Design and measurement methods for a lithium vapor box similarity experiment.

The lithium vapor box divertor is a concept for handling the extreme divertor heat fluxes in magnetic fusion devices. In a baffled slot divertor, plasma interacts with a dense cloud of Li vapor which radiates and cools the plasma, leading to recombination and detachment. Before testing on a tokamak, the concept should be validated: we plan to study detachment and heat redistribution by a Li vapor cloud in laboratory experiments. Mass changes and temperatures are measured to validate a direct simulation Monte Carlo model of neutral Li. The initial experiment involves a 5 cm diameter steel box containing 10 g of Li held at 650 °C as vapor flows out a wide nozzle into a similarly sized box at a lower temperature. Diagnosis is made challenging by the required material compatibility with lithium vapor. Vapor pressure is a steep function of temperature, so to validate mass flow models to within 10%, absolute temperature to within 4.5 K is required. The apparatus is designed to be used with an analytical balance to determine mass transport. Details of the apparatus and methods of temperature and mass flow measurements are presented.

Methods of improving spatial resolution for IR spectroscopy in atmospheric-pressure plasma systems.

High-temperature, atmospheric pressure plasma systems operated in molecular gases present complex diagnostic challenges. Infrared spectroscopy has been used to make measurements of the absorbance spectrum of complex molecular gas mixtures and thereby calculate the concentrations and species temperatures in these systems. For atmospheric-pressure systems, high spatial gradients arise and high spatial-resolution measurements are thus desirable. Some systems have achieved increased spatial resolution by reducing the beam diameter. However, this increase in spatial resolution comes at the expense of the optical throughput. Here we propose modifying a commercial Fourier Transform, Infrared spectrometer system with a set of simple optical elements. This design allows for scannable, high spatial resolution absorbance spectrum measurements of a complex molecular gas mix. We analyze the signal-to-noise ratio for this design and compare it with the diameter reduction method. For sufficiently low plasma radiation levels, this design improves the signal-to-noise ratio relative to reducing the beam diameter size while transmitting nearly all of the beam power. However, whether this design can achieve the desired sub-mm spatial resolution depends on the radiating area of the infrared light source in the spectrometer.

Integrated plasma facing component calorimetry for measurement of shot integrated deposited energy in the NSTX-U.

The upgrade to the National Spherical Torus eXperiment (NSTX-U) [J. Menard et al., Nucl. Fusion 52, 083015 (2012)] increases the injected neutral beam power up to 12 MW and the plasma current up to Ip = 2 MA for plasma durations up to 5 s. The graphite plasma facing components have been re-designed to handle greater heat and energy fluxes than were seen in NSTX using a castellated design. We present the experimental testing and validation of a castellated graphite target, similar to the prototype tile design, instrumented with thermocouples at various depths in the castellation. During testing, incident heat flux is provided by a programmed electron beam system and surface temperatures are measured via infrared thermography directly viewing the target surface. It was found that the thermocouple response scaled linearly with the measured surface temperature rise regardless of thermocouple depth in the castellation. A sensitivity of 14.3 °C/kJ of deposited energy was found when treating individual castellations as a semi-infinite solid.

Design and characterization of a prototype divertor viewing infrared video bolometer for NSTX-U.

The InfraRed Video Bolometer (IRVB) is a powerful tool to measure radiated power in magnetically confined plasmas due to its ability to obtain 2D images of plasma emission using a technique that is compatible with the fusion nuclear environment. A prototype IRVB has been developed and installed on NSTX-U to view the lower divertor. The IRVB is a pinhole camera which images radiation from the plasma onto a 2.5 µm thick, 9 × 7 cm2 Pt foil and monitors the resulting spatio-temporal temperature evolution using an IR camera. The power flux incident on the foil is calculated by solving the 2D+time heat diffusion equation, using the foil's calibrated thermal properties. An optimized, high frame rate IRVB, is quantitatively compared to results from a resistive bolometer on the bench using a modulated 405 nm laser beam with variable power density and square wave modulation from 0.2 Hz to 250 Hz. The design of the NSTX-U system and benchtop characterization are presented where signal-to-noise ratios are assessed using three different IR cameras: FLIR A655sc, FLIR A6751sc, and SBF-161. The sensitivity of the IRVB equipped with the SBF-161 camera is found to be high enough to measure radiation features in the NSTX-U lower divertor as estimated using SOLPS modeling. The optimized IRVB has a frame rate up to 50 Hz, high enough to distinguish radiation during edge-localized-modes (ELMs) from that between ELMs.

