Structural Integrity Assessment of Long Focus - Spectro Telescope (LF-ST) for ITER

  • Structural analysis of the LF-ST of the H-alpha instrument for ITER
  • Analyses encompassing dead weight, seismic loads, thermal loads, and electromagnetic loads
  • Multidisciplinary analyses including computation of eddy currents and resulting electro-magnetic forces
  • Structural assessment according to RCC-MR / SDC-IC standards (stress categorization and linearization)



Design and Analysis for Flexure Hinge Concept for Detector of ITER Bolometer Sensor

  • Bolometer sensors are based on Platinum absorber, which are deposited on thin Silicon or Silicon Nitride membranes (3µm). These absorb the plasma light and the resulting temperature increase is used as measure for the plasma power.
  • Due to the different coefficients of thermal expansion between Silicon and Platinum and the induced temperature increase of several 100K, significant mechanical stress levels are generated in the Silicon membrane
  • Previous experiments and FE analyses showed that especially the transition area between the detector membrane and the 600µm thick base Silicon substrate are critical
  • By introducing Silicon flexure hinges between the detector membrane and the substrate, the mechanical stress levels could be reduced significantly.
  • The design of the flexure hinges as well as their effectiveness have been verified by extensive FE analyses and optimization.
  • Furthermore, the flexure hinges have been implemented in prototype detectors and their thermos-mechanical strength has been verified in respective experiments.



Experimental Thermal Investigation of ITER Bolometer Camera

  • Bolometer cameras are subject to significant thermal loads induced by nuclear heating as well as radiation (collimator area)
  • The heat transfer to the vacuum vessel wall (acting as heat sink) has decisive influence on the temperatures in the Bolometer camera and thus its expected life span and sensor performance
  • FE analyses showed the high sensitivity of the sensor temperatures on the thermal contact conductivity towards the vessel wall as well as between the different camera components
  • For the verification of the used FE model, an experiment has been set up for the complete Bolometer camera for investigating and verifying the thermal contact conductivities
  • The results of the experiments showed a good agreement with the FE analyses with respect to temperatures and temperature distribution. Thus the quality and accuracy of the FE model (and the applied thermal contact conductivity parameters) has been verified successfully.
  • The verified FE model can now be applied to further thermal load cases with a high degree of confidence



Biaxial load test of ITER Vacuum Vessel Support

  • An ITER vacuum vessel support is subject to forces in two directions and to moments in three directions.
  • The worst case loads are caused Vertical Disruption Events and are in the MN / MNm range.
  • The experimental verification of the design has been performed using scaled down (1:3) mock-up built by KRP.
  • For the test, the operational load cases have been transformed to test load cases in such a way that they could be realized with only a 2-axis load introduction. The additional moment loads are considered by applying appropriate offsets to the load introduction points.
  • A test set-up for loads up to 5.6MN (560t) in the first axis and 2.0MN (200t) in the seconds axis has been developed and manufactured
  • The measurement equipment include ~ 100 stran gauges and ~10 displacement sensors
  • Permanent deformations have been evaluated using a coordinate measuring machine.
  • The measured strain levels were used for the verification of corresponding FE models as well as for the definition of manufacturing tolerances for the ITER vacuum vessel support



Experimental Investigation of Thermal Contact Conductivity for Clamped and Bolted Connections for ITER Bolometer Camera

  • A big variation of TCC values found for the respective material combinations in literature ranging from 500W/m2K to 20.000 W/m2K lead to high uncertainty in the thermal analysis results
  • For the ITER Bolometer Camera, analyses showed the high sensitivity of the thermal analysis results on the TCC parameters
  • The accurate knowledge of the thermal contact conductivity (TCC) is important for the quality and accuracy for FE models used for the thermal analysis
  • The objective of the experimental campaign was the precise determination of the TCC for the specific thermal contact combinations in the ITER Bolometer camera
  • In the first test campaign, an ideal specimen geometry with a homogenous contact pressure distribution has been employed
  • Various studies with respect to the influence of varying contact pressure as well as interface materials (graphite foils) have been performed.
  • In the second test campaign, a typical geometry of a bolted connection has been tested (flange geometry)
  • The local pretension forces of the bolts lead to a inhomogeneous contact pressure distribution and thus varying thermal contact conductance
  • In this test campaign the effect of bolt pretension, bolt distance, and again interface foils have been investigated.
  • A special test set up for these experiments has been designed and manufactured




Design and Manufacturing of a Mock-Up of the ITER Vacuum Vessel Support and Performance of a Vertical Load Test

