Current clamp at zero level in JT-60U current hole plasmas

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Magnetohydrodynamics

Background:

• Tokamak devices are crucial for magnetic confinement fusion energy.
• Understanding plasma behavior, especially current drive mechanisms, is essential for reactor operation.
• Previous models did not fully explain the absence of current in specific plasma regions.

Purpose of the Study:

• To investigate the formation and characteristics of the "current hole" phenomenon in tokamak plasmas.
• To understand why current drive fails in the central plasma region under specific conditions.
• To identify the nature of the observed magnetic field structure.

Main Methods:

• Experiments were conducted on the JT-60U tokamak.
• Current drive was achieved using a combination of a toroidal electric field and radio-frequency waves.
• Measurements focused on central current density and magnetic field structure in an axisymmetric toroidal plasma.

Main Results:

• A
• current hole", where central current density approaches zero, was observed.", "This phenomenon occurred despite the plasma
• high electric conductivity.
• A new, stiff, self-organized magnetic field structure was identified as the cause.

Conclusions:

• The
• current hole" represents a novel, self-organized magnetic structure in toroidal plasmas.", "This structure fundamentally limits current drive in the plasma core.", "Further research is needed to fully understand the implications for tokamak operational limits and future fusion reactors."]}, Meta_Description=
• current hole" phenomenon in tokamak plasma: self-organized magnetic structure prevents core current drive despite high conductivity.
• Area_of_Science
• Plasma Physics
• Fusion Energy Research
• Magnetohydrodynamics