Joint European Torus

About: Joint European Torus is a facility organization based out in Oxford, United Kingdom. It is known for research contribution in the topics: Tokamak & Divertor. The organization has 54 authors who have published 27 publications receiving 688 citations. The organization is also known as: JET.

Persistent density perturbations at rational-q surfaces following pellet injection in the Joint European Torus.

Abstract: In the Joint European Torus the ablation of injected pellets produces a striking resonance effect when the pellets reach surfaces with q values 1 and (3/2. Subsequently, structures with mode numbers m=1,n=1 and m=3,n=2 are observed with the soft-x-ray cameras for up to 2 s as compact snakelike perturbations. These structures, which persist through several sawtooth collapses, give information on the radii of the q=1 and q=(3/2 surfaces and the q-profile evolution. The observations can be explained by the formation of magnetic islands.

More on core‐localized toroidal Alfvén eigenmodes

Abstract: A novel type of ideal toroidal Alfven eigenmode, localized in the low‐shear core region of a tokamak plasma, is shown to exist, whose frequency is near the upper continuum of the toroidal Alfven gap. This mode converts to a kinetic‐type toroidal Alfven eigenmode above a critical threshold that depends on aspect ratio, pressure gradient, and shear. Opposite to the usual ideal toroidal Alfven eigenmode, this new mode is peaked in amplitude on the small‐major‐radius side of the plasma.

Tritium retention in next step devices and the requirements for mitigation and removal techniques

Abstract: Mechanisms underlying the retention of fuel species in tokamaks with carbon plasma-facing components are presented, together with estimates for the corresponding retention of tritium in ITER. The consequential requirement for new and improved schemes to reduce the tritium inventory is highlighted and the results of ongoing studies into a range of techniques are presented, together with estimates of the tritium removal rate in ITER in each case. Finally, an approach involving the integration of many tritium removal techniques into the ITER operational schedule is proposed as a means to extend the period of operations before major intervention is required.

Three-dimensional non-linear magnetohydrodynamic modeling of massive gas injection triggered disruptions in JET

Abstract: JOREK 3D non-linear MHD simulations of a D2 Massive Gas Injection (MGI) triggered disruption in JET are presented and compared in detail to experimental data. The MGI creates an overdensity that rapidly expands in the direction parallel to the magnetic field. It also causes the growth of magnetic islands ( m/n=2/1 and 3/2 mainly) and seeds the 1/1 internal kink mode. O-points of all island chains (including 1/1) are located in front of the MGI, consistently with experimental observations. A burst of MHD activity and a peak in plasma current take place at the same time as in the experiment. However, the magnitude of these two effects is much smaller than in the experiment. The simulated radiation is also much below the experimental level. As a consequence, the thermal quench is not fully reproduced. Directions for progress are identified. Radiation from impurities is a good candidate.