Tungsten damage and melt losses under plasma accelerator exposure with ITER ELM relevant conditions

Makhlaj, V.A.; Garkusha, I.E.; Aksenov, N.N.; Базылев, Б.; Landman, I.; Linke, J.; Malykhin, S.V.; Pugachov, A T; Sadowski, M.; Składnik‐Sadowska, E.; Wirtz, M.

doi:10.1088/0031-8949/2014/t159/014024

Cited by 20 publications

(27 citation statements)

References 16 publications

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“…In general, the damages of tungsten targets due to the cracking and the development of instabilities at the surface layer lead to the particle ejection from the exposed surfaces. Earlier, it was found experimentally that the sizes of particles re-deposited on surfaces around the target are in range of (1 ... 60) m [15]. In the current experiment, as was mentioned above, most of the particles have sizes in the interval (10 ... 70) m. But the particles with size more than 200 m are observed as well.…”

Section: Resultssupporting

confidence: 64%

Erosion of the Combined Three-Dimensional Tungsten Target Under the Impacts of QSPA Kh-50 Powerful Plasma Streams

Herashchenko

Makhlai²,

Aksenov

et al. 2016

Ukr. J. Phys.

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For the first time, the features of the interaction of plasma with materials and the erosion mechanisms have been evaluated for surfaces in a three-dimensional geometry exposed by powerful plasma. Experimental studies of the powerful interaction of plasma with the three-dimensional structures have been carried out on a quasistationary plasma accelerator QSPA Kh-50. The plasma streams with surface heat loads of 0.9 MJ/m 2 and plasma pulse duration 0.25 ms, relevant to ITER ELM, have been used in the experiments. The significant erosion occurs under the action of plasma heat loads. Erosion is accompanied by the separation of material particles from the irradiated surfaces. It is found that the number and the velocity of particles emitted from the surface depend on the number of plasma pulses. The most significant factors causing a macroscopic erosion for a three-dimensional tungsten structure have been studied.

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Section: Resultssupporting

confidence: 64%

Erosion of the Combined Three-Dimensional Tungsten Target Under the Impacts of QSPA Kh-50 Powerful Plasma Streams

Herashchenko

Makhlai²,

Aksenov

et al. 2016

Ukr. J. Phys.

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“…SEM of the tungsten surface treated with the 1 ms pulse shows turbulence with liberation of micron-sized particulates, droplets splashing from melt layer, and generation of cracks on the treated surface. At a similar range of energy density, with 0.25 ms [3,17] and 0.5 ms [18] pulses, the melting, melt splashing and vapour shielding have also been observed both with plasma and H ion beam irradiation. With successive pulses, the melting threshold shifted to smaller energy load which is in favour to more splashing from melt layer.…”

Section: Resultsmentioning

confidence: 92%

Cracking and damage behavior of tungsten under ELM’s like energy loads using millisecond laser pulses

Farid

De-you

Oderji

et al. 2015

Journal of Nuclear Materials

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“…Also, it should be noted that development of mesh of cracks (mesh of cells) took two to eight plasma pulses for single forged W and WL10 [10]. During the previous ITER-related studies considering tungsten (DFW and ultra-pure tungsten) grades, the samples were irradiated with either laser, plasma (in tokamak GlobusM and QSPA Kh-50) or electrons (JUDITH) pulses with ELM-related heat load factors [1,5,11,20,24]. The results concerning surface defects and their development during the increase of particle pulses are similar to those obtained in this study.…”

Section: Discussionmentioning

confidence: 99%

“…Investigation of bulk defects in tungsten by cross-sections (on samples those have been irradiated without powerful ion fl uxes) has revealed the occurrence of re-crystallisation and development of subgrains in depth of about 100 m and less [1,20,24]. On the other hand, a decrease in materials' microhardness in a cross-section has been observed in both single-forged tungsten samples, as well as in WL10 [10] irradiated within the PF-12 with plasma incorporated with fast (100 keV) ion fl uxes.…”

Section: Discussionmentioning

confidence: 99%

“…0.25 ms (see [1] for detailed experimental set-up and device parameters). Garkusha et al have shown that (a) irradiation of cracked tungsten causes the appearance of tungsten dust from intersections of the cracks [1], (b) the molten layer generated by plasma may lead to covering and disappearance of cracks, microcracks and to smoothing of a surface layer [20].…”

Section: Experimental Set-upmentioning

confidence: 99%

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The experimental and theoretical investigations of damage development and distribution in double-forged tungsten under plasma irradiation-initiated extreme heat loads

et al. 2016

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Abstract. The infl uence of extreme heat loads, as produced by a multiple pulses of non-homogeneous fl ow of slow plasma (0.1-1 keV) and fast ions (100 keV), on double-forged tungsten (DFW) was investigated. For generation of deuterium plasma and fast deuterons, plasma-focus devices PF-12 and PF-1000 are used. Depending on devices and conditions, the power fl ux density of plasma varied in a range of 10 7 -10 10 W/cm 2 with pulse duration of 50-100 ns. Power fl ux density of fast ions was 10 10 -10 12 W/cm 2 at the pulse duration of 10-50 ns. To achieve the combined effect of different kind of plasmas, the samples were later irradiated with hydrogen plasma (10 5 W/cm 2 , 0.25 ms) by a QSPA Kh-50 plasma generator. Surface modifi cation was analysed by scanning electron microscopy (SEM) and microroughness measurements. For estimation of damages in the bulk of material, an electrical conductivity method was used. Investigations showed that irradiation of DFW with multiple plasma pulses generated a mesh of micro-and macrocracks due to high heat load. A comparison with single forged tungsten (W) and tungsten doped with 1% lanthanum-oxide (WL10) reveals the better crack-resistance of DFW. Also, sizes of cells formed between the cracks on the DFW's surface were larger than in cases of W or WL10. Measurements of electrical conductivity indicated a layer of decreased conductivity, which reached up to 500 m. It depended mainly on values of power fl ux density of fast ions, but not on the number of pulses. Thus, it may be concluded that bulk defects (weakening bonds between grains and crystals, dislocations, point-defects) were generated due to mechanical shock wave, which was generated by the fast ions fl ux. Damages and erosion of materials under different combined radiation conditions have also been discussed.

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Tungsten damage and melt losses under plasma accelerator exposure with ITER ELM relevant conditions

Cited by 20 publications

References 16 publications

Erosion of the Combined Three-Dimensional Tungsten Target Under the Impacts of QSPA Kh-50 Powerful Plasma Streams

Erosion of the Combined Three-Dimensional Tungsten Target Under the Impacts of QSPA Kh-50 Powerful Plasma Streams

Cracking and damage behavior of tungsten under ELM’s like energy loads using millisecond laser pulses

The experimental and theoretical investigations of damage development and distribution in double-forged tungsten under plasma irradiation-initiated extreme heat loads

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