Performance Scaling in Magnetized Liner Inertial Fusion Experiments.

We present experimental results from the first systematic study of performance scaling with drive parameters for a magnetoinertial fusion concept. In magnetized liner inertial fusion experiments, the burn-averaged ion temperature doubles to 3.1 keV and the primary deuterium-deuterium neutron yield increases by more than an order of magnitude to 1.1×10^{13} (2 kJ deuterium-tritium equivalent) through a simultaneous increase in the applied magnetic field (from 10.4 to 15.9 T), laser preheat energy (from 0.46 to 1.2 kJ), and current coupling (from 16 to 20 MA). Individual parametric scans of the initial magnetic field and laser preheat energy show the expected trends, demonstrating the importance of magnetic insulation and the impact of the Nernst effect for this concept. A drive-current scan shows that present experiments operate close to the point where implosion stability is a limiting factor in performance, demonstrating the need to raise fuel pressure as drive current is increased. Simulations that capture these experimental trends indicate that another order of magnitude increase in yield on the Z facility is possible with additional increases of input parameters.

HIGH-PRESSURE PHYSICS. Direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium.

Eighty years ago, it was proposed that solid hydrogen would become metallic at sufficiently high density. Despite numerous investigations, this transition has not yet been experimentally observed. More recently, there has been much interest in the analog of this predicted metallic transition in the dense liquid, due to its relevance to planetary science. Here, we show direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium. Experimental determination of the location of this transition provides a much-needed benchmark for theory and may constrain the region of hydrogen-helium immiscibility and the boundary-layer pressure in standard models of the internal structure of gas-giant planets.

Experimental demonstration of fusion-relevant conditions in magnetized liner inertial fusion.

This Letter presents results from the first fully integrated experiments testing the magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)], in which a cylinder of deuterium gas with a preimposed 10 Taxial magnetic field is heated by Z beamlet, a 2.5 kJ, 1 TW laser, and magnetically imploded by a 19 MA, 100 ns rise time current on the Z facility. Despite a predicted peak implosion velocity of only 70 km = s, the fuel reaches a stagnation temperature of approximately 3 keV, with T(e) ≈ T(i), and produces up to 2 x 10(12) thermonuclear deuterium-deuterium neutrons. X-ray emission indicates a hot fuel region with full width at half maximum ranging from 60 to 120 µm over a 6 mm height and lasting approximately 2 ns. Greater than 10(10) secondary deuterium-tritium neutrons were observed, indicating significant fuel magnetization given that the estimated radial areal density of the plasma is only 2 mg = cm(2).

Understanding fuel magnetization and mix using secondary nuclear reactions in magneto-inertial fusion.

Magnetizing the fuel in inertial confinement fusion relaxes ignition requirements by reducing thermal conductivity and changing the physics of burn product confinement. Diagnosing the level of fuel magnetization during burn is critical to understanding target performance in magneto-inertial fusion (MIF) implosions. In pure deuterium fusion plasma, 1.01 MeV tritons are emitted during deuterium-deuterium fusion and can undergo secondary deuterium-tritium reactions before exiting the fuel. Increasing the fuel magnetization elongates the path lengths through the fuel of some of the tritons, enhancing their probability of reaction. Based on this feature, a method to diagnose fuel magnetization using the ratio of overall deuterium-tritium to deuterium-deuterium neutron yields is developed. Analysis of anisotropies in the secondary neutron energy spectra further constrain the measurement. Secondary reactions also are shown to provide an upper bound for the volumetric fuel-pusher mix in MIF. The analysis is applied to recent MIF experiments [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] on the Z Pulsed Power Facility, indicating that significant magnetic confinement of charged burn products was achieved and suggesting a relatively low-mix environment. Both of these are essential features of future ignition-scale MIF designs.

Architecture, implementation, and testing of a multiple-shell gas injection system for high current implosions on the Z accelerator.

Tests are ongoing to conduct ~20 MA z-pinch implosions on the Z accelerator at Sandia National Laboratory using Ar, Kr, and D2 gas puffs as the imploding loads. The relatively high cost of operations on a machine of this scale imposes stringent requirements on the functionality, reliability, and safety of gas puff hardware. Here we describe the development of a prototype gas puff system including the multiple-shell nozzles, electromagnetic drivers for each nozzle's valve, a UV pre-ionizer, and an inductive isolator to isolate the ~2.4 MV machine voltage pulse present at the gas load from the necessary electrical and fluid connections made to the puff system from outside the Z vacuum chamber. This paper shows how the assembly couples to the overall Z system and presents data taken to validate the functionality of the overall system.

Observations of modified three-dimensional instability structure for imploding z-pinch liners that are premagnetized with an axial field.

