Using one of the greatest sources of radiation energy created by
man, University of Nevada, Reno researcher and faculty member Roberto
Mancini is studying ultra-high temperature and non-equilibrium plasmas
to mimic what happens to matter in accretion disks around black holes.
Physics department professor and chair Mancini has received a
$690,000 grant from the U.S. Department of Energy to continue his
research in high energy density plasma; plasmas are considered to be
the fourth state of matter. He will serve as principal investigator for
a project titled "Experiments and Modeling of Photo-ionized Plasmas at
Z."
Roberto Mancini stands next to the experiment chamber of the Nevada Terawatt Facility 2-terawatt Zebra accelerator, where researchers come to conduct high energy density plasma experiments.
"Receiving awards such as this exemplifies the academic caliber and
national importance of the work in our Physics Department," Jeff
Thompson, dean of the College of Science said. "We're proud of the team
of researchers here working on cutting-edge science."
Mancini has been studying the atomic and radiation properties of
high-energy density plasmas for more than 15 years, and this new grant
will allow him to further explore what happens to matter when it is
subjected to extreme conditions of temperature and radiation
– similar to what happens to many astrophysical objects in
the universe.
The research will enable astrophysicists to better understand what
happens around black holes and in active galactic nuclei. Scientists
will also better understand the application of high-energy density
plasmas to energy production, such as controlled nuclear fusion
(produced in the laboratory), and production of X-ray sources for a
variety of applications.
"Using theories and tools created here at the University to design
and analyze experiments, we then go to the only national facility that
has the capacity to deliver the high-intensity flux of X-rays required
to perform and measure these experiments," Mancini said. "We custom
build instrumentation in our machine shop that meets the high standard
set by the national facility so that it will fit onto the target
chamber of the pulsed-power Z-machine, enabling us to conduct this
unique experiment."
The pulsed-power machine at the Sandia National Laboratories in New
Mexico (similar in concept but larger than the University's Nevada
Terawatt Facility Zebra accelerator) is the most powerful source of
X-rays on earth, Mancini said.
"We subject a very small cell – a 1-inch by
½-inch cube – filled with a gas, such as neon, to
this tremendous, short burst of X-ray energy," he said. "It's about 10
nanoseconds of the most intense power on earth – creating
conditions of hundreds of thousands of degrees and millions of
atmospheres in pressure – in the form of X-rays."
The researchers can then compare their extensive computer modeling
and calculations with the measurements so they can study and explain
the extreme state of matter (plasma) created during those 10
nanoseconds, which mimics the majority of matter found throughout the
universe.
"We are using a unique imaging X-ray spectrometer to measure the
intensity distribution of radiation as a function of wavelength, which
tells us what happens with the plasma," Mancini said. From detailed
analysis of the data, Mancini can extract the plasma's density,
ionization and temperature.
He said the plasma reaches extreme conditions, very unlike the
low-energy plasma found in a neon light or a plasma television screen,
with light 1,000 times more energetic than visible light, temperature
as high as 100,000 degrees Fahrenheit, and ionization mainly driven by
the action of the X-ray flux going through the plasma.
The University of Nevada, Reno Physics Department has a team of
about 20 scientists, faculty and research associates working on a
variety of projects in the field of High Energy Density Plasma Physics
Research. Mancini emphasized that having strong research programs is
critical for the quality of education and training that the University
can provide to students.
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