Fusion Engineering and Design 53 (2001) 105 – 111 Fast ion collective Thomson scattering, JET results and TEXTOR plans H. Bindslev a, *, L. Porte b , A. Hoekzema c , J. Machuzak b , P. Woskov b , D. Van Eester d , J. Egedal b , J. Fessey e , T. Hughes f a FOM Instituut oor Plasmafysica 1 , Rijnhuizen, Postbus 1207, NL-3430 BE Nieuwegein, The Netherlands b MIT Plasma Science and Fusion Center, Cambridge, MA 02139, USA c Institut fu ¨r Plasmaphysik 1 , Forschungszentrum Ju ¨lich GmbH, D-52425 Ju ¨lich, Germany d Laboratory for Plasma Physics 1 , Koninklijke Militaire School /Ecole Royale Militaire, Brussels, Belgium e JET Joint Undertaking, Abingdon, UK f Uniersity of Essex, Colchester, UK Abstract Diagnosis of MeV range fast ions by collective Thomson scattering (CTS) of millimetre waves was successfully demonstrated at JET. Building on the experiences from JET, a new millimetre wave based CTS fast ion diagnostic is being built for the TEXTOR tokamak. With this we intend to address both generic issues of energetic ion dynamics and specific issues for ion cyclotron resonance heating. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Fast ions; Collective Thomson scattering; JET; TEXTOR; ICRH (Ion Cyclotron Resonance Heating) www.elsevier.com/locate/fusengdes 1. Introduction Much theoretical effort has been devoted to developing the modelling base for exploiting col- lective Thomson scattering (CTS) for diagnosing fast ions [1–6]. It was predicted that CTS could provide spatial profiles of fast ion velocity distri- butions, including anisotropy. This diagnostic ca- pability remains unique to CTS and is ideal for the study of energetic ion distributions generated by fusion reactions and ion cyclotron resonance heating (ICRH). CTS has been successfully ap- plied to the diagnosis of the bulk ion temperature using a D 2 O laser (385 m) [7] and using millime- tre waves generated by gyrotrons [8–12]. The small scattering cross-section, combined with con- siderations of access, plasma noise and spectral cleanliness of the probing radiation, implies that at present CO 2 lasers and gyrotrons are the main realistic sources of the probing radiation for fast ion CTS. With the wave length of the probing radiation provided by gyrotrons, the scattering from collective fluctuations dominates for a wide range of scattering angles, giving good spatial localisation and flexible scattering geometry [13]. Refraction and electron cyclotron emission (ECE) from the plasma can be significant problems [11]. * Corresponding author. 1 Euratom-Association and partner in the Trilateral Euregio Cluster (TEC). 0920-3796/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S0920-3796(00)00483-X