347 research outputs found
Improved Collective Thomson Scattering measurements of fast ions at ASDEX Upgrade
Understanding the behaviour of the confined fast ions is important in both
current and future fusion experiments. These ions play a key role in heating
the plasma and will be crucial for achieving conditions for burning plasma in
next-step fusion devices. Microwave-based Collective Thomson Scattering (CTS)
is well suited for reactor conditions and offers such an opportunity by
providing measurements of the confined fast-ion distribution function resolved
in space, time and 1D velocity space. We currently operate a CTS system at
ASDEX Upgrade using a gyrotron which generates probing radiation at 105 GHz. A
new setup using two independent receiver systems has enabled improved
subtraction of the background signal, and hence the first accurate
characterization of fast-ion properties. Here we review this new dual-receiver
CTS setup and present results on fast-ion measurements based on the improved
background characterization. These results have been obtained both with and
without NBI heating, and with the measurement volume located close to the
centre of the plasma. The measurements agree quantitatively with predictions of
numerical simulations. Hence, CTS studies of fast-ion dynamics at ASDEX Upgrade
are now feasible. The new background subtraction technique could be important
for the design of CTS systems in other fusion experiments.Comment: 4 pages, 4 figures, to appear in Proc. of "Fusion Reactor
Diagnostics", eds. F. P. Orsitto et al., AIP Conf. Pro
New Polyfluorinated ligands Based on 2,2'-bypyridines and 1,2,4triazines in the Design of Manganese and Copper Metal Complexes
The study was carried out with the financial support of the Russian Foundation for Basic Research in the framework of a research project 18-33-00226
Synthesis of meso-2,2’-bipyridyl-substituted calix[4]arenes and their response to metal cations
A convenient synthetic approach to meso-substituted with 2,2’-bipyridine and 1-(pyridin-2-yl)isoquinoline residues calix[4]arenes is reported. This approach involves the reaction of generated in situ 2-lithio-calix[4]arene with 1,2,4-triazine precursor with the following aromatization of the obtained adduct, and the aza-Diels-Alder reaction of the 1,2,4-triazinyl-substituted calix[4]arene with 2,5-norbornadien or in-situ generated 1,2-dehydrobenzene. The UV/fluorescence response of thus obtained meso-pyridyl-substituted calix[4]arenes to metal cations is studied
Measurement of a 2D fast-ion velocity distribution function by tomographic inversion of fast-ion D-alpha spectra
We present the first measurement of a local fast-ion 2D velocity distribution function f(v||, v⊥). To this end, we heated a plasma in ASDEX Upgrade by neutral beam injection and measured spectra of fast-ion Dα (FIDA) light from the plasma centre in three views simultaneously. The measured spectra agree very well with synthetic spectra calculated from a TRANSP/NUBEAM simulation. Based on the measured FIDA spectra alone, we infer f(v||, v⊥) by tomographic inversion. Salient features of our measurement of f(v||, v⊥) agree reasonably well with the simulation: the measured as well as the simulated f(v||, v⊥) are lopsided towards negative velocities parallel to the magnetic field, and they have similar shapes. Further, the peaks in the simulation of f(v||, v⊥) at full and half injection energies of the neutral beam also appear in the measurement at similar velocity-space locations. We expect that we can measure spectra in up to seven views simultaneously in the next ASDEX Upgrade campaign which would further improve measurements of f(v||, v⊥) by tomographic inversion
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