Student Designs Research Probe

Physics major experiences success at Princeton Plasma Physics Lab

By: Becky St. Clair

A massive disc of hot dust (known to experts as an accretion disc) swirls around a black hole. Scientists are still learning about the phenomena that surround such discs.

During the summer of 2007, senior physics major Brandon Fetroe spent nine weeks studying at Princeton Plasma Physics Laboratory (PPPL). This experience at PPPL gave Fetroe the opportunity to work with a research group studying massive stellar objects (such as black holes or binary systems) and the orbiting matter that falls into them.

At the encouragement of his advisor, Fetroe had applied to the National Undergraduate Fellowship Program, a summer research program hosted by Princeton University and several other institutions such as MIT and UCLA that focuses on plasma science and fusion energy research.

“My advisor was very pleased with my performance,” Fetroe says, “and strongly encouraged me to apply to the program, offering to write a very positive letter of recommendation.”

He was accepted, and in June, Fetroe began his research and probe designing at PPPL.

The research team he was working with needed to find a way to study massive stellar objects, but “since you can’t just grab a star and put it in your lab for study,” says Fetroe, “they needed another source of plasma, and they had to make it spin.”

This is where Fetroe came in.

The team already had a source of plasma, but gave Fetroe the job of designing and building a probe to make the plasma spin. By combining specific voltages and an axial magnetic field, Fetroe found a way to make the plasma spin, therefore allowing the team to conduct their research.

As plasma is a hostile environment for almost all materials, Fetroe had to design the probe so that it would not do what is called “sputtering,” which refers to the ions in the plasma “slamming into my probe, causing tiny bits of metal to fly off and coat the quartz window, which would, to put it mildly, be bad,” explains Fetroe.

Though he would have liked to assist with the research following the creation of his probe, it took Fetroe the entire 9-week period of his time at PPPL to design and build the probe.

Since the probe’s creation, it has been used to verify the research team’s initial results from previous experiments. The team will soon move on to use the probe for the more technically challenging experiments for which it was designed.

As a result of his successful work at PPPL, Fetroe was given the opportunity to present his probe in the form of a poster at the annual American Physics Society and Department of Plasma Physics meeting in Orlando, Florida, in November 2007.

Following his graduation in June 2008, Fetroe plans to attend graduate school in either Northern California or on the East coast, possibly at Princeton. Where he will end up going will remain a mystery until March when he will hear back from the dozen or so schools to which he applied.

More anxiously, however, Fetroe happily awaits the end of June, when he will be wed to his fiancée, Rachel Dettwiler.

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