The jets of plasma that doctors might use, however, often become turbulent with the direction and velocity changing dramatically. Now, researchers have found this turbulence likely emerges from heat-induced sound waves generated at the plasma electrodes. This new insight is critical for more consistent and effective medical therapies.
Now that we understand where the induced turbulence in atmospheric pressure plasma jets is coming from, it may be possible to better control it, said Amanda Lietz of the University of Michigan, who is an author of a new report discussing these results, based on computer simulations, appearing as the cover article this week in the journal Applied Physics Letters.
A plasma is an ionized gas consisting of the positively charged ions and free-flowing electrons. They tend to be extremely hot, like those found in fusion devices. Non-equilibrium atmospheric pressure plasma jets, however, are cool to the touch.
In a typical medical device, atmospheric pressure plasma is made from a noble gas such as helium. An electric field ionizes the helium by removing an electron from each atom, creating a plasma thats not only at atmospheric pressure, but is also near room temperature.
The plasma flows through a handheld, pen-sized instrument and exits as a high-speed jet. The jet mixes with ambient air, which is filled with chemical species such as oxygen, nitrogen and water vapor molecules. The fast-movin...