Alfvén waves
E679640
Alfvén waves are magnetohydrodynamic oscillations in a plasma where magnetic tension acts as the restoring force, fundamental to understanding space and astrophysical plasmas.
Statements (51)
| Predicate | Object |
|---|---|
| instanceOf |
magnetohydrodynamic wave
ⓘ
plasma wave ⓘ |
| approximationRegime |
low-frequency compared to ion cyclotron frequency
ⓘ
wavelength large compared to ion gyroradius ⓘ |
| compressibility | approximately incompressible ⓘ |
| densityPerturbation | small ⓘ |
| discoveredBy | Hannes Alfvén NERFINISHED ⓘ |
| discoveryYear | 1942 ⓘ |
| dispersionRelation | ω = k_parallel * v_A ⓘ |
| energyTransportDirection | along magnetic field lines ⓘ |
| fieldLineEffect | cause field line oscillations ⓘ |
| frequencyRange | low-frequency MHD regime ⓘ |
| governedBy | magnetohydrodynamics ⓘ |
| groupVelocity | Alfvén speed NERFINISHED ⓘ |
| magneticFieldPerturbation | perpendicular to background field ⓘ |
| mathematicalDescription | linearized MHD equations ⓘ |
| medium |
astrophysical plasmas
ⓘ
laboratory plasmas ⓘ space plasmas ⓘ |
| namedAfter | Hannes Alfvén NERFINISHED ⓘ |
| observedIn |
Earth magnetosphere
NERFINISHED
ⓘ
laboratory fusion devices ⓘ magnetospheres of other planets ⓘ solar corona ⓘ solar wind ⓘ spacecraft plasma measurements ⓘ tokamaks NERFINISHED ⓘ |
| phaseVelocity | Alfvén speed NERFINISHED ⓘ |
| polarization | transverse to background magnetic field ⓘ |
| pressurePerturbation | small ⓘ |
| propagateAlong | magnetic field lines ⓘ |
| propagateIn | magnetized plasma ⓘ |
| propagationCondition | magnetic field nonzero ⓘ |
| propagationCondition | plasma electrically conducting ⓘ |
| relatedConcept |
Alfvén speed
NERFINISHED
ⓘ
Alfvénic turbulence NERFINISHED ⓘ compressional Alfvén wave ⓘ kinetic Alfvén wave ⓘ shear Alfvén wave ⓘ |
| restoringForce | magnetic tension ⓘ |
| roleIn |
coronal heating theories
ⓘ
energy transport in plasmas ⓘ magnetospheric physics ⓘ momentum transport in plasmas ⓘ solar wind dynamics ⓘ space weather processes ⓘ turbulence in magnetized plasmas ⓘ |
| speedDependsOn |
magnetic field strength
ⓘ
plasma mass density ⓘ |
| usedIn | diagnostics of plasma parameters ⓘ |
| velocityPerturbation | perpendicular to background field ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.