  • Design of a 1:3 scaled Mock Up of the ITER vacuum vessel support (mass ~600kg)
  • Support and supervision of manufacturing
  • Determination of strain gauge measurement points using FEM analyses
  • Development and optimisation of assembly procedure
  • Application of strain gauges (15 rosettes and 28 single strain gauges)
  • Development, design, and manufacturing of test set-up
  • Performance of vertical load test:
    • Maximum pressure forcet: 1,7MN (=170to)
    • Functional test of MoS2-coating on one axis
      • Integration of a 17kNm hydraulic  rotary actuator
      • Rotating of the lower support bolt +/- 1° and measuring of the friction coefficient under load
      • Life cycle test: 300 cycles
    • Investigation of load paths for different load introduction positions
  • Identification of damages on coating
  • Derivation of improvement proposals for design and assembly



Determination of Emissivity Coefficients of TZM for Different Surface Treatments

  • Experimental determination and optimisation of TZM (Titanium-Zirconium-Molybdenum) emissivity coefficient for different machining procedures:
    • Milled and turned
    • Water jet cut
    • Sandblasted (different  blast media)
    • Glass bead blasted
    • Electropolished

Structural Dynamics Investigation of ITER Bolometer Detector

  • Dynamic loading of ceramic components of the detector support as well as the detector membrane
    • Determination of expected dynamic load during disruption events in ITER
    • Application of dynamic load using electro-dynamic shaker
    • Monitoring of detector membranes during the tests
    • Determination of eigenfrequencies of the detector membrane
    • Contactless vibration measurement of the 5µm detector membrane with a 2 beam laserinferometer (SIOS) with a sampling rate of 10kHz


Life Cycle Test for Coatings of the ITER Vacuum Vessel Supports

  • Investigation of coating materials for the ITER vacuum vessel supports (vacuum vessel mass: 10.000.000 kg)
  • Elaboration of test campaign and modification of the friction test facility
  • Boundary conditions for the test set-up:
    • Temperature: RT to 200°C (electric and water heating)
    • vacuum: 1e-6mbar
    • Force: up to  900kN
    • Friction force: up to 200kN
    • Sensors: mechanical, thermal and acoustic
  • Performance of qualification test for the Korean National Fusion Research Institute (NFRI) in collaboration with ITER Organisation and the Korean Domestic Agency (KO DA)



Thermomechanical FEM Analysis of the ITER bolometer detectors

  • Determination and evaluation of the thermal loads
    • thermal radiation from the plasma and the neighbouring divertor modules
    • heat conduction from the vacuum vessel
    • nuclear heating
  • Investigation and implementation of temperture dependent material properties
  • Calculation of thermal displacements
  • Local analysis of the collimators line-of-sight and stresses in the detector foil
  • Investigation of the change of the screw pretension due to different coefficients of thermal expansion·of the connected components and the screw itself
  • Investigation of alternative materials for selected camera components in order to minimize thermal deformation and stresses
  • Detailled evaluation of the heat fluxes at a variation of the heat transfer coefficients and materials

Electromagnetic mechanical FEM Analysis of the ITER bolometer detectors

  • Setup of a FEM model for the calculation of the structural load of the bolometer due to electromagnetic loads induced by disruptions
  • Development of a simulation routine for electromagnetic loads on fusion experiments (see Service)
  • Extraction, visualisation and implementation of the time-varying magnetic field (B-field) from DINA simulations
  • Calculation of the eddy currents due to variation of the magnetic field
  • Calculation of the magnetic forces due to the eddy currents and the static magnetic field
  • Calculation of the resulting displacements, stresses and bolt loads
  • Investigations on the minimisation of the electromagnetic loads by insulation layers (reduction of eddy currents) and non-magnetic and non-conductive materials
ITER Bolometer DINA B export.gifITER Bolometer electromagnetic analysis.jpg
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Vibration test for an Endoscope for the Fusion Experiment Joint European Torus (JET)

  • Resonance search and sinus test in all three axis
  • Verification of the optical performance and mirror allignment before and after the test
  • Design and manufacturing of the vibration interface structure·
JET Endoscope Vibration Test Optical Head.jpgJET Endoscope Vibration Test Overview.jpg
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Thermal-Vacuum test for an Endoscope for the Fusion Experiment Joint European Torus (JET)

  • Design, assembly and commissioning of a TV-chamber and thermal actuator with optical feed-through
  • Performance of thermal vacuum cycles up to 320°C
  • Verification of the optical performance at elevated temperatures
  • Performance of a mass spectroscopy measurement
JET Endoscope Thermal Vacuum Test Heater.jpgJET Endoscope Thermal Vacuum Test Chamber.jpg

Development of a measurment device for divertor tartet modules

  • Device for the verification of the assembly tolerance of the divertor hight for the fusion experiment W7-X
  • Inspection of 10 different module types on a dedicated control surface plate with realistic mechanical support elements
Divertortarget dimensional Measurement Equipment.jpg



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FEM Analyses for an Endoscope for the Fusion Experiment Joint European Torus (JET)

  • Computation of the magnetic forces resulting from the transient magnetic field changes during disruption of the plasma
  • Strength analyses of the endoscope structure
  • Computation of the temperature distribution resulting from the thermal radiation of the plasma
  • Computation of the thermal deformation of the optical components as basis for subsequent optical analyses


