Velocity vectors of a quiescent prominence observed by Hinode/SOT and the MSDP (Meudon)

The dynamics of prominence fine structures is a challenge to understand the formation of cool plasma prominence embedded in the hot corona. Recent observations from the high resolution Hinode/SOT telescope allow us to compute velocities perpendicularly to the line-of-sight or transverse velocities. Combining simultaneous observations obtained in H-alpha with Hinode/SOT and the MSDP spectrograph operating in the Meudon solar tower we derive the velocity vectors of a quiescent prominence. The velocities perpendicular to the line-of-sight are measured by time slice technique, the Dopplershifts by the bisector method. The Dopplershifts of bright threads derived from the MSDP reach 15 km/s at the edges of the prominence and are between +/- 5 km/s in the center of the prominence. Even though they are minimum values due to seeing effect, they are of the same order as the transverse velocities. These measurements are very important because they suggest that the verticalstructures shown in SOT may not be real vertical magnetic structures in the sky plane. The vertical structures could be a pile up of dips in more or less horizontal magnetic field lines in a 3D perspective, as it was proposed by many MHD modelers. In our analysis we also calibrate the Hinode H-alpha data using MSDP observations obtained simultaneously.Comment: 7 pages, 7 figures, submitted to A &

Top-Gated Chemical Vapor Deposited Mos2 Field-Effect Transistors On Si3N4 Substrates

We report the electrical characteristics of chemical vapor deposited (CVD) monolayer molybdenum disulfide (MoS2) top-gated field-effect transistors (FETs) on silicon nitride (Si3N4) substrates. We show that Si3N4 substrates offer comparable electrical performance to thermally grown SiO2 substrates for MoS2 FETs, offering an attractive passivating substrate for transition-metal dichalcogenides (TMD) with a smooth surface morphology. Single-crystal MoS2 grains are grown via vapor transport process using solid precursors directly on low pressure CVD Si3N4, eliminating the need for transfer processes which degrade electrical performance. Monolayer top-gated MoS2 FETs with Al2O3 gate dielectric on Si3N4 achieve a room temperature mobility of 24 cm(2)/V s with I-on/I-off current ratios exceeding 10(7). Using HfO2 as a gate dielectric, monolayer top-gated CVD MoS2 FETs on Si3N4 achieve current densities of 55 mu A/mu m and a transconductance of 6.12 mu S/mu m at V-tg of -5V and V-ds of 2V. We observe an increase in mobility at lower temperatures, indicating phonon scattering may dominate over charged impurity scattering in our devices. Our results show that Si3N4 is an attractive alternative to thermally grown SiO2 substrate for TMD FETs. (C) 2015 AIP Publishing LLC.STTR programNSF NASCENT ERCArmy Research Office under STTR W911NF-14-P-0030Microelectronics Research Cente