372 research outputs found

    A crude model to study radio frequency induced density modification close to launchers

    Get PDF
    The interplay between radio frequency (RF) waves and the density is discussed by adopting the general framework of a 2-time-scale multi-fluid treatment, allowing to separate the dynamics on the RF time scale from that on the time scale on which macroscopic density and flows vary as a result of the presence of electromagnetic and/or electrostatic fields. The focus is on regions close to launchers where charge neutrality is incomplete and waves are commonly evanescent. The fast time scale dynamics influences the slow time scale behavior via quasilinear terms (the Ponderomotive force for the case of the equation of motion). Electrons and ions are treated on the same footing. Also, both fast and slow waves are retained in the wave description. Although this work is meant as a subtopic of a large study-the wave induced "convective cell" physics at hand is of a 2- or 3-dimensional nature while this paper limits itself to a single dimension-a few tentative examples are presented

    Modeling of Particle Transport, Neutrals and Radiation in Magnetically-Confined Plasmas with Aurora

    Get PDF
    We present Aurora, an open-source package for particle transport, neutrals and radiation modeling in magnetic confinement fusion plasmas. Aurora's modern multi-language interface enables simulations of 1.5D impurity transport within high-performance computing frameworks, particularly for the inference of particle transport coefficients. A user-friendly Python library allows simple interaction with atomic rates from the Atomic Data and Atomic Structure database as well as other sources. This enables a range of radiation predictions, both for power balance and spectroscopic analysis. We discuss here the superstaging approximation for complex ions, as a way to group charge states and reduce computational cost, demonstrating its wide applicability within the Aurora forward model and beyond. Aurora also facilitates neutral particle analysis, both from experimental spectroscopic data and other simulation codes. Leveraging Aurora's capabilities to interface SOLPS-ITER results, we demonstrate that charge exchange is unlikely to affect the total radiated power from the ITER core during high performance operation. Finally, we describe the ImpRad module in the OMFIT framework, developed to enable experimental analysis and transport inferences on multiple devices using Aurora.Comment: 8 pages + references, 5 figure

    TOPLHA: an accurate and efficient numerical tool for analysis and design of LH antennas

    Get PDF
    This paper presents a self-consistent, integral-equation approach for the analysis of plasma-facing lower hybrid (LH) launchers; the geometry of the waveguide grill structure can be completely arbitrary, including the non-planar mouth of the grill. This work is based on the theoretical approach and code implementation of the TOPICA code, of which it shares the modular structure and constitutes the extension into the LH range. Code results are validated against the literature results and simulations from similar code

    Cellular Immunity to Predict the Risk of Cytomegalovirus Infection in Kidney Transplantation: A Prospective, Interventional, Multicenter Clinical Trial

    Get PDF
    Background: Improving cytomegalovirus (CMV) immune-risk stratification in kidney transplantation is highly needed to establish guided preventive strategies. Methods: This prospective, interventional, multicenter clinical trial assessed the value of monitoring pretransplant CMV-specific cell-mediated immunity (CMI) using an interferon-γrelease assay to predict CMV infection in kidney transplantation. One hundred sixty donor/recipient CMV-seropositive (D+/R+) patients, stratified by their baseline CMV (immediate-early protein 1)-specific CMI risk, were randomized to receive either preemptive or 3-month antiviral prophylaxis. Also, 15-day posttransplant CMI risk stratification and CMI specific to the 65 kDa phosphoprotein (pp65) CMV antigen were investigated. Immunosuppression consisted of basiliximab, tacrolimus, mycophenolate mofetil, and corticosteroids in 80% of patients, whereas 20% received thymoglobulin induction therapy. Results: Patients at high risk for CMV based on pretransplant CMI developed significantly higher CMV infection rates than those deemed to be at low risk with both preemptive (73.3% vs 44.4%; odds ratio [OR], 3.44 [95% confidence interval {CI}, 1.30-9.08]) and prophylaxis (33.3% vs 4.1%; OR, 11.75 [95% CI, 2.31-59.71]) approaches. The predictive capacity for CMV-specific CMI was only found in basiliximab-treated patients for both preemptive and prophylaxis therapy. Fifteen-day CMI risk stratification better predicted CMV infection (81.3% vs 9.1%; OR, 43.33 [95% CI, 7.89-237.96]). Conclusions: Pretransplant CMV-specific CMI identifies D+/R+ kidney recipients at high risk of developing CMV infection if not receiving T-cell-depleting antibodies. Monitoring CMV-specific CMI soon after transplantation further defines the CMV infection prediction risk. Monitoring CMV-specific CMI may guide decision making regarding the type of CMV preventive strategy in kidney transplantation. Clinical Trials Registration: NCT02550639
    corecore