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Final design studies in preparation for manufacturing have been performed for functional components of the vacuum portion of the ITER Low-Field Side Reflectometer (LFSR). These components consist of an antenna array, electron cyclotron heating (ECH) protection mirrors, phase calibration mirrors, and vacuum windows. Evaluation of these components was conducted at the LFSR test facility and DIII-D. The antenna array consists of six corrugated-waveguide antennas for simultaneous profile, fluctuation, and Doppler measurements. A diffraction grating, incorporated into the plasma-facing miter bend, provides protection of sensitive components from stray ECH at 170 GHz. For in situ phase calibration of the LFSR profile reflectometer, an embossed mirror is incorporated into the adjacent miter bend. Measurements of the radiated beam profile indicate that these components have a small, acceptable effect on mode conversion and beam quality. Baseline transmission characteristics of the dual-disk vacuum window are obtained and are used to guide ongoing developments. Preliminary simulations indicate that a surface-relief structure on the window surfaces can greatly improve transmission. The workability of real-time phase measurements was demonstrated on the DIII-D profile reflectometer. The new automated real-time analysis agrees well with the standard post-processing routine. [ABSTRACT FROM AUTHOR]

The National Compact Stellarator Experiment (NCSX) was designed to test physics principles of an innovative stellarator design developed by Princeton Plasma Physics Laboratory and Oak Ridge National Laboratory. Construction of some of the major components and subassemblies was completed, but the estimated cost and schedule for completing the project grew as the technical requirements and risks became better understood, leading to its cancellation in 2008. The project's risks stemmed from its technical challenges, primarily the complex component geometries and tight tolerances that were required. The initial baseline, which was established in 2004, was supported by a risk management plan and risk-based contingencies, both of which proved to be inadequate. Technical successes were achieved in the construction of challenging components and subassemblies, but cost and schedule growth was experienced. As part of an effort to improve project performance, a new risk management program was devised and implemented in 2007-2008. It led to a better understanding of project risks, a sounder basis for contingency estimates, and improved management tools. Although the risks were ultimately unacceptable to the sponsor, valuable lessons in risk management were learned through the experiences with the NCSX project. [ABSTRACT FROM AUTHOR]

Studies the properties of a reference quasi-axisymmetric plasma configuration. Features of stellarators and advanced tokamaks; Evaluation of quasi-omnigeneous plasma configurations stable to ballooning modes; Economic benefits of steady-state magnetic confinement systems for magnetic fusion energy power plants.

Recent progress in the theoretical understanding and design of compact stellarators is described. Hybrid devices, which depart from canonical stellarators by deriving benefits from the bootstrap current which flows at finite beta, comprise a class of low aspect ratio A<4 stellarators. They possess external kink stability (at moderate beta) in the absence of a conducting wall, possible immunity to disruptions through external control of the transform and magnetic shear, and they achieve volume-averaged ballooning beta limits (4%-6%) similar to those in tokamaks. In addition, bootstrap currents can reduce the effects of magnetic islands (self-healing effect) and lead to simpler stellarator coils by reducing the required external transform. Powerful physics and coil optimization codes have been developed and integrated to design experiments aimed at exploring compact stellarators. The physics basis for designing the national compact stellarator will be discussed. [ABSTRACT FROM AUTHOR]

The external inductance of an axisymmetric toroidal plasma with an arbitrary aspect ratio and cross section is obtained using a Green’s function method. By varying an equivalent skin current density over the plasma surface, while keeping the total toroidal current fixed, the plasma boundary is made to coincide with a magnetic surface. Numerical computations of the self-inductance and mutual inductance as functions of aspect ratio and elongation are fitted to simple analytic formulas. The effect of distributed plasma current on the volt-seconds required to reach a prescribed net current is considered. [ABSTRACT FROM AUTHOR]