Preliminary design of a tangentially viewing imaging bolometer for NSTX-U.

The infrared imaging video bolometer (IRVB) measures plasma radiated power images using a thin metal foil. Two different designs with a tangential view of NSTX-U are made assuming a 640 × 480 (1280 × 1024) pixel, 30 (105) fps, 50 (20) mK, IR camera imaging the 9 cm × 9 cm × 2 µm Pt foil. The foil is divided into 40 × 40 (64 × 64) IRVB channels. This gives a spatial resolution of 3.4 (2.2) cm on the machine mid-plane. The noise equivalent power density of the IRVB is given as 113 (46) µW/cm2 for a time resolution of 33 (20) ms. Synthetic images derived from Scrape Off Layer Plasma Simulation data using the IRVB geometry show peak signal levels ranging from ∼0.8 to ∼80 (∼0.36 to ∼26) mW/cm2.

Electrical detection of liquid lithium leaks from pipe joints.

A test stand for flowing liquid lithium is under construction at Princeton Plasma Physics Laboratory. As liquid lithium reacts with atmospheric gases and water, an electrical interlock system for detecting leaks and safely shutting down the apparatus has been constructed. A defense in depth strategy is taken to minimize the risk and impact of potential leaks. Each demountable joint is diagnosed with a cylindrical copper shell electrically isolated from the loop. By monitoring the electrical resistance between the pipe and the copper shell, a leak of (conductive) liquid lithium can be detected. Any resistance of less than 2 kΩ trips a relay, shutting off power to the heaters and pump. The system has been successfully tested with liquid gallium as a surrogate liquid metal. The circuit features an extensible number of channels to allow for future expansion of the loop. To ease diagnosis of faults, the status of each channel is shown with an analog front panel LED, and monitored and logged digitally by LabVIEW.

Divertor electron temperature and impurity diffusion measurements with a spectrally resolved imaging radiometer.

A divertor imaging radiometer (DIR) diagnostic is being studied to measure spatially and spectrally resolved radiated power P(rad)(λ) in the tokamak divertor. A dual transmission grating design, with extreme ultraviolet (~20-200 Å) and vacuum ultraviolet (~200-2000 Å) gratings placed side-by-side, can produce coarse spectral resolution over a broad wavelength range covering emission from impurities over a wide temperature range. The DIR can thus be used to evaluate the separate P(rad) contributions from different ion species and charge states. Additionally, synthetic spectra from divertor simulations can be fit to P(rad)(λ) measurements, providing a powerful code validation tool that can also be used to estimate electron divertor temperature and impurity transport.

High-harmonic fast-wave power flow along magnetic field lines in the scrape-off layer of NSTX.

A significant fraction of high-harmonic fast-wave (HHFW) power applied to NSTX can be lost to the scrape-off layer (SOL) and deposited in bright and hot spirals on the divertor rather than in the core plasma. We show that the HHFW power flows to these spirals along magnetic field lines passing through the SOL in front of the antenna, implying that the HHFW power couples across the entire width of the SOL rather than mostly at the antenna face. This result will help guide future efforts to understand and minimize these edge losses in order to maximize fast-wave heating and current drive.

Continuous improvement of H-mode discharge performance with progressively increasing lithium coatings in the National Spherical Torus Experiment.

Lithium wall coatings have been shown to reduce recycling, improve energy confinement, and suppress edge localized modes in the National Spherical Torus Experiment. Here, we show that these effects depend continuously on the amount of predischarge lithium evaporation. We observed a nearly monotonic reduction in recycling, decrease in electron transport, and modification of the edge profiles and stability with increasing lithium. These correlations challenge basic expectations, given that even the smallest coatings exceeded that needed for a nominal thickness of the order of the implantation range.

High density Langmuir probe array for NSTX scrape-off layer measurements under lithiated divertor conditions.

