Hot Job

Dan Barnak '10 enhances Dickinson's unique device

by Bill Sulon

December 8, 2009

Dan Barnak '10 (right) and Hans Pfister, chair of the Department of Physics & Astronomy, with the plasma Hall thruster Pfister built.

Dan Barnak ’10 likes fiddling with a two-million-degree plasma Hall thruster and strumming a cool one-string Whamola.

With regard to the former, the physics and mathematics double major is doing cutting-edge work with the plasma Hall thruster, located inside a vacuum chamber, which is surrounded by numerous blue electromagnets. The device was built a decade ago and is being tweaked regularly by Barnak’s advisor, Hans Pfister, associate professor of physics and chair of the Department of Physics & Astronomy. 

Barnak, who lives in Telford, a suburb of Philadelphia, spends more than 10 hours a week overseeing the work and data collection in the lab, which he and others call the “hottest thing” on campus.

The kind of plasma thruster that Pfister and Barnak work on is typically used to either keep satellites in proper orbit or serve as the propulsion unit for deep-space missions. Closer to home, plasma research has applications in the manufacturing of microprocessors, which we find in devices such as computers, cell phones, digital cameras and plasma televisions.

A plasma thruster accelerates ions by means of an electric field between a so-called ring anode and an electron-emitting cathode. The position of the ring anode greatly influences the performance of the thruster. To investigate the effect of the anode position one would normally have to build multiple thrusters with various anode positions and then test one after another, each time opening the vacuum chamber, replacing the thruster with the next version, and preparing the chamber for the next test firing—a painstaking and time-consuming procedure Pfister equates to changing engines in a car to measure different output levels.

Adjustable anode

Dickinson’s plasma thruster features one of Pfister’s ideas—an anode, whose location can be adjusted from outside the vacuum chamber, allowing students to measure various degrees of ion acceleration even while the thruster is in operation. Using Pfister’s analogy, there’s no need to park the car in the garage after each test, remove the old engine and install a new one before the next test. It is more like changing the engine while the engine is running.

“That’s one of the key features of our thruster,” said Barnak. “Here we can change the depth of the acceleration channel without interruption.”

Last year as a junior, Barnak presented details of the Dickinson plasma thruster at the annual meeting of the American Physical Society - Division of Plasma Physics in Dallas.

“Something like that—a junior making a presentation in that kind of forum—happens rarely,” Pfister said. “How many undergraduates in the United States even have the chance to work with a plasma thruster?”

Computer upgrade

Barnak recently enhanced the setup in the plasma lab by creating and installing a computer program that reads the pressure inside the vacuum chamber from a pressure gauge controller and stores the value alongside other data obtained from their plasma thruster. Previously, he and other student workers observed the gauge, wrote the pressure information on paper and later typed the data into a computer database.

As far as being the hottest thing on campus, the two-million degree exhaust plume of the plasma thruster is an estimate, give or take a couple of hundred thousand kelvins, based on analysis of the speed of the ions. By comparison the sun’s surface temperature is about 6,000 kelvins.

Barnak, who also works as a teacher’s assistant in the Department of Physics & Astronomy, plans to continue his plasma-thruster research in graduate school. Beyond that, he is considering a career as a professor or in private-industry plasma research.

In his limited spare time, Barnak enjoys playing the saxophone, drums—and Whamola, an instrument he designed and named after a song of the same title by Primus bassist Les Claypool.

The Whamola is an odd but not unexpected instrument for a physics major with innate curiosity, a musical ear and a desire to invent things. He built it using aluminum, steel, a lever, a guitar pickup wire coil and a double-bass G string.

Like the plasma thruster, the Whamola can be adjusted on the fly, generating a wide and fluid range of sounds. Barnak recently tried an “unplugged” performance on the Whamola during open-mic night at the Center for Sustainable Living (Treehouse), but didn’t generate the volume he believed was necessary to wow the crowd.

“I want to try it again, though the next time I’ll plug it into a guitar amp,” he said.