The beam from an electron gun was used to trace flux surfaces in the Advanced Toroidal Facility (ATF) torsatron. The ATF magnetic field was run steady state at 0.1 T, and the electron beam was detected optically with an image-intensified, solid-state camera when it impinged on a phosphor-coated screen. Closed flux surfaces and islands at several low-order resonances were observed. The largest island, located at the t = ½ surface, was from 5 to 6 cm in width, and its presence implied the existence of magnetic field errors. To determine if these error fields could be traced to small misalignments of the magnetic coils, a device capable of accurately measuring the radial and vertical magnetic field components of individual coil sets was placed in the center of ATF. This device allowed for a determination of the precise location of each of the coils that make up the ATF coil set. No significant coil misalignments were found. A further investigation of the coil configuration led to the identification of dipole fields in the helical field coil leads as the source of the field errors. The techniques developed in making these measurements are described in the text. [ABSTRACT FROM AUTHOR]

Runaway electron formation and confinement occur readily in pulsed torsatrons and heliotrons because of the high loop voltages during initiation and termination of the helical and vertical fields (‘‘field ramping’’) and the inherently good containment of the electrons on the flux surfaces in the vacuum fields. This has been confirmed for the Advanced Toroidal Facility (AFT) [Fusion Technol. 10, 179 (1986)] and other stellarators by orbit calculations. Since runaway electrons can cause an unacceptable level of hard x rays near the machine, a runaway electron suppression system was incorporated in ATF. The main component of the system is a movable paddle, which is normally left in the center of the plasma chamber during the field ramps. This device, in conjunction with programmed vertical field ramping, which reduces the volume of good flux surfaces, has proved to be very effective in reducing the runaway electron population. Measurements of hard x rays from ATF have shown that the runaway electrons are produced primarily during the field ramping but that there is usually also a small steady-state runaway electron component during the‘‘flat-top’’ portion of the fields. The paddle is the main source of the hard x radiation (thick-target bremsstrahlung). There is evidence that some of the runaway electrons may be confined to islands. The maximum x-ray energy found by pulse height analysis is ∼12–15 MeV. The mean energy appears to be a few million electron volts. There is a noticeable forward peaking of the bremsstrahlung from the paddle. The limiters do not appear to be major sources of x rays. [ABSTRACT FROM AUTHOR]

The understanding of tokamak transport depends on the exploration of a wide range of theoretical models and of a variety of toroidal experiments. This report considers the contributions that nontokamak, but toroidal, experiments can make to our understanding of tokamak transport as well as theoretical alternatives to the standard drift wave model of tokamak transport. [ABSTRACT FROM AUTHOR]

Thirty five cases of Ebstein's anomaly were diagnosed by cardiac catheter study or echocardiography between 1962 and 1984. The anomaly was an isolated abnormality in 27 patients; the remainder had additional heart lesions. Six patients have died and four of these had other cardiac lesions. Thirteen are currently symptom free. Twelve cases presented with cyanosis and heart murmur on the first day of life. Eight of these had associated thrill which is a rare finding in neonates. As pulmonary vascular resistance fell there was clinical improvement. This was assisted by oxygen treatment. Another two cases presented in the first week of life and 10 in the first decade with a murmur or supraventricular tachycardia. Eleven cases presented as adolescents or adults with a murmur, cardiomegaly, or cardiac symptoms. Three patients were seen initially in the sixth decade. Clinical diagnosis was correct in only one adult. Twenty five patients had cardiac catheterisation. Important arrhythmias occurred in 10 cases, and two required cardioversion. Difficulty was experienced in entering the pulmonary artery in 11 infants and children. Diagnosis at initial catheter study was incorrect in four patients. Echocardiograms were recorded in 29 cases. Earlier M mode measurements of time delay of tricuspid closure compared with mitral closure did not always lead to the correct diagnosis. Cross sectional studies gave good images of tricuspid leaflet displacement, its tethering, and the atrialised portion of the right ventricle and have facilitated the diagnosis of more cases in recent years. Echocardiography is the procedure of choice for diagnosis of Ebstein's anomaly. [ABSTRACT FROM PUBLISHER]

