Radomir PanekEU PWI Task Force Meeting - CEA Cadarache1 PWI work in Association-IPP.CR Presented by R. Panek Content: 1. Collisions of hydrocarbon ions with carbon surfaces. 2. Plasma spraying of tungsten. 3. Retention of tokamak atomic hydrogen in metalic membranes.

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache2 Collisions of hydrocarbon ions with surfaces* dissociations and chemical reactions from mass spectra, product ion translational energy and angular distributions C 1 ions: CH 3 +, CH 4 +, CH 5 + C 2 ions: C 2 H 2 +, C 2 H 3 +, C 2 H 4 +, C 2 H 5 + Influence of internal energy of projectiles on the extent of fragmentation* Collisions of doubly-charged vs. singly charged ions with surfaces* (effect of charge: C 7 H 8 +, C 7 H 7 + ) (* collaboration with the University of Innsbruck) ENERGY RANGE 10 eV - 55 eV SURFACE Carbon: HOPG (highly oriented pyrolytic graphite), TOKAMAK tiles SURFACE TEMPERATURE - non-heated (room temperature) - heated to 1000 K Collisions of Hydrocarbon Ions with Carbon Surfaces Z. Herman, J. Žabka, J. Roithová, J. Hrušák, J. Jašík, I. Ipolyi, L. Feketeová J. Heyrovský Institute of Physical Chemistry, Acad. Sci.

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache3 Experiment Setup PROCESSES OBSERVED neutralization of ions (survival probability) surface-induced dissociations (energy partitioning) chemical reactions at surfaces (H-atom, CHn-transfer) quasi-elastic scattering of projectiles

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache4 Percentage of Surviving Ions, S a (%)

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache5 Product Ion Translation Energy Distributions C 2 H 3 +, C 2 H 5 +, HOPG, N =60 o

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache6 Angular Distributions: Summary of C 2 H n + HEATEDNON HEATED

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache7 Summary 1.Heating to about 1000 K practically removes the hydrocarbon layer covering at room temperature the carbon surfaces 2. Ion survival probability S a (%) for incident angle of Ф n = about < 1% ( %) for radical ion projectiles (CH 4 +, C 2 H 2 +, C 2 H 4 + ) - about 5-15 % for closed-shell projectile ions (CH 5 +, C 2 H 3 +, C 2 H 5 + ) 3. Inelasticity of dissociative collisions (dissociation after interaction with the surface): translational energy of surface-energized projectile ions % for non-heated (hydrocarbon covered ) surfaces % for heated (clean) surfaces

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache8 Plasma Sprayed Tungsten J. Matejicek 1, V. Weinzettl 1, E. Dufkova 1, V. Piffl 1, V. Perina 2 1 Institute of Plasma Physics, Prague, CZ 2 Institute of Nuclear Physics, Prague, CZ Plasma spraying of tungsten Water- and hybrid-stabilized plasma torches Coating properties and optimization Testing in tokamak CASTOR Use of biasing to increase the power load

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache9 Spraying optimization: – powder size selection – reduced oxidation – reduced porosity, increased thermal conductivity Spraying techniques: - water-stabilized plasma - hybrid-stabilized plasma (water+argon) - in air Reducing the oxidation: – Auto-shrouding: admixture of WC decarburization of WC -> W 2 C -> W C reacts with oxygen, forms carbon oxide limits oxygen access to tungsten – Very little oxide in the coatings (~ % surface, 0.05% inside) Spraying development

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache10 Reducing the in-flight oxidation pure W W+WC 5:1 pure W - lower plasma temperatures - Ar stabilizes and elongates the arc - lower porosity - fewer unbonded interfaces - less oxide Hybrid torch

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache11 Testing at tokamak CASTOR

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache12 Surface morphology Surface composition (EMPA, RBS, ERDA) Plasma sprayed W Plasma sprayed W+Cu (50:50 vol.) Bulk W Bulk Cu Bulk graphite Biasing head materials: Plasma sprayed W Plasma sprayed W - detail Testing at CASTOR (2)

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache13 Retention of tokamak atomic hydrogen in metalic membranes M. Hron, J. Stöckel, F. Žáček, M. Notkin, V. Livshiths Collaboration: Bonch-Bruyevich University, St.Petersburg Metalic membranes (Nb, V) absorb suprathermal atoms of hydrogen isotops that pass through an adsorbed layer on the membrane surface Absorbed atoms can move freely inside the membrane but the adsorbed layer hampers their exit Principle

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache14 Hydrogen desorption from the membrane Temporal evolution of the desorbed hydrogen pressure (membrane heated up to 1000 o C during desorption)

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache15 Highest sensitivity to atomic hydrogen (relative to the background) was observed with the exposure temperature 400 K H 2 + H membrane exposed to plasma H 2 membrane exposed to neutral gas Dependence of the desorption on membrane temperature during exposure H hydrogen atoms originating from plasma

Radomir PanekEU PWI Task Force Meeting - CEA Cadarache16 Recent experiments have shown that in the tokamak conditions in CASTOR: A/ membrane absorbs suprathermal hydrogen atoms B/ number of absorbed atoms can be measured absolutely, so the neutral particle flux can be determined (calculation of particle balance?) Conclusions