SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Petersson S) ;pers:(Kreter A)"

Sökning: WFRF:(Petersson S) > Kreter A

  • Resultat 1-10 av 17
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Overview of the JET results
  • 2015
  • Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 55:10
  • Tidskriftsartikel (refereegranskat)
  •  
2.
  • Petersson, Per, et al. (författare)
  • Overview of nitrogen-15 application as a tracer gas for material migration and retention studies in tokamaks
  • 2014
  • Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; T159, s. 014042-
  • Tidskriftsartikel (refereegranskat)abstract
    • Experimental and analytical procedures related to the application of nitrogen-15 isotope for material migration studies have been developed and used for tracer experiments in the TEXTOR and ASDEX-Upgrade tokamaks in order to assess the retention of nitrogen in plasma-facing components made of graphite and tungsten. The surface study was performed by time-of-flight heavy ion elastic recoil detection analysis and by means of nuclear reaction analysis based on the N-15(p, gamma alpha)C-12 process. In both tokamaks nitrogen retention has exceeded 10% of the injected gas. In ASDEX-Upgrade the largest fraction of N-15 has been detected on protruding parts near the injection port, while around 4% has been found in the divertor. The ASDEX-Upgrade results have also been modeled. Helium trapping has been measured in deposits containing tungsten and nitrogen.
  •  
3.
  • Rubel, Marek, et al. (författare)
  • Tracer techniques for the assessment of material migration and surface modification of plasma-facing components
  • 2015
  • Ingår i: Journal of Nuclear Materials. - : Elsevier. - 0022-3115 .- 1873-4820. ; 463, s. 280-284
  • Tidskriftsartikel (refereegranskat)abstract
    • Tracer techniques were used in the TEXTOR tokamak to determine high-Z metal migration and the deposition of species used for plasma edge cooling or wall conditioning under different types of operation conditions. Volatile molybdenum hexa-fluoride, nitrogen-15 and oxygen-18 were used as markers in tokamak or ion cyclotron wall conditioning discharges (ICWC). The objective was to obtain qualitative and quantitative of a global and local deposition pattern and material mixing effects. The deposition and retention was studied on plasma-facing components, collector probes and test limiters. Optical spectroscopy and ex-situ analysis techniques were used to determine the plasma response to tracer injection and the modification of surface composition. Molybdenum and light isotopes were detected on all types of limiters and short-term probes retrieved from the vessel showing that both helium and nitrogen are trapped following wall conditioning and edge cooling. Only small amounts below 1 x 10(19) m(-2) of O-18 were detected on surfaces treated by oxygen-assisted ICWC.
  •  
4.
  • Rubel, Marek, et al. (författare)
  • Tungsten migration studies by controlled injection of volatile compounds
  • 2013
  • Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 438, s. S170-S174
  • Tidskriftsartikel (refereegranskat)abstract
    • Volatile tungsten hexa-fluoride was locally injected into the TEXTOR tokamak as a marker for material migration studies. The injection was accompanied by puffing N-15 rare isotope as a nitrogen tracer in discharges with edge cooling by impurity seeding. The objective was to assess material balance by qualitative and quantitative determination of a global and local deposition pattern, material mixing effects and fluorine residence in plasma-facing components. Spectroscopy and ex situ ion beam analysis techniques were used. Tungsten was detected on all types of limiter tiles and short-term probes retrieved from the vessel. Over 80% of the injected W was identified. The largest tungsten concentration, 1 x 10(18) cm(-2), was in the vicinity of the gas inlet. Co-deposits contained tungsten and a mix of light isotopes: H, D, He-4, B-10, B-11, C-12, C-13, N-14, N-15, O-16 and small quantities of F-19 thus showing that both He and nitrogen are trapped following wall conditioning (He glow) and edge cooling.
  •  
5.
  •  
6.
  • Ström, Petter, et al. (författare)
  • Characterisation of surface layers formed on plasma-facing components in controlled fusion devices : Role of heavy ion elastic recoil detection
  • 2015
  • Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 122, s. 260-267
  • Tidskriftsartikel (refereegranskat)abstract
    • Wall components retrieved from the TEXTOR tokamak after tracer experiments with nitrogen-15 and molybdenum hexafluoride (MoF6) injection were studied to determine deposition patterns and, by this, to conclude on material migration. Toroidal limiter tiles made of carbon fibre composites and fine grain graphite were examined using time-of-flight heavy ion elastic recoil detection analysis. Molybdenum deposition patterns indicated migration based on erosion and prompt re-deposition. Nitrogen-15 was trapped together with the deposited molybdenum. Some information on the depth distribution of species in the top 400 nm layer of the limiters was obtained; however surface roughness of the samples strongly limited resolution. In the case of molybdenum, the largest concentration was found in the 100 nm outermost layer, whereas fluorine and nitrogen-15 displayed more irregular profiles. Other species, besides deuterium fuel and carbon-12, were also identified: boron-10 and boron-11 originating from boronisations, carbon-13 from earlier tracer experiments, nitrogen-14 from plasma edge cooling and metals eroded from the Inconel wall.
