In
, a lower hybrid oscillation is a
longitudinal
Longitudinal is a geometric term of location which may refer to:
* Longitude
** Line of longitude, also called a meridian
* Longitudinal engine, an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicl ...
oscillation of
ion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
s and
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
s in a magnetized
plasma. The direction of propagation must be very nearly perpendicular to the stationary
magnetic field, within about
radian
The radian, denoted by the symbol rad, is the unit of angle in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. The unit was formerly an SI supplementary unit (before tha ...
s. Otherwise the electrons can move along the
field line
A field line is a graphical visual aid for visualizing vector fields. It consists of an imaginary directed line which is tangent to the field vector at each point along its length. A diagram showing a representative set of neighboring field ...
s fast enough to
shield the oscillations in potential. The frequency of oscillation is
:
,
where Ω
i is the ion
cyclotron frequency
Cyclotron resonance describes the interaction of external forces with charged particles experiencing a magnetic field, thus already moving on a circular path. It is named after the cyclotron, a cyclic particle accelerator that utilizes an oscillati ...
, Ω
e is the electron cyclotron frequency and ω
pi is the ion
plasma frequency Plasma oscillations, also known as Langmuir waves (after Irving Langmuir), are rapid oscillations of the electron density in conducting media such as plasmas or metals in the ultraviolet region. The oscillations can be described as an instability i ...
. This is the lower hybrid frequency, so called because it is a "hybrid", or mixture, of two frequencies. There are also an upper hybrid frequency and
upper hybrid oscillation
In plasma physics, an upper hybrid oscillation is a mode of oscillation of a magnetized plasma. It consists of a longitudinal motion of the electrons perpendicular to the magnetic field with the dispersion relation
:
\omega^2 = \omega_^2 + \ome ...
.
The lower hybrid oscillation is unusual in that the ion and electron masses play an equally important role. This mode is relatively unimportant in practice because the necessary precise orientation relative to the magnetic field is seldom achieved. Exceptions are the use of
lower hybrid waves to heat and drive current in
fusion
Fusion, or synthesis, is the process of combining two or more distinct entities into a new whole.
Fusion may also refer to:
Science and technology Physics
*Nuclear fusion, multiple atomic nuclei combining to form one or more different atomic nucl ...
plasmas, and the
lower hybrid drift instability, which was thought to be an important determinant of transport in the
Field-Reversed Configuration
A field-reversed configuration (FRC) is a type of plasma device studied as a means of producing nuclear fusion. It confines a plasma on closed magnetic field lines without a central penetration. In an FRC, the plasma has the form of a self-stabl ...
(but was not found experimentally
).
See also
*
Electrostatic ion cyclotron wave In plasma physics, an electrostatic ion cyclotron wave is a longitudinal oscillation of the ions (and electrons) in a magnetized plasma, propagating nearly (but not exactly) perpendicular to the magnetic field. The angle (in radians) between the d ...
*
Waves in plasmas In plasma physics, waves in plasmas are an interconnected set of particles and fields which propagate in a periodically repeating fashion. A plasma is a quasineutral, electrically conductive fluid. In the simplest case, it is composed of electron ...
*
Ion acoustic wave In plasma physics, an ion acoustic wave is one type of longitudinal oscillation of the ions and electrons in a plasma, much like acoustic waves traveling in neutral gas. However, because the waves propagate through positively charged ions, ion aco ...
*
Upper hybrid oscillation
In plasma physics, an upper hybrid oscillation is a mode of oscillation of a magnetized plasma. It consists of a longitudinal motion of the electrons perpendicular to the magnetic field with the dispersion relation
:
\omega^2 = \omega_^2 + \ome ...
*
List of plasma (physics) articles
References
{{Reflist
Waves in plasmas