Development Of A Heating-/Cooling-System Including A Moveable Specimen Holder For The Thermal-Vacuum-Test Stand For Bolometer

  • Development, design, and manufacturing of a heating-/cooling-system for the thermal-vacuum-chamber of a bolometer test stand
    • thermal design
    • integration and assembly
    • initial operation
  • Development, design, and manufacturing of a moveable specimen holder for bolometer sensors (detectors)
    • development of the actuator system (linear drive) for moving the specimen holder under the test laser




Development of a LabView-Interface for the Thermal-Vacuum-Test Stand For Bolometer Experiments

  • Development of an integrated LabView interface including a grapical user interface:
    • thermal control
    • control of the linear drive of the moeveable specimen holder
    • control of the laser
    • operation of the data aquisition system


Life Cycle Tests of NSE-Connection-Elements for the Wendelstein W7-X Fusion Experiment

  • Development test for determination of service life of friction surfaces of the NSE connection elements (Narrow-Support-Elements) for the W7-X fusion experiment (W7-X pages of the IPP)
  • Bixaial load introduction
  • Nomal loads up to 1.5MN
  • Test at cryo-vaccum conditions (77K, 1E-6 mbar)
  • Development and design of test rig
  • Manufacturing and installation of test rig in 2MN testing machine
  • Test operations:
    • Evaluation of different materials for friction surfaces
    • Test of different contact geometries
    • Test of extreme inclination angles of friction surfaces and imperfections of friction surfaces
    • Life cycle tests up to 4000 cycles

Schnitt Vakuum und Kryostat_Proj.png



Testing of Highly Loaded Bolted Connections of W7-X Fusion Experiment

  • Biaxial load test of highly stressed bolted connection of W7-X fusions experiment
  • Loads up to 1MN
  • Tests at cryogenic conditions (77K)
  • Life cycle test (up to 4000 load cycles) and determination of failure load
  • Development and design of test rig
  • Manufacturing and installation of hydraulic test rig
  • Definition, development, and installation of complex test instrumentation (DMS, displacement sensors, acoustic sensors)
  • Test operations
  • Analysis and evaluation of test results

BC CAD Gesamtaufbau_Proj.png



Strength Analysis of Weld Seams of the Calorimeter Plates for the ASDEX Upgrade Fusion Experiment

  • Computation of stresses in the weld seams between the cooling channels of the calorimeter plates for the ASDEX Upgrade fusion experiment (perfomance test of neutral particle heating)
  • Prediction of strength failure of weld seams due to thermo-mechanical loads during operation
  • Non-linear analysis with consideration of temperatur dependent and plastic material characteristics
  • static and transient analysis




Dynamic Analysis of Non-Planar Coil (NPC) of the W7-X Fusion Experiment for Impact Loads

  • Simulation based investigation of dynamic response of a NPC to impact loads for the definition of the Magnetic Quench Tests (MQ-Test) in Saclay
  • Computation of the dynamic response of a NPC to synthetic reference impact load
    • time efficient simulation using modal representaion based state space model
  • Simulation of actual impact process in the projected impact device for the MQ-test
    • simulation of impact process using a 3D model and explicit FEM analyis (LS-Dyna)
    • time efficient simulation of impact process with simplified semi-analytical model (Matlab/Simulink)


Development of Machine for Application of Coating on NSE-Friction Surfaces for the Wendelstein W7-X Fusion Experiment

  • Development of coating machine for automized application of lubricants on the friction surfaces of the NSE-connection elements
  • Features:
    • orbital burnishing of powder lubricants (e.g. MoS2) on the friction surfaces
    • homogenising of sprayed lubricant coatings (e.g. ROCOL-MoS2-Spray)
    • polishing at adjustable contact pressing force
    • establishing a defined moisture level during coating process
  • Design, manufacturing, and initial operation of machine



Development of a Displacement-Measurement-Module for the Divertor-Target-Elements of the W7-X Fusion Experiment

  • Development of a system of the displacement measuring of the divertor-target-elements for weld seam monitoring during operation
  • Application in the GLADIS-project at extreme environmental conditions (vacuum, very highl/low temperatures)
  • Development, manufacturing, and calibration of the system




Electron-Beam-Welded Divertor-Elements for the W7-X Experiment

  • Development and Realisation of a method for mechanical testing the electron-beam welded divertor elements
  • Mechanical measurement of the gap between the cooling channels of the welded (closed) component
  • Design of a test element for hydro-thermal investigations of the gap size




Fatigue Tests and Determination of the Mechanical and Thermal Properties of Electro-Deposed Copper for the Accelerator Grid (SPIDER)

  • Fatigue tests at RT and 300°C in a servohydraulic testing machine with radiation furnace, inert gas atmosphere, and high temperature strain gauges
  • Tension tests at elevated temperatures from RT to 360°C
  • Determination of hardness and corn size
  • Determination of thermal expansion, - capacity, and -conductivity