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These top-notch magnets require a top-notch infrastructure. So later this year, lab staff will install a new heat exchanger to keep up with the demands of its boundary-pushing instruments.
"We're trying to upgrade everything as the lab upgrades," explained plant engineer Tra Hunter. "The magnets are getting bigger and requiring more cooling water."
Magnets in the lab's DC Field Facility are powered by as much as 32 megawatts (MW) of electricity each and generate the heat to match. A complex array of pipes, chillers, heat exchangers, chilled water storage tanks and cooling towers keeps the instruments from overheating by flushing them with thousands of gallons of cold, de-ionized water a minute.
The new 35,000-pound heat exchanger features a stack of nearly 600 8x4-feet stainless steel plates. Warm water from the magnets flows in through one pipe and zigzags through alternating plates; chilled water flows in another pipe, snaking its way through the second set of plates. The cooled water picks up heat from the magnet water and carries it away.
"It's basically transferring 36 MW of heat from the magnet cooling water loop and transferring that to the chilled water loop," Hunter explained.
The $130,000 instrument is one of several end-of-year upgrades to the chilling system that will also include larger pipes and new water filters. It will help the plant run more efficiently and, as one of two similar units, and help ensure chilled water for the more than 1,700 users who come to perform research on the lab’s world–record magnets each year.
Story by Kristen Coyne. Photo by Stephen Bilenky.
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The National MagLab is known for its world-record magnets, like the 45-tesla hybrid magnet — the strongest on the planet.
But for some physics experiments, there’s another critical ingredient to good results: extremely cold temperatures. And thanks to a fancy cooling machine called the portable dilution refrigerator (dil fridge, or PDF, for short), the National MagLab is able to offer a potent combination of experimental conditions unique in the world.
This month, the PDF is set up in one of our magnets, allowing scientists to observe what happens to materials when they are under magnetic fields as high as 35 teslas and at temperatures just above absolute zero (-459 degrees Fahrenheit or -273 degrees Celsius).
Leveraging the cooling power of liquid helium, the PDF removes thermal energy from the materials the researchers are studying. “This allows scientists to see the physical properties of materials, such as quantized energy states and quantum phase transitions,” said MagLab physicist Hongwoo Baek, who is in charge of the apparatus.
“If you add magnetic fields,” Baek continued, “you will also see magnetic properties, such as magnetic phase transitions, and other detailed electronic features that are not normally shown at zero field, that can be utilized in future electronics and applications.”
The National MagLab is the only place scientists can throw that one-two punch of very high fields and very low temperatures.
“Many institutes have 20-millikelvin dilution refrigerators, and some have 35-tesla magnets,” said Baek, “but none of them can provide the experimental platform with 20 millikelvin and 35- to 45-tesla magnet together.”
The MagLab system offers another big bonus: it can rotate samples within the magnetic field without generating much heat, allowing the sample to align to the magnetic field and stay nice and cold.
Over the next few weeks, research groups from Rice University, Princeton University, Northwestern University, the University of Cambridge and the MagLab will conduct experiments in this unique setup, studying phenomena ranging from the fractional quantum Hall states to exotic magnetic phase transitions of various materials.
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Text by Kristen Coyne. Photo by Stephen Bilenky.
Game-changing technology may hold the key to ever-stronger magnets needed by scientists.
Combining tremendous strength with a high-quality field, the MagLab’s newest instrument promises big advances in interdisciplinary research.