Speaker
Arne Sahlberg
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/O5.104.pdf
Component wise DT fusion yield extrapolation with neutron spectrometry
A. Sahlberg1 , C. Hellesen1 , J. Eriksson1 , S. Conroy1 ,
G. Ericsson1 , L. Garzotti2 , D. King2 and JET Contributors∗
1 Dept. of Physics and astronomy, Uppsala University, Sweden
2 CCFE, Culham Science Centre, Abingdon, Oxfordshire, UK
As part of the preparation for ITER, a second Deuterium-Tritium campaign (DTE2) is planned
at JET. To this end, methods for quickly and robustly predicting fusion yields of DT plasmas
are sought. This paper investigates how neutron emission spectroscopy can predict equivalent
DT fusion power of a deuterium discharge.
The energy spectrum of the emitted neutrons has three major components (thermonuclear,
beam-target, RF-target) which scale differently when going from a DD to a DT plasma. For
each reaction component, a DD to DT scale-up factor can be calculated as the ratio between
the DT and DD reaction rates. The scale-up factors depend on the cross sections, the energy
distributions of the plasma ion species as well as the assumed fuel ion ratio nt /nd .
From the component scale-up factors the total neutron rate scale-up factor can be calculated if
the relative intensities of the neutron rate components are known. These can be estimated from
the neutron energy spectrum, which is here measured with the time-of-flight spectrometer TO-
FOR. The component scale-up factors are calculated using an ion temperature, either measured
with charge exchange recombination spectroscopy or estimated from the neutron spectrum,
along with a beam-ion distribution obtained from slowing down calculations.
This method for identifying and separating the neutron reaction components and scaling them
up from DD to DT has been applied to several JET pulses and compared to both earlier DT
shots at JET (from the 1997 campaign DTE1) and DT extrapolations made with the transport
codes JINTRAC and TRANSP. The comparisons with TRANSP fall within error bars while
comparisons with JINTRAC differ by around 15-25%. The reason for this discrepancy is under
investigation. Predicted DT fusion yields fall in line with comparable shots from DTE1. The
current record baseline and hybrid discharges are both predicted to reach 6-7 MW of fusion
power.
The above results indicate that this method is useful for making quick and robust predictions
for future DT pulses.
∗
See the author list of “X. Litaudon et al 2017 Nucl. Fusion 57 102001"