A high density Langmuir probe array has been developed for measurements of scrape-off layer parameters in NSTX. Relevant scale lengths for heat and particle fluxes are 1-5 cm. Transient edge plasma events can occur on a time scale of several milliseconds, and the duration of a typical plasma discharge is ∼1 s. The array consists of 99 individual electrodes arranged in three parallel radial rows to allow both swept and triple-probe operation and is mounted in a carbon tile located in the lower outer divertor of NSTX between two segments of the newly installed liquid lithium divertor. Initial swept probe results tracking the outer strike point through probe flux measurements are presented.

Biasing, acquisition, and interpretation of a dense Langmuir probe array in NSTX.

A dense array of 99 Langmuir probes has been installed in the lower divertor region of the National Spherical Torus Experiment (NSTX). This array is instrumented with a system of electronics that allows flexibility in the choice of probes to bias as well as the type of measurement (including standard swept, single probe, triple probe, and operation as passive floating potential and scrape-off-layer SOL current monitors). The use of flush-mounted probes requires careful interpretation. The time dependent nature of the SOL makes swept-probe traces difficult to interpret. To overcome these challenges, the single- and triple-Langmuir probe signals are used in complementary fashion to determine the temperature and density at the probe location. A comparison to midplane measurements is made.

Thermoelectric magnetohydrodynamic stirring of liquid metals.

The direct observation of a thermoelectric magnetohydrodynamic (TEMHD) flow has been achieved and is reported here. The origin of the flow is identified based on a series of qualitative tests and corresponds, quantitatively, with a swirling flow TEMHD model. A theory for determining the dominant driver of a free-surface flow, TEMHD or thermocapillary (TC), is found to be consistent with the experimental results. The use of the analytical form for an open geometry develops a new dimensionless parameter describing the ratio of TEMHD to TC generated flows.

Clinician information activities in diverse ambulatory care practices.

Ambulatory care is assuming an increasing role in health-care delivery. Yet, most health-care information systems were developed for the acute-care setting. To address the needs of ambulatory care, developers need a comprehensive understanding of the information-related activities of clinicians in heterogeneous outpatient practices. We studied the information activities of clinicians in seven diverse (primary-care, specialty-care, faculty, and independent private practices) ambulatory care sites. The results of our study allow us to characterize clinicians' information-related activities, their perceived information needs, and their satisfaction with computer resources. Developers of health-care information systems can use the results to design applications for clinicians in ambulatory care.

Methods for assessing information needs of clinicians in ambulatory care.

Clinical information systems that provide physicians with relevant information at the time and place where decisions are being made can positively affect the quality and cost of health care. We have developed an assessment methodology to study clinicians' information needs in the context of the work flow and operational constraints of the ambulatory care practice environment. We employed a combination of methods, including observational studies, process flowcharting, semi-structured interviews, and surveys to comprehensively define clinicians' needs. Results from our study point to functional requirements not commonly found in hospital-based systems, such as access to problem lists and medications, computer-based support for health-care team communications, and patient-specific instructions and education.

Genetic conditions among Canadian Mennonites: evidence for a founder effect among the old colony (Chortitza) Mennonites.

Distinctive disease patterns exist among Canadian Old Colony (Chortitza) Mennonites. This religious and genetic isolate is of 16th century Dutch/German ancestry. The group originated in the Netherlands, then settled in the Vistula delta area of western Prussia for 200 years. A small number of founding families later migrated to Chortitza, the "Old Colony", in the Ukraine in the late 18th/early 19th century, where they remained a distinct genetic isolate. This group has come to Canada over the past 100 years. The more conservative Canadian Mennonites of Chortitza descent practice strict endogamy, have a large family size and live predominantly in rural public health subdistricts in the four western provinces, and in southern Ontario. The world's largest reported familial aggregations of insulin-dependent diabetes mellitus, of autoimmune diseases and of Tourette syndrome were initially ascertained in a small northern Alberta public health subdistrict. Clusterings of malformations, inborn errors of metabolism, and other conditions were also found in the subdistrict, and in group descendents living in other provinces. A founder effect, or genetic drift, accounts for the familial aggregations of autosomal recessive and dominant conditions, some diseases of multifactorial determination, and other inherited conditions in Canadian kinships descending from this ancestral group. The medical literature on genetic conditions among Canadian Mennonites is reviewed and re-evaluated in the light of this information. There is biochemical, serologic, and molecular biologic evidence in favour of genetic homogeneity amongst patients with certain inherited conditions in this special population group. This genetic isolate offers potential for the study of the genetic epidemiology and molecular biology of inherited diseases. A computerized genealogic data base on about 1400 group members, as well as a cryopreserved lymphocyte/DNA bank on over 100 individuals with genetic conditions has been established in this special population group.

