Hysteresis in the tearing mode locking/unlocking due to resonant magnetic perturbations in EXTRAP T2R

• The physical mechanisms behind the hysteresis in the tearing mode locking and unlocking to a resonant magnetic perturbation (RMP) are experimentally studied in EXTRAP T2R reversed-field pinch. The experiments show that the electromagnetic and the viscous torque increase with increasing perturbation amplitude until the mode locks to the wall. At the wall-locking, the plasma velocity reduction profile is peaked at the radius where the RMP is resonant. Thereafter, the viscous torque drops due to the relaxation of the velocity in the central plasma. This is the main reason for the hysteresis in the RMP locking and unlocking amplitude. The increased amplitude of the locked tearing mode produces further deepening of the hysteresis. Both experimental results are in qualitative agreement with the model in Fitzpatrick et al (2001 Phys. Plasmas 8 4489)

Subject headings

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

Keyword

EXTRAP T2R

hysteresis

locking unlocking

resonant magnetic perturbation

reversed-field pinch

tearing modes

Magnetic resonance

Magnetism

Pinch effect

Wave plasma interactions

Resonant magnetic perturbations

Reversed field pinch

Locks (fasteners)

Publication and Content Type

ref (subject category)

art (subject category)