Anisotropy-driven collisional separation of impurities in magnetized compressing and expanding cylindrical plasmas

When a cylindrically-symmetric magnetized plasma compresses or expands, velocity-space anisotropy is naturally generated as a result of the different adiabatic conservation laws parallel and perpendicular to the magnetic field. When the compression timescale is comparable to the collision timescale, and both are much longer than the gyroperiod, this pressure anisotropy can become significant. We show that this naturally-generated anisotropy can dramatically affect the transport of impurities in the compressing plasma, even in the absence of scalar temperature or density gradients, by modifying the azimuthal frictions that give rise to radial particle transport. Although the impurity transport direction depends only on the sign of the pressure anisotropy, the anisotropy itself depends on the pitch magnitude of the magnetic field and the sign of the radial velocity. Thus, pressure anisotropy effects can drive impurities either towards or away from the plasma core. These anisotropy-dependent terms represent a qualitatively new effect, influencing transport particularly in the sparse edge regions of dynamically-compressing screw pinch plasmas. Such plasmas are used for both X-ray generation and magneto-inertial fusion, applications which are sensitive to impurity concentrations.Comment: 11 pages, 3 figure

Particle Orbits in a Force-Balanced, Wave-Driven, Rotating Torus

The wave-driven rotating torus (WDRT) is a recently proposed fusion concept where the rotational transform is provided by the E x B drift resulting from a minor radial electric field. This field can be produced, for instance, by the RF-wave-mediated extraction of fusion-born alpha particles. In this paper, we discuss how macroscopic force balance, i.e. balance of the thermal hoop force, can be achieved in such a device. We show that this requires the inclusion of a small plasma current and vertical magnetic field, and identify the desirable reactor regime through free energy considerations. We then analyze particle orbits in this desirable regime, identifying velocity-space anisotropies in trapped (banana) orbits, resulting from the cancellation of rotational transforms due to the radial electric and poloidal magnetic fields. The potential neoclassical effects of these orbits on the perpendicular conductivity, current drive, and transport are discussed.Comment: 13 pages, 7 figure

Alpha Channeling with High-field Launch of Lower Hybrid Waves

Although lower hybrid waves are effective at driving currents in present-day tokamaks, they are expected to interact strongly with high-energy particles in extrapolating to reactors. In the presence of a radial alpha particle birth gradient, this interaction can take the form of wave amplification rather than damping. While it is known that this amplification more easily occurs when launching from the tokamak high-field side, the extent of this amplification has not been made quantitative. Here, by tracing rays launched from the high- field-side of a tokamak, the required radial gradients to achieve amplification are calculated for a temperature and density regime consistent with a hot-ion-mode fusion reactor. These simulations, while valid only in the linear regime of wave amplification, nonetheless illustrate the possibilities for wave amplification using high-field launch of the lower hybrid wave.Comment: 7 pages, 7 figure

The effects of dietary peuNDF-240 and rumen fermentable starch on the milk proteome of dairy cows

The milk proteome is affected by many factors, including diet, and characterizing the impact of diet on the milk proteome can aid in the identification of potential biomarkers that can be used as indicators of cow health and production in dairy systems. The objectives of this study were to 1) identify proteins that were affected by changes in dietary physically effective undegraded neutral detergent fiber (peuNDF-240) and rumen fermentable starch (RFS) levels and 2) determine if milking time affected any proteins due to proximity to feeding. Sixteen Holsteins cows were included in a 4x4 Latin square design experiment, including 4 28-d periods. Cows were milked thrice daily (4:30, 12:30, and 20:30 h). Samples collected from cows receiving two of the diets were analyzed in the current trial: diets were a high peuNDF-240 high RFS diet (HFHS; 8% peuNDF-240, 19.0 ±0.7% RFS) and a low peu-NDF-240 low RFS diet (LFLS; 6.35% peuNDF-240, 16.7±1.0% RFS). Milk samples were collected from each cow during 6 consecutive milkings on d 26-28 of each period. Samples were snap frozen and stored until analysis, and subsequently fractionated for protein isolation. Isolated proteins were quantified and labeled using TMT labels before being analyzed for low abundance proteins using LC-MS/MS. The results were analyzed using PROC MIXED in SAS (v 9.4) to identify the effect of treatment, time, and the interaction of treatment x time. There were 13 proteins identified that were either being affected by time, treatment, and the interaction of treatment x time. Proteins affected by diet, time, or the interaction of diet x time included serpin A3-1, a protease inhibitor, xanthine dehydrogenase/oxidase, which is involved in lipid droplet formation and secretion, and zinc-alpha-2-glycoprotein, which is involved in defense/immunity. Milk proteomics can help to further our understanding of how diet and other factors affect the cow in ways that might not be observed from looking at the cow

Point-wise mutual information-based video segmentation with high temporal consistency

In this paper, we tackle the problem of temporally consistent boundary detection and hierarchical segmentation in videos. While finding the best high-level reasoning of region assignments in videos is the focus of much recent research, temporal consistency in boundary detection has so far only rarely been tackled. We argue that temporally consistent boundaries are a key component to temporally consistent region assignment. The proposed method is based on the point-wise mutual information (PMI) of spatio-temporal voxels. Temporal consistency is established by an evaluation of PMI-based point affinities in the spectral domain over space and time. Thus, the proposed method is independent of any optical flow computation or previously learned motion models. The proposed low-level video segmentation method outperforms the learning-based state of the art in terms of standard region metrics