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

1

2345

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

II

ISNR

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.