Elevated Electron Temperature Coincident with Observed Fusion Reactions in a Sheared-Flow-Stabilized Z Pinch

The sheared-flow-stabilized Z pinch concept has been studied extensively and is able to produce fusion-relevant plasma parameters along with neutron production over several microseconds. We present here elevated electron temperature results spatially and temporally coincident with the plasma neutron source. An optical Thomson scattering apparatus designed for the FuZE device measures temperatures in the range of 1-3 keV on the axis of the device, 20 cm downstream of the nose cone. The 17-fiber system measures the radial profiles of the electron temperature. Scanning the laser time with respect to the neutron pulse time over a series of discharges allows the reconstruction of the T_{e} temporal response, confirming that the electron temperature peaks simultaneously with the neutron output, as well as the pinch current and inductive voltage generated within the plasma. Comparison to spectroscopic ion temperature measurements suggests a plasma in thermal equilibrium. The elevated T_{e} confirms the presence of a plasma assembled on axis, and indicates limited radiative losses, demonstrating a basis for scaling this device toward net gain fusion conditions.

A multi-chord, two-color interferometer using Hilbert transform phase detection for measuring electron density in spheromak plasmas

A new, four-chord, CO₂/He-Ne heterodyne interferometer has been designed and built for measuring line-averaged plasma density in the HIT-SI3 and subsequent HIT-SIU sustained spheromak devices. The two-color system successfully eliminates vibration-induced errors caused by mirrors that are secured to the vacuum chamber and is able to resolve electron densities n_e in the full operating range of 10¹⁸-10²⁰ m^-3 in both experiments with an integrated error of 4.7 × 10¹⁷ m^-2. Data are presented from high toroidal current plasma discharges, showing the time evolution of electron densities n_e and j_ϕ/n_e along multiple chords.

High-speed feedback control of an oscillating magnetic helicity injector using a graphics processing unit

A real-time control system has been developed to control the amplitude, phase, and offset of bulk plasma parameters inside an oscillating magnetic helicity injector. Control software running entirely on an Nvidia Tesla P40 graphical processing unit is able to receive digitizer inputs and send response patterns to a Pulse Width Modulation (PWM) controller with a minimum control loop period of 12.8 µs. With an input digitization rate of 10 MS/s, a three-parameter proportional integral differential controller is shown to be sufficient to inform the PWM controller to drive the desired oscillating plasma waveform with a frequency of 16.6 kHz that is located near the resonance of a coupled RLC circuit. In particular, the temporal phase of the injector waveform is held within 10° of the target value. Control is demonstrated over the toroidal modal structure of the imposed magnetic perturbations of the helicity injection system, allowing a new class of discharges to be studied.

Direct observations of submarine melt and subsurface geometry at a tidewater glacier

Ice loss from the world's glaciers and ice sheets contributes to sea level rise, influences ocean circulation, and affects ecosystem productivity. Ongoing changes in glaciers and ice sheets are driven by submarine melting and iceberg calving from tidewater glacier margins. However, predictions of glacier change largely rest on unconstrained theory for submarine melting. Here, we use repeat multibeam sonar surveys to image a subsurface tidewater glacier face and document a time-variable, three-dimensional geometry linked to melting and calving patterns. Submarine melt rates are high across the entire ice face over both seasons surveyed and increase from spring to summer. The observed melt rates are up to two orders of magnitude greater than predicted by theory, challenging current simulations of ice loss from tidewater glaciers.

Nutritional support team vs nonteam management of enteral nutritional support in a Veterans Administration Medical Center teaching hospital

One hundred one patients receiving enteral nutritional support (ENS) by tube feeding during a 5-month period were prospectively studied. Fifty patients were managed by a nutritional support team (T) and 51 patients were managed by the nonteam approach (NT). Demographics, primary diagnosis, chronic diseases, medical service, calculated basal energy expenditure (BEE), duration of ENS, and final patient disposition were recorded. Enteral formula, formula modifications, results of laboratory tests and calories delivered were obtained daily. Results of nitrogen balance studies were obtained when available and each patient was monitored for pulmonary, mechanical, gastrointestinal, and metabolic abnormalities. No significant difference was found between the team and nonteam managed groups in regard to total feeding days, mean feeding days per patient, total laboratory tests, laboratory tests per patient or laboratory tests per day. Significantly more team patients attained 1.2 times BEE (T = 47, NT = 38, p less than 0.05) for a significantly greater period of time (T = 398 days, NT = 281 days, p less than 0.05). Significantly more team patients achieved a measured positive nitrogen balance than nonteam patients (T = 42, NT = 1, p less than 0.05). Formula modifications to correct nutritional or metabolic aberrations were made in 15 (30%) team patients and five (9.8%) nonteam patients (p less than 0.05). The number of individual abnormalities (pulmonary, mechanical, gastrointestinal, and metabolic), as well as total abnormalities occurring in the team-managed group, was significantly lower than in the nonteam managed group (160 vs 695, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Haemolytic-uraemic syndrome. A report of an outbreak

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