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

Coupler conditioning bench

This document reports on the design of the coupler conditioning benc

Asynchronous ultrafast pump-probe experiments: Towards high speed ultrafast imaging with ultrahigh spectral resolution

Femtosecond pump-probe experiments allow the generation/detection of acoustic waves in the GHz-THz frequency range for investigating matter properties at sub-micron scales. To circumvent the main drawback of these experiments, namely their limited acquisition speed due to the use of mechanical delay line, asynchronous optical sampling (ASOPS) has emerged in the 80's. The key feature of this method consists in using two different lasers for pump and probe pulses. A slight difference between their repetition rates creates the pump-probe delay, the mechanical delay line being then no longer needed: The acquisition rate is considerably sped up. Pump-probe delays from zero to the inverse of the repetition rate are scanned during one beating period (in the millisecond range) between pump and probe asynchronous pulse trains. The strong potential of this technique has been demonstrated in the ultrafast acoustics community with 1 GHz repetition rate lasers

Asynchronous ultrafast pump-probe experiments: Towards high speed ultrafast imaging with ultrahigh spectral resolution

Femtosecond pump-probe experiments allow the generation/detection of acoustic waves in the GHz-THz frequency range for investigating matter properties at sub-micron scales. To circumvent the main drawback of these experiments, namely their limited acquisition speed due to the use of mechanical delay line, asynchronous optical sampling (ASOPS) has emerged in the 80's. The key feature of this method consists in using two different lasers for pump and probe pulses. A slight difference between their repetition rates creates the pump-probe delay, the mechanical delay line being then no longer needed: The acquisition rate is considerably sped up. Pump-probe delays from zero to the inverse of the repetition rate are scanned during one beating period (in the millisecond range) between pump and probe asynchronous pulse trains. The strong potential of this technique has been demonstrated in the ultrafast acoustics community with 1 GHz repetition rate lasers

D5 - Power coupler conditioning bench

This documents reports on the design of the power coupler conditioning bench

Developments and Tests of a 700 MHz Cryomodule for the Superconducting Linac of MYRRHA

The MYRRHA projects aims at the construction of an Accelerator Driven System demonstrator. The criticality will be sustained by an external spallation neutron flux; produced thanks to a 600 MeV high intensity proton beam. This beam will be delivered by a superconducting linac which must fulfil very stringent reliability requirements. To carry out “real scale” reliability-oriented experiments a 700 MHz Cryomodule was developed. Several tests were performed to commission the experimental set-up. We review here the obtained results and the lessons learnt by operating this module, as well as the on-going developments

Four different approaches for the measurement of IC surface temperature: application to thermal testing

Silicon die surface temperature can be used to monitor the health state of digital and analogue integrated circuits (IC). In the present paper, four different sensing techniques: scanning thermal microscope, laser reflectometer, laser interferometer and electronic built-in differential temperature sensors are used to measure the temperature at the surface of the same IC containing heat sources (hot spots) that behave as faulty digital gates. The goal of the paper is to describe the techniques as well as to present the performances of these sensing methods for the detection and localisation of hot spots in an IC