Determining How Plasma Spontaneously Develops a Localized Hot Spot That Radiates X-rays and Produces Related Dramatic Phenomena

This project will experimentally explore the eruptive behavior of a plasma, a gas of electrically charged ions and electrons, under conditions similar to those on the sun and in other astrophysical objects. This will be done by creating plasma jets in a vacuum chamber and observing how they can erupt by exhibiting sudden and dramatic dynamic behaviors mimicking the eruptive behaviors associated with solar flares, astrophysical gamma ray bursts, and X-rays from lightening.

The research program will build and use new diagnostic instruments that will measure the eruptive behavior and test the hypothesis that eruption results when an instability tries to interrupt the electric current in a plasma jet. The project will engage a local high school with a vast majority of students from under-represented minority groups to have students build a device that measures the concentration of atmospheric charged particles, thereby motivating interest in science and encouraging them to pursue careers in plasma physics or other science and engineering fields.

The research program will determine how a seemingly benign, cold, collisional plasma can suddenly erupt and generate a burst of energetic particles, extreme ultra-violet radiation, hard X-rays, and high-frequency waves. In doing so, it will contribute to the goals of NSF's "Windows on the Universe: The Era of Multi-Messenger Astrophysics" Big Idea. The knowledge and understanding to be gained will apply to many astrophysical and laboratory plasmas, such as solar flares, astrophysical gamma ray bursts, X-ray bursts from terrestrial lightning, and dense plasma foci devices.

The program will employ a well-diagnosed, reproducible laboratory device in which an initially cold plasma spontaneously erupts and generates these bursts. The details of the eruptive process have been partly established via high-speed imaging of visible light and extreme ultraviolet radiation, via X-ray measurements, and via whistler wave measurements.

New diagnostics will be constructed to measure previously unquantified aspects of the eruptive process such as rapid density depletion, rapid particle heating, and rapid development of strong localized electric and magnetic fields. These diagnostics will image highly localized reductions of density and increases of temperature associated with the eruption. These new measurements will be modeled using advanced analytic and numerical methods.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.