Rotational Instability (n=2)
Resolving this instability allowed FRC plasma lifetimes to extend by orders of magnitude.
01 Definition
A destructive magnetohydrodynamic mode in FRCs where plasma rotation induces an elliptical deformation that contacts the chamber wall.
02 Detailed_Analysis
The n=2 rotational instability is a classic destructive mode in Field-Reversed Configuration (FRC) plasmas. As the plasma column accelerates azimuthally due to particle loss or end-shorting, it deforms into a rotating elliptical (n=2) cross-section, leading to rapid deconfinement via wall contact. Experiments on LANL's FRX-C machine demonstrated that applying weak external quadrupole magnetic fields effectively suppresses this mode without degrading plasma confinement.
03 Key_Facts
- ▸ Primary destructive instability terminating early Field-Reversed Configuration plasmas
- ▸ Driven by centrifugal force and azimuthal spin-up of the confined ion column
- ▸ Definitively stabilized using external quadrupole magnetic fields on LANL's FRX-C
04 Deep_Dive_Intelligence
Overview
The primary destructive mode for FRCs, where the plasma cross-section deforms into a rotating ellipse and hits the wall. This issue was definitively solved on the FRX-C device using weak quadrupole magnetic fields, a breakthrough that extended plasma lifetimes from tens to hundreds of microseconds.
Entity Type: Technology — Rotational Instability (n=2) represents a specific technology or capability.
Source Documents
Intelligence derived from 3 source documents:
06 Related_Terms (3)
08 Timeline_Mentions (7)
Magnetorotational Instability Identified
Velikhov identifies the magnetorotational instability (MRI), a key mechanism for angular momentum transport in magnetized discs.
fusion-physicsDiscovery of FRC Anomalous Stability
Experiments at LANL discover that Field-Reversed Configurations (FRCs) are significantly more stable than predicted by MHD theory.
fusion-physicsLANL Field-Reversed Experiment (FRX) Series
Foundational research at Los Alamos National Laboratory (FRX-A, B, C) masters the control of the n=2 rotational instability in FRCs using quadrupole magnetic fields.
fusion-physicsFRX-A Experiment
LANL conducts the FRX-A experiment, discovering that FRCs possess anomalous stability.
fusion-physicsFRX-B Operations and Anomalous Stability Discovery
Upgraded experiment FRX-B identifies the n=2 rotational instability and discovers that FRCs are 100x more stable than MHD theory predicts.
fusion-physicsFRX-C Quadrupole Stabilization Breakthrough
The FRX-C experiment at LANL demonstrates that weak quadrupole magnetic fields can suppress the n=2 rotational instability, extending FRC lifetimes to 300 microseconds.
fusion-physicsFRX-C Operations and Translation Demonstration
A major scale-up (FRX-C) begins investigating confinement scaling; the device is later modified (FRX-C/T) to demonstrate FRC translation.
fusion-physics09 FAQ
What is Rotational Instability (n=2)? ▾
Why does Rotational Instability (n=2) matter? ▾
How does Rotational Instability (n=2) relate to other concepts? ▾
When did Rotational Instability (n=2) appear in the research timeline? ▾
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Quick_Facts
- Category
- Fusion Physics
- Aliases
- Rotational Instability (n=2), rotational-instability-n2, n=2 Instability, Rotational Instability, Quadrupole-Stabilized Mode
- Sources
- 0
- Related Terms
- 3
- Timeline Events
- 7