Charge Exchange Spectroscopic Diagnostic for the TJ-II José Miguel Carmona Torres Laboratorio Nacional de Fusion EURATOM-CIEMAT

Contents Motivation Stellarator TJ-II Diagnostic Neutral Beam Injector Multichannel Diagnostic Beam Characterization Interaction and corrections Estimation of Counts

Motivation DNBI has been installed on TJ-II CXRS local measurements of Ion Temperatures Poloidal & Toroidal Velocities Electric fields Impurity densities using experimental data + simulation code A lot of work to do…

Contents Motivation Diagnostic Neutral Beam Injector Stellarator TJ-II Multichannel Diagnostic Beam Characterization Interaction and corrections Estimation of Counts

Stellarator TJ-II An Heliac Flexible device Minor and mayor radii from 0.22 m to 1.5 m B created by external coils (B max =1 T) ECRH y NBI heating Plasma cross section is bean-shaped TJ-II Mag. flux surfaces for 2 diferent magnetic configurations. Magnetic Islands appers on diferent configurations as 58_83_61. Fully tridimensional plasma structure with easy access to portholes

Contents Motivation Stellarator TJ-II Diagnostic Neutral Beam Injector Multichannel Diagnostic Beam Characterization Interaction and corrections Estimation of Counts

Diagnostic Neutral Beam Injector DNBI SECTOR A7 TOP PORTHOLE NBI_1NBI_2 Scheme of DNBI Picture of DNBI installed in the TJ-II Dnbi Parameters -Focal length 170 cm -Pulse length 5 ms -Beam Energy ~30 KeV -1/e divergence <0.7 º -1/e radius at focus ~21 mm -Extracted ion current 4 A/cm 2 -Beam Components (H,H 2,H 3 ) ~90%, ~8%, 2% DNBI sector A7, mounted on a support structure Rev. Sci. Instrum. 75, 3499 (2004)

Contents Motivation Stellarator TJ-II Diagnostic Neutral Beam Injector Multichannel Diagnostic Beam Characterization Interaction and corrections Estimation of Counts

Multichannel Diagnostic Canon 85 mm F/1.2 l USM 12 fiber array Fiberguide Industries diameter 600  m Holospec Spectrograph f/1.8 high resolution and high dispertion grating CCD Pixis Princeton Instrum. back-illuminated 1024 x 1024 Pixels (13  m) J.M. Carmona et al. HTTP Conference 2006, Virginia, USA * * Ilustration from Alcator

Multichannel Diagnostic J.M. Carmona et al. Rev. Sci. Instrum. 77, (2006) In press

Contents Motivation Stellarator TJ-II Diagnostic Neutral Beam Injector Multichannel Diagnostic Beam Characterization Interaction and corrections Estimation of Counts

Beam Characterization Hypothesis: Homogeneos source Elemental beams emitted from source dS of neutrals  Termal Distrib.  Multiple sum of coaxial Gaussians Convolution between Gaussians and Q(r  z)=Q(r  1-z/z f ) Neutral beam profile in vacuum: P. Bosshard Thesis, TCV

Contents Motivation Stellarator TJ-II Diagnostic Neutral Beam Injector Multichannel Diagnostic Beam Characterization Interaction and corrections Estimation of Counts

Interaction and corrections Beam attenuation by means of collisions attenuation coefficient Proton and Imp.densities?

Interaction and corrections Some corrections on are needed  v  e ADAS database V neutrals <<V electrons f (T e ) V neutrals =30 KeV V neutrals  10 6 m/s V electrons  10 7 m/s J.M. Carmona et al. EPS Conference. Tarragona 2005

Contents Motivation Stellarator TJ-II Diagnostic Neutral Beam Injector Multichannel Diagnostic Beam Characterization Interaction and corrections Estimation of Counts

Photons? Charge-Exchange h (CVI 8  7) Number of photons Branching Ratio Rate coefficients for 30, 15, 10 KeV Optical window, lens, fibers, coupling, spectrograph and CCD total efficiency  

Some results An ‘artistic view’ of the simulation code, showing attenuated (red) vs non-attenuated beam (green) First measurements are expected to be obtained in the next campaign