Trilateral Euregio Cluster

Simultaneous observation of CD and C2 in the near UV region in the JET divertor

• spectral window for the observation of CD and C2

• examplesa) nitrogen seeding – observation of CN (last week)

b) argon seeding – reduction of CD and C2 light

c) high triangular plasmas – different behaviour of CD and C2

S. Brezinsek, A. Pospieszczyk A. Meigs, M. Stamp

Trilateral Euregio Cluster

Standard CD and C2 spectroscopy

• sources, particle fluxes, chemical erosion yield …

• observation of CD at 431 nm (A-X band)• observation of C2 at 517 nm (Swan band)

• wide range & low resolution (e.g. KS3)• different devices & l-o-s (e.g. KT3)• good resolution & low time resolution (e.g. KME)

often necessary: simultaneous measurement of CD and C2

• good spectral resolution• good spatial resolution and the same l-o-s• good time resolution

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C2 and CD spectroscopy in the near UV

C2 spectrum CD spectrum

observed and identified at JET (10/2003)

KT3A outer divertor ch2

Trilateral Euregio Cluster

example: N2 seeding

CNC2

Identification of CN radicals

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example: Ar seeded plasmas

strike point on the outer horizontal target plate (14 MW NBI)

with Argon

without Argon

C2

C2CD

CD

Trilateral Euregio Cluster

example: Ar seeded plasmas

strike point on the outer horizontal target plate (14 MW NBI)

with Argon

without Argon

C2

C2

CD

CD

influence of Ar on the local plasma parameters?

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example: high triangular plasmas

strike point on the outer horizontal target plate

different behaviour

of CD and C2

observationalong the

outer verticaltarget plate

high power: 14 MW NBI

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conclusion

• spectral region is good for the observation of relative changes of CD and C2

• KT3A system in combination with this spectral range very useful (time / spatial resolution)

• only theoretical data for CD (B-X) transition available