Advances in the FTU collective Thomson scattering system.

The new collective Thomson scattering diagnostic installed on the Frascati Tokamak Upgrade device started its first operations in 2014. The ongoing experiments investigate the presence of signals synchronous with rotating tearing mode islands, possibly due to parametric decay processes, and phenomena affecting electron cyclotron beam absorption or scattering measurements. The radiometric system, diagnostic layout, and data acquisition system were improved accordingly. The present status and near-term developments of the diagnostic are presented.

Design optimization of a deflectable guidewire.

Over the years, the design of the tip of available catheters and guidewires has evolved into various shapes whose geometry is mostly based on common sense and experimentation. However, while the tip shape of conventional instruments can be easily modified and tested, the length of the tip of a deflectable guidewire cannot. Hence, other approaches are necessary in order to determine the proper dimensions of original instruments. In this paper, we formulate the length of the different parts of the deflectable tip of a guidewire as an optimization problem with the objective to obtain a design that is suitable for cannulating several target bifurcations of the peripheral vasculature. A direct relationship between the design of the deflectable tip and the geometry of the target bifurcations was found and the optimal dimension of the tip of the instrument was computed. Following the length specifications defined by the optimization, a new prototype was assembled, and evaluated. The deflectable guidewire could successfully cannulate most of the pre-selected branches except those bifurcations with an angle α>70°. The latter limitation could be ascribed to the mechanical properties of the instrument.

A fast multichannel Martin-Puplett interferometer for electron cyclotron emission measurements on JET.

A Martin Puplett interferometer for electron cyclotron emission (ECE) measurements from JET tokamak plasmas was extended to multichannel operation for simultaneous radial and oblique ECE measurements. This paper describes the new optics and the instrument's performance.

Measure of electron cyclotron emission at multiple angles in high T(e) plasmas of JET.

The oblique electron cyclotron emission (ECE) diagnostic installed at JET allows simultaneous analysis of the ECE spectra along three lines of sight (with toroidal angles of 0°, ∼ 10°, and ∼ 20°) and two linear polarizations for each oblique line of sight. The diagnostic is capable of measuring EC emission over the band of 75­800 GHz with 5 ms time resolution and 7.5 GHz spectral resolution, and it is designed to investigate the features of ECE spectra related to electron distribution in the thermal velocity range. Instrumental accuracy was assessed using sources at different temperatures (77­900 K) and with plasma emission. ECE from high temperature plasmas and in the presence of fast ions has been compared to simulations performed with the modeling code SPECE, setting an upper limit to possible discrepancies from thermal emission.

Evolution of the millimeter-wave collective Thomson scattering system of the high-field tokamak Frascati Tokamak Upgrade.

We first describe the improved receiving system of the diagnostic experiment of millimeter-wave collective Thomson scattering being run on the Frascati Tokamak Upgrade (FTU), and then discuss some peculiar problems and new operating procedures related to the investigation of strong anomalous spectra of nonthermal origin, many-orders-of-magnitude stronger than the ion thermal feature merged in them, systematically observed in the experimentation, and finally ascribed to a perturbation of the gyrotron that generates the probing beam. Arguments in favor of a more general valence of the solutions actuated for the specific case of FTU are finally given.

Dynamics of tearing modes during strong electron cyclotron heating on the FTU tokamak.

The localized electron cyclotron resonance heating power that can suppress sawteeth reconnection often drives m = 2 tearing modes in a tokamak operating at constant current. The dynamics of mode onset and coupled mode evolution is described in detail and compared with a nonlinear theoretical model that identifies the effects of mode coupling, finite inertia of the rotating islands, and wall braking.

The effect of in vitro fermentation on specific gravity and sedimentation measurements of forage particles.

Dry matter degradability (DMD), gas production (GP), functional specific gravity (FSG), volume of gas associated (GA), water-holding capacity (WHC), and sedimentation measurements of orchard-grass (OG) and alfalfa (AA) hays (ground through a 8-mm screen) were studied before and after in vitro incubation with ruminal fluid for 2, 4, 8, 24, 48, and 72 h. The DMD was higher for AA than for OG (P < .001), but GP did not differ. The FSG of unfermented OG and AA was .59 and .73, respectively (P < .01). During fermentation, the FSG of OG increased more than did that of AA (from .93 to 1.39 for OG and from .97 to 1.27 for AA after 2 and 72 h, respectively), and GA decreased more rapidly (from .94 to -.04 mL/g DM and from .74 to .15 mL/g DM, respectively). The DMD was positively correlated with FSG (r = .83; P < .001) and, therefore, negatively with GA (r = -.72; P < .01). The WHC increased similarly in the two forages with fermentation time. Unfermented and fermented samples were incubated in sedimentation columns filled with distilled water for 19, 37, 75, 150, and 300 s. After 300 s of sedimentation time, the unfermented AA and OG samples tended to float (91.1 and 72.7% of DM, respectively). In contrast, fermented samples tended to sediment (90.7 and 90.9% of DM, respectively). There were only small effects of forage species and fermentation time on sedimentation tendency. Correlations between sedimentation measurements and DMD and FSG were not significant, with the only exception of DM recovered in the lower section of sedimentation columns after 75 s, which was particularly correlated with DMD (P < .01) and FSG (P < .05). The results suggest that degradation rate of fibrous particles is related to changes in FSG and GA and, therefore, could influence ruminal transit. However, FSG was unable to predict accurately the sedimentation behavior of samples.