Liquid Protection Schemes for Inertial Fusion Energy
In inertial fusion
energy (IFE), a specially designed target (usually a few mm in diameter)
containing deuterium and tritium fuel is heated and compressed in a reactor
chamber (typically with a radius of 4-6 m) by more than 100 laser or heavy-ion
beams to the temperatures and pressures required to create fusion. The lead
American IFE research facility, the National Ignition Facility in
Our work focuses on the basic “building block flows” for two types of liquid protection schemes: 1) Thick liquid protection, where high-speed liquid curtains, or turbulent liquid sheets, are used to absorb virtually all the radiation from the fusion event; and 2) Thin liquid protection , where liquid films attached to the reactor walls (created by low-speed injection of liquid through a porous wall and high-speed injection of liquid tangential to the reactor walls), are used to absorb photons and charged particles. The important design issues for all liquid protection schemes are:
Thick Liquid Protection
The HYLIFE-II conceptual IFE power plant design proposes using a combination of oscillating and stationary turbulent sheets of a molten salt, Flibe (Li2BeF4) at a Reynolds number Re = 240,000 to protect the reactor chamber first walls from damaging radiation and charged particles. We are experimentally modeling these flows using sheets of water issuing from a rectangular exit into atmospheric pressure air at Re up to 150,000 (Figure 1). A variety of flow diagnostics are employed to characterize this flow including. laser-Doppler velocimetry (LDV), planar laser-induced fluorescence (PLIF), flow visualization, and droplet collection.
Figure 1 Photo of turbulent sheet of water at Re = 34000 issuing into air from a nozzle with exit dimensions of 10 cm x 1 cm. Flow is in x-direction.
Figure 3 Determination of initial conditions of the turbulent liquid sheet using Laser Doppler Velocimetry (LDV). The laser lines are simulated in this figure.
The objectives of this research involving fluid mechanics, fusion engineering and optical diagnostics are:
Figure 4 Photo of three different nozzles (all with exit dimensions 10 cm x 1 cm) fabricated using stereolithography rapid prototyping: from left to right, a matched circular-arc contraction, a fifth-order polynomial contraction, and a fifth-order polynomial contraction with rounded corners.
Figure 5 Edge view of turbulent liquid sheet. Droplets appear to emanate from the free surface. Exposure time for this image is 5 ms. The streaks are due to the droplet ejection speeds and trajectories.
Thin Liquid Protection
The objectives of this research involving fluid mechanics, fusion engineering and heat transfer are:
Figure 4 Side view of water film (flowing from left to right) at Re = 9000 on the underside of a horizontal glass plate. The scale at the top is in inches measured from the slot exit.
Figure 5 Time sequence from a finite-volume numerical simulation showing drop formation for liquid lead at 700 deg C with an initial film thickness of 0.5 mm injected with a speed of 1 mm/s down through the underside of a horizontal porous plate. The ratio of the liquid to surrounding gas density is essentially infinite. Time increases from left to right, with the first drop forming 0.31 s after the start of injection. [simulation courtesy S. Shin]
This project, a collaboration with S. Abdel-Khalik and D. Sadowski in Mechanical and Nuclear Engineering, is supported by the Department of Energy through the Office of Fusion Energy Sciences and the ARIES-IFE study. Financial support for S. Durbin is provided by the Fusion Energy Sciences Fellowship Program administered by Oak Ridge Institute for Science and Education under a contract between the U.S. Department of Energy and the
Publications (contact M. Yoda for reprints)