Donald “Bruce” Montgomery SM ’57, a highly influential engineer and longtime MIT researcher whose career centered around the development of large-scale electromagnets, died on July 1. He was 89 years old.
Montgomery’s contributions have been essential for many major installations in the field of fusion energy, in the design of magnets for particle accelerators for physics and medical applications, for transport by magnetic levitation and in many other disciplines. He was a recognized international leader in magnet design and fusion engineering, a Fellow of the National Academy of Engineering, and the recipient of numerous awards, including the Dawson Prize for Excellence in Plasma Physics Research (1983) and the Fusion Power Associates Distinguished Career Award (1998). ).
Montgomery earned a BA from Williams College and an MS from MIT in the Department of Electrical Engineering in 1957. In 1967 he earned an ScD from the University of Lausanne.
After graduating from MIT, he joined the staff of MIT Lincoln Laboratory and shortly thereafter began work on high-field magnets under Francis Bitter, famous magnet designer and founder of the National Magnet Laboratory at MIT. Montgomery became associate director of what was later renamed the Francis Bitter National Magnet Laboratory. During this period he authored the book “Solenoid Magnet Design: The Magnetic and Mechanical Aspects of Resistive and Superconducting Magnets”, which remains a standard reference.
A turning point towards fusion
Montgomery’s expertise was then harnessed in a burgeoning fusion energy program. Following the measurement of plasma temperatures exceeding 10 million degrees in the Soviet T3 tokamak, a race was launched to build ever more efficient magnetic confinement experiments. Working with Bruno Coppi of MIT’s Department of Physics and Ron Parker of Electrical Engineering, Montgomery led a team that designed and built two tokamak devices capable of operating with magnetic fields up to 12 Tesla and still exceeding today, an unprecedented magnetic field for fusion research. The initial device, known as Alcator A, set a world record for the key plasma confinement metric. The follow-up device, Alcator C, extended this record into the 1980s and provided assurance that sufficient plasma conditions for a fusion power plant could indeed be achieved.
The record-breaking performance of both devices was made possible through the use of revolutionary magnet technology developed with Montgomery’s insight and leadership. A straight line can be drawn between these early breakthroughs in magnet technology and the resulting scientific advancements for the evolution of magnet technology used in SPARC, a demonstration fusion device led by MIT and the start-up. up Commonwealth Fusion Systems which is designed to produce more energy than it consumes.
Montgomery also had a well-recognized ability to manage very large projects and lead diverse groups of scientists, engineers, technicians, and students. As a result, he was appointed chief engineer on several national fusion system construction projects and played a leading role in the early days of the international fusion project known as ITER. In the 1990s, he led one of three national consortia teams vying to develop maglev technology under the US Department of Transportation’s Maglev Initiative.
Creation of a revolutionary cable
At the National Magnet Lab, Montgomery, Henry Kolm, and Mitch Hoenig invented the cable-in-conduit (CICC) concept. In the early days of large-scale superconducting magnet research, large-diameter, high-field superconducting magnets were constructed using a type of brute-force method. These older designs were unstable and unsuited to the need for ever higher magnetic fields, and larger sizes increase the performance of magnetic confinement fusion machines. This technology was hampering progress, especially for the tokamak’s poloidal field magnets which had to provide rapidly changing fields.
Montgomery, Kolm, and Hoenig solved these problems by combining many superconducting wires into a cable, using standard industrial equipment, and then placing the cable inside a steel or other alloy tube (conduit) high strength metal. The magnet was cooled and maintained at 4K by circulating supercritical helium through the conduit. Since each conductor could be insulated against high voltages, large bore, high field and high storage magnetic energy magnets could be safely protected against quenching. The solid metal alloy conduit provided high mechanical strength optimally distributed over the entire cross-section of the winding. And the circulating helium provided excellent heat transfer from all the superconducting wires in the cable, resulting in very high electrothermal stability, especially for the fast-ramp magnets.
Although the CICC concept was deemed heretical within the international applied superconductivity community and dismissed as impractical, under Montgomery’s leadership the MIT group quickly developed and proved the concept. Today, all functional fusion devices in the world that use superconducting magnets use this conductor, including tokamaks (e.g., EAST, KSTAR, JT60-SA), helical machines (LHD), and stellarators (Wendelstein 7-X). It is the basic driver design for ITER and has found application in particle accelerators and magnetic levitation.
Explore magnetic levitation and propulsion
In the 1970s, Montgomery and Kolm of the Francis Bitter Magnet Laboratory collaborated with Richard Thornton of MIT’s Department of Electrical Engineering to formulate the concept of the “magplane” of magnetic levitation and propulsion. A first demonstration of a model-scale device was built and tested on the sports grounds of MIT. Montgomery and Henry Kolm went on to found Magplane Technology, Inc. (MTI), a small company focused on developing advanced magnetic levitation and propulsion applications. A working version of this technology was built in China, where it was used to deliver coal from coal mines, avoiding excessive coal dust and resulting waste from open trucking vehicles. In the 1980s, Montgomery worked with Peter Marston and Mitch Hoenig, leading an MIT team developing very large-scale superconducting magnets for magnetohydrodynamic electrical power generation.
Engineers and scientists know that failure can be the best instructor. Montgomery took this lesson to heart, diagnosing failure mechanisms in large magnet systems and authoring several meta-studies that analyzed and tabulated the underlying causes. This work allowed engineers to focus on the most critical aspects of their designs and contributed to the increasing reliability of research magnets. After retiring from MIT in 1996, Montgomery was the founder and president of MTECHNOLOGY Inc., an engineering consulting firm specializing in risk and reliability.
An engineer’s engineer
Joe Minervini, one of Montgomery’s proteges, notes, “Bruce was considered by me and most people who knew him to be an ‘engineering engineer.’ Although he always possessed a deep scientific understanding of the technological problem he was tackling, he always seemed to formulate a brilliant yet practical engineering solution. During his long career at MIT, he repeatedly demonstrated many of the most advanced and exciting new technologies built around conventional and superconducting magnets.
Beyond the breadth of his technical contributions and committed mentorship, Bruce Montgomery will be remembered for his warm personality and calm, steady demeanor, which was invaluable when the going got tough – a common occurrence. when pushing the boundaries of research. He had a unique ability to take control of contentious technical and management discussions and gently pull or nudge everyone towards effective consensus and action. He will be greatly missed by his friends, family and colleagues.
Montgomery is predeceased by his wife of 52 years, Nancy Ford Fenn, who died in 2006, and by Elizabeth Bartlett Sturges, with whom he spent many happy years until his death in 2021. He is survived by his son Timothy Montgomery and his wife Susan of Scituate, Massachusetts; his daughter Melissa Sweeny and her husband Tom of Groton, Massachusetts; as well as his grandchildren, Jenna Sweeny, Christopher Sweeny and Benjamin Sweeny.