Charge Exchange Spectroscopic Diagnostic for the TJ-II

José Miguel Carmona Torres

Laboratorio Nacional de FusionEURATOM-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

IonTemperatures

Poloidal & ToroidalVelocities

Electric fieldsImpurity 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 (Bmax=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

DNBISECTOR

A7

TOPPORTHOLE

NBI_1 NBI_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/cm2

-Beam Components (H,H2,H3) ~90%, ~8%, 2%

DNBI sector A7, mounted on a support structureRev. 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 mmF/1.2 l USM

12 fiber arrayFiberguide Industries

diameter 600m

Holospec Spectrographf/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 CharacterizationHypothesis:• Homogeneos source• Elemental beams emitted from source dS• of neutrals Termal Distrib.Multiple sum of coaxial Gaussians

V

2

2

exp)(),(zrzgrzzj f

b

b

t

b

TE

vv

2

2

• Convolution between Gaussians and Q(rz)=Q(r1-z/zf)

20,exp0,),( rzj

Izjrzj

j(z,0) I

a2

z*2

z2 1 exp a2

z*2

Neutral beam profile in vacuum:

2

*

2

2

*

2 0,expexp1),( 2

2

rzjIz

azz

aIrzj

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

totimpimp

totpp

b

eee nn

vv

n

•Beam attenuation by means of collisions

z

z

dzzIzIdzI

dI

0

exp)(/)( 0 attenuation coefficient

Proton and Imp.densities?

eeff

impeeff

p nZZ

Znn

ZZZ

n)1(

11

Interaction and corrections•Some corrections on are needed ve

ADAS databaseVneutrals<<Velectrons

f (Te)

•Vneutrals=30 KeV Vneutrals106 m/s Velectrons107 m/s

e

be

b

e

e

eber T

EvMT

mEvvv 132

b

e

Mmwith

32

effreff TvE 2/32/1 2

2/1 ebeeff TETT

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

•Photons? Charge-Exchange

h (CVI 87)

•Number of photons

PCX

14

Aij(8 7)

Aijv i N idl

i

N imp t sist

Branching RatioRate 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