It’s safe to say that without the Sun life would not exist on Earth and this fact was known even during ancient times when the Sun was worshiped as a God. Over the years scientific advances allowed us to learn more about the Sun and we figured out that it was a Star and like all stars made up mostly of Hydrogen and other gases. However the temperature there is so hot that most of the gas actually exists as plasma, the fourth state of matter. (This is not the same Plasma as what’s in our blood) To recap, the first state of matter is a Solid, when that is heated it will convert to Liquid state and then to gaseous state. When gas is superheated atoms break apart into charged particles turning it into plasma.
Even though we can see the sun there are a lot of mysteries about how things work in it. For example, we know that Sun has a magnetic field that we think is generated because of the spinning Plasma and this along with the temperature of the plasma creates charged particles that can escape from the Sun’s gravity, which is called Solar Wind and is of great interest because so far, we didn’t know exactly how/why these plasmas escape the sun’s magnetic fields. There are efforts ongoing to directly study the phenomenon directly, for example we have the Parker Solar Probe which was launched in August 2018 which is expected to reach and even dip below the Alfvén surface (The point some distance from the sun’s surface, where the magnetic field weakens and plasma breaks away from the sun) but that is expensive and not always available. Plus we can only observer a limited area at a time due to the sheer size of Space.
So scientists set about trying to recreate the plasma layer & magnetic field in a lab and a research team from University of Wisconsin, Madison has achieved this goal by creating a 3-meter-wide plasma containment chamber called the “Big Red Ballâ€. In it they placed a permanent magnet about 10 centimeters wide and 10 centimeters long and filled the ball with a plasma made from helium gas and drove an electrical current through it. This created a force on the plasma that made it spin around the dipole. Using this technique, the team was able to successfully re-create the shape of the Parker spiral, as they describe in a paper published today in Nature Physics. With their mini-sun in place, the researchers can take measurements at many points inside the ball, allowing them to study solar phenomena in three dimensions. While this is not a perfect recreation of the sun, it is a significant advancement and will give us a greater understanding of how/why the sun works the way it does.
The experiment was also able to mimic a region around the sun where the plasma hangs in a precarious balance. Within this boundary, plasma’s are contained by magnetic fields, but outside it, centrifugal forces from the sun’s rotation overpower the magnetic fields, and plasmas stream outward. The researchers found that “if you spin [the plasma] hard enough, you can get it to spin out from centrifugal force,†Peterson said. The team believes that the plasma blobs they generated are analogous to those in space that fuel the sun’s slow solar wind.
Some aspects of the model, like the density of the plasma and its proportion of charged and neutral particles, don’t reflect the composition of the real sun’s corona and solar wind. But the experiment is still informative, said Aleida Higginson, a solar physicist at the Johns Hopkins University Applied Physics Laboratory who works on simulations of the solar wind and was not involved in the study. “We’re talking about lab conditions on Earth versus the sun, so there are obviously going to be some differences. I’m still impressed,†she said. “If they really did get reconnection, and got blobs, I think that’s really cool and promising.â€
Overall this is very cool, and I am looking forward to more advances in this area.
Source: Sun’s Puzzling Plasma Recreated in a Laboratory
– Suramya