Achievement of quasi-steady sustainment of transport barriers
On JT-60U, a reversed shear plasma that accompanied by clear and wide transport barriers was successfully sustained in a quasi-steady state by applying lower hybrid current drive (LHCD) to control the current profile. The total plasma current was 0.85 MA and almost fully driven non-inductively by the bootstrap (~23%) and the LH driven (~77%) currents.
In a steady state fusion reactor based on a reversed shear mode, the reversed shear with high plasma confinement should be maintained by the bootstrap and externally driven currents. The result revealed the potential experimentally. Furthermore, by using LH waves, which interacted with the electrons, the discharge was electron heating dominant and thus relevant to a fusion plasma in which electron heating by a particles is dominant. The results have an important contribution to steady state fusion research. Higher performance and bootstrap fraction will be further pursued.
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| Wave forms of the qusi-steady reversed magnetic shear discharge. Zero one-turn voltage indicates the full non-inductive current drive. | The safety factor (reversal in the central region corresponds to the reversed shear) and the electron temperature (with transport barrier) profiles almost in a steady state.. |