Overview of the CMOS cameras used at JET Itziar Balboa, Scott Silburn, Guy Matthews, Dave Kinna, Bernhard Sieglin, Thomas Eich, Michael Faitsch, Tim May-Smith, Alexander Huber, Valentina Huber, Marcus Price, Graham Jones and JET contributors* * See the author list of “X. Litaudon et al 2017 Nucl. Fusion 57 102001″ Date: 26.06.18 Contents .Joint European Torus (JET) . Camera diagnostics at JET . Applications: - Plasma Imaging - Infrared Thermography . Summary I. Balboa | 2018 EIROforum workshop: CMOS Sensors| CERN | 26.06.18 | Page 2 JOINT EUROPEAN TORUS (JET) JET is a research facility that houses the world largest tokamak for fusion research Goals: Develop a new form of renewable energy to supply electricity How: Capturing the energy released in fusion reactions Plasma confined by magnetic fields JET ENVIRONMENT . High Magnetic Fields (1-3 Teslas) . High Current to >4.106 Amps . High Current Transients > 108 A/s . Neutrons and gamma rays DIAGNOSTICS: . Instrumentation to a) Measure plasma properties b) Evaluate plasma performance c) Investigate plasma instabilities, etc.. c) Protect components inside tokamak . Total: ~ 100 diagnostics . Camera Diagnostics: 32 I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 3 JOINT EUROPEAN TORUS (JET) JET TOKAMAK inside the TORUS HALL (38 m2 x 25m (height)) BIOLOGICAL SHIELD WALL - protection from radiation I. Balboa | 2018 EIROforum workshop: CMOS Sensors| CERN | 26.06.18 | Page 4 Inside the JET tokamak Inside of tokamak and superimposed with a photo of the plasma Tokamak is made of individual components known as “Tiles” Main tile materials: Beryllium, Bulk Tungsten and Tungsten coated carbon tiles I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN | 26.06.18 | Page 5 Camera diagnostics at JET • Camera diagnostic = camera + filter + optics + software • Goal: Imaging the plasma/tiles from optical windows at the vacuum boundary • Applications: - Displaying the plasma pulse (see video) - Machine protection – keeping within thermal limits in order to prevent damage to tiles inside the vessel - Characterizing events within the plasma - Monitoring of plasma impurities - Infrared Thermography for quantitative scientific analysis • Total: 32 systems I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 6 Camera diagnostics at JET • Location: - Most systems are next to the tokamak (inside Torus Hall ) - Recently: selection of cameras systems installed outside Torus Hall • Why installing systems outside the TH?: - Radiation damage – camera reliability affected by neutrons/gammas - Examples given in the next slides Name of presenter | Conference | Venue | Date | Page 7 CMOS camera systems at JET . In the past CMOS camera systems have been used for - High Speed Imaging (visible) - Quantitative Infrared Thermography (Hybrid CMOS) . New CMOS camera systems have been installed for -Visible plasma imaging to support operation (qualitative) - Machine protection (quantitative) I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 8 Plasma Imaging Example of a camera located outside the TH and used to display the plasma pulse SPECIFICATIONS KLDT-O5WB Supplier ZWO Sensor Type Colour CMOS (1/1.2”) Model ASI174MC-COOL Pixel Array 1936 x 1216 (2.3Mega Pixels) https://astronomy-imaging-camera.com Pixel Pitch 5.86µm Sensor Size 11.3 x 7.1 mm2 Exposure Range 32µs - 300s Interface USB 3.0 ADC 12 bits I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 9 Plasma Imaging - Video Video of a plasma pulse (speed x16) I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 10 High Speed Imaging - Function: Identify fast events and structures during the plasma pulse (qualitatively) SPECIFICATIONS Diagnostic Names: KL8 & KLDT-E5WE Supplier PHOTRON Model FASTCAM APX-RS Sensor Type CMOS Monochrome Pixel Array 1024 x 1024 Pixel Pitch 17µm https://photron.com/ Sensor Size 17.4 x17.4 mm2 Frame Rate (FPS) 60 (full frame) 250,000 (128 x 16) Interface IEEE 1394 (FireWire) ADC 10 bits I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 11 High Speed Plasma Imaging Identical cameras in different locations (inside TH and outside TH) to identify plasma structures Name of presenter | Conference | Venue | Date | Page 12 Infrared Thermography - Functionality • Measuring Surface Temperature of Plasma Facing Components • Calculating Heat Fluxes • Goal: Understand the plasma load onto plasma facing components to allow performance optimisation I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 13 Infrared Thermography – Specifications SPECIFICATIONS Diagnostic Name: Diagnostic Name: KL7 KL3B, KL9s Supplier CEDIP FLIR Sensor Type InSB (FPA1) InSB (FPA1) Pixel Array 640 x 512 320x 256 Pixel Pitch 25 30 Sensor Size 16 x 12.8 mm2 9.6 x 1.68 mm2 https://www.flir.com NETD2 < 20mK < 20mK Frame Rate 60Hz (Full Frame) 380Hz (Full Frame) Sensor 77K 77K Temperature Wavelength 1-5.4µm 1.5-5.0µm Response Interface CamLink Gigabit Ethernet ADC 14 bits 14 bits 1FPA: Focal Plane Array 2NETD: Noise Equivalent Temperature Difference I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 14 Infrared Thermography – Magnetic Fields • Magnetic fields can induced eddy currents which affect camera electronics • Cameras exposed to: - DC magnetic field < 0.2T - Time varying magnetic field: 0.25T/s • Measures taken against effects of magnetic field: i. Placing the camera inside a magnetic shielding box - Shield box: material: soft iron thickness: 30mm weight: 250kg ii. Removal of ferrites from sensor & cooler electronics I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 15 Infrared Thermography – Magnetic Fields Installation of a camera inside magnetic shielding box I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 16 Infrared Thermography – Applications Group Selfie - Infrared image of the inside of the tokamak - Colours represent Temperatures Temperature of inner & outer wall Beryllium tiles Temperature range: 200-1200C Spatial resolution: tens of millimetres per pixel I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 17 Infrared Thermography –Tiles in-vessel JET Tokamak Divertor or Exhaust Castellated structure Materials: - Bulk Tungsten -Tungsten coated Spatial resolution < 2mm per pixel HEAT FLUX PROFILE (#91735 @ 48.4s) Pulse 91735 Stack C I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 18 Infrared Thermography – Calibration - Calibration of the entire camera system using a hot source inside the vessel - Goal : Convert Raw signal to Temperature - Hot source held by robotic arm and pointing towards optical window - Calibration only takes place when there are no operations (maintenance & servicing) Robotic Arms Infrared image of hot source Hot Source I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 19 Infrared Thermography – NUC • Focal Plane arrays (FPA) show - Variations in gain and offset for each individual pixel • Result: noise pattern added to the image • Correction: Non-Uniformity correction (NUC) • NUC Set up: - relative large hot source in front of the camera (20cm2) taking measurements at two temperatures - Gold mirror in front of the sensor I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 20 Infrared Thermography – Failure Mode Failure: Loss of communication with Device Impact: No acquisition Loss of Data during the JET pulse (1 JET pulse costs ~€20k) Cause: Ancillary electronics are damaged by neutron/gamma-rays I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 21 Infrared Thermography – Failure Mode Level of Damage – Escalation: Rebooting Camera Uploading firmware FPGA Board Replacement Camera Replacement Firmware Upload: - This is done via serial port of the camera - Frequency: ~ 1 month - Neutron yield: 1.6 x 1018 n (see reference [1]) - Neutron fluence in the area: 4.3 x 109 n/cm2 (see reference [1]) Moving Forward: Two solutions - Solution 1: Remove ancillary electronics from Torus Hall - Solution2: Relocate camera system to outside the Torus Hall Reference [1]: “Response of the imaging camera to hard radiation during JET operation”, A. Huber et. Al, Fusion Engineering and Design 123 (2017) 669-673 Name of presenter | Conference | Venue | Date | Page 22 Infrared Thermography – Solution 1 IN-HOUSE ALTERNATIVE SOLUTION SPLIT THE CAMERA DEVICE IN TWO BIOLOGICAL SHIELD WALL IN TORUS HALL OUTSIDE TORUS HALL SENSOR & COOLER ONLY FRAME GRABBER . In this configuration the sensor is inside the tokamak building but the frame grabber is located outside the tokamak building. Detector connected to frame grabber via optical link . This configuration has been tested successfully for three months I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 23 Infrared Thermography – Solution 1 SPECIFICATIONS Diagnostic Name: KL9B Supplier SEMICONDUCTOR DEVICES Model Pelican-D Sensor Type InSB (FPA) Pixel Array 640 x 512 Pixel Pitch 15µm Sensor Size 9.6 x 7.68 mm2 Frame Rate (FPS) 300 Hz (full frame) http://www.scd.il Sensor Temperature 77k (Stirling Cooler) Wavelength 3.6 – 4.9µm Response I. Balboa | 2018 EIROforum workshop: CMOS Sensors | CERN| 26.06.18 | Page 24 Infrared Thermography – Solution 2 Concept: BIOLOGICAL OUTSIDE TOKAMAK BUILDING TOKAMAK BUILDING SHIELD WALL SELECTED CAMERA SYSTEMS PENETRATION TUBE 1 Total: 5 cameras sys. MIRROR + RELAYS PENETRATION TUBE 2 Total: 2 systems