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.

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.

Novel deuterium-tritium (DT) neutron activation diagnostics for increased neutron yield operations at Sandia's Z-facility (invited).

As inertial confinement fusion experiments at Sandia National Laboratories' Z-facility begin using deuterium-tritium (DT) fuels, the expected DT-neutron yields are expected to increase many orders of magnitude. This brings about the need for diagnostics that have a significantly higher dynamic range of operation and ability to obtain yields where there will be significant radiation holds. Using the current activation diagnostic infrastructure at the Z-facility, a pair of activation diagnostics are being developed. The first is fluorine activation, which will be used in a similar manner to current copper activation diagnostics that are fielded in a rabbit for quick removal from the experiments without opening the vacuum experiment containment. The second is a prompt DT-neutron detector that exploits the activation of oxygen with similar operation characteristics as the current Be-probes fielded at Z. We will discuss the design of this pair of instruments, along with calibration work performed at Sandia's Ion Beam Laboratory in support of the development and anticipated instrument performance.

Assembly of high-areal-density deuterium-tritium fuel from indirectly driven cryogenic implosions.

The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of ~1.0±0.1 g cm(-2), which is 67% of the ignition requirement. These conditions were obtained using 192 laser beams with total energy of 1-1.6 MJ and peak power up to 420 TW to create a hohlraum drive with a shaped power profile, peaking at a soft x-ray radiation temperature of 275-300 eV. This pulse delivered a series of shocks that compressed a capsule containing cryogenic deuterium-tritium to a radius of 25-35 µm. Neutron images of the implosion were used to estimate a fuel density of 500-800 g cm(-3).

Inferring neutron yields using indium activation samples for small fractions of tritium added to deuterium fuel in inertial confinement fusion (ICF) experiments.

In inertial confinement fusion experiments, the neutron yield is an important metric for thermonuclear fusion performance. Neutron activation diagnostics can be used to infer neutron yields. The material used for neutron activation diagnostic undergoes a threshold reaction so that only neutrons having energies above the threshold energy are observed. For thermonuclear experiments using deuterium (D) and tritium (T) fuel constituents, neutrons arising from D + D reactions (DD-neutrons) and neutrons resulting from D + T reactions (DT-neutrons) are of primary interest. Indium has two neutron activation reactions that can be used to infer yields of DD-neutrons and DT-neutrons. One threshold is high enough that only DT-neutrons can induce activation, the second reaction can be activated by both DD-neutrons and DT-neutrons. Thus, to obtain the DD-neutron yield, the contribution made by DT-neutrons to the total induced activity must be extracted. In DD-fuel experiments, DT-neutrons arise from secondary reactions, which are significantly lower in number than primary DD-neutrons, and their contribution to the inferred DD-neutron yield can be ignored. When the DD- and DT-neutron yields become comparable, such as when low tritium fractions are added to DD-fuel, the contribution of DT-neutrons must be extracted to obtain accurate yields. A general method is described for this correction to DD-neutron yields.

Neutron time-of-flight detectors (nTOF) used at Sandia's Z-Machine.

Neutron time-of-flight (nTOF) detectors have been used on Sandia National Laboratories' Z-Machine for inertial confinement fusion and magnetized liner fusion experiments to infer physics parameters including the apparent fuel-ion temperature, neutron yield, the magnetic-radius product (BR), and the liner rho-r. Single-paddle, dual-paddle, and co-axial scintillation nTOF detectors are used in axial lines-of-sight (LOS) and LOS that are 12° from the midplane. Detector fabrication, characterization, and calibration are discussed.

Asymmetry of spermiation and sperm surface charge patterns over the giant acrosome in the musk shrew Suncus murinus.

Spermatozoa of the shrew Suncus murinus, a mammal with abdominal testes, exhibit four unusual features: a giant acrosome; a dorsoventral asymmetry of their spermiation; a dorsoventral asymmetry of their head surface character; and also apparent surface maturity as they enter the epididymis. A Sertoli cell-periacrosomal cisternal complex envelops the giant acrosome during spermatid maturation. Spermiation is heraled by asymmetrical disorganization of the subplasmalemmal components of this complex and is completed by retraction of the Sertoli cell from the ventral and then the dorsal face of the spermatid head. This sequence or release is correlated with an asynchronous acquisition of negative surface charges on the spermatid head-demonstrable on glutaraldehyde-stabilized cells by the binding at pH 1.8 of positively charged colloidal particles of ferric oxide. Mature epididymal spermatozoa exhibit an asymmetry in the patterns of distribution of bound colloid over the dorsal vs. ventral surfaces of the sperm head, as well as regional differences between the tail midpiece and principal piece. Surface distributions of anionic residues and lectin (Con A)-binding sites characteristic of mature Suncus spermatozoa are demonstrable within the testis, unlike the situation in most nannals where distinct modifications of the sperm surface occur during epididymal passage.

