Plasma ion heating by cryogenic pellet injection

Runaway electron generation during plasma shutdown by killer pellet injection

Tokamak discharges are sometimes terminated by disruptions that may cause large mechanical and thermal loads on the vessel. To mitigate disruption-induced problems it has been proposed that “killer” pellets could be injected into the plasma in order to safely terminate the discharge. Killer pellets enhance radiative energy loss and thereby lead to rapid cooling and shutdown of the discharge. Bu...

Suppression of heating rates in cryogenic surface-electrode ion traps.

Dense arrays of trapped ions provide one way of scaling up ion trap quantum information processing. However, miniaturization of ion traps is currently limited by sharply increasing motional state decoherence at sub-100 mum ion-electrode distances. We characterize heating rates in cryogenically cooled surface-electrode traps, with characteristic sizes in the 75 to 150 mum range. Upon cooling to ...

Lithium Pellet Injection Experiments

A pellet enhanced performance (PEP) mode, showing significantly reduced core transport, is regularly obtained after the injection of deeply penetrating lithium pellets into Alcator C-Mod discharges. These transient modes, which typically persist about two energy confinement times, are characterized by a steep pressure gradient (4, <a/5) in the inner third of the plasma, indicating the presence ...

Cryogenic pellet launcher adapted for controlling of tokamak plasma edge instabilities.

One of the main challenges posed recently on pellet launcher systems in fusion-oriented plasma physics is the control of the plasma edge region. Strong energy bursts ejected from the plasma due to edge localized modes (ELMs) can form a severe threat for in-vessel components but can be mitigated by sufficiently frequent triggering of the underlying instabilities using hydrogen isotope pellet inj...

Effect of Transport Processes on Tokamak Refueling by Pellet Injection