Fast Ions in Tokamak Plasmas
Fast-ion populations in Alcator C-Mod plasma can be
detected and localized in space and time via their
interaction with a diagnostic neutral beam. A new
diagnostic system is being developed to Specifically,
super-thermal, fully-stripped ions in a plasma can be
detected by observing emission from the singly-ionized ion
which are formed by charge exchange of the full-stripped
ion in a beam of fast neutrals. This will contribute to two
active research areas on C-Mod. One is the validation of
the physics models for IC deposition physics via minority
ions. (Wave Plasma Interactions) The other is the study of
alfven eigenmodes via their diffusive effect on fast ion
Electron Transport in the no-man's land between
pedestal and core
Electron transport will be investigated in the little
studied, but critical, region that links the edge pedestal
with the confinement region of the plasma. Edge localized
modes (ELMs) are sudden, episodic losses of energy from the
plasma. An ELM launches a cold pulse into the plasma that
is carried by both electrons and ions. We will use the cold
pulse to measure the electron thermal transport in a
neglected, but important region of the plasma. The outcome
will be thermal transport measurements and energy loss
through the electrons due to an ELM. More...
Light Impurity transport on Alcator C-Mod
Accumulation of impurities in a tokamak discharge leads to
dilution of the fusion fuel and to enhanced energy loss.
Confluence of the measurement of a few characteristic
profiles shapes and their prediction by turbulence theory
provides the opportunity to make progress both toward
fusion and toward identification of the physics of
Measure ER and E×B shear in an internal transport
barrier in Alcator C-Mod.
There appears to be an Er well in the vicinity of the ITB.
Is this the critical controlling feature for transport at
the ITB as it is for the pedestal? More...