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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
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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 Ion Temperatures Poloidal & Toroidal Velocities Electric fields Impurity densities using experimental data + simulation code • DNBI has been installed on TJ-II • CXRS local measurements of 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 (Bmax=1 T) • ECRH y NBI heating • Plasma cross section is bean-shaped Fully tridimensional plasma structure with easy access to portholes TJ-II Mag. flux surfaces for 2 diferent magnetic configurations. Magnetic Islands appers on diferent configurations as 58_83_61 .
Contents • Motivation • Stellarator TJ-II • Diagnostic Neutral Beam Injector • Multichannel Diagnostic • Beam Characterization • Interaction and corrections • Estimation of Counts
Diagnostic Neutral Beam Injector NBI_1 NBI_2 Picture of DNBI installed in the TJ-II TOP PORTHOLE Scheme of DNBI SECTOR A7 DNBI • 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/cm2 • Beam Components (H,H2,H3) ~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 CCD Pixis Princeton Instrum. back-illuminated 1024 x 1024 Pixels (13 mm) Holospec Spectrograph f/1.8 high resolution and high dispertion grating * 12 fiber array Fiberguide Industries diameter 600mm 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 Neutral beam profile in vacuum: • Hypothesis: • Homogeneos source • Elemental beams emitted from source dS • of neutrals Termal Distrib.Multiple sum of coaxial Gaussians • Convolution between Gaussians and Q(r,j,z)=Q(r,j)/(1-z/zf) 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 l attenuation coefficient Proton and Imp.densities? • Beam attenuation by means of collisions
Interaction and corrections • Vneutrals=30 KeV Vneutrals»106 m/s Velectrons»107 m/s ADAS database Vneutrals<<Velectrons • Some corrections on are needed <sv>e f (Te) 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
Estimation of Counts hn (CVI 87) • Number of photons Branching Ratio Optical window, lens, fibers, coupling, spectrograph and CCD total efficiency » 17.6 % Rate coefficients for 30, 15, 10 KeV • Photons? Charge-Exchange
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