Intracellular accumulation of protocollagen and extrusion of collagen by embryonic cartilage cells.

The synthesis of collagen can be interrupted, after the assembly of proline-rich and lysine-rich polypeptide chains called protocollagen, by incubating connective tissues anaerobically. Under these conditions the proline and lysine residues in protocollagen are not hydroxylated to hydroxyproline and hydroxylysine, and protocollagen molecules accumulate intracellularly. Chemical data and radioautographs at the level of the light and electron microscopes indicated that in tissues labeled with proline-3,4-(3)H under nitrogen, there appeared to be an accumulation of radioactivity over the ground cytoplasm. When the inhibition of protocollagen hydroxylase was reversed by exposing the tissue to oxygen, the accumulated protocollagen-(3)H was converted to collagen-(3)H and there was a rapid transfer of label from the ground cytoplasm to the extracellular matrix. There was no significant change in distribution of label over either the Golgi vacuoles or the cisternae of the endoplasmic reticulum. The failure to find a significant change in distribution of label over the Golgi vacuoles or the cisternae does not completely exclude the possibility that these two compartments are involved in the extrusion, but the data are consistent with the simpler notion that the completed collagen molecules pass directly from the ground cytoplasm to the extracellular matrix.

Sulfur and hydrogen isotope anomalies in meteorite sulfonic acids.

Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

Hydroxylation of proline and the intracellular accumulation of a polypeptide precursor of collagen.

Autoradiographs of embryonic cartilage indicated that labeled protein accumnulated intracellularly when the tissue was incubated with tritiated proline, and when the hydroxylation of proline was inhibited by anaerobic conditions or by a chelator for ferrous iron. The labeled protein apparently corresponds to protocollagen. the polypeptide precursor of collagen which serves as a substrate for the enzymatic synthesis of hydroxyproline.

Renal erythropoietic factor: role of ions and vasoactive agents in erythropoietin formation.

Evidence is provided for the existence of a renal erythropoietic factor, devoid of vasopressor activity, which upon interaction in vitro with normal serum yields erythropoietin. When undialyzed serum is used, erythropoietin inactivation develops in the incubation mixtures, and this inactivation appears to be dependent on an enzymatic component in preparations of the factor and on ions in serum.

Average neutron time-of-flight instrument response function inferred from single D-T neutron events within a plastic scintillator.

The apparent ion temperature and neutron-reaction history are important characteristics of a fusion plasma. Extracting these quantities from a measured neutron-time-of-flight signal requires accurate knowledge of the instrument response function (IRF). This work describes a novel method for obtaining the IRF directly for single DT neutron interactions by utilizing n-alpha coincidence. The t(d,α)n nuclear reaction was produced at Sandia National Laboratories' Ion Beam Laboratory using a 300 keV Cockcroft-Walton generator to accelerate a 2.5 µA beam of 175 keV D+ ions into a stationary ErT2 target. The average neutron IRF was calculated by taking a time-corrected average of individual neutron events within an EJ-228 plastic scintillator. The scintillator was coupled to two independent photo-multiplier tubes operated in the current mode: a Hamamatsu 5946 mod-5 and a Photek PMT240. The experimental setup and results will be discussed.

Modeling the one-dimensional imager of neutrons (ODIN) for neutron response functions at the Sandia Z facility.

The one-dimensional imager of neutrons (ODIN) at the Sandia Z facility consists of a 10-cm block of tungsten with rolled edges, creating a slit imager with slit widths of either 250, 500, or 750 µm. Designed with a 1-m neutron imaging line of sight, we achieve about 4:1 magnification and 500-µm axial spatial resolution. The baseline inertial confinement fusion concept at Sandia is magnetized liner inertial fusion, which nominally creates a 1-cm line source of neutrons. ODIN was designed to determine the size, shape, and location of the neutron producing region, furthering the understanding of compression quality along the cylindrical axis of magnetized liner implosions. Challenges include discriminating neutrons from hard x-rays and gammas with adequate signal-to-noise in the 2 × 1012 deuterium-deuterium (DD) neutron yield range, as well as understanding the point spread function of the imager to various imaging detectors (namely, CR-39). Modeling efforts were conducted with MCNP6.1 to determine neutron response functions for varying configurations in a clean DD neutron environment (without x-rays or gammas). Configuration alterations that will be shown include rolled-edge slit orientation and slit width, affecting the resolution and response function. Finally, the experiment to determine CR-39 neutron sensitivity, with and without a high density polyethylene (n, p) converter, an edge spread function, and resolution will be discussed.

Iodinated contrast agents in myasthenia gravis.

