arXiv subjects

D. Carnevale

Publications and source records attributed to D. Carnevale.

4 recordsLinked to original sources

arXiv2021

Latest results on quiescent and post-disruption runaway electron mitigation experiments at Frascati Tokamak Upgrade

Results from the last FTU campaigns on the deuterium large (wrt FTU volume) pellet REs suppression capability, mainly due to the induced burst MHD activity expelling REs seed are presented for discharges with 0.5 MA and 5.3T. Clear indications of avalanche multiplication of REs following single pellet injection on 0.36 MA flat-top discharges is shown together with quantitative indications of dissipative effects in terms of critical electrical field increase due to fan-like instabilities. Analysis of large fan-like instabilities on post-disruption RE beams, that seem to be correlated with low electrical field and background density drops, reveal their strong RE energy suppression capability suggesting a new strategy for RE energy suppression controlling large fan instabilities. We demonstrate how such density drops can be induced using modulated ECRH power on post-disruption beams.

physics.plasm-ph↗

arXiv2020

Fast dynamics of radiofrequency emission in plasmas with runaway electrons

Radiofrequency emission in the 0.4 - 3 GHz range from FTU plasmas in presence of runaway electrons (RE) has been measured with unprecedentedly high time resolution. Rapid emission bursts associated with enhanced RE pitch angle scattering reveal kinetic instabilities affecting evolution of the RE population from the buildup phase. Such measurements also provide a sensitive monitor for instabilities during early RE formation. The leading edge of radio bursts is much shorter than interleaving periods of low emission; spectral broadening during growth indicates nonlinear wave coupling as an explanation for the observed intermittency. Radiofrequency emission disappears at the beginning of post-disruption RE plateaus, and subsequently reappears in the shape of very intense bursts accompanied by strong rises of suprathermal electron cyclotron emission.

physics.plasm-ph↗

arXiv2020

Exoway: an exoskeleton on actuated wheels

In this short work we present a low cost exoskeleton with actuated wheels that allows movements as well as skating-like steps. The simple structure and the actuated wheels allows to minimize the use of motors for locomotion. The structure is stabilized by an active control system that balances the structure and permit to be maneuvered by the driver whose commands are acquired by a dedicated hardware interface.

cs.RO↗

arXiv2015

Runaway Electron Control in FTU

Experimental results on the position and current control of disruption generated runaway electrons (RE) in FTU are presented. A scanning interferometer diagnostic has been used to analyze the time evolution of the RE beam radial position and its instabilities. Correspondence of the interferometer time traces, radial profile reconstructed via magnetic measurements and fission chamber signals are discussed. New RE control algorithms, which define in real-time updated plasma current and position references, have been tested in two experimental scenarios featuring disruption generated RE plateaus. Comparative studies among 52 discharges with disruption generated RE beam plateaus are presented in order to assess the effectiveness of the proposed control strategies as the RE beam interaction with the plasma facing components is reduced while the current is ramped-down.

physics.plasm-ph↗