Current-driven rotating-kink mode in a plasma column with a non-line-tied free end

Area of Science:

• Plasma Physics
• Magnetohydrodynamics
• Instability Phenomena

Background:

• Kink instability is a critical phenomenon in plasma confinement.
• Previous theoretical models did not fully capture experimental observations in linear plasma columns.
• Finite sheath resistivity at axial boundaries plays a significant role.

Purpose of the Study:

• To present the first experimental measurements of kink instability in a linear plasma column.
• To investigate the effects of finite sheath resistivity on instability thresholds.
• To compare experimental results with recent theoretical advancements.

Main Methods:

• Experimental generation of a linear plasma column.
• Measurement of plasma behavior under conditions of finite sheath resistivity.
• Comparison of experimental data with theoretical predictions including axial flow and non-line-tied boundary conditions.

Main Results:

• Experimental observation of kink instability below the classical Kruskal-Shafranov threshold.
• Detection of axially asymmetric mode structure and plasma rotation.
• Accurate reproduction of observed phenomena by a recent kink theory.

Conclusions:

• Finite sheath resistivity significantly modifies kink instability thresholds.
• Axial plasma flow and non-line-tied boundary conditions are crucial factors in kink instability.
• Experimental validation of advanced theoretical models for plasma confinement.