Plasma Pulses Student to the Top

You might not think that a squadron commander in the Air Force ROTC, who investigated water quality issues in Sri Lanka, published a paper about the issues, created a solar-powered water purification system, co-founded Students on Capitol Hill, and was president of the leadership honors society, Omicron Delta Kappa, would have time for nuclear fusion. But, Michael Sherburne, a just-graduated student of the Bradley Department of Electrical and Computer Engineering at Virginia Tech, did just that. 

The attempt at fusion was his capstone project, and for his efforts there and elsewhere he was named the 2018 Outstanding Senior for the College of Engineering.

“In about three and a half months of work we were able to achieve a plasma and a full working control system,” says Sherburne. “We were pulsing over 90,000 amps and we were doing 36,000 volts for our max pulses.”

Sherburne and his fellow students built their dense plasma focus on the cheap, which was, in a way, the purpose of the project. “We were able to put together a bunch of items in a cheap manner and do this as undergrads,” he says. Some of those items included “power resistors we found in someone’s attic.” He describes the setup as something like a gatling gun: “You ignite a little plasma in the back of it,” he explains. “As the plasma propagates forward it will look like a jellyfish. It will go back in on itself at the end and then implode, which will cause nuclear fusion.” 

Or will likely cause nuclear fusion. Whenever they ran the system, things around the lab tended to shut down. “In terms of figuring out if fusion was occurring, it’s kind of inconclusive because every time we fired it, our nuclear diagnostics turned off on us because of the intense current.” Those diagnostics were a moderator box which was supposed to slow the neutron flux down enough to radiate a silver foil. This then, could be measured. In theory, they could have tweaked it and eventually found out if fusion had been achieved. “But by the time we got everything firing it was the last week of testing we could do,” says Sherburne. With the deadline for the project three days away, one of the resistors blew up and took a few other components along with it. But thanks to express shipping they were able to complete the project on time. 

Sherburne’s chief contribution was the control system. With 90,000 amps, wireless is not a viable option due to strong electromagnetic pulses that can corrupt wireless communication. Nor is cable which can send currents back toward the people at the control end. So Sherburne used fiber optics. With a USB cable from a computer and an Arduino, he was able to keep costs down so “if something blows up we didn’t lose a lot of money.”

Competing against nearly 50 teams, the project won the most innovative and creative project award at the capstone project fair.

Professors in the department plan to keep the dense plasma focus system around for future students to tinker with. One idea is to combine it with a rail gun that is shot into a vacuum chamber. “Have the plasma focus somewhere else in the chamber firing, and see how certain phenomenon occur.” 

Sherburne likes to emphasize that none of his work was done in a vacuum, as it were. “It was a team effort,” he says. “It’s not just about me.”

Michael Abrams is a technology writer based in New Jersey.