This week at the lab, scientists from across North America are learning the theory and practice of radio frequency (RF) coils.
RF coils are used in magnetic resonance imaging (MRI) to transmit and receive RF signals. The MagLab’s Advanced Magnetic Resonance Imaging and Spectroscopy (AMRIS) Facility at the University of Florida has an entire lab devoted to RF coil manufacture and development, led by RF engineer Malathy Elumalai.
In response to a growing need for visiting scientists to be able to troubleshoot and design their own RF coils, Elumalai is sharing her expertise at this week’s inaugural coil workshop. Empowering scientists to make their own coils makes sense. The demand for specialized coils has outpaced the rate at which Elumalai can design them. Additionally, sometimes the coils break, causing an experiment to come to a halt.
Throughout this week’s workshop, participants will learn the physics behind RF coils and be trained in specialized software for designing and modeling how the coils will behave under different magnetic fields and with different samples. Participants also have the chance to build their own coil and test it in the MagLab’s 4.7 tesla imaging magnet.
How do RF coils in MRI machines work? First, the coil transmits an RF signal, which produces a magnetic field perpendicular to the one already being produced by the magnet. Then, the same RF coil (or a separate one) receives signals indicating how the nuclear spins inside the subject are relaxing. This information is then processed as an image. Without RF coils, there’d be no "I" (imaging) in MRI!
The workshop is an example of the ongoing training we offer our "users" so that they can make the most of their time with our magnets. The MagLab also offers a User Summer School and a Theory Winter School once a year.
Text and image by Elizabeth Webb.
This week at the lab, a prosaic-looking box is being prepared to assume a very exciting job this summer as a key component to a scientific time machine.
Although researchers won't be able to use the approximately 4-foot-high box to travel to other eras, they will use it to get a tantalizing glimpse of science in the future.
Delivered to the lab last week from Switzerland, the "box" is in fact a one-of-a-kind console specifically designed and built by Bruker Corp. for a new, one-of-a-kind instrument, the MagLab's 36 tesla series connected hybrid (SCH) magnet. Due to come online in a few months, the SCH will offer the highest magnetic fields in the world for nuclear magnetic resonance (NMR) research. With an operating frequency of 1.5 gigahertz, it will be one and a half times stronger than any other NMR magnet, said Ilya Litvak, who is coordinating the NMR instrumentation for the new magnet.
The MagLab already has numerous magnets for NMR, used to study the structure of molecules by interacting with the nuclei of atoms such as hydrogen, nitrogen and carbon. What's special about the new magnet is that, operating at 1.5 gigahertz, it will allow scientists to efficiently target so-called "low-gamma" nuclei such as oxygen, which are too hard to see at conventional NMR field strengths, opening up a whole new frontier for scientific exploration.
"In the two areas where structure is important, biological research and materials, you have a lot of oxygen," said Litvak. "Currently, scientists cannot use oxygen in NMR efficiently."
A Bruker engineer is testing the new console with another magnet while construction on the SCH magnet is completed. In NMR experiments, the console receives and records the signals sent to it by the probe, which holds the sample inside the magnet.
Text by Kristen Coyne, photo by Stephen Bilenky.
This week at the lab, engineers are fine-tuning a new magnet that will offer scientists a novel way to do nuclear magnetic resonance (NMR).
The magnet, along with a new cabinet and console, comprise the lab’s new 600 MHz spectrometer, which will be used for a new measurement technique with a very long name: magic angle spinning dynamic nuclear polarization. MAS DNP, as it is more reasonably called, gives scientists deciphering the structure of molecules a clearer picture of what they are looking at.
The 2,000-pound Bruker superconducting magnet was installed earlier this month, connected to cryogen and a power supplies, and ramped up to full field, 14.1 teslas. A special feature of the instrument is a second, small, "sweepable" magnet coil that allows scientists to fine-tune the field and frequency of the instrument.
In NMR spectroscopy, scientists put the material they are studying – let’s say a protein – inside the magnet, then direct radio waves of a specific frequency at it. These in turn send back signals identifying certain atoms, thus helping scientists piece together the sample’s structure. In the MAS DNP technique, a solvent containing free radicals is added to the sample. When irradiated with microwaves, the result is much stronger NMR signals and thus a clearer idea of the material’s structure.
This new setup, located in the MagLab’s Nuclear Magnetic Resonance and Magnetic Resonance Imaging / Spectroscopy Facility, is among just a few in the world and the only one open to outside scientists, said Thierry Dubroca, a MagLab physicist who has helped develop the capability. The new system will be available to scientists in early 2016. Scientists interested in using MAS DNP should contact Thierry Dubroca, Zhehong Gan, Ivan Hung, Joanna Long.
Video by Stephen Bilenky / Text by Kristen Coyne
Inspired by the SIM card technology used in modern cell phones, MagLab engineers designed and built a versatile magnet probe that makes it easier and more efficient for scientists to see the structure of molecules.
Andreas Neubauer took the extended stay option during his recent trip to the MagLab. After all, you can't rush art — especially when it's mixed with science.
An overpressure furnace capable of developing high current density in significant-sized coils (up to 15 cm diameter and 50 cm long) has been brought into commission. The furnace is enabling reaction of solenoids made out of Bi-2212 destined for tests of NMR quality magnets at proton frequencies greater than 1 GHz.