Design of the Prototypical Cryomodule for the EUROTRANS Superconducting Linac for Nuclear Waste Transmutation

International audienceOne task of the accelerator workpackage of the EUROTRANS program for the design of a nuclear waste transmutation system is dedicated to the engineering and realization of a prototype cryomodule of the high energy section of the linac, equipped with elliptical superconducting niobium cavities. We review here the present status of the design and the planned program that foresees the experimental characterization of the fully equipped cavity and RF system under its nominal operating conditions

Precise control of thermal conductivity at the nanoscale through individual phonon-scattering barriers

International audienceThe ability to precisely control the thermal conductivity (κ) of a material is fundamental in the development of on-chip heat management or energy conversion applications. Nanostructuring permits a marked reduction of κ of single-crystalline materials, as recently demonstrated for silicon nanowires. However, silicon-based nanostructured materials with extremely low κ are not limited to nanowires. By engineering a set of individual phonon-scattering nanodot barriers we have accurately tailored the thermal conductivity of a single-crystalline SiGe material in spatially defined regions as short as ∼15 nm. Single-barrier thermal resistances between 2 and 4×10−9 m2 K W−1 were attained, resulting in a room-temperature κ down to about 0.9 W m−1 K−1, in multilayered structures with as little as five barriers. Such low thermal conductivity is compatible with a totally diffuse mismatch model for the barriers, and it is well below the amorphous limit. The results are in agreement with atomistic Green’s function simulations

Determination of Thermophysical Properties of Si/SiGe Superlattices with a Pump-Probe Technique

A Time Domain Thermo-Reflectance technique (TDTR) is used for the non-destructive evaluation of thermal and acoustic properties of Si/SiGe superlattices (SL) at room temperature. In particular, this technique allows the determination of the SL cross-plan thermal conductivity, the thermal boundary resistance at the interface between the metallic film and the SL, and the longitudinal sound velocity inside the SL. We discuss the effect of both transducer thickness and pump power on the measurements and then on values of the extracted thermophysical properties of the superlattice

Scanning Thermal Microscopy measurements for the determination of the thermal conductivity of Bi2Te3 Nanowire Composites

Comunicación presentada en el V European School on Molecular Nanoscience (ESMOLNA2012) celebrado en Cuenca del 28 de octubre al2 de noviembre de 2012.Peer reviewe

Joule Expansion Imaging Techniques on Microlectronic Devices

We have studied the electrically induced off-plane surface displacement on two microelectronic devices using Scanning Joule Expansion Microscopy (SJEM). We present the experimental method and surface displacement results. We show that they can be successfully compared with surface displacement images obtained using an optical interferometry method. We also present thermal images using Scanning Thermal Microscopy (SThM) technique to underline that SJEM is more adapted to higher frequency measurements, which should improve the spatial resolution

3-omega scanning thermal microscopy to evaluate the thermal conductivity of Bi2Te3 nanowires

Comunicación presentada en el 2nd European Workshop on Electrochemical Deposition of Thermoelectric Materials, celebrado en Madrid del 4 al 5 de octubre de 2012.Peer Reviewe

Joule Expansion Imaging Techniques on Microlectronic Devices

We have studied the electrically induced off-plane surface displacement on two microelectronic devices using Scanning Joule Expansion Microscopy (SJEM). We present the experimental method and surface displacement results. We show that they can be successfully compared with surface displacement images obtained using an optical interferometry method. We also present thermal images using Scanning Thermal Microscopy (SThM) technique to underline that SJEM is more adapted to higher frequency measurements, which should improve the spatial resolution