Volume 127, Number 4, August 2019
|Number of page(s)||7|
|Section||Physics of Gases, Plasmas and Electric Discharges|
|Published online||01 October 2019|
Spontaneous rapid rotation and breakup of metal droplets in tokamak edge plasmas
1 Blackett Laboratory, Imperial College London - London, SW7 2BW, UK
2 Culham Centre for Fusion Energy, Culham Science Centre - Abingdon, Oxfordshire, OX14 3DB, UK
3 Aalto University, Department of Applied Physics - Espoo, Finland
Received: 29 July 2019
Accepted: 28 August 2019
Fast-camera observations of distinctive forked patterns caused by disintegrating molten metal particles in the JET tokamak are presented. These patterns are characterised by repeated splitting of particles into pairs of equally sized sub-particles; such regularity can only be explained by the two-lobed bifurcations of liquid droplets rotating with velocities in excess of . These speeds are consistent with longstanding theories of particle spin-up in magnetized plasmas but are at least two orders of magnitude greater than any previous measurement of rotating particles in plasmas. The verification of spontaneous liquid particle spinning processes in plasmas has widespread implications in astrophysics, particularly for the explanation of anomalous microwave radiation and its associated measurements of the cosmic magnetic field. Furthermore, by incorporating the rotation of droplets into the dust tracking code DTOKS, the fast-camera observations are reliably replicated in JET and predictions for future droplet behaviour in next-generation tokamaks can be made. These simulations show that the higher magnetic fields, plasma temperatures and densities of ITER will enhance the breakup process, thus protecting the core plasma from acute impurity deposition and subsequent disruption events and providing significant operational benefits.
PACS: 52.55.Fa – Tokamaks, spherical tokamaks / 52.25.Xz – Magnetized plasmas / 98.38.Cp – Interstellar dust grains; diffuse emission; infrared cirrus
© EPLA, 2019
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.