A5087202400- Fusion materials and technologies
- Nuclear Materials and Properties
- Ion-surface interactions and analysis
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Metal and Thin Film Mechanics
- Advanced materials and composites
- Nuclear materials and radiation effects
- Laser-induced spectroscopy and plasma
- Laser-Plasma Interactions and Diagnostics
- Advanced Materials Characterization Techniques
- Hydrogen embrittlement and corrosion behaviors in metals
- Nuclear reactor physics and engineering
- Thermography and Photoacoustic Techniques
- Microstructure and Mechanical Properties of Steels
- Superconducting Materials and Applications
- Diamond and Carbon-based Materials Research
- Cold Fusion and Nuclear Reactions
- Spectroscopy and Laser Applications
- Thermal properties of materials
- Mass Spectrometry Techniques and Applications
- Vacuum and Plasma Arcs
- Laser Material Processing Techniques
- Dust and Plasma Wave Phenomena
- X-ray Diffraction in Crystallography
University of California, San Diego
2016-2025
Molina Center for Energy and the Environment
2017
The helicon-plasma based-linear plasma-materials-interaction device, Pisces-RF is introduced. Steady-state plasma parameters in the target region are electron density up to ∼1019 m−3, temperature ∼10 eV, and ion flux ∼1023 m−2s−1 D2 He, with an associated maximum peak heat of ∼1 MWm−2 a few when accelerating ions electrical bias. Attached detached regimes both gaseous species can be achieved, as characterized by high low Te (<1eV) plasmas fractions singly ionized atomic ions. downstream...
Numerical diffuse scattering cross-section calculations are used to establish a rigorous basis for determining the concentration and size distribution of dislocation loops in irradiated single crystals from integral X-ray (XRDS) measurements. Differential XRDS intensities prismatic {111} type numerically calculated as function loop radius R wavevectors q relative Bragg reflections tungsten. The results show well known 1/ 2 Huang form at small that transitions ∼1/ 4 dependence associated with...
Tungsten samples are exposed to 3He plasma quantify their helium retention behavior. The saturates quickly with fluence and increases only slightly from 4.3 × 1019 He/m2 at 773 K, 7.5 973 K. content dramatically 6.8 1020 when fuzz is formed on the surface of a sample 1173 but majority retained (5.1 He/m2) found reside below layer tendrils. Additional tungsten were either simultaneous, or sequential, D/He plasma, followed by TDS. Measurements show D during simultaneous exposures located in...
Abstract Radio-frequency (RF) driven helicon plasma sources can produce relatively high-density plasmas ( n > 10 19 m −3 ) at moderate powers (<2 kW) in argon. However, to similar for fusion relevant gases such as hydrogen (H), deuterium (D) and helium (He), much higher RF are needed. For very high powers, thermal issues of the RF-transparent dielectric window, used source design, limit operation timescales. To mitigate this constraint, we have designed, built tested a novel assembly...
Abstract Properties of deuterium (D) supersaturated surface layers (DSSLs) formed in tungsten (W), such as thickness, internal microstructures, and D retention, are experimentally investigated a function the incident ion energy, E i . W samples were exposed to plasmas PISCES-A linear plasma device range ∼ 45–175 eV, while other exposure parameters fixed: sample temperature, T s , ∼423 K, flux, Γ ∼1.2 × 10 21 m −2 −1 fluence, Φ ∼3.0 24 High-resolution, cross-sectional, transmission electron...
Tungsten targets produced by the additive manufacturing (AM) method of electron-beam powder-bed fusion, or 3–D metal printing, are exposed to high flux D plasma in Pisces-RF linear device with plasma-exposed surface normal AM build direction. retention was measured thermal desorption mass spectrometry following exposure an associated ∼50eV D+ ion flux. fluence, and operational temperature, ranges 5×1024–5×1026 m−2 400–1000 K, explored. values for W compared identically exposed'conventional'...
The thermal transport and elastic properties of materials are often measured using the laser-induced transient grating spectroscopy (TGS) technique. analysis TGS signal usually involves fitting well-known expressions, derived assuming limiting cases opaque or transparent materials, to data. In this paper, system thermoelastic equations is analytically solved for an isotropic homogeneous material finite laser penetration depth, which important consideration when depth on order acoustic...
