Tandem Mirror Confinement Control
Confinement in a tandem mirror depends on maintaining the axial potential profile and mirror fields against particle and energy losses.
The confinement scheme
A tandem mirror confines a long central plasma between two end plugs. Magnetic mirrors at each end reflect most particles, and electrostatic potentials built up in the plugs confine the ions that the magnetic mirror alone would lose out the ends. Confinement quality depends on sustaining both the mirror fields and the axial potential profile.
Maintaining the potential
The confining potential in the plugs is created by localized heating that raises the plug density and temperature, often with radio-frequency heating tuned to build the potential barrier. Control regulates this heating to hold the potential profile that plugs ion losses. Losing the potential lets ions stream out the ends, so this is a continuous, active control task, not a set-and-forget condition.
Stability control
Simple mirrors are prone to interchange and other instabilities because of unfavourable field-line curvature. Tandem mirrors add stabilizing regions or wall stabilization to keep the plasma from bulging out. Control monitors for the onset of these modes and adjusts the field shaping and heating to keep the plasma stable, much as a tokamak actively manages its own instabilities.
- Mirror fields plus electrostatic plugs confine ions
- Localized plug heating builds the confining potential
- Losing the potential opens the end losses
- Active stabilization counters interchange modes
Kronos burner context
The Kronos burner is a D-3He tandem-mirror generator whose confinement rests on a 26.49 T plug field and a 17 T throat, with a direct energy converter collecting the charged-particle output. Confinement control coordinates plug magnets, heating, and the converter load. The machine is a design and simulation case in fixed Aegis and MetroVolt configurations, not built hardware, and no net-gain claim precedes its first-of-a-kind demonstration.
Mirror confinement is an active balance of fields, potentials, and heating held steady by control.