Development of surface topography due to gas ion implantation

Scherzer, B.M.U.

doi:10.1007/3-540-12593-0_7

Cited by 67 publications

(32 citation statements)

References 371 publications

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“…Blisters and ruptured blisters of morphology similar to those seen in sample LT (Fig. 4) have been found in many previous studies, not only on W surfaces, but also on other metal surfaces, such as Nb, V and Mo [3]. A number of different models have been put forward to describe and explain the formation of surface blisters on He-bombarded metal surfaces [3,12].…”

Section: Discussionsupporting

confidence: 53%

“…The as-received material was recrystallized at 1400 °C (1673 K) under argon gas, resulting in an average grain size of ~24 μm. Samples for investigation of surface damage were cut with dimensions of 12×10×3 mm 3 . The samples were mechanically polished on top surface to a mirror finish before loading.…”

Section: Methodsmentioning

confidence: 99%

“…The mechanism for the formation of these surface morphologies is, however, not fully understood, especially the effects of temperature dependence. In addition, some studies have found an orientation dependence for He-induced damage [3,5,8]. This is interesting as it may provide a way to optimize the plasma facing material by control of the crystallographic texture.…”

Section: Introductionmentioning

confidence: 96%

“…During such usage it will be exposed to both particle irradiation and high heat flux loads. Particle irradiation from the fusion plasma, especially helium (He) bombardment, is expected to lead to performance degradation of W components due to the development of significant changes in surface morphology, such as the formation of blisters, holes, fiber-form nanostructures and coral-like structures [2][3][4][5][6][7]. In addition, synergistic effects between heat loading and particle irradiation can accelerate such surface damage [2].…”

Section: Introductionmentioning

confidence: 99%

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Effects of temperature on surface modification of W exposed to He particles

Greuner

Yuan

et al. 2014

Journal of Nuclear Materials

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The effect of combined heating and helium particle flux on annealed tungsten samples has been studied in the neutral beam facility GLADIS. He beams with power densities of 2.4 MW/m 2 and 9.5 MW/m 2 were used to adiabatically load the samples to peak surface temperatures from ~ 950 °C (1223 K) to ~ 2700 °C (2973 K). Changes in the surface morphology resulting from combined heat and the flux exposure were studied for He fluences up to 3×10 22 /m 2 . Typical structures for the sample loaded at ~ 950 °C (1223 K) were blisters with a clear grain orientation dependence and the largest blisters formed on grains with <001> surface normal. However at higher temperatures, blistering was more easily suppressed for grains near this orientation because the growth of larger blister takes place more slowly. An evolution from a "porous structure" to a "coral-like structure" with increasing fluence was observed on the samples loaded at the highest temperature. Based on these results mechanisms for surface modification at different temperatures are discussed and a texture with <001> parallel to the normal direction of the grains is suggested to optimize the plasma facing material due to their stronger resistance to early stage blistering.

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Section: Discussionsupporting

confidence: 53%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Effects of temperature on surface modification of W exposed to He particles

Greuner

Yuan

et al. 2014

Journal of Nuclear Materials

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“…1 Under appropriate conditions these bubbles may grow into larger bubbles, becoming visible on the target surface as small bumps, also known as blisters. Under prolonged implantation these blisters may rupture, ejecting gas atoms and fragments of the solid.…”

Section: Introductionmentioning

confidence: 99%

The Depths of Hydrogen and Helium Bubbles in Tungsten: A Comparison

Henriksson

Nordlund

Krasheninnikov

et al. 2006

Fusion Science and Technology

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Contribution of the Different Erosion Processes to Material Release from the Vessel Walls of Fusion Devices during Plasma Operation

Behrisch

2002

Contrib. Plasma Phys.

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In high temperature plasma experiments several processes contribute to erosion and loss of material from the vessel walls. This material may enter the plasma edge and the central plasma where it acts as impurities. It will finally be re‐deposited at other wall areas. These erosion processes are: • evaporation due to heating of wall areas. At very high power deposition evaporation may become very large, which has been named “blooming”. Large evaporation and melting at some areas of the vessel wall surface may occur during heat pulses, as observed in plasma devices during plasma disruptions. • At tips on the vessel walls and/or hot spots on the plasma exposed solid surfaces electrical arcs between the plasma and the vessel wall may ignite. They cause the release of ions, atoms and small metal droplets, or of carbon dust particles. • Finally, atoms from the vessel walls are removed by physical and chemical sputtering caused by the bombardment of the vessel walls with ions as well as energetic neutral hydrogen atoms from the boundary plasma. All these processes have been, and are, observed in today's plasma experiments. Evaporation can in principle be controlled by very effective cooling of the wall tiles, arcing is reduced by very stable plasma operation, and sputtering by ions can be reduced by operating with a cold plasma in front of the vessel walls. However, sputtering by energetic neutrals, which impinge on all areas of the vessel walls, is likely to be the most critical process because ions lost from the plasma recycle as neutrals or have to be refuelled by neutrals leading to the charge exchange processes in the plasma. In order to quantify the wall erosion, “Materials Factors” (MF) have been introduced in the following for the different erosion processes.

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Development of surface topography due to gas ion implantation

Cited by 67 publications

References 371 publications

Effects of temperature on surface modification of W exposed to He particles

Effects of temperature on surface modification of W exposed to He particles

The Depths of Hydrogen and Helium Bubbles in Tungsten: A Comparison

Contribution of the Different Erosion Processes to Material Release from the Vessel Walls of Fusion Devices during Plasma Operation

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