In strong-field laser physics, ponderomotive energy is the cycle-averaged quiver energy of a free electron in an electromagnetic field.
Equation
The ponderomotive energy is given by
,
where is the electron charge, is the linearly polarised electric field amplitude, is the laser carrier frequency and is the electron mass.
In terms of the laser intensity , using , it reads less simply: ,
where is the vacuum permittivity.
For typical orders of magnitudes involved in laser physics, this becomes:
,
where the laser wavelength is , and is the speed of light. The units are electronvolts (eV), watts (W), centimeters (cm) and micrometers (μm).
Atomic units
In atomic units, , , where . If one uses the atomic unit of electric field, then the ponderomotive energy is just
Derivation
The formula for the ponderomotive energy can be easily derived. A free particle of charge interacts with an electric field . The force on the charged particle is .
The acceleration of the particle is
.
Because the electron executes harmonic motion, the particle's position is
.
For a particle experiencing harmonic motion, the time-averaged energy is
.
In laser physics, this is called the ponderomotive energy .
See also
Ponderomotive force
Electric constant
Harmonic generation
List of laser articles
References and notes
Laser science
Energy (physics)