HIGH-EFFICIENCY PLASMA REFUELING BY PELLET INJECTION FROM THE MAGNETIC HIGH-FIELD SIDE INTO ASDEX UPGRADE

High-efficiency refuelling of ELMy H-mode tokamak discharges with soli d deuterium pellets injected from the magnetic high-field side is demo nstrated. Compared to standard low-field side injection, the fuelling efficiency was enhanced by a factor of 4, the pellet penetration more than 2 times. This experimental result can be qualitatively explained by the magnetic force pushing a diamagnetic plasma cloud towards lower magnetic field, causing rapid particle loss for shallow low-field sid e injection, but enhancing fuelling efficiency and pellet penetration for high-field side injection.