12th ITPA TG Meeting on Diagnostics th March 07, Princeton Radiation Effects WG Benoit Brichard for Eric Hodgson Last meeting of Radiation Experts at 16th IEA Workshop held during SOFT-24 (13th Sept 06) in Warsaw. 21 people attended the 5 h meeting - (EU:15, JA:3, EFDA:2, ITER:1) unfortunately no RF or US colleagues. Updates given on activities: JA (M. Yamauchi) EU / RF / US (E. Hodgson) Extended presentations on: TIEMF / RIEMF (R. Vila and L. Vermeeren) Optical fibres (B. Brichard) Common issues for Magnetic and Inertial Confinement (J.L. Bourgade, M. Decreton, E. Hodgson) Radiation R&D requirements for diagnostics - table update (G. Vayakis) Following is a summary of the presentations + recent work/results ==>

EU Optical fibres (Belgium, France, Rumania): Benoit Brichard (separate presentation) Resistance type bolometers (Belgium, Germany, Spain): Pt on 3 different substrates: alumina, AlN, “SiN” to be irradiated in BR2, SCK/CEN General electrical contact problem* being addressed Ferroelectric type bolometers (Austria, Latvia, Spain): PbZrO 3 with reliable electrical contacts* being prepared - but long delay Hall sensors (IPP:CR + Ukraine): New sensors based on solid solutions of InSb and InAs potential for > 200°C But problems with electrical connections*, solder joints, thin wire insulation Reactor irradiation later this year * Electrical contacts for small devices / components giving problems during irradiation

EU Plan to test various cable types for RIEMF/TIEMF effects with active heating, so a new rig design is necessary. Should give a clue on the performances of various types of MI cables (stainless steel vs. copper core; size effect; single-core vs. twin-core) and of ceramic coated wires and twisted-pair Sultzer cable (OFC). Awaiting cable delivery

EU RIEMF and TIEMF in MI cables and cables (Belgium, Spain): TIEMF (centre conductor) detailed study Examine EMF (V) vs T for Cu, Ni, and SS cored cables Will need some standard “QA” test (e.g. TIEMF for fixed temperature gradient over 1 m) Large EMF Cu related to damage to soft Cu conductor during manufacture - probably no solution Probable cause of high EMF for Ni core also ==> use SS or twisted ceramic coated cables ? Severe damage in CuIncrusted silica

EU Alternative radiation resistant glasses (Belgium, Spain): Tests with Na 2 O-CaO-SiO 2 (+ CeO 2 ) glasses. Radiation induced absorption and RL ≥ 200 ºC shows much lower absorption: Na 2 O-CaO-SiO 2 glass Absorption 0.5 MGy, 70ºC Absorption 0.6 MGy, 200ºC

EU Alternative radiation resistant glasses (Belgium, Spain): Absorption recovers at RT following irradiation ==> unstable defects need in-situ measurements RL (and absorption) is intense in both glasses compared with KU1 and KS-4V: Now preparing RL measurements at high T (≤ 250 C) Absorption 0.2 MGy, 20ºC Radioluminescence, 20ºC

EU Windows, ceramics, mirrors (Spain): Enhanced surface degradation (optical and electrical) by low energy H and He bombardment. XPS analysis shows extreme O sputtering loss for silicas and aluminas Results => Si or Al rich surface zone Potential problem ? Ion conductivity at low residual gas (He, H) pressures (Spain): Necessary to determine potential currents - measure RIC at low pressure => pA/cc/Gy at mbar

EU Secondary overcoated mirrors (Spain): UV enhanced mirrors degrade - radiation modification of coating (thickness, refr. index) Manufacturers specifications not always reliable: HfO 2 for MgF 2 ==> activation ? SiO / SiO 2 ratio ==> swelling cracking corrosion (LOCA)

JA (M. Yamauchi, T. Shikama, S. Nagata, K. Toh, B. Tsuchiya, A.Inouye) 1. RL (Radiation induced luminescence): Fused silica, Cr doped sapphire, and Eu and Dy doped strontium aluminates gamma-ray, ion, and 14 MeV neutron irradiation. Aim to separate ionization and displacement dose effects. RL as sensor for 14 MeV neutrons. Possibility of monitoring ion energy has been demonstrated (Cr in sapphire).

