Design of a custom insertable probe platform for measurements of C-2W inner divertor plasma parameters

A custom motor controlled probe system has been designed to make spatially resolved measurements of temperature, density, flow, and plasma potential in the C-2W inner divertors. Measurements in the inner divertors, which have a 1.7 m radius and are located on either end of the confinement vessel, are critical in order to gauge exactly how local settings affect the plasma conditions, confinement, and stability in the field-reversed configuration core. The inner Divertor Insertable Probe Platform (iDIPP) system consists of a custom motor controlled linear rack and pinion transporter that has a 1.9 m travel length in order to reach the center of the divertor. Mounted to the end of the transporter is a 1 m long segmented probe shaft made of individually floating stainless steel rings to prevent shorting out the electrode plates, which are biased up to 5 kV/m. A variety of interchangeable probe tips, including a triple Langmuir probe, a baffled probe, and a Gundestrup probe, can plug into the end of the probe shaft. Custom UHV coiled cabling comprised of 9 shielded conductors expands/retracts with the motion of the transporter in/out of the divertor. The physics motivating plasma parameter measurements in the inner divertors and the details of the design of the iDIPP system will be discussed.

X-ray analysis of electron Bernstein wave heating in MST

A pulse height analyzing x-ray tomography system has been developed to detect x-rays from electron Bernstein wave heated electrons in the Madison symmetric torus reversed field pinch (RFP). Cadmium zinc telluride detectors are arranged in a parallel beam array with two orthogonal multi-chord detectors that may be used for tomography. In addition a repositionable 16 channel fan beam camera with a 55° field of view is used to augment data collected with the Hard X-ray array. The chord integrated signals identify target emission from RF heated electrons striking a limiter located 12° toroidally away from the RF injection port. This provides information on heated electron spectrum, transport, and diffusion. RF induced x-ray emission from absorption on harmonic electron cyclotron resonances in low current (<250 kA) RFP discharges has been observed.

Electron-ion hybrid instability experiment upgrades to the Auburn Linear Experiment for Instability Studies

The Auburn Linear EXperiment for Instability Studies (ALEXIS) is a laboratory plasma physics experiment used to study spatially inhomogeneous flows in a magnetized cylindrical plasma column that are driven by crossed electric (E) and magnetic (B) fields. ALEXIS was recently upgraded to include a small, secondary plasma source for a new dual source, interpenetrating plasma experiment. Using two plasma sources allows for highly localized electric fields to be made at the boundary of the two plasmas, inducing strong E × B velocity shear in the plasma, which can give rise to a regime of instabilities that have not previously been studied in ALEXIS. The dual plasma configuration makes it possible to have independent control over the velocity shear and the density gradient. This paper discusses the recent addition of the secondary plasma source to ALEXIS, as well as the plasma diagnostics used to measure electric fields and electron densities.

Maternal intestinal flora and wheeze in early childhood

BACKGROUND

Increasing evidence links altered intestinal flora in infancy to eczema and asthma. No studies have investigated the influence of maternal intestinal flora on wheezing and eczema in early childhood.

OBJECTIVE

To investigate the link between maternal intestinal flora during pregnancy and development of wheeze and eczema in infancy.

METHODS

A total of 60 pregnant women from the Boston area gave stool samples during the third trimester of their pregnancy and answered questions during pregnancy about their own health, and about their children's health when the child was 2 and 6 months of age. Quantitative culture was performed on stool samples and measured in log(10)colony-forming units (CFU)/gram stool. Primary outcomes included infant wheeze and eczema in the first 6 months of life. Atopic wheeze, defined as wheeze and eczema, was analysed as a secondary outcome.

RESULTS

In multivariate models adjusted for breastfeeding, day care attendance and maternal atopy, higher counts of maternal total aerobes (TA) and enterococci (E) were associated with increased risk of infant wheeze (TA: OR 2.32 for 1 log increase in CFU/g stool [95% CI 1.22, 4.42]; E: OR 1.57 [95% CI 1.06, 2.31]). No organisms were associated with either eczema or atopic wheeze.

CONCLUSIONS AND CLINICAL RELEVANCE

In our cohort, higher maternal total aerobes and enterococci were related to increased risk of infant wheeze. Maternal intestinal flora may be an important environmental exposure in early immune system development.

Quantitative and qualitative effects of douche preparations on vaginal microflora

OBJECTIVE

To determine the effect of douching on the quantitative and qualitative makeup of the vaginal microflora.

METHODS

We first evaluated the effect of douching with a solution of physiologic saline to determine the effect of washing the vaginal surface. Two douche preparations, one containing 0.04% acetic acid and one containing 0.30% povidone-iodine, were evaluated subsequently to determine whether any effects occurred in addition to those noted with saline. Duplicate vaginal swab samples were obtained at predetermined intervals from ten healthy volunteers for three sampling cycles before and after use of the douche preparations for various periods of time. Samples were analyzed for total facultative and obligately anaerobic bacterial populations.

RESULTS

The use of a douche preparation containing acetic acid caused a transient reduction of the total bacterial counts, with most of the change attributable to the effect of washing the surface of the vaginal vault as noted with physiologic saline. In contrast, the povidone-iodine preparation caused a significant reduction in total counts compared with those obtained after use of a physiologic saline solution by the same subjects (P = .02). Little change in the qualitative makeup of the vaginal microflora occurred.

CONCLUSION

The use of povidone-iodine douches decreases the numbers of the dominant bacterial species beyond those expected with other douches. In some individuals, such changes may allow rapid proliferation of potential pathogens during this altered state, increasing the risk of associated infections.