13) A. Weller, SPO@AUG, Garching 2011

SPO Data Acquisition - Fast Camera TooL (Ch. Veth) - ● Shot synchronized DAQ ● SPO C++ software using Phantom toolkit routines for camera control & data transfer ● black balance before shot ● image processing: - mean intensities (t), (reduced frame rate) - intensity profiles (t) from ROI processing (not yet used) ● video stored in .cin format in requested time interval (optional) A. Weller, SPO@AUG, Garching 2011

Data Analysis (Stored Video Processing) ● image display (single frame, aver. frames, contrast optimization) ● full image histogram ● profiles along line ● ROI generation ● intensity calibration ● S-coordinate transf. ● time resolved intens. A. Weller, SPO@AUG, Garching 2011

Ha Signal from SPO - compared with ELM Ha signal ELMa-Han - (4000 fps, averaged over profile) A. Weller, SPO@AUG, Garching 2011

SPO Data in AUG DL Discharge - shift of strike point (outer divertor plate) - #26901 Ha-Emission across Outer Divertor A. Weller, SPO@AUG, Garching 2011

SPO Data in ELM and Inter-ELM Phases - low field side Ha profiles, #27028 - A. Weller, SPO@AUG, Garching 2011

SPO Raw Data in ELM and Inter-ELM Phases - low field side Ha profiles, #27028 klick in frame to start movie … low field side fibres high field side fibres (disordered) #27028, 3.25 – 3.50 sec, 4000 fps, 304 x 104 pixels ● Vibrations during shot  shift of light pattern on CMOS chip ● poloidal movement of strike point during ELM, field perturbation ? A. Weller, SPO@AUG, Garching 2011

Single ELM Profile Evolution - low field side Ha profiles, #27028 - ● ELM induced particle fluxes strongly peaked on target plate ● poloidal movement of strike point during ELM, field perturbation ? A. Weller, SPO@AUG, Garching 2011

SPO Data in AUG ELM Mitigated Discharge - low field side Ha profiles, #26853 A. Weller, SPO@AUG, Garching 2011

SPO Data in AUG ELM Mitigated Discharge - low field side Ha profiles, #27076 A. Weller, SPO@AUG, Garching 2011

SPO Data in AUG ELM Mitigated Discharge - low field side Ha profiles, #26840 - residual ELMs at lower density ELM-free phase #26840 A. Weller, SPO@AUG, Garching 2011

First EMC3/EIRENE Modelling - ELM mitigated shot 26081@4.9 s - Tilmann Lunt no RMP coils with RMP coils SPO plane ion flux across div. along toroidal angle SPO plane electron density ne A. Weller, SPO@AUG, Garching 2011

Conclusions & Outlook  SPO (Strike Point Observation Diagn.) operational again (not fully) new camera (Phantom Miro 4eX), new support & magn. shielding  Issues with inner divertor fibre bundle, window light reflexes and port movements / vibrations to be resolved  pre-processing of ROIs by Fast Camera Tool requires vibrationless recording, not yet realized; videos stored  first experimental data (low field side): - light emission during ELMs strongly localized in poloidal direction, poloidal movement during ELMs - very broad in inter-ELM and ELM-mitigated phases - no distinct strike line splitting observed so far (structures smoothed by LOS integration effects ?) - changes of equilibrium seen by strike point movements  calibrations to be checked by comparison with other measurements and with edge modelling, high spatial resolution desirable A. Weller, SPO@AUG, Garching 2011

Conclusions & Outlook  SPO (Strike Point Observation Diagn.) operational again (not fully) new camera (Phantom Miro 4eX), new support & magn. shielding  Issues with inner divertor fibre bundle, window light reflexes and port movements / vibrations to be resolved  pre-processing of ROIs by Fast Camera Tool requires vibrationless recording, not yet realized; videos stored  first experimental data (low field side): - light emission during ELMs strongly localized in poloidal direction, poloidal movement during ELMs - very broad in inter-ELM and ELM-mitigated phases - no distinct strike line splitting observed so far (structures smoothed by LOS integration effects ?) - changes of equilibrium seen by strike point movements  calibrations to be checked by comparison with other measurements and with edge modelling, high spatial resolution desirable A. Weller, SPO@AUG, Garching 2011