JA 2. Conversion of nuclear radiation energy directly into electricity: RIC is being studied in perovskite oxides with high proton conductivity. Neutron irradiation enhances proton conductivity even at low temperatures ( C). Importance of hydrogen in radiation effects in oxide ceramics. May cause technological problems in nuclear fusion machines, so far not considered.

JA 3. Large EMF in proton conductors (CaZrInO) : Large EMFs observed in some proton conductors  ionizing dose rate (monitor ?) Not the case in other similar materials (SrCeYbO)

RF (Ilya Orlovskiy and Konstantin Vukolov) Development of multilayer dielectric mirrors: heating and neutron irradiation Thermal loads play important role in damaging mirror coating. Sufficient adhesion of coating to substrate for large size mirrors. Sustain neutron fluences and temperatures expected in ITER (0.01 dpa little effect), shift to shorter Luch mirror ZrO 2 / SiO 2

RF Recent multilayer dielectric mirrors: heating and neutron irradiation TiO 2 /SiO 2 23 layers KU1 and K8 substrates - stable under thermal loading

RF Multilayer dielectric mirrors: heating tests Stable under thermal loading repeated heating in vacuum to T ≤ 300 C for times up to 10 h Coatings undamaged, initially range shifts to longer, then stable

US (K. Leonard, R. Goulding, L. Snead and S. Zinkle) Post irradiation loss measurements at 100 MHz in ceramics for ICRH: Single crystal sapphire and spinel show lowest initial losses, but by dpa all oxides similar (possible problem with Deranox sample). BeO almost insensitive. Nitrides worse.

US For oxides little change from to 0.1 dpa - importance of ionization at onset Important to remember PIE, and low T (≈ 65C) irradiation in water - not vacuum or He

US Post irradiation thermal conductivity measurements in ceramics for ICRH: Relative insensitivity of loss to irradiation of BeO and high thermal conductivity make it an interesting potential candidate material (considered a candidate for many years for LH): Future work planned: Thermal conductivity for more ceramics Irradiation of multilayer mirrors

EU database work TW6-IRRCER Database task now underway: UKAEA: Development of the implementation of the ceramic irradiation database, (M. Brooks and P. Karditsas + A. Gusarov and E. Hodgson) Provide reference to the results of the EFDA Ceramic Irradiation Programme by recording all relevant information Provide a searchable repository of documents Provide a searchable database suitable for designer of diagnostics and H&CD systems to find the available information and facilitate design choices. Will use the current EU Fusion Materials Database as framework To be extended for full ITER partner use at a later date Now discussing how the data should be presented and what information it should contain ==>

George’s table - Irradiation tests: needs for ITER (Comments / input from RF and EU only) WBSComponent to be tested Critical parameters Comments C03 /Thomson scat. X pt. Plasma facing and ML mirrors Refectivity change Dose rate 0.2 Gy/s for ML mirror. Corrosion ? C03 /Thomson scat. Divertor Silica, Al 2 O 3 prism reflector, gold reflector ML mirrors Laser damageKU-1 windows have been tested, data for sapphire exists E02/H-alphaML dielectric mirrors No fibers in vessel Heating, reflectivity change KU-1 windows have been tested E12/CXRSML mirrors, Fibres Heating, reflectivity, transmission change KU-1 windows have been tested ML mirrors are common components - joint effort ? G07/Langmuir probes MI cablesThermal path, RIC, RIED, R/TIEMF

George’s table - Irradiation tests: needs for ITER WBSComponent to be tested Critical parameters Comments A01/Outer vessel sensors Hall probesBehaviour at high T Electrical contacts/connections A04/Ext Rogowski Optical fibre as current sensor V. coeff stability, transmission, background Need on-line irradiation test and neutron tests (between and n/m 2 ; ≤3 MGy) G06/IR thermography Sapphire fibreAbsorption / RL Need neutron tests to n/m 2 Systems with transmission fibres large core (600 µm) Al-coated H2-loaded fibres. Rad- induced absorption and RL (~ 1 to 5 10^17 n/cm2)