Tischcenko V.N.   Zakharov Y.P.   Posukh V.G.   Berezutskiy A.   Boyarintsev E.   Melekhov A.V.   Miroshnichenko I.B.   Shaikhislamov I.F.  

The mechanism of merging of torsional Alfvén and slow magnetosonic waves created by a train of laser pulses upon irradiation of a target located in cosmic plasma with a magnetic field. Laboratory modeling

Reporter: Tischcenko V.N.

        The authors propose a mechanism of merging of shock waves (MMW) created by periodic optical breakdowns on a target or other explosive plasma bunches. It was shown, using laboratory modeling at the KI-1 facility and calculations on clusters, that bunches allow solving the problem of generation of low-frequency waves in the atmosphere and in cosmic plasma with a magnetic field. The effect is manifested when the conditions for the resonance of bunches with the environment are satisfied. When irradiating air targets with pulsed-periodic laser radiation with a high pulse repetition frequency, it is possible to simultaneously generate intense infrasound or ultrasound, which is unattainable in traditional acoustics because of the broad pattern of low-frequency waves, the absorption of ultrasound in air, or the low efficiency of other methods.

      It is shown for the first time that a train of optical breakdowns on a target in a collisionless plasma with a magnetic field or in a magnetic field in a vacuum forms a long narrow waves that transfer a momentum, angular momentum, currents, strong variations of magnetic and electric fields in the power tube of an external magnetic field. Transportation is carried out by two types of waves: slow magnetosonic (MW) and torsion Alfvén (AW), which formed when the criteria for the manifestation of MMW and additional conditions to the parameters of plasma bunches are met. The wavelength linearly depends on the number of bunches, which allows to create extended weakly damped waves. If the resonance conditions are violated, the bunches are created by a sequence of individual AB and MB, which rapidly decay.                 

       Depending on the parameters of bunches and concentration of the background plasma, the following modes of transport along the magnetic field tube are possible. Separate transfer of momentum (MW) and angular momentum (AW), which is due to the difference in the propagation velocities of AW and MW in the ionosphere. A joint transfer is possible in a magnetic field in a vacuum, where bunches form unbroken stream of rotating plasma, whose length is linearly depends on the number of bunches, and the diameter is determined by the energy of one bunch. The effect was observed when using bunches containing light and heavy ions. The flow is unbroken when the MMW criteria are satisfied in the magnetoplasma tube, in which AW and MW propagate. The velocity of the leading edge of the stream is 90 km/s.

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