Uppsala University

ITPA St Petersburg 20-24 April 2009 G.Gorini 1

JET results on the determination of thermal/non-thermal fusion yield from

neutron emission spectroscopy

Uppsala University

Istituto di Fisica del Plasma “Piero Caldirola”,CNR & Milano-Bicocca University, Milano, Italy

EFDA JET Collaborators

Giuseppe Gorinion behalf of


Issue: Thermal and non-thermal neutron yield (Q value)used nowadays for physics analysis of fusion plasmas (e.g. JET). Not measured.Qnth/Qth desirable measurement on ITER.Can Neutron Emission Spectroscopy determinethe thermal and non-thermal neutron yield and their ratio?

Here: JET results from selected D dischargeswith NBI heating.


TOFOR neutron spectromer

neutrons

TOFOR is a new 2.5 MeV Time-Of-Flight neutron spectrometer Optimized for high Rate operation (>200 kHz range)


TOFOR neutron spectraMain features in the measured TOF spectrum:

• Broad component (e.g. due to NBI deuterons)

• Low energy tail due to neutron scattering

•Higher energy neutrons: missing in the absence of RF heating

#69242, D plasma, NB heating, single injector tof[ns]


TOFOR neutron spectra (linear scale)

#69242, D plasma, NB heating, single injector


NBI in JET

• Full model in TRANSP


TRANSP• Input experimental data

• Simulation of:– Equilibrium– Trasport– Fast ion dynamics– Radiation emission etc (e.g. for diagnostic comparison)

• NUBEAM


NUBEAM

• Motion of particles• Neutral deposition• Ionizzation• Orbits• Collisions and

thermalization


Control Room

Control Room is a MonteCarlo code first developed in 1994.

The original system consisted on a C++ library and a few applicationswhose purpose was the calculation of slowing-down ion distributions and the resulting neutron emission in thermonuclear plasmas.

Now it is possible to use the library from within the Python programming language. In fact, one could say the library was designed for being used as a Python module. This gives the user a number of advantages. On theone hand, this allows one to test-drive the library through the interactivePython interpreter and makes it easier to experiment with its features. On the other hand, this enables the user to write simple scripts.


Example of spectrum

#69625t = 58 s.


TOFOR data

Pulse: 69652

PNBI = 13 MWIp = 2.6 MABT = 2.2 T

T= 1.7 keV

Chi2 = 0.98


Pulse


Missing Neutrons


Yth/Ynth


Role of sight line• To what extent is the plasma volume seen by TOFOR representative of the TOTAL volume?

Equation: y = a*(x-b) R2 = 0.98364 a = 1.216 ± 0.02391b= 0.00269 ± 0.00369


Conclusions

TRANSP-based accurate simulation of neutron emission spectra

with thermal and non-thermal components.

Separation of thermal/non-thermal components possible.

Accuracy depends on shape difference.

On ITER shape will be very different => separation easier.

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