# A Benchtop Cryogen-Free 23.5-T/25-mm-RT-Bore Magnet for 1-GHz microcoil NMR Spectroscopy

> **NIH NIH R01** · MASSACHUSETTS INSTITUTE OF TECHNOLOGY · 2022 · $394,532

## Abstract

Project Summary
In this project we propose to develop a benchtop cryogen-free 23.5-T high-temperature superconducting (HTS)
magnet for 1-GHz microcoil nuclear magnetic resonance (NMR) spectroscopy. Higher-field magnet offers better
resolution and sensitivity, enabling analysis of larger molecules like complex proteins, however currently
available ≥1-GHz NMR magnets are very expensive and require a vast installation site, limiting ≥1-GHz NMR
spectroscopy to a few labs in the world. A benchtop microcoil NMR magnet by definition is compact and thus its
cost will be less by nearly an order of magnitude than that of the standard NMR magnet, and placeable on a
workbench. Also, LHe-free operation enables the user to be independent from a cooling source in short supply.
As a preliminary work (R21GM129688), we have completed a 12.5-mm-cold-bore HTS REBCO magnet
prototype and successfully operated it up to 25 T at 10 K cooled by a cryocooler only, without liquid helium,
verifying our high-field REBCO magnet design with the proposed screening-current reduction method. Based on
these preliminary results and pioneering design concept, we will first design and build a cryogen-free, shielded
all-REBCO 23.5-T/25-mm-RT-bore magnet having a 5-gauss fringe field radius of 1.5 m, and then convert this
non-NMR-field 23.5-T magnet to a benchtop 1-GHz microcoil NMR magnet having a high homogeneity of <0.1
ppm over a 5-mm-diameter, 10-mm-length cylindrical volume. We also intend to use an in-house built NMR
probe to demonstrate the proposed magnet. This benchtop magnet will incorporate all the innovative design and
operation concepts validated by the prototype magnet in our preliminary R21 program: 1) all-HTS composition
and operation at above 4.2 K cooled only by a cryocooler, the first ever >4.2-K operation among all ultra-high-
field superconducting magnets; 2) extremely-thin-copper-layered no-Insulation winding technique that makes a
REBCO magnet very compact, mechanically robust, and self-protecting; 3) a single coil formation that leads,
compared with the traditional multi-nested high-field NMR magnet, to simpler and more affordable manufacturing
processes; 4) operational temperature-controlled screening-current reduction method which reduces peak
stresses within the REBCO coil and field errors; and 5) cryogenic design for conduction-cooling operation. We
intend to adopt a passive shielding by using iron to reduce the 5-gauss radius within 1.5 m. To achieve a target
field homogeneity, we will adopt three—superconducting, ferromagnetic, and room-temperature—shimming
technique which will be complemented by our 1.3-GHz/54-mm high-resolution NMR magnet, currently under
development at the FBML, for which we are developing innovative field-shimming techniques. We envision this
benchtop cryogen-free 1-GHz microcoil NMR magnet will become a very powerful and affordable research tool
for the NMR based structural biology community who eagerly anticipates higher operating fr...

## Key facts

- **NIH application ID:** 10503243
- **Project number:** 1R01GM147794-01
- **Recipient organization:** MASSACHUSETTS INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** Dongkeun Park
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $394,532
- **Award type:** 1
- **Project period:** 2022-09-23 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10503243

## Citation

> US National Institutes of Health, RePORTER application 10503243, A Benchtop Cryogen-Free 23.5-T/25-mm-RT-Bore Magnet for 1-GHz microcoil NMR Spectroscopy (1R01GM147794-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10503243. Licensed CC0.

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