An outstanding concern raised over the implementation of liquid metal plasma facing components in fusion reactors is the potential for ejection of liquid metal into the fusion plasma. The influences of Rayleigh–Taylor-like and Kelvin–Helmholtz-like instabilities were experimentally observed and quantified on the thermoelectric-driven liquid-metal plasma-facing structures (TELS) chamber at the University of Illinois at Urbana–Champaign. To probe the stability boundary, plasma currents and velocities were first characterized with a flush probe array. Subsequent observations of lithium ejection under exposure in the TELS chamber exhibited a departure from previous theory based on linear perturbation analysis. The stability boundary is mapped experimentally over the range of plasma impulses of which TELS is capable to deliver, and a new theory based on a modified set of the shallow water equations is presented which accurately predicts the stability of the lithium surface under plasma exposure.

Liquid metal plasma facing components have shown a potential to supplant solid plasma facing components materials in the high heat flux regions of magnetic confinement fusion reactors due to the reduction or elimination of concerns over melting, wall damage, and erosion. The viability of liquid metal plasma facing components, however, is dependent upon understanding their interaction with the substrates upon which they are mounted. To this end, the wetting of lithium compounds (lithium nitride, oxide, and carbonate) by 200 ℃ liquid lithium at various surface temperature from 230 to 330 ℃ was studied by means of contact angle measurements. Wetting temperatures, defined as the temperature above which the contact angle is less than 90°, were measured. The wetting temperature was 257 ℃ for nitride, 259 ℃ for oxide, and 323 ℃ for carbonate. Surface tensions of solid lithium compounds were calculated from the contact angle measurements. Highlights  Contact angles of liquid lithium and Li 3 N, Li 2 O, Li 2 CO 3 were measured  Liquid lithium wets lithium compounds at relatively low temperatures: Li 3 N at 257 ℃, Li 2 O at 259 ℃, Li 2 CO 3 at 323 ℃ Abbreviations PFC, plasma-facing components; CPS, capillary porous system; LIMIT, liquid metal infused trench;

No abstract

No abstract

To improve the photocatalytic activity of TiO 2 film, Ti substrates are irradiated by He ions with different incident ion energy, temperature, and fluence. Anatase TiO 2 films are then coated on the plasma-irradiated substrates via chemical vapor deposition followed by calcination. Photocurrent tests and photocatalytic oxidation (PCO) of formaldehyde are used to assess photocatalytic performance. The optimal plasmairradiated samples showed a four times higher photocurrent and a three fold increase in the rate constant of the PCO reaction compared to the TiO 2 coated, untreated control sample. It is found that the enhanced photocatalytic activity and photocurrent are related to the changes of Ti crystal structure and surface morphology through plasma irradiation. K E Y W O R D Sion bombardment, photocatalytic activity, plasma treatment, TiO 2 film, Ti substrate