Inherited diseases in North American Mennonites: focus on Old Colony (Chortitza) Mennonites.

The patterns of migration and the genetic disorders occurring among North American Mennonites are reviewed, and inherited conditions recently recognized in a religious and genetic isolate, the Old Colony (Chortitza) Mennonites, are described. Old Colony Mennonites are of Dutch/German origin and descend from approximately 400 founding families who settled in the Old Colony, Chortitza (the Ukraine, USSR) in the late 1700s, and then migrated to Canada and Central and South America in the past century. We investigated over 6 generations of a Canadian Old Colony kindred in which there was extensive intermarriage, and in whom 28 individuals developed diabetes mellitus. Insulin-dependent diabetes mellitus (IDDM) occurred in 14 affected individuals in 10 closely related sibships; the 11 living IDDM patients were all concordant for the immunogenetic marker HLA-DR4. Fourteen close relatives had other disorders of carbohydrate metabolism, including gestational diabetes and non-insulin-dependent diabetes mellitus. Other close relatives had autoimmune diseases, including rheumatoid arthritis, hyper- and hypothyroidism, multiple sclerosis, and red cell aplasia. Other inherited diseases, including Alport syndrome, congenital defects, and inborn errors of metabolism were also found in the kindred. In the almost exclusively (99%) Old Colony Mennonite public health district in which the kindred was ascertained, there were multiple cases of Tourette syndrome, of malformations (including congenital heart defects and cleft lip +/- palate), and familial clusters of inborn errors of metabolism. We report this Old Colony (Chortitza) Mennonite isolate because 1) there are large familial aggregations of tissue-specific autoimmune diseases, malformations, inborn errors of metabolism, and of some other conditions whose genetic basis is still unknown; 2) there are multiple cases of rare genetic conditions, 3) we have established a computerized genealogic data base on over 1,000 kindred members as well as a cryopreserved lymphocyte/DNA bank on over 100 closely related individuals with various genetic conditions; and 4) this religious isolate, which extends across North, Central, and South America, offers an excellent opportunity for studying the epidemiology and molecular genetics of both common and rare inherited diseases.

Preferential infiltration of macrophages during early stages of insulitis in diabetes-prone BB rats.

The subpopulation of lymphoid cells at the different stages of insulitis in BB rats was determined by immunohistochemical techniques with various monoclonal antibodies, including the recently developed OX41, which distinguishes macrophages from T-lymphocytes, OX19 for pan-T-lymphocytes, W3/25 for both helper T-lymphocytes and macrophages, OX8 for cytotoxic T-lymphocytes and natural killer cells, and OX12 for B-lymphocytes. The major population of infiltrated cells found during the early stages of insulitis appeared to be macrophages. This preceded invasion by a mixed population of cells, including both T- and B-lymphocytes and/or natural killer cells. The preferential infiltration of macrophages during the early stages of insulitis strongly suggested that there might be an initial change in the target beta-cells that precedes their immune destruction, although the amplification of immune response by activated T-lymphocytes and natural killer cells at a later stage seemed to be required for the clinical expression of the disease.

Unusual clustering of diseases in a Canadian Old Colony (Chortitza) Mennonite kindred and community.

