The experiments on solitons in plasmas performed during the period 1970 to 1982 are reviewed. Suggestions for future experiments are presented.

https://iopscience.iop.org/article/10.1088/0032-1028/25/9/001/pdf

Soliton experiments in plasmas

Plasma surface waves were discovered in 1958. The experiments done since then on these waves are critically reviewed and analysed in terms of appropriate models and corresponding dispersion relations. Discrepancies and unresolved issues are identified and discussed. Wave damping experiments and analysis, and results of more recent works on nonlinear aspects of these waves, are also reported.

https://iopscience.iop.org/article/10.1088/0032-1028/24/11/001/pdf

Experimental investigations of the propagation of surface waves along a plasma column

Experiments on ion-acoustic solitons are reviewed. Theories and numerical simulations which are relevant to experimental results are also presented. The measured velocity and width of planar solitons are compared with the predictions of the Korteweg-deVries (KdV) equation which includes a finite ion temperature. The spatial evolution of compressive or rarefactive pulses is discussed. Cylindrical and spherical solitons are introduced together with a modified KdV equation and numerical results. Oblique collisions and their evolution, including overtaking and head-on collisions of two planar, cylindrical, or spherical solitons are described. Reflection, diffraction, and other topics related with ion-acoustic solitons are presented.

Experiments on Ion-Acoustic Solitons in Plasmas Invited Review Article

Experiments on the propagation of ion acoustic solitons that propagate in a positive ion–negative ion plasma are described. The solitons are launched from a solid metal disk to which a small negative step voltage [Δφ≊−2(Te/e) V] is applied. The mechanism for the excitation of the soliton, the identification of the fast and the slow modes in such a plasma, and the observation of a transient sheath are presented.

Experiments on Korteweg–de Vries solitons in a positive ion–negative ion plasma

Experiments on the propagation and collision of a Korteweg–deVries soliton in a positive ion–negative ion plasma are described. Both a one‐dimensional overtaking collision and a two‐dimensional resonant collision are examined. Soliton propagation into a steady‐state plasma sheath created by an additional biased metal plate in such a plasma is large enough that the detailed soliton motion in the locally inhomogeneous plasma can be easily studied. A partial reflection and partial transmission of the soliton at a critical density within the sheath is observed and interpreted.

Soliton propagation, collision, and reflection at a sheath in a positive ion–negative ion plasma

The ion acoustic wave response to an impulse disturbance is experimentally examined for two different exciting mechanisms. The differences and similarities are noted for the double-plasma (D-P) and plate excitation methods. The observed response agrees well with that predicted from a self-similar study of a fluid equation model which includes the effects of Poisson's equation.

https://iopscience.iop.org/article/10.1088/0032-1028/15/11/008/pdf

Ion-acoustic wave response to an impulse disturbance

Reviews four experimentally measured properties of waves which propagate in a medium having a dispersion relation D(k,ω)=1-ω02/ω2+k02/k2=0 where ω0 and k0 are characteristics of the medium. A transmission line, ion acoustic waves and electron plasma waves are examined and some similarity is found in their properties.

Properties of plasma waves defined by the dispersion relation

The analogy between certain equations which describe wave propagation in plasmas and in a particular transmission line is observed. This observation has led to the construction of such a line and several current plasma problems are experimentally simulated on the line.

C. M. Burde

Papers

Ion-acoustic wave response to an impulse disturbance

Properties of plasma waves defined by the dispersion relation

An Experimental Simulation of Waves in Plasmas