PPPL summer program empowers next generation of plasma scientists

July 9, 2007 12:11 p.m.
Greenland and Chlton

At left: Abbas Haider (left), a senior at South Brunswick (N.J.) High School, works with his lab partner, David Newby, a senior at Drew University, under the supervision of their mentor, staff scientist Jill Foley. Through close one-on-one interaction with their mentors, program participants rapidly gain insight into the fundamentals of plasma physics.

Silicon Wafer

The future of nuclear fusion and its promise of limitless, clean energy has arrived at the Princeton Plasma Physics Laboratory in the form of 28 budding scientists, many of them still in their teens.

This contingent of top-notch university and high school students from across the country has gathered for a summer of intensive lab work in plasma physics, the field that could someday provide a way to create power the way the sun does -- by pressing two uncommon forms of hydrogen together until they combine to form helium atoms, releasing a burst of energy in the process. Fusion energy, which does not produce greenhouse gases, has the potential to help mitigate global warming.

Because a practical fusion reactor may still be decades away, the current generation of fusion experts is already preparing to pass their nuclear torch on to the next, and the lab's research internship program aims to provide a smooth handoff.

"As a lab, just as at the University, we want to train the next generation of scientists," said Andrew Zwicker, head of the laboratory's science education program. "The point is to give them a real lab experience, with nothing canned, from the initial research to presenting the results at a national conference. We want to give them the most hands-on training we possibly can."

Haider, Newby and Foley

Providing this experience requires the joint commitment of a score of lab scientists, who mentor the students; Princeton University, which provides room and board; and the U.S. Department of Energy, which funds the internship program. This marks the 16th year that student groups have come to the lab for summer training, which Zwicker said is crucial to the future of the field.

"We track our students for up to eight years after they finish the program, and it turns out it makes a big difference in their career choices," he said. "We find that if we don't expose bright students to plasma physics when they are getting started, we lose them to other fields."

The university students arrived first for a week-long intensive introduction to the physics of plasmas. Even for physics majors, the 25-hour course is often their first exposure to the substances' inner workings.

"Undergraduate physics majors don't get plasma physics as a rule," Zwicker said. "So we give them a crash course in everything from the beginning to the most advanced topics. Then they have the theoretical background to work here for the summer."

Fridman and Hvasta

A plasma is simply a gas that has been heated to such high temperature that electrons whirling about each of its atoms escape their orbits, leaving behind positively-charged ions. This excited cloud has such unusual properties -- such as the abilities to conduct electricity and to respond to magnetic fields -- that scientists consider plasma to be a state of matter distinct from solids, liquids and gases.

It is within pressurized plasmas in the interior of the sun that natural nuclear fusion takes place, and recreating these distinctly un-Earthlike conditions will be necessary to create a working reactor. But plasmas are not so exotic as to be unrecognizable to the Earthbound observer: They form candle flames, they fill the interiors of fluorescent light bulbs, and they are mixed with the dust in the tails of comets.

In fact, though the lab's overarching mission is to develop a working fusion reactor, the need to understand the behavior of these ionized gases has led some scientists to explore plasma behavior in fields such as astrophysics. Mike Hvasta, a college senior who Zwicker is mentoring, said he was excited to spend his summer in Princeton with a dusty plasma chamber.

"Most of the universe is either empty void or plasma, and there's often dust there too," said Hvasta, a physics major at the College of New Jersey. "Learning about dusty plasmas helps us understand things like the rings of Saturn."

Hvasta, who intends to go on for an advanced degree in physics, said he grows more comfortable with his career choice as he spends time with the lab's state-of-the-art equipment.

"I'm having a great time with the responsibility Andrew has given me," he said. "Five days after I got here, he turned me loose and let me fix a key component of a machine that we use for experiments. It's rewarding knowing what we're doing will contribute to the scientific body of knowledge, and tinkering with these machines helps me to really learn about them."

Two weeks after the university students arrived, an additional 10 high schoolers joined them in the lab. Ruslan Fridman, Hvasta's lab partner, said that even after four days at the lab, he could tell the experience would be unlike anything he had done in high school.

"In school, you have a project and the teacher knows what's supposed to happen," said Fridman, now entering his senior year at New Jersey's Livingston High School. "Here, we have absolutely no idea what's supposed to happen, and we have to figure it out. Things happen all the time that defy logic."

Fridman and Hvasta will spend the next eight weeks figuring out the behavior of dusty plasma so they can make an original contribution to physics. They will have a chance to present their findings in November at the national conference of the American Physical Society, to be held this year in Orlando, Fla.

Kelly Greenland, who just finished her senior year at Lock Haven University of Pennsylvania, said she remains undecided about the specific topic she will pursue in graduate school, but that the summer program was giving her more perspective on her options.

"It's definitely helping," said Greenland, a physics major. "I love the hands-on aspect of my work here but I'm also very into theory, so I hope between this and graduate school it will help me decide which route I want to take."

Zwicker said the research process is rigorous, but the numbers show it gives students the background they need to continue in the field.

"Of the students who finish the summer program, about two-thirds go on to get an advanced degree in physics, math or engineering, and a fifth of those specialize in plasma physics," he said. "A third of those specialists over the past four years have been women, which is a fact we're particularly proud of, especially because in physics graduate programs overall, women constitute only about half that amount."

The program has also seen its share of students return to Princeton for further schooling. Joshua Kallman, who finished the summer program in 2005, is now in his second year of graduate school in plasma physics.  

"I wasn't sure at that point what subfield of physics I wanted to study, and my time here inspired me to choose plasma physics as my career path," Kallman said. "I like the connection to fusion, to creating power. But it's also because I liked the work. I had a really great mentor, and the experience has led me to a great lab here at the Forrestal Campus too."

Kallman is currently working with Leonid Zakharov, a principal research physicist at the laboratory, on issues concerning plasma when it is at equilibrium, and is growing interested in developing the lithium walls that might form a blanket to shield the reactor from hot plasma. He said he might like the opportunity to continue these investigations in his professional career.

"A lot of this sort of research goes on right here at the laboratory, and they have a machine here I'd like to work on," Kallman said. "I could definitely see myself here."