Novel experimental data are reported that reveal helical instability formation on imploding z-pinch liners that are premagnetized with an axial field. Such instabilities differ dramatically from the mostly azimuthally symmetric instabilities that form on unmagnetized liners. The helical structure persists at nearly constant pitch as the liner implodes. This is surprising since, at the liner surface, the azimuthal drive field presumably dwarfs the axial field for all but the earliest stages of the experiment. These fundamentally 3D results provide a unique and challenging test for 3D-magnetohydrodynamics simulations.

Design and implementation of a 120 GHz tracking interferometer with near diffraction limited focal spot.

The design and implementation of a 120 GHz monostatic tracking interferometer with near diffraction limited focal spot size, used to measure line-averaged plasma density in the source of a plasma opening switch (POS), is described. Physical dimensions of the switch source place an upper limit on the focal spot size. Focusing quasioptics utilize a standard pyramidal horn and a pair of cylindrical lenses that are easily fabricated. The combination of the two cylindrical lenses transforms the asymmetric and approximately Gaussian beam produced by the pyramidal horn into a small focal spot. The circuit utilizes a tracking receiver configuration to track oscillator frequency drifts, which allow for full heterodyne quadrature operation, while avoiding the added complexity of phase or frequency locking of the sources. In order to reduce system noise in the POS pulsed power environment, all sources and amplifiers are battery powered and other noise-reducing techniques are employed. Finally, an improved Gaussian optics design methodology, which tracks the phase center of the Gaussian beam, is proposed. While not critical to this application, this method may yield improvements in systems with short focal lengths.

Group involvement in decision-making: a pilot study.

BACKGROUND: The Vroom-Yetton-Jago Leadership Model served as a model to determine if leaders could be taught the appropriate level of group involvement in decision-making. METHOD: A convenience sample of 27 health care leaders who attended a 90-minute class offered in one institution were eligible for inclusion in the study and pre- and post-performance on similar case studies was measured. RESULTS: Using a paired t test, results for this sample were statistically significant (t [21] = 6.02, p < .001). CONCLUSION: These results suggest that participating in a class on the use of this leadership model may help leaders gain the skill needed to appropriately delegate decision-making to groups.

Peri-operative blood loss and non-steroidal anti-inflammatory drugs: an investigation using diclofenac in patients undergoing transurethral resection of the prostate.

Peri-operative blood loss was compared in a prospective, randomized double-blind study between two groups of patients undergoing transurethral prostatectomy (TURP) under spinal (subarachnoid) analgesia: the first received the non-steroidal anti-inflammatory drug diclofenac sodium, the second group received placebo. The total blood loss and the blood loss per gram of prostate resected did not differ significantly. Some 80% of patients were completely pain free at 8 and 24 h post-operation, and low pain scores recorded by the remaining 20% of patients supported the conclusion that TURP performed under spinal analgesia is not commonly associated with severe post-operative pain.

Treatment of nasopharyngeal carcinoma with human leukocyte interferon.

Nasopharyngeal carcinoma (NPC) is a human neoplasm closely associated with Epstein-Barr virus (EBV). Human leukocyte interferon (IFN) has known antiviral and antineoplastic properties. After initial IFN treatment in one NPC patient demonstrated acceptably low toxicity, 12 additional patients were treated on a protocol with IFN, 10 X 10(6) units intramuscularly (IM) daily for 30 days. IFN did not affect serum anti-EBV antibody titers (IgA and IgG antiviral capsid and early antigens). Of six patients tested, none was found to excrete EBV in saliva before, during, or after IFN. Four patients had measurable tumor regression (two partial responses and two minor responses), three had stable disease, and five patients plus the initial preprotocol patient had progressive disease. Toxicity included fever, fatigue, and myalgias in all patients, thrombocytopenia in two patients, and neutropenia in three patients. Three patients were withdrawn from the study, one each for severe fatigue, neutropenia, and hypotension. This study demonstrates that IFN has sufficient activity in advanced NPC to justify further investigation.

Use of cloned probes to detect Epstein-Barr viral DNA in tissues of patients with neoplastic and lymphoproliferative diseases.

Cloned fragments of the Epstein-Barr virus (EBV) genome were used to examine tissues from 145 patients for the presence of EBV DNA by two techniques: (1) nucleic acid hybridization of cell spots from which the DNA had been extracted in situ and (2) hybridization of DNA that had been transferred to nitrocellulose by Southern blotting. EBV DNA was found in tissues from four adults and five children with American Burkitt's lymphoma, infectious mononucleosis, lymphoma following bone marrow transplant, central nervous system lymphoma, nasopharyngeal carcinoma, and fatal polyclonal B-cell lymphoma following mononucleosis; two patients also had chronic pneumonitis, failure to thrive, and abnormal immune function. Six of the nine patients whose tissues contained EBV DNA had a demonstrable or presumed associated immunologic disorder. EBV DNA was not found in normal tissues or in a variety of hematologic neoplasms and other disorders. Nucleic acid hybridization methods can be used for the routine examination of the association of EBV with lymphomas and other lymphoproliferative syndromes occurring in immunodeficient individuals.