Administration of intravenous iodinated contrast agents has been reported to cause increased weakness in myasthenia gravis (MG) patients. We reviewed the records of 136 patients with MG who had at least one radiologic procedure involving intravenously administered contrast media. Seven patients (5.1%) had contrast reactions, which compares with the 5% rate of contrast reactions in the general population. Five patients had either a subjective or objective increase in weakness that could be explained by reasons other than contrast administration. Only one patient was found to have increased respiratory muscle weakness, which could have been attributed to either contrast infusion or pulmonary embolism. We conclude that intravenous contrast agents are not contraindicated in MG, but extra care should be taken when they are given.

The effects of administration of ethyl alcohol to mice on megakaryocyte and platelet development.

The effects of administration to laboratory mice of 5-20% ethyl alcohol (v:v) as drinking water on megakaryocyte and platelet development were studied and compared with data on controls given tap water. In two separate experiments, mice given 5-15% ethyl alcohol (v:v) for 13 or 11 weeks showed decreases in platelet counts and platelet 35S uptake when compared to the control groups. Mice fed 5-20% alcohol for five weeks showed platelet counts, bone marrow megakaryocyte numbers and diameters that were significantly reduced to 72% (P less than 0.001), 45% (P less than 0.001), and 71% (P less than 0.01), respectively. The data implied that ethyl alcohol ingestion had a direct inhibitory effect on megakaryocyte and platelet development in mice, which resulted in a marked reduction in the levels of circulating platelets.

Detection in human sera of antibodies directed against the hamster egg oolemma.

Heteroantibodies were demonstrated by indirect immunofluorescence in human sera, which reacted with unfertilized and fertilized hamster eggs. Oolemmal antigens to which these antibodies were directed were distinct from antigen present on the surface of living human spermatozoa. Both species-specific and tissue-specific heteroantibodies were demonstrated by absorption with hamster liver and ovary. An increased degree of heteroantibody binding was noted following penetration of zona-free hamster eggs by human spermatozoa, indicating that an alteration in oolemmal antigen distribution had occurred. No evidence was found, however, that antisperm antibodies in these sera reacted with zona-free hamster eggs following their fertilization.

Characterization of humoral antibodies reactive with spermatozoa, N-acetyl galactosamine, and a putative blood group antigen in seminal plasma.

Antisperm antibodies in sera of infertile women may react differently with spermatozoa of different men. We studied the reactivity of these antibodies with spermatozoa from men of varying blood group status. Increased immunoglobulin binding to sperm of group A or AB men was noted when compared with group O men. A diminution in binding of immunoglobulins to spermatozoa after absorption of these sera with human group A or AB red blood cells was noted as well as after coincubation of sera and sperm with N-acetyl galactosamine, the terminal sugar of blood group antigen A. These observations suggest that antibodies directed against blood group antigens adsorbed to sperm of secretor males may account in part for variations in immunobead binding levels between sperm of different men.

Autoimmunity to spermatozoa: effect on sperm penetration of cervical mucus as reflected by postcoital testing.

In couples with abnormal postcoital tests, where husbands exhibited autoimmunity to spermatozoa, the degree of impairment of sperm penetration into cervical mucus correlated with the proportion of sperm in ejaculates exhibiting surface-bound immunoglobulins. Residual sperm-directed antibodies detected within seminal fluid were not representative of the cell-bound immunoglobulins present on the sperm surfaces. When all sperm were antibody-bound, spermatozoa were rarely seen in cervical mucus. Conversely, the number of motile sperm seen at postcoital testing was normal, that is, no different from that of antibody-negative couples, when less than 50% of sperm were antibody-bound in the ejaculate. In this group, other causes of infertility should be explored. The extent of autoimmunity to spermatozoa as reflected in the proportion of sperm exhibiting immunobead binding, then, provides guidelines for treatment of these men.

Sperm-specific isoantibodies and autoantibodies inhibit the binding of human sperm to the human zona pellucida.

Heterologous antisperm antibodies induced by immunization with Freund's adjuvants are known to inhibit sperm-zona binding. We have tested whether spontaneously occurring sperm-directed isoantibodies and autoantibodies inhibit the binding of human sperm to the human zona pellucida. Zonae pellucidae were obtained from the ovaries of a woman of reproductive age undergoing surgery for uterine malignancy. Couples at risk for immunity to spermatozoa were screened for humoral antisperm antibodies by immunobead binding. Sera containing head-directed antibodies of IgA and/or IgG classes were selected for passive antibody transfer. Populations of spermatozoa exhibiting differing proportions of antibody-bound sperm were obtained by exposure of antibody-negative sperm of a fertile donor to untreated sera or sera depleted of head-directed antisperm antibodies by prior absorption. Each zona pellucida was challenged sequentially with two populations of sperm. an inverse relationship was found between the number of spermatozoa adherent to the zona and the proportion of sperm exhibiting binding of IgA or IgG immunoglobulins over the head, indicating that the presence of these antibodies in the acrosomal region of the sperm head inhibited their ability to attach to the zona pellucida.