Pulsed laser deposition and subsequent thermal treatment were used to create compact tungsten layers with various grain sizes (1μm, 100 nm, 10 nm). The self-damaged at room temperature up 0.23 dpa using 20.3 MeV W ions annealed in vacuum 473 K or 673 prior exposure deuterium plasma populate the surviving displacement defects. Thermal desorption spectroscopy was measure retention study profile. Rate-equation modeling of spectra performed behavior individual traps both annealing temperatures....
Retention of plasma-implanted D is studied in W targets damaged by a Cu ion beam at up to 0.2 dpa with sample temperatures between 300 K and 1200 K. At plasma fluence 1024/m2 on samples K, the retained retention inventory 4.6 × 1020 D/m2, about ∼5.5 times higher than undamaged samples. The drops 9 1019 D/m2 for 1000 consistent onset vacancy annealing rate sufficient overcome elevated damage; damage temperature nearly equal values seen materials. A nano-scale technique provides thermal...
Be-D co-deposit samples are produced over an extended range of plasma-material interaction parameters reflective the conditions expected in ITER deposition dominant locations. Deposition temperature, D impact energy, atomic Be rate, and D2 neutral pressure were varied ranges 373–623 K, ∼2–100 eV, 1–10 × 1019 m2 s−1, 0.27–13.3 Pa respectively. Thermal desorption spectrometry was carried out on samples, subsequently, to measure release profile retention. It found that retention agrees well...
Retention and desorption of hydrogenic species need to be accurately modeled predict the tritium inventory next generation fusion devices, which is needed both for fuel recovery safety concerns. In this paper, experiments on thermal deuterium from intrinsic polycrystalline tungsten defects using laser heating are compared TMAP-7 modeling. The samples during plasma exposure were at a temperature 373 K benchmark study with ion fluence 0.7–1.0 × 1024 Dm−2. Following exposure, fiber (λ = 1100...
The light-ion helicon plasma source of the Proto-MPEX linear device has been recently upgraded to enable pulsed (0.5–1 s) operation up 200 kW. main objective this work is report on plasma-induced surface heat fluxes incident window during high power (60–150 kW net power) for purpose design upcoming material exposure eXperiment (MPEX). IR imaging system and associated physics models extraction are presented. Experimental results demonstrate that control strike point via magnetic flux mapping...
Fuel retention in plasma facing tungsten components is a critical phenomenon affecting the mechanical integrity and radiological safety of fusion reactors. It known that hydrogen can become trapped small defect clusters, internal surfaces, dislocations, and/or impurities, so it common practice to seed W subsurfaces with irradiation defects an attempt precondition system absorb hydrogen. The amount H later be tallied by performing careful thermal desorption tests where released temperature...
An updated analysis method for laser-induced transient grating spectroscopy measurements of near-surface thermal diffusivity using gigahertz frequency instrumentation is presented. Considering the particular application characterizing materials with heavy ion damage, prior methods typically assume a very short excitation pulse relative to relaxation time response signal. For longer durations, this can be an increasingly poor assumption decreasing probing depth. This work presents convolution...
Recent plasma-material-interaction (PMI) studies of relevance to fusion PMI science are discussed. The results a mix experiments and in situ diagnostic technology development. Scientific issues addressed include the nature He W atom migration evolution fuzz surfaces, understanding D retention damaged surfaces via modeling with tritium analysis program, an examination synergistic effects associated trapping on composite Be codeposit substrate surfaces. In developments discussed laser-induced...
A laboratory scale laser induced thermal desorption spectroscopy system is developed and tested on tungsten-deuterium titanium-deuterium codeposits, its feasibility as a hydrogenic inventory measurement diagnostic demonstrated over range of retention values from 5 × 1019 m-2 to 7 1023 for absorbed power densities low 8 MW m-2. Codeposit layer samples are grown by magnetron sputtering immersed in weak argon rf plasma. 1 kW fiber (λ = 1100 nm) heats the up peak surface temperature ranging 900...