Related Experiment Video
Updated: Aug 9, 2026
07:17
Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry
Published on: August 1, 2017
Parametric instability in the formation of plasma waveguides
J H Cooley1, T M Antonsen, H M Milchberg
1Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Summary
Laser-induced plasma waveguides can become unstable due to axial modulations. A new model explains these instabilities arise from nonlinear coupling between the laser field and scattered modes within the plasma channel.
Area of Science:
- Plasma physics
- Laser-plasma interactions
- Nonlinear optics
Background:
- Plasma waveguides are crucial for high-intensity laser propagation.
- Axicon lenses generate these waveguides by focusing lasers into neutral gas.
- Instabilities, specifically axial modulations, can disrupt waveguide stability.
Purpose of the Study:
- To investigate the cause of axial modulations in laser-generated plasma waveguides.
- To develop a theoretical model explaining the observed instabilities.
- To validate the model against experimental data.
Main Methods:
- Utilizing an axicon lens to focus a moderate intensity laser into neutral gas.
- Developing a theoretical model based on nonlinear coupling.
- Comparing model predictions with experimental measurements of channel modulations.
Main Results:
- The proposed model successfully explains the generation of axial modulations.
- Nonlinear coupling between the axicon field and scattered modes is identified as the primary mechanism.
- The model shows good agreement with experimental observations.
Conclusions:
- Axial modulations in plasma waveguides are a result of nonlinear coupling effects.
- The developed model provides a robust framework for understanding and predicting these instabilities.
- This research contributes to the control and optimization of laser-plasma channel formation.
Related Concept Videos
01:28Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
01:07Propagation of Waves
When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second medium. In such a case, the interface of the two mediums can be considered as a boundary that is neither fixed nor free.
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
01:17Sound as Pressure Waves
Sound waves, which are longitudinal waves, can be modeled as the displacement amplitude varying as a function of the spatial and temporal coordinates. As a column of the medium is displaced, its successive columns are also displaced. As the successive displacements differ relatively, a pressure difference with the surrounding pressure is created. The gauge pressure varies across the medium.
The pressure fluctuation depends on the difference in displacements between the successive points in the...
The pressure fluctuation depends on the difference in displacements between the successive points in the...
01:30Plane Electromagnetic Waves I
The existence of combined electric and magnetic fields that propagate through space as electromagnetic (EM) waves is the most significant prediction of Maxwell's equations. As Maxwell's equations hold in free space, the predicted electromagnetic waves do not require a medium for their propagation. An EM wave comprises an electric field, defined as the force per charge on a stationary charge, and a magnetic field, which is the force per charge on a moving charge.
The EM field is assumed to be a...
The EM field is assumed to be a...
01:15Standing Electromagnetic Waves
Electromagnetic waves can be reflected; the surface of a conductor or a dielectric can act as a reflector. As electric and magnetic fields obey the superposition principle, so do electromagnetic waves. The superposition of an incident wave and a reflected electromagnetic wave produces a standing wave analogous to the standing waves created on a stretched string.
Suppose a sheet of a perfect conductor is placed in the yz-plane, and a linearly polarized electromagnetic wave traveling in the...
Suppose a sheet of a perfect conductor is placed in the yz-plane, and a linearly polarized electromagnetic wave traveling in the...
01:23Steady, Laminar Flow in Circular Tubes
Hagen-Poiseuille flow describes a viscous fluid's steady, incompressible flow through a cylindrical tube with a constant radius R. This flow profile is often applied to understand fluid transport in narrow channels, such as capillaries. It serves as a foundational example of laminar flow. In this model, cylindrical coordinates (r,θ,z) are used to describe the radial (r), angular (θ), and axial (z) dimensions within the tube. For Hagen-Poiseuille flow, the velocity profile is purely axial,...