Skip to Main content Skip to Navigation
Theses

Conception, réalisation et caractérisation de systèmes mécaniques pour l'expérience française de « balance du watt »

Abstract : To contribute to a possible redefinition of the Système international d'unités, french national metrology institutes are developping a watt balance experiment.
This experiment, whose principle has been proposed in 1976 by B. Kibble (NPL), allows to link a standard mass m (calibrated against the international prototype of the kilogram) to the Planck constant h. To redefine the unit of mass by fixing the value of this constant, measurement of the h/m ratio must be performed with a relative uncertainty of 10−8.
Realization of the experiment requires to build mechanical systems, a magnetic circuit and a translation stage in particular. For our experiment, we have chosen to design (i) a magnetic circuit with permanent magnets producing an axisymetric flux density field of about one tesla whose relative variations must be smaller than 10−4 in the air gap, and (ii) a flexure stage constraining a coil to travel inside the air gap of the circuit along a 80mm rectilinear and vertical translation.
We study the effects, on the result of the experiment, of the deviations of the magnetic circuit and the translation stage from their nominal definitions. Considering compromises inherent in any realization, we deduce from this study acceptable differences and we present the design, realization, and characterization of these two mechanical systems.
Complete list of metadatas

Cited literature [21 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00369283
Contributor : François Villar <>
Submitted on : Thursday, March 19, 2009 - 8:32:33 AM
Last modification on : Thursday, February 2, 2017 - 11:30:39 AM
Long-term archiving on: : Tuesday, June 8, 2010 - 8:11:40 PM

Identifiers

  • HAL Id : tel-00369283, version 1

Collections

LNE

Citation

François Villar. Conception, réalisation et caractérisation de systèmes mécaniques pour l'expérience française de « balance du watt ». Mécanique [physics.med-ph]. Conservatoire national des arts et metiers - CNAM, 2008. Français. ⟨tel-00369283⟩

Share

Metrics

Record views

481

Files downloads

16494