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Access provided by: anon Sign Out. Cosmology in the plasma universe: an introductory exposition Abstract: Acceptance of the plasma universe model is now leading to drastically new views of the structure of the universe. The basic aspects of cosmological importance are: a the same basic laws of plasma physics hold everywhere; b mapping of electric fields and currents is necessary to understand cosmic plasma; c space is filled with a network of currents leading to the cellular and filamentary structure of matter; and d double layers, critical velocity, and pinch effects are of decisive importance in how cosmic evolves.
Observations that began at optical wavelengths now extend to wavelengths ranging from hundreds of kilometres down to tens of nanometres, and satellites have also proved immensely useful in refining our image of the Universe. But, despite the assiduous measurements, the radiation is often produced, particularly at radio and X-ray wavelengths, by very complex processes that we struggle to understand.
Nevertheless, a positive step has now been taken: in Physical Review Letters , J. Maggs and G. For some years, the aim of these authors has been a laboratory study of magnetohydrodynamic turbulence — that is, turbulence in the interactions between a plasma and a magnetic field.https://senjouin-renshu.com/wp-content/10/717-como-hackear.php
These waves are thought to be intimately involved in diverse phenomena, such as the precipitation of electrons through the atmosphere in the auroral regions that are connected with the dazzling northern and southern lights — and that can take out power distribution systems. This is analogous to light waves trapped between the mirrors of a resonant cavity of a laser. Laser action at microwave frequencies — a 'maser' — is a known astrophysical phenomenon. In general, laboratory experiments attempting to mimic the behaviour of the aurora, the solar chromosphere or more exotic cosmic objects have met with scepticism, if not outright hostility, in the astrophysical community.
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Ever since William Gilbert, in about , used a magnetized sphere — a terrella — to explain the magnetic compass to Queen Elizabeth I, many brave attempts have been made in terrestrial laboratories to pin down exotic cosmic phenomena. For example, it is extremely difficult to make a laboratory experiment long enough and wide enough to allow the wave to propagate in a natural way and not have it cramped up and its motion constricted.
Also, the laboratory plasma needs to be created from a background gas, which will collide with the plasma and damp out waves. This really does not exist in the vacuum of space.
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Maggs and Morales' experiment was performed using the Large Plasma Device at the Basic Plasma Science Facility at the University of California, Los Angeles , a unique facility with 90 magnetic-field coils surrounding a column of helium plasma 19 m long Fig. At one end of the column, a pulsed voltage draws electrons out of a thermionic cathode towards an anode made of copper mesh, located 55 cm away.
The magnetic field, the plasma density and the degree of ionization need to be manipulated so that the ion cyclotron frequency the frequency with which the positively charged ions rotate around the magnetic field is much greater than the ion neutral collision frequency the rate at which plasma collides with the background gas. The Large Plasma Device is one of the very few experimental devices in the world in which such a happy combination of operational parameters can be achieved.
Maggs and Morales describe the phenomenon as "spectacular flares of extremely coherent signals [that] develop at low magnetic fields and extremely high plasma currents" — a little reminiscent of sci-fi writer E.
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Maggs and Morales' experiment demonstrates the great potential for carrying out experiments of cosmic importance in the laboratory. Reprints and Permissions. Physics of Plasmas By submitting a comment you agree to abide by our Terms and Community Guidelines.
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