Wave Besselian beams

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Idioma: English
Encuadernación: Rústica

RESUMEN

In this work we discuss the propagation of the wave radiation focused by the axicon, and analyze optical discharges created by laser Besselian beam in gases, fluids and on solid surfaces. We consider formation processes of discharges, properties and structures of the plasma channels. Also, we describe the methods of research of Besselian beams, breakdowns, discharges and plasmas created by the beams.

The optical discharge arisen under the action of the Bessel beam field Jn(r) of solid (n = 0) or tubular (n > 0) configuration turns into the plasma solid or tubular cylinder (waveguide), thereof Rayleigh length being large, Zr = πd2/λ >>> 1, at the diameter of the diffraction limit. While the heating pulse front is short, the breakdown wave propagates along the beam in a mode of running focus at a velocity exceeding the light speed. The channel plasma parameters at the initial stage depend on the Besselian beam intensity level and distribution. The radial expansion velocity of the plasma channel is approximately in general agreement with the theory of cylindrical strong explosion.

The channel axial symmetry provides important advantage over the plasma of spherical symmetry, for it implies effective application of magnetic field. Besselian beams can be formed by electromagnetic radiation of any frequency range, as well as by wave radiation of any other nature, e.g. acoustic.

The capability of the plasma parameter distribution and that of the channel structure to be varied are important for applications. Examples of beam and plasma channel applications are considered in the book.

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Descripción

Table of contents

Preface
Acknowledgments
Introduction

Chapter 1. Wave Besselian beams
1.1. Basic equations
1.2. The beam field and nonlinear structures
1.3. Tubular Besselian beams

Chapter 2. Besselian beam formation
2.1. Intensity distribution along the beam
2.2. The field kinds of longitudinal distribution
2.3. Axicon optics
2.4. Axicon manufacturing methods

Chapter 3. Laser systems in Besselian beam experiment
3.1. The laser oscillators
Laser oscillator with passive Q-switch
Laser oscillator with active Q-switch
Laser oscillator with unstable resonator
3.2. The laser amplifier system
Amplification for laser oscillator G1
Amplification for laser oscillator G2
Amplifier for laser oscillator G3
3.3. Generation of probe radiation

Chapter 4. Research methodology
4.1. Diagram of experimental setup
4.2. Visualization of processes in Besselian beam field
Optical discharge in the light of plasma radiation
Optical discharge in the light of scattered radiation
Scattering indicatrix recording
Shadow and schlieren pictures of discharges
Spectroscopy of optical discharge plasma
4.3. Electron-optical registration of the discharge
Linear scanning of processes
Frame scanning of processes
Directional coupler
4.4. Synchronization system
Block diagram of experiment control
Digital devices for synchronization
Sequence regulating of rapid processes

Chapter 5. Optical discharges and plasma channels in Besselian beam field
5.1. Plasma channel creation techniques
5.2. Besselian beam discharge propagation
5.3. Discharge length in Besselian beam
5.4. Propagation velocity of the optical discharge

Chapter 6. Radial expansion of plasma channels
6.1. Expansion of plasma channel in air
6.2. Comparison with self-similar solution
6.3. Plasma channel expansion in some other gases
6.4. Structures of plasma channels in Besselian beams
6.5. Lifetime prolongation of Besselian beam channel

Chapter 7. Discharge structures in Besselian beams
7.1. Typical structures of laser spark
7.2. Breakdown mechanism in Besselian beam field
7.3. Confusing structures of optical discharge

Chapter 8. Hydrodynamics of plasma channel created by Besselian beam
8.1. Evolution of axisymmetric thermal explosion
8.2. Radial expansion of the plasma channel
8.3. Channels in radiation field of high power
8.4. Instability of the plasma waveguide
The modulation linear theory
Numeral analysis of channel mode structure

Chapter 9. Parameters of the plasma channels
9.1. Plasma channels of various kinds
9.2. Electro-physical properties of plasma channels
9.3. Emission spectra of plasma channels
9.4. Diagnostics of cannel plasma parameters
9.5. Spectral lines observed in plasma of some gases

Chapter 10. Possible applications of Besselian beams and the plasma channels
10.1. Precise measurement of optical breakdown threshold
10.2. Nonlinear effects in the fields below breakdown
10.3. High-speed switch for current and voltage wide ranges
10.4. Short-wave plasma laser
10.5. Superpower laser pulses
Laser plasma acceleration of electrons
Generation of electromagnetic radiation
10.6. Controlled thermonuclear synthesis
Nuclear fusion with magnetically confined plasma
Eelectrodynamic compression of plasma
Nuclear fusion with inertial plasma confinement
10.7. Some other possible applications

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