UNIVERSITY PARK, Pa. — According to Penn State NMR Facility Director Tapas Mal, the push to acquire a helium recovery system in the Chemistry Building began in 2019 with a global helium shortage dramatically driving up cost and squeezing supply to dangerously low levels.
Not only had prices roughly doubled that year (a trend that still continues), but the facility couldn’t secure on-time delivery of its required supply — potentially putting its instruments at risk of irreversible damage and bringing research to a standstill.
Nuclear magnetic resonance (NMR) spectrometers are used in a wide range of scientific fields to analyze molecular structures at the atomic level, and they rely on superconducting magnets, which require liquid helium to keep them cooled to -452 F (helium’s boiling point, 4.2 K, the lowest of all the elements).
If the magnets rise above this temperature, they will quench — abruptly losing their superconductivity — and may be permanently damaged.
Despite these instruments’ highly insulated design, the liquid helium within boils off unavoidably and continually, necessitating periodic top-offs to maintain the proper level; and the boil-off happens regardless of whether the instruments are in active use, so there is no scenario where top-offs are no longer needed.
“We always keep a note of what the liquid helium level is so we know when to top off the magnet,” Mal said. “If the liquid helium drops even a little bit below the minimum level and the magnet quenches, we may not be able to bring that magnet back to its superconducting state.”
Designing a solution
Mal recalled how amid the helium shortage his colleague Carsten Krebs, professor of chemistry and of biochemistry and molecular biology, told him about a new National Institutes of Health (NIH) grant program offering up to $250,000 for the purchase of helium recovery systems, which capture gaseous helium boil-off and return it to a liquid state for reuse.
Given the circumstances, Mal said he figured the facility’s best option would be to invest in such a system — which they were able to do thanks to one of those same NIH awards of $250,000 to Associate Professor of Chemistry Amie Boal, plus around $150,000 from the Dean’s Office, the Department of Chemistry, and the facility’s users.
With a team of Penn State engineers, Mal, NMR Spectroscopist Christy George, and Facilities Representative Larry Johns designed a system that would recover the liquid helium boil-off from not only the NMR Facility’s nine instruments in the basement of the Chemistry Building but also five more instruments on the building’s third floor.
“We had to plan all that plumbing — from the basement to the third floor and back down — and build in safeguards and backflow preventers so that if a particular instrument went down, it wouldn’t destroy the entire system,” Johns explained.
George, who had just recently joined the NMR Facility, designed the manifolds connecting 11 of the building’s 14 spectrometers — nine NMR instruments and two Mössbauer spectrometers — to the helium recovery system; the remaining manifolds, for three electron paramagnetic resonance (EPR) spectrometers, were designed by Alexey Silakov, assistant professor of chemistry.
“We used a software application called Autodesk Inventor that allowed us to design the parts virtually, connect them together, and see whether they would work,” George explained. “So everything could be preplanned based on those designs.”
Johns and the engineers then integrated George’s and Silakov’s manifold designs into the system, which was completed in early October.