We investigated a large Old Colony (Chortitza) Mennonite kindred with branches across Canada. Six generations of the kindred were traced. There was intermarriage among numerous family members. Insulin-dependent diabetes mellitus (IDDM) was identified in 10 members; all 7 living patients were found to carry the immunogenetic marker HLA-DR4. Nine other close relatives had disorders of carbohydrate metabolism, including gestational diabetes mellitus and non-insulin-dependent diabetes mellitus progressing to insulin use. Ten other relatives had autoimmune diseases, including rheumatoid arthritis, hyperthyroidism, hypothyroidism and multiple sclerosis. Cases of Alport's syndrome, congenital malformations, inborn errors of metabolism and unusual malignant diseases were also found in the kindred. In the small Alberta community in which the kindred was ascertained there were people of Old Colony Mennonite descent with genetic conditions such as Gilles de la Tourette's syndrome and congenital malformations, including congenital heart disease. This kindred represents the largest reported familial aggregation of IDDM. This disease and other disorders of carbohydrate metabolism occur in the context of a strong familial predisposition to autoimmune disease. Study of this family may permit empiric testing of proposed models of inheritance of diseases of complex origin such as IDDM. We report this Old Colony (Chortitza) Mennonite community because it is one of the settlements populated by this religious and genetic isolate, which extends across Canada and Central and South America and affords opportunities for the study of both common and rare inherited diseases.

Immunosuppression in autoimmune disease: the double-edged sword.

We have developed a protocol of prophylactic cyclosporin A administration which confers complete and permanent protection against insulin-dependent diabetes mellitus in diabetes-prone BioBreeding rats. Spontaneous insulin-dependent diabetes mellitus developed in about 50% of BioBreeding rats, between 10 and 18 weeks of age. Prophylactic cyclosporin A (10 mg/kg/day p.o.), started at 6 weeks of age and terminated at 21 weeks of age, completely prevented insulin-dependent diabetes mellitus: 0% (0/25) cyclosporin A-treated compared to 46% (11/24) control rats developed insulin-dependent diabetes mellitus (p less than 0.001). Protection against insulin-dependent diabetes mellitus was lifelong, provided cyclosporin A prophylaxis was initiated when insulitis was minimal or absent, and pancreatic insulin content was normal. Cyclosporin A prophylaxis initiated later, but still before the onset of clinical symptoms (8-9 weeks), and terminated at 22-23 weeks, was only partially effective; 5/20 (25%) of cyclosporin A-treated rats developed insulin-dependent diabetes mellitus, compared to 60% (12/20) of controls (p less than 0.05). Cyclosporin A prophylaxis started at the appropriate time (6 weeks) but terminated prematurely (17-19 weeks of age) was not effective; insulin-dependent diabetes mellitus developed in 20% (3/15), compared to 50% (7/14) controls (p greater than 0.05); insulin-dependent diabetes mellitus developed after cessation of therapy. We conclude that effective and permanent moderate-dose cyclosporin A prophylaxis of insulin-dependent diabetes mellitus in BioBreeding rats requires (1) early initiation of treatment, when islet morphology and hormone content are still normal; and (2) prolonged treatment, with continuation of prophylaxis past the end of the at-risk period.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclosporin prophylaxis induces long-term prevention of diabetes, and inhibits lymphocytic infiltration in multiple target tissues in the high-risk BB rat.

Spontaneous insulin-dependent diabetes mellitus (IDDM) and other autoimmune manifestations, such as lymphocytic thyroiditis and atrophic gastritis, develop in diabetes-prone (high-risk) lines of Wistar-derived BioBreeding (BB) rats. To examine whether Cyclosporin A (CsA) would abrogate multiple autoimmune manifestations in BB rats, we treated them prophylactically with CsA from 5-6 weeks to 23-25 weeks of age. IDDM developed in 0/58 CsA-treated rats; 47% (29 out of 62) of sex- and age-matched controls treated with vehicle developed IDDM (p less than 0.001). CsA-treated rats had no or minimal lymphocytic infiltration and parenchymal changes in the pancreas, stomach and thyroid at the time of cessation of treatment. IDDM, glycosuria and hyperglycemia developed in 0/22 rats followed up to 370 days of age (up to 210 days following the cessation of CsA therapy); histologic examination of their islets was normal. We conclude that CsA completely abrogates the development of clinical IDDM in the BB rat, and that it inhibits or abolishes lymphocyte infiltration in several organs against which there is autoimmunity. The data also suggest that the protective effect of CsA persists well past the duration of therapy, and that cell-mediated autoimmunity (with or without humoral immunity) may be an important pathogenetic mechanism in the destruction of beta cells in the BB rat.