Surface Structure Transformation in Double Forged Tungsten upon Single and Sequenced Irradiation Using Different Types of Radiation Facilities
- 17 Downloads
Structural changes in the surface layer of target samples made of double forged tungsten were investigated after successive pulsed plasma irradiation thereof using different irradiation facilities such as plasma focus (PF), plasma gun (PG), and plasma accelerator (PA). The irradiation modes simulated hard conditions occurring under the action of thermonuclear plasma on the material in modern tokamaks in such extreme situations as plasma disruption, vertical displacement, and edge localized mode effects (ELMs). Hydrogen and deuterium were used as working gases. Double forged tungsten (DFW) samples were irradiated using PF facilities (PF-6 and PF-1000U) with a subsequent irradiation using PG or PA, as well as another sequence consisting in the initial irradiation using PA and a subsequent irradiation using PF-6 at the final stage. The DFW samples in the experiments were positioned normal to the incident energy flux. The following irradiation modes were used. The PF-1000U facility provides a power density of the deuterium plasma flux onto the target surface qpl = 109–1010 W/cm2, pulse duration τpl = 50–100 ns, power density of the of fast ion beam (with energy Ei > 100 keV) qfi = 1011–1012 W/cm2, pulse duration τfi = 10–50 ns. The PF-6 facility provides qpl = 109–1010 W/cm2, τpl = 50 ns, qfi = 1010–1011 W/cm2, τfi = 10–50 ns. The PG facility provides energy density Q = 0.8 MJ/m2, density of hydrogen plasma q ≈ 5 × 106 W/cm2, pulse duration τ = 15 μs. The PA facility provides Q = 0.75 MJ/m2, power density of deuterium plasma q = 3.6 × 105 W/cm2, τ = 0.25 ms. General features and peculiarities inherent in tungsten damage and changes in the structural state thereof under the action of energy flows in the hard mode of preliminary irradiation in PF facilities with subsequent radiation exposure in softer modes implemented in PG and PA facilities are considered. It is shown that, in the irradiation modes under investigation, the character of material degradation depends not only on the magnitude and duration of the single energy pulses generated by a testing facility but also on the number of energy pulses. The depth of the apparent damaged layer, wherein the crippling of the material occurs, is about 200 μm in almost all the studied irradiation modes, the damage being of thermal and shock-wave nature.
Keywordsdouble forged tungsten irradiation plasma focus plasma gun plasma accelerator material defects scanning electron microscopy XRD structure analysis lattice parameter
Unable to display preview. Download preview PDF.
- 3.Pitts, R.A., Carpentier, S., Escourbiac, F., et al., Physics basis and design of the ITER plasma-facing components, J. Nucl. Mater., 2011, vol. 415, pp. S957–S964.Google Scholar
- 8.Pimenov, V.N., Demina, E.V., Ivanov, L.I., et al., Damage and modification of materials produced by pulsed ion and plasma streams in Dense Plasma Focus device, Nukleonika, 2008, vol. 53, pp. 111–121.Google Scholar
- 13.Lemahieu, N., Linke, J., Pintsuk, G., van Oost, G., Wirtz, M., and Zhou, Z., Performance of yttrium doped tungsten under’ edge localized mode’-like loading conditions, Phys. Scr., 2014, vol. 159, p. 014035.Google Scholar
- 17.Morozov, E.V., Maslyaev, S.A., Pimenov, V.N., et al., Evolution of tungsten surface affected by powerful energy fluxes, Perspekt. Mater., 2015, no. 10, pp. 32–45.Google Scholar
- 18.Vali, B., Laas, T., Paju, J., Shirokova, V., Paduch, M., Gribkov, V.A., Demina, E.V., Pimenov, V.N., Makhlai, V.A., and Antonov, M., The experimental and theoretical investigations of damage development and distribution in double-forget tungsten under plasma irradiation-initiated extreme heat loads, Nukleonika, 2016, vol. 61, no. 2, pp. 169–177. doi 10.1515/nuka-2016-0029CrossRefGoogle Scholar
- 20.Budaev, V.P., Martynenko, Yu.V., Karpov, A.V., et al., Tungsten recrystallization and cracking under ITER relevant heat loads, Vopr. At. Nauki Tekh., Ser.: Termoyad. Sint., 2013, vol. 36, no. 3, pp. 53–60.Google Scholar
- 21.Voronin, A.V., Semenov, B.N., and Sud’enkov, Yu.V., Mechanism of tungsten destruction under thermal load and a plasma jet, Vestn. S.-Peterb. Univ., Ser. 1: Mat., Mekh., Astron., 2015, vol. 2 (60), no. 1, pp. 106–111.Google Scholar
- 22.Garkusha, I.E., Malykhin, S.V., Makhlai, V.A., Pugachev, A.T., Bazdyrieva, S.V., and Aksenov, N.N., Changes in the structure and substructure of tungsten during irradiation by hydrogen plasma flows at the specific energy close to the heat loads on the ITER surface, Tech. Phys., 2014, vol. 59, no. 11, pp. 1620–1625.CrossRefGoogle Scholar