title: Upgrade of the JET far infrared interferometer diagnostic.
abstract: In recent years there has been a major upgrade of the JET far infrared diagnostic             system consisting of a new laser system with the wavelength at 118.8 μm at and             more advanced processing electronics for phase counting. This provides a second colour             measurement of the electron plasma density on the vertical system. Due to the shorter             wavelength, the plasma induced laser beam refraction is reduced by a factor of three             alleviating density errors caused by loss of signal (so-called "fringe             jumps" [A. Murari et al., Rev. Sci. Instrum. 77, 073505 (2006)]),             in particular during high performance plasmas experiments in JET.
authors.affiliation: EURATOM/CCFE Association, Culham Science Centre, Abingdon, United Kingdom. Alexandru.Boboc@ccfe.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Boboc
authors.forename: C
authors.initials: C
authors.lastname: Gil
authors.forename: P
authors.initials: P
authors.lastname: Pastor
authors.forename: P
authors.initials: P
authors.lastname: Spuig
authors.forename: T
authors.initials: T
authors.lastname: Edlington
authors.forename: S
authors.initials: S
authors.lastname: Dorling