  •  
7.
  • Garcia Carrasco, Alvaro, et al. (författare)
  • Impact of ion cyclotron wall conditioning on fuel removal from plasma-facing components at TEXTOR
  • 2014
  • Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T159, s. 014017-
  • Tidskriftsartikel (refereegranskat)abstract
    • Ion cyclotron wall conditioning (ICWC) is based on low temperature and low density plasmas produced and sustained by ion cyclotron resonance (ICR) pulses in reactive or noble gases. The technique is being developed for ITER. It is tested in tokamaks in the presence of toroidal magnetic field (0.2-3.8 T) and heating power of the order of 10(5) W. ICWC with hydrogen, deuterium and oxygen-helium mixture was studied in the TEXTOR tokamak. The exposed samples were pre-characterized limiter tiles mounted on specially designed probes. The objectives were to assess the reduction of deuterium content, the uniformity of the reduction and the retention of seeded oxygen. For the last objective oxygen-18 was used as a marker. ICWC in hydrogen caused a drop of deuterium content in the tile by a factor of more than 2: from 4.5x10(18) to 1.9x10(18) D cm(-2). A decrease of the fuel content by approximately 25% was achieved by the ICWC in oxygen, while no reduction of the fuel content was measured after exposure to discharges in deuterium. These are the first data ever obtained showing quantitatively the local decrease of deuterium in wall components treated by ICWC in a tokamak. The oxygen retention in the tiles exposed to ICWC with oxygen-helium was analyzed for different orientations and radial positions with respect to plasma. An average retention of 1.38x10(16) O-18 cm(-2) was measured. A maximum of the retention, 4.4x10(16) O-18 cm(-2), was identified on a sample surface near the plasma edge. The correlation with the gas inlet and antennae location has been studied.
  •  
8.
  • Garcia Carrasco, Alvaro, et al. (författare)
  • Nitrogen removal from plasma-facing components by ion cyclotron wall conditioning in TEXTOR
  • 2015
  • Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 463, s. 688-692
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The efficiency of ion cyclotron wall conditioning (ICWC) in the removal of nitrogen from plasma-facing components in TEXTOR was assessed. In two experiments the wall was loaded with nitrogen and subsequently cleaned by ICWC in deuterium and helium. The retention and removal of nitrogen was studied in-situ by means of mass spectrometry, and ex-situ by surface analysis of a set of graphite, tungsten and TZM plates installed on test limiter systems. N-15 rare isotope was used as a marker. The results from the gas balance showed that about 25% of the retained nitrogen was removed after ICWC cleaning, whereas surface analysis of the plates based on ToF-HIERDA showed an increase of the deposited species after the cleaning. This indicates that during ICWC operation on carbon devices, nitrogen is not only pumped out but also transported to other locations on the wall. Additionally, deuterium surface content was studied before and after ICWC cleaning.
  •  
9.
  •  
10.
  • Moeller, S., et al. (författare)
  • Fundamental processes of fuel removal by cyclotron frequency range plasmas and integral scenario for fusion application studied with carbon co-deposits
  • 2015
  • Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 463, s. 1109-1112
  • Tidskriftsartikel (refereegranskat)abstract
    • Plasma impact removal using radio frequency heated plasmas is a candidate method to control the co-deposit related tritium inventory in fusion devices. Plasma parameters evolve according to the balance of input power to losses (transport, radiation, collisions). Material is sputtered by the ion fluxes with impact energies defined by the plasma sheath. H-2, D-2 and O-18(2) plasmas are produced in the carbon limiter tokamak TEXTOR. Pre-characterised a-C:D layers are exposed to study local removal rates, The D-2 plasma exhibits the highest surface release rate of 5.7 +/- 0.9 * 10(19) D/m(2)s. Compared to this the rate of the O-2 plasma is 3-fold smaller due to its 11-fold lower ion flux density. Re-deposition of removed carbon is observed, indicating that pumping and ionisation are limiting the removal in TEXTOR. Presented models can explain the observations and allow tailoring removal discharges. An integral application scenario using ICWC and thermo-chemical removal is presented, allowing to remove 700 g T from a-C:DT co-deposits in 20 h with fusion compatible wall conditions using technical specifications similar to ITER.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 17

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy