Status of Equatorial CXRS System Development

S. Tugarinov, Yu. Kaschuck, A. Krasilnikov, V. Serov

SRC RF TRINITI, Troitsk, Moscow reg, Russia.E-mail: tugar@triniti.ru

Main directions of the CXRS diagnostic development in RF

• 1. Collection optical system design and integration into the equatorial port plug # 3.

• 2. Numerical simulation.• 3. Data analysis development.• 4. Measurement methodology development.• 5. Specific spectroscopic instruments

development.

General scheme of CXRS for ITER

-Distribution of the CXRS periscopes looking at the DNB.

-Russia responsible for two periscopes at the E-port # 3 for plasma edge measurements.

Five mirrors optical system integration into E-port #3

r/a=0.5

r/a=1 Version September 2005

1. Collection optical system design and integration in to port plug

• Optical system design and imaging properties optimization was carried out by ZEMAX software.

• Imaging scale is 10 : 1. • Collection optical system has agree with

spectral instrument light throughput.• Individual spectrometer will be used for

each view chord.

Five mirrors optical system focusing properties• Five view chords distributed from r = a to r = a/2• Color of spot correspond to Hα, He II and CVI wavelength

r/a=1

r/a=0.5

Focal plane

At the RF - EU Workshop devoted to ITER CXRS diagnostic development that took place in TRINITI (14–16 September, 2005) was suggested:

• Extend equatorial port observation system up to r = 0.3a for deep overlap of edge and core measurement systems and extend the plasma region where poloidal and toroidal plasma rotation could be separate.

• Achieve the best possible spatial resolution at the plasma periphery for edge physics studies.

Version December 2005

r/a=1

r/a=0.3

r/a=0.5

• Only flat and spherical mirrors was used for design to make optical system more simple in alignment and practically feasible.

Four mirrors optical system focusing properties

r/a=0.3

r/a=1

Focal plane

r/a=0.5

2. Numerical simulation

• Involve all physical processes analysis that be the result of CXR reaction inside beam volume.

• Allow estimate measured signals value and SNR value.

• In general, allow estimate abilities and efficiency of CXRS diagnostic for ITER application.

Experimental scheme for numerical simulation

r/a=1

r/a=0.3

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6

7

8

Plasma parameters for numerical simulation• Electron density 1 1020 m-3 with a flat profile.• Center temperature ~20 keV with parabolic shape.• Equal electron and ion temperature.• Uniform impurity composition along radius :

D and T = 77%, C = 1.2%, Be = 2%, He = 4% with respect to ne ( that correspond Zeff = 1.7 ).

• Integration time = 0.1 sec .• The simulation was carried out for He II 468.6 nm;

BeIV 465.8 nm and C VI 529.1 nm lines.

DNB’s parameters for numerical simulation"Negative Ion" Beam

( 100 keV/amu)"Positive Ion" Beam

(80 keV/amu)

Voltage (kV) 100 H0 160 D0

Current densityin focal position (mA/cm2)

70 183, 23, 29 E, E/2, E/3

Beam 1/e – radius (m)

0.1 0.042, 0.056, 0.07

stop (10-20 m2) 2.28 2.63, 4.16, 5.32

• “Negative Ion” beam – this is a beam which created with negative ion source use.

• “Positive Ion” beam – this is a beam which created with positive ion source use.

We have create original software for CXRS numerical modeling, instead of DINA code simulation.

Atomic data for cross section <σ> and rate coefficients <σv> was simulated using ADAS code. (We are very appreciate to Dr. M. von Hellermann for help with atomic data)

DNB’s profiles• “Negative” DNB “Positive” DNB

DNB’s attenuation in plasma column• “Negative” DNB “Positive” DNB

Radial distribution of active CX He II line (white) and background (red) intensity along view chord

integrated• “Negative” DNB “Positive” DNB

Radial distribution of active CX CVI line (white) and background (red) intensity along view chord

integrated• “Negative” DNB “Positive” DNB

- With DNB modulation the signal-to-noise ratio (SNR) is calculated for the case of continuum radiation fluctuations as the main noise source. - Thus, the SNR value calculated as:

cxff

cx

III

SNR

2

• I’cx – signal from CX lines [ 1/s ]

• I’cx – signal from continuum radiation [ 1/s ]

- integration time [ s ]

Signal-noise ratio value radial distribution for uniform 2.5 A0 (red) and variable 2.5 - 0.5 A0 (white)

spectral resolution for He II line• “Negative” DNB “Positive” DNB

Signal-noise ratio value for uniform 2.5 A0 (red) and variable 2.5 - 0.5 A0 (white) spectral

resolution for CVI line

• “Negative” DNB “Positive” DNB

• Comparison of "negative" and "positive" DNB show advantageous of "positive" DNB application for edge CXRS and acceptability for core CXRS measurements.

• "Negative" DNB with 100 keV/amu energy have less attenuation coefficient and penetrate further into the plasma core, therefore gives advantageous for core measurements.

5. Specific spectroscopic instruments development

• For the CXRS diagnostic, high resolution, high light throughput spectrometer (HRS) based on echelle grating was design.

• Spectral range: 200 – 900 nm.• F-number = 3.• Stigmatic image.• Max. spectral resolution: 0.1 A0.• Average linear dispersion: 2.5 - 3 A0/mm.• Dispersion range: 2 – 20 A0/mm.

Optical scheme of new HRS design

• 1 – Entrance slit• 2 – Flat mirror• 3 – Spherical mirror• 4 – Flat mirror with

hole• 5 – Correction

element• 6 – Echelle grating• 7 – Image plane

New design of HRS

• 1. Entrance slit. 3. Spherical mirror. 5. Correction element• 6. Echelle grating. 7. Detector box.

New design of HRS

• 1. Entrance slit. 5. Correction element.• 3. Spherical mirror. 6. Echelle grating (400 mm length).• 4. Flat mirror with hole.

Conclusion• We plan continue activity in all directions of

the CXRS diagnostic development :• 1. Collection optical system design and

integration into the port plug # 3.• 2. Numerical simulation.• 3. Data analysis development.• 4. Measurement methodology development.• 5. Specific spectroscopic instruments

development.