Wave absorption in the ISX-B tokamak [Phys. Rev. Lett. 44, 647 (1980)] at the second harmonic (ω = 2ω[sub ce]) of the electron-cyclotron frequency is reported. Measurements of the absorption of a wave polarized in the extraordinary mode and propagating perpendicular to the toroidal magnetic field are in agreement with computations. [ABSTRACT FROM AUTHOR]

The diamagnetic diagnostic on ATF consists of two systems. The first uses a single-turn diamagnetic loop in a stainless-steel reentrant tube inside the vacuum vessel Compensation signals are derived from Rogowski coils mounted on the main helical and vertical coil buses. This arrangement provides maximum sensitivity and the fastest time response, but results in signals which are dominated by noise created by the large ATF SCR power supplies. The nonlinear nature of these supplies, and their coupling, requires the use of hybrid noise reduction processing. The analog compensation loops remove the low-frequency components and digital post-processing removes the high-frequency ones. The second diamagnetic signal is derived from a set of saddle loops which respond directly to the Pfirsch-Schlüter current in the plasma. Typical results are presented. This research was sponsored by the Office of Fusion Energy, U.S. Department of Energy, under contract DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc. [ABSTRACT FROM AUTHOR]

Treadmill exercise testing was performed on 23 patients with isolated congenital aortic stenosis. It was found that eight patients, with a negative exercise test and a normal rise in systolic blood pressure on exercise, had gradients less than 45 mmHg. Fifteen patients with gradients greater than 50 mmHg had positive exercise tests and their systolic blood pressure did not rise normally. It is suggested that the left heart studies to measure aortic valve gradients can safely be postponed if an exercise test is negative. Serial exercise testing of such patients will give an indication when left heart catheterization should be considered.

Five hundred and eighty-eight patients with mitral valve disease were studied. The incidence of systemic emboli was found to be higher in patients with pure mitral stenosis (16.6%) and mixed mitral stenosis and incompetence (19.4%) than in patients with mitral incompetence (3.1%). The patients with mitral stenosis who had episodes of systemic emboli tended to be older than 40 years, with moderate or severe valve lesions, atrial fibrillation and moderate or gross enlargement of the left atrial appendage or left atrium. The following factors were found to be unrelated to systemic embolism---associated aortic valve disease, sex, smoking habit, history of rheumatism, parity, haemoglobin, blood urea, pulmonary hypertension, duration of antifailure treatment, presence of heart failure, and cardiothoracic ratio.

Oral tocainide and disopyramide were compared in a double-blind, crossover trial in 10 outpatients with stable ventricular premature beats (VPBs). Efficacy was assessed by suppression of VPB activity and reduction of VPB grade during an exercise test and an 18-h Holter recording. An estimate of variance of VPB activity was obtained from two separate placebo periods, and a 95% confidence limit for VPB suppression was calculated. During Holter recording, both drugs produced a significant reduction in VPB frequency and grade (p less than 0.05). During the exercise challenge, tocainide produced a reduction in VPB frequency and grade, but this did not reach statistical significance; VPB frequency was unaltered by disopyramide, but VPB grade was significantly reduced (p less than 0.01).

Thirteen patients with proven Q fever endocarditis and three additional patients with probable endocarditis are reviewed. The most helpful diagnostic test is the demonstration of a high complement fixing antibody titre to Phase 1 antigen of Coxiella burneti. The macroscopic pathology of the aortic valve is described and includes aneurysmal pockets in the aortic wall and valve annulus which are demonstrable angiographically. Evidence is presented that the infection may be controlled by prolonged tetracycline therapy and that this is accompanied by a falling antibody titre to Phase 1 antigen. Valve replacement is undertaken only for symptomatic and hemodynamic indications. The combined tetracycline therapy and valve replacement have produced a fall in titres with eradication of infection and palliation of the cardiac disability in all patients followed for long periods.