Modeling Earth's magnetosphere in the laboratory
Date:
April 12, 2022
Source:
American Institute of Physics
Summary:
Scientists report a method to study smaller magnetospheres,
sometimes just millimeters thick, in the laboratory. The new
experimental platform combines the magnetic field of the Large
Plasma Device with a fast laser- driven plasma and a current-driven
dipole magnet. The LAPD magnetic field provides a model of the
solar system's interplanetary magnetic field, while the laser-driven
plasma models the solar wind and the dipole magnet provides a model
for the Earth's inherent magnetic field. Motorized probes allow
system scans in three dimensions by combining data from tens of
thousands of laser shots.
FULL STORY ==========================================================================
A magnetosphere forms around any magnetized object, such as a planet,
that is immersed within a stream of ionized gas, called plasma. Because
Earth possesses an intrinsic magnetic field, the planet is surrounded by a large magnetosphere that extends out into space, blocks lethal cosmic rays
and particles from the sun and stars, and allows life itself to exist.
========================================================================== InPhysics of Plasmas, by AIP Publishing, scientists from Princeton,
UCLA, and the Instituto Superior Te'cnico, Portugal, report a method
to study smaller magnetospheres, sometimes just millimeters thick,
in the laboratory.
These mini-magnetospheres have been observed around comets and
near certain regions of the moon and have been suggested to propel
spacecraft. They are good testbeds for studying larger planet-sized magnetospheres.
Previous laboratory experiments have been carried out utilizing plasma
wind tunnels or high-energy lasers to create mini-magnetospheres. However, these earlier experiments were limited to 1D measurements of magnetic
fields that do not capture the full 3D behavior scientists need to
understand.
"To overcome these limitations, we have developed a new experimental
platform to study mini-magnetospheres on the Large Plasma Device (LAPD)
at UCLA," said author Derek Schaeffer.
This platform combines the magnetic field of the LAPD with a fast
laser-driven plasma and a current-driven dipole magnet.
==========================================================================
The LAPD magnetic field provides a model of the solar system's
interplanetary magnetic field, while the laser-driven plasma models
the solar wind and the dipole magnet provides a model for the Earth's
inherent magnetic field.
Motorized probes allow system scans in three dimensions by combining
data from tens of thousands of laser shots.
One advantage to using this setup is that the magnetic field and other parameters can be carefully varied and controlled.
If the dipole magnet is switched off, all signs of a magnetosphere
disappear.
When the magnetic field of the dipole is switched on, a magnetopause can
be detected, which is key evidence of the formation of a magnetosphere.
A magnetopause is the place in the magnetosphere where pressure from
the planetary magnetic field is exactly balanced by the solar wind. The experiments revealed that as the dipole magnetic field is increased,
the magnetopause gets larger and stronger.
The effect on the magnetopause was predicted by computer simulations,
which were carried out by the investigators to understand and validate
their experimental results more fully. These simulations will also
guide future experiments, including studies utilizing a cathode recently installed on the LAPD.
"The new cathode will enable faster plasma flows, which in turn will allow
us to study the bow shocks observed around many planets," Schaeffer said.
Other experiments will study magnetic reconnection, an important process
in Earth's magnetosphere in which magnetic fields annihilate to release tremendous energy.
========================================================================== Story Source: Materials provided by American_Institute_of_Physics. Note: Content may be edited for style and length.
========================================================================== Journal Reference:
1. D. B. Schaeffer, F. D. Cruz, R. S. Dorst, F. Cruz, P. V. Heuer,
C. G.
Constantin, P. Pribyl, C. Niemann, L. O. Silva,
A. Bhattacharjee. Laser- driven, ion-scale magnetospheres
in laboratory plasmas. I. Experimental platform and first
results. Physics of Plasmas, 2022; 29 (4): 042901 DOI:
10.1063/5.0084353 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220412141011.htm
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