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Alfvén Velocity Calculator.

Calculate magnetohydrodynamic Alfvén speed from field strength and mass density.

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velocity: 892,062.058076

velocity

892,062.058076

Use Cases

Plasma Physics Research

Determine the speed of Alfvén waves in laboratory or astrophysical plasmas to understand wave propagation and energy transport.

Example: Calculate Alfvén speed in the solar corona with B = 0.001 T and ρ = 1e-12 kg/m³.

MHD Simulations

Set initial conditions or verify results in magnetohydrodynamic simulations by computing characteristic wave speeds.

Example: Use for a tokamak plasma with B = 5 T and ρ = 1e-7 kg/m³.

Frequently Asked Questions

What is Alfvén velocity?
Alfvén velocity is the speed at which Alfvén waves travel along magnetic field lines in a plasma. It depends on the magnetic field strength and the mass density of the plasma.
How is Alfvén velocity calculated?
The Alfvén velocity is calculated using the formula v = B / sqrt(μ₀ρ), where B is the magnetic field strength in teslas, ρ is the mass density in kg/m³, and μ₀ is the permeability of free space (4π × 10⁻⁷ H/m).
What units are used for the inputs?
The calculator requires the magnetic field in teslas (T) and the mass density in kilograms per cubic meter (kg/m³). The result is given in meters per second (m/s).

Tips & Common Mistakes

Tips

  • Ensure the magnetic field is in teslas; convert from gauss by dividing by 10,000.
  • Mass density must be in kg/m³; convert from g/cm³ by multiplying by 1000.
  • For quick estimates, remember that Alfvén speed increases with magnetic field strength and decreases with density.
  • Use consistent units to avoid errors; the calculator assumes SI units.

Common Mistakes to Avoid

  • Forgetting to convert magnetic field from gauss to teslas, leading to results off by a factor of 10,000.
  • Using mass density in g/cm³ instead of kg/m³, which overestimates the speed by a factor of about 31.6.
  • Confusing Alfvén velocity with sound speed; they are different wave speeds in plasma.

Last updated: August 13, 2026