In strong-field
laser physics
Laser science or laser physics is a branch of optics that describes the theory and practice of lasers.
Laser science is principally concerned with quantum electronics, laser construction, optical cavity design, the physics of producing a popula ...
, 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
The elementary charge, usually denoted by is the electric charge carried by a single proton or, equivalently, the magnitude of the negative electric charge carried by a single electron, which has charge −1 . This elementary charge is a fundame ...
,
is the linearly
polarised electric field amplitude,
is the laser
carrier frequency
In telecommunications, a carrier wave, carrier signal, or just carrier, is a waveform (usually sinusoidal) that is modulated (modified) with an information-bearing signal for the purpose of conveying information. This carrier wave usually has a ...
and
is the
electron mass
The electron mass (symbol: ''m''e) is the mass of a stationary electron, also known as the invariant mass of the electron. It is one of the fundamental constants of physics. It has a value of about or about , which has an energy-equivalent of ...
.
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
The Hartree atomic units are a system of natural units of measurement which is especially convenient for atomic physics and computational chemistry calculations. They are named after the physicist Douglas Hartree. By definition, the following four ...
,
,
,
where
. If one uses the
atomic unit of electric field,
[CODATA Value]
atomic unit of electric field
/ref> 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
In physics, a ponderomotive force is a nonlinear force that a charged particle experiences in an inhomogeneous oscillating electromagnetic field. It causes the particle to move towards the area of the weaker field strength, rather than oscilla ...
*Electric constant
Vacuum permittivity, commonly denoted (pronounced "epsilon nought" or "epsilon zero"), is the value of the absolute dielectric permittivity of classical vacuum. It may also be referred to as the permittivity of free space, the electric const ...
*Harmonic generation
Harmonic generation (HG, also called multiple harmonic generation) is a nonlinear optical process in which n photons with the same frequency interact with a nonlinear material, are "combined", and generate a new photon with n times the energy of ...
* List of laser articles
References and notes
Laser science
Energy (physics)
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