Preliminary experimental scaling of the helical mirror confinement effectiveness

• Published in: Journal of plasma physics 2020-10, Vol.86 (5), Article 905860515
• Main Authors: Sudnikov, Anton V., Beklemishev, Aleksey D., Inzhevatkina, Anna A., Ivanov, Ivan A., Postupaev, Vladimir V., Burdakov, Aleksandr V., Glinskiy, Vladimir V., Kuklin, Konstantin N., Rovenskikh, Andrey F., Ustyuzhanin, Viktor O.
• Format: Article
• Language: English
• Subjects: Active control; Confinement; Efficiency; Electric fields; Experiments; Integrals; Magnetic fields; Nuclear physics; Open Magnetic Systems for Plasma Confinement; Plasma; Plasma density; Plasma physics; Rotating plasmas
• ISSN: 0022-3778; 1469-7807
• DOI: 10.1017/S0022377820001245

The paper presents experimental results from the SMOLA device that is the first facility with a helical mirror section of the magnetic field. This device is built in the Budker Institute of Nuclear Physics for the verification of the helical mirror confinement idea that is the recently introduced technique of the active control of axial losses from a confinement zone. Theory predicts that with rotating plasma, a helical mirror will provide suppression of the axial plasma flow and, simultaneously, density pinching to the axis. Experiments demonstrated that plasma density at the exit from the transport section is suppressed with activation of the helical field, the effect is significant and highly reproducible. The most pronounced effect is observed on the plasma periphery, where the mirror ratio is the highest. The integral suppression ratio reaches 2–2.5 in the discussed experiments. Experimental results are compared with simplified theoretical estimates. The integral suppression ratio matches the simple theoretical estimates even if the transversal diffusion is neglected.