The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and...The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and then tends to saturate with the increase of hydrogen–plasma flux.When the temperature of the sample eroded by hydrogen plasma is above 300°C,the hybridization of electrons outside the carbon atom would change.Then the carbon atoms combine with hydrogen atoms to form massive spherical nanoparticles of hydrocarbon compounds and deposit on the surface at the flux condition of 1.77×10^(22) m^(−2)·s^(−1).Under the irradiation of hydrogen plasma loaded with negative bias,the surface morphology of the matrix carbon is changed dramatically.Moreover,the energy dependence of mass loss does not increase in proportion to the increase of hydrogen–plasma energy,but reaches a peak around 20 V negative bias voltage.Based on the analysis of different samples,it can be concluded that the enhancement of energy could make a contribution to chemical erosion and enlarge the size of pores existing on the surface.展开更多
Steady high-flux helium(He)plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum(Mo)surface.Enhanced hydrogen(H)pulsed plasma in a w...Steady high-flux helium(He)plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum(Mo)surface.Enhanced hydrogen(H)pulsed plasma in a wide power density range of 12 MW/m^(2)-35 MW/m^(2)is subsequently used to bombard the fuzzy Mo,thereby simulating the damage of edge localized mode(ELM)to fuzz.The comparisons of surface morphologies,crystalline structures,and optical reflectivity between the original Mo and the Mo treated with various He^(+)energy and transient power densities are performed.With the increase of He ion energy,the Mo nano-fuzz evolved density is enlarged due to the decrease of filament diameter and optical reflectivity.The fuzz-enhanced He release should be the consequence of crystalline growth and the lattice shrinkage inside the Mo-irradiated layers(^(2)00 nm).The fuzz induced by lower energy experiences more severe melting damage and dust release under the condition of the identical transient H plasma-bombardment.The H and He are less likely to be trapped due to aggravated melting evidenced by the enhanced crystalline size and distinct lattice shrinkage.As the transient power density rises,the thermal effect is enhanced,thereby causing the fuzz melting loss to aggravate and finally to completely disappear when the power density exceeds 21 MW/m^(2).Irreversible grain expansion results in huge tensile stress,leading to the observable brittle cracking.The effects of transient thermal load and He ion energy play a crucial role in etching Mo fuzz during ELM transient events.展开更多
基金by National Natural Science Foundation of China(No.11875198)Young Scientists Fund of National Natural Science Foundation of China(No.11905151)+1 种基金Fundamental Research Funds for the Central Universities of China(No.2019SCU12072)the China Postdoctoral Science Foundation(No.2019M663487).
文摘The net erosion yield of CX-2002U carbon fiber composites under high-flux low-temperature hydrogen plasma is investigated using a linear plasma device.It is found that the net erosion yield decreases rapidly first,and then tends to saturate with the increase of hydrogen–plasma flux.When the temperature of the sample eroded by hydrogen plasma is above 300°C,the hybridization of electrons outside the carbon atom would change.Then the carbon atoms combine with hydrogen atoms to form massive spherical nanoparticles of hydrocarbon compounds and deposit on the surface at the flux condition of 1.77×10^(22) m^(−2)·s^(−1).Under the irradiation of hydrogen plasma loaded with negative bias,the surface morphology of the matrix carbon is changed dramatically.Moreover,the energy dependence of mass loss does not increase in proportion to the increase of hydrogen–plasma energy,but reaches a peak around 20 V negative bias voltage.Based on the analysis of different samples,it can be concluded that the enhancement of energy could make a contribution to chemical erosion and enlarge the size of pores existing on the surface.
基金Project supported by the Sichuan Provincial Science and Technology Program,China(Grant Nos.2021YFSY0015and 2021YJ0510)the China Postdoctoral Science Foundation(Grant No.2019M663487)the National Natural Science Foundation of China(Grant No.11905151)。
文摘Steady high-flux helium(He)plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum(Mo)surface.Enhanced hydrogen(H)pulsed plasma in a wide power density range of 12 MW/m^(2)-35 MW/m^(2)is subsequently used to bombard the fuzzy Mo,thereby simulating the damage of edge localized mode(ELM)to fuzz.The comparisons of surface morphologies,crystalline structures,and optical reflectivity between the original Mo and the Mo treated with various He^(+)energy and transient power densities are performed.With the increase of He ion energy,the Mo nano-fuzz evolved density is enlarged due to the decrease of filament diameter and optical reflectivity.The fuzz-enhanced He release should be the consequence of crystalline growth and the lattice shrinkage inside the Mo-irradiated layers(^(2)00 nm).The fuzz induced by lower energy experiences more severe melting damage and dust release under the condition of the identical transient H plasma-bombardment.The H and He are less likely to be trapped due to aggravated melting evidenced by the enhanced crystalline size and distinct lattice shrinkage.As the transient power density rises,the thermal effect is enhanced,thereby causing the fuzz melting loss to aggravate and finally to completely disappear when the power density exceeds 21 MW/m^(2).Irreversible grain expansion results in huge tensile stress,leading to the observable brittle cracking.The effects of transient thermal load and He ion energy play a crucial role in etching Mo fuzz during ELM transient events.
