Observation of Flat Electron Temperature Profiles in the Lithium Tokamak Experiment.

It has been predicted for over a decade that low-recycling plasma-facing components in fusion devices would allow high edge temperatures and flat or nearly flat temperature profiles. In recent experiments with lithium wall coatings in the Lithium Tokamak Experiment (LTX), a hot edge (>200 eV) and flat electron temperature profiles have been measured following the termination of external fueling. Reduced recycling was demonstrated by retention of ∼60% of the injected hydrogen in the walls following the discharge. Electron energy confinement followed typical Ohmic confinement scaling during fueling, but did not decrease with density after fueling terminated, ultimately exceeding the scaling by ∼200%. Achievement of the low-recycling, hot edge regime has been an important goal of LTX and lithium plasma-facing component research in general, as it has potentially significant implications for the operation, design, and cost of fusion devices.

A frequency-modulated continuous-wave reflectometer for the Lithium Tokamak Experiment.

The frequency-modulated continuous-wave reflectometer on LTX (Lithium Tokamak Experiment) and the data analysis methods used for determining electron density profiles are described. The diagnostic uses a frequency range of 13.1-33.5 GHz, for covering a density range of 0.21-1.4×1013 cm-3 (in O-mode polarization) with a time resolution down to 8 µs. The design of the diagnostic incorporates the concept of an "optimized" source frequency sweep, which minimizes the large variation in the intermediate frequency signal due to a long dispersive transmission line. The quality of the raw data is dictated by the tuning characteristics of the microwave sources, as well as the group delay ripple in the transmission lines, which can generate higher-order nonlinearities in the frequency sweep. Both effects are evaluated for our diagnostic and best practices are presented for minimizing "artifacts" generated in the signals. The quality of the reconstructed profiles is also improved using two additional data analysis methods. First, the reflectometer data are processed as a radar image, where clutter due to echoes from the wall and backscattering from density fluctuations can be easily identified and removed. Second, a weighed least-squares lamination algorithm POLAN (POLynomial ANalysis) is used to reconstruct the electron density profile. Examples of density profiles in LTX are presented, along with comparisons to measurements from the Thomson scattering and the λ = 1 mm interferometer diagnostics.

Development progress of the Materials Analysis and Particle Probe.

The Materials Analysis and Particle Probe (MAPP) is a compact in vacuo surface science diagnostic, designed to provide in situ surface characterization of plasma facing components in a tokamak environment. MAPP has been implemented for operation on the Lithium Tokamak Experiment at Princeton Plasma Physics Laboratory (PPPL), where all control and analysis systems are currently under development for full remote operation. Control systems include vacuum management, instrument power, and translational/rotational probe drive. Analysis systems include onboard Langmuir probes and all components required for x-ray photoelectron spectroscopy, low-energy ion scattering spectroscopy, direct recoil spectroscopy, and thermal desorption spectroscopy surface analysis techniques.

Magnetic diagnostics for equilibrium reconstructions with eddy currents on the Lithium Tokamak eXperiment.

The Lithium Tokamak eXperiment is a spherical tokamak with a close-fitting low-recycling wall composed of thin lithium layers evaporated onto a stainless steel-lined copper shell. Long-lived non-axisymmetric eddy currents are induced in the shell and vacuum vessel by transient plasma and coil currents and these eddy currents influence both the plasma and the magnetic diagnostic signals that are used as constraints for equilibrium reconstruction. A newly installed set of re-entrant magnetic diagnostics and internal saddle flux loops, compatible with high-temperatures and lithium environments, is discussed. Details of the axisymmetric (2D) and non-axisymmetric (3D) treatments of the eddy currents and the equilibrium reconstruction are presented.

[Accidental papillary disinsertions during gastroduodenectomies. Report of two cases (author's transl)]. / Les désinsertions papillaires accidentelles au cours des gastro-duodénectomies. A propos de deux observations.

This is a report of two accidental papillary disinsertions. The first had a good result up to 23 years after a duodenal reimplantation. The second, referred from elsewhere was reimplanted in a pediculated intestinal segment interposed between the papilla and the afferent loop of the gastrectomy : the result ten years after is favorable. The authors stress the difficulty of recognizing an unexpected disinsertion and insist on the necessity of an early reoperation. Despite the optimism of some statistics there are serious operative complications. The best prevention in the surgical treatment of low situated duodenal ulcers remains a vagotomy associated to a gastric suction.

Operative injuries to the bile ducts. Report on 12 cases.

We have reported on a series of 12 operative injuries to the bile ducts. We estimate the frequency of these accidents at 0.2% during cholecystectomy and 0.4% after gastroduodenectomy. We stress the importance of systematic cholangiography during the operation to prevent unrecognized lesions. Immediate repair of these lesions by an end-to-end anastomosis appears to be the best technical method. When faced with a high mortality rate, often due to non-recognition of a lesion, we stress the importance of prevention to limit the risk of such accidents occurring and non-recognition of those that do occur.

[Volvulus of the ascending colon. Apropos of 5 cases]. / Les volvulus du côlon droit. A propos de cinq observations.

The authors report five cases of volvulus of the right side of the colon, including 3 with complications, which required segmental colonic resection. They recall the diagnostic and therapeutic problems, emphasising the interest of barium enema, the necessity of early diagnosis, the high level of mortality and the treatment of choice which is right hemicolectomy.

[Operative wounds of the main biliary tract: immediate repair (author's transl)]. / A propos des plaies opératoires de la voie biliaire principale et de leur réparation immédiate.

The authors report a series of eleven surgical wounds, all immediately repaired. They consider the frequency of these biliary accidents to be 2% in cholecystectomies and 4% in gastrectomies. In such instances end-to-end suture seems the first choice procedure with the best longterm results. They stress the importance of prevention methods that will help to limit the risks of such operative accidents and not to overlook them, should they occur.

[Acute cholecystitis without stones (author's transl)]. / Les cholécystites aiguës alithiasiques. A propos de 10 observations

The authors report on ten cases of cholecystites without stones. Two were typhic in origin, six apparently primitive, one postoperative and one posttraumatic. They stress the importance of histologic lesions in each of these etiologies and insist on the high frequency of gangrenous forms in postoperative and posttraumatic cases. Previous antibiotherapy deserves no credit. Emergency cholecystectomy remains the best treatment.