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A new thermal helium beam diagnostic has been implemented in the outer lower divertor of the ASDEX Upgrade tokamak. The purpose of this diagnostic is to measure two-dimensional profiles of electron density (ne) and temperature (Te) with high temporal and spatial resolution. The geometry of the lines of sight is chosen to avoid the influence of prompt recycling and to optimize the resolution without significantly impacting the divertor structure. Moreover, the effect of long-term helium recycling has been analyzed, and its amplitude compared to the active signal is negligible. Finally, the reconstruction of ne and Te is done via a collisional radiative model, while a static and a dynamic model were implemented and compared with SOLPS simulations as well as divertor Thomson scattering data. Furthermore, a new 2D parameterization of the outer divertor volume, which is required for the dynamic model, was developed. Due to its fast and local ne and Te profile measurements, the diagnostic is suitable for investigating fast processes such as divertor transitions and filaments. [ABSTRACT FROM AUTHOR]

In the scrape-off layer (SOL) of fusion plasmas, radial particle and energy transport is mainly carried by plasma filaments. The plasma parameters of such filaments can be measured by the thermal helium beam diagnostic (THB). By means of an extended collisional radiative model (CRM) used for the evaluation of the diagnostic data, the light intensity response of neutral helium transitions from filaments is studied, which depends on the parameters of the filament and the background. The electron density of the filament is found to be the dominant parameter impacting the line intensities. By applying a numerical reconstruction algorithm based on the CRM, electron temperatures and densities as well as the sizes of experimentally measured filaments are obtained. This method allows for the first time measurements of the temporal decay rates of filament density and temperature in the co-moving frame of the filament and its radial propagation velocity. [ABSTRACT FROM AUTHOR]

The I-mode confinement regime is promising for future reactor operation due to high energy confinement without high particle confinement. However, the role of edge turbulence in creating I-mode's beneficial transport properties is still unknown. New measurements of edge turbulence ( ρ pol = 0.9 − 1.0) in L-modes and I-modes at low and high densities at ASDEX Upgrade are presented in this paper. A high radial resolution correlation electron cyclotron emission radiometer measures the broadband turbulence throughout the L-mode and I-mode edge and pedestal. The weakly coherent mode (WCM) is measured in both L-mode and I-mode near the last closed flux surface with Te fluctuation levels of 2.3%–4.2%, with a frequency shift between the two phases related to a deeper Er well in I-mode. An n e T e phase diagnostic captures a change of the WCM n e T e phase between L-mode and I-mode from − 171 ° to − 143 °. The thermal He beam diagnostic measures a WCM wavenumber range of −0.5 to −1.0 cm−1. A low-frequency edge oscillation (LFEO) appears in the I-mode phase of these discharges and displays coupling to the WCM, but the LFEO does not appear in the L-mode phase. Linear gyrokinetic simulations of the outer core and pedestal top turbulence indicate that while the dominant turbulent modes in the outer core are ion directed and electrostatic, the turbulence becomes increasingly electron directed and electromagnetic with increasing radius. Collisionality is not found to impact characteristics of the L-mode and I-mode edge turbulence with respect to the presence of the WCM; however, the quality of global confinement decreases with collisionality. [ABSTRACT FROM AUTHOR]

We introduce a new correlation analysis technique for thermal helium beam (THB) diagnostics. Instead of directly evaluating line ratios from fluctuating time series, we apply arithmetic operations to all available He I lines and construct time series with desired dependencies on the plasma parameters. By cross-correlating those quantities and by evaluating ensemble averages, uncorrelated noise contributions can be removed. Through the synthetic data analysis, we demonstrate that the proposed analysis technique is capable of providing the power spectral densities of meaningful plasma parameters, such as the electron density and the electron temperature, even under low-photon-count conditions. In addition, we have applied this analysis technique to the experimental THB data obtained at the ASDEX Upgrade tokamak and successfully resolved the electron density and temperature fluctuations up to 90 kHz in a reactor relevant high power scenario. [ABSTRACT FROM AUTHOR]

Context: Understanding the consent process that organ procurement organizations (OPOs) use is crucial to improving the process and thereby reducing the number of individuals who die each year for want of an organ transplant. However, no data exist on OPOs' current consent practices.Objective: To assess whose wishes OPOs follow when procuring solid organs from deceased individuals and whether advance directives and computerized registries might improve the consent process for solid organ procurement.Design, Setting, and Participants: Telephone survey conducted from June to August 1999 of all 61 active OPOs.Main Outcome Measures: Responses to the 49-question survey addressing consent practices in specific scenarios of deceased and next of kin wishes.Results: Widespread divergence exists in OPOs' consent practices for cadaveric solid organ procurement. Regarding overall consent practices, 19 (31%) OPOs reported that they follow the deceased's wishes, 19 (31%) follow the next of kin's wishes, 13 (21%) procure organs if neither party objects, 8 (13%) procure organs if either party consents or neither objects, and 2 (3%) do not follow any of these 4 overall practices. These differences appear to be traceable to implicit ethical disagreements about whose wishes should be followed. A total of 29 (48%) OPOs reported having an official policy to address whether they follow the family's or deceased's wishes. Regarding factors that influence OPOs' choice of consent practice, 29 (48%) respondents ranked impact on the deceased's family as the most important factor, 13 (21%) ranked state law as most important, and 7 (11%) ranked the priority of the deceased's wishes as most important. Durable power of attorney appeared to have substantial weight in OPOs' decisions; for example, in the scenario in which the deceased supported organ donation and the next of kin opposed it, 34 (56%) OPOs reported they were likely to procure organs based on the consent of the holder of the deceased's durable power of attorney, whereas only 7 (11%) reported they were likely to procure organs based on a document of gift (a living will, donor card, or driver's license).Conclusions: Expanding the legal scope of living wills to cover individuals' organ donation preferences would likely have little impact on procurement rates. In contrast, expanding the legal scope of durable powers of attorney for health care may have a significant impact. A national discussion should take place addressing the underlying ethical issues that appear to account for much of the divergence among OPOs' consent practices for cadaveric solid organ procurement. [ABSTRACT FROM AUTHOR]