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“A bet became unavoidable”

The terms of a wager between two prominent plasma physicists drawn on a napkin 34 years ago were fulfilled last week when Robert Goldston, a former director of the U.S. Department of Energy’s Princeton Plasma Physics Laboratory, presented a plaque to his friend Jean Jacquinot, former director of the Joint European Torus (JET), EUROfusion's flagship fusion experiment.

The plaque honored the record-breaking achievements of JET in 2021. But instead of delivering hundreds of Happy Meals across Europe, the wager was amended to support refugees from Ukraine.

Goldston and Jacquinot recalled the story of the wager and its final denouement at the opening day of the 48th European Physical Society Division of Plasma Physics (EPS-DPP) meeting, which was held virtually from June 27 to July 1. You can view the video with the two physicists here.

Video interview about the fusion wager with Rob Goldston (L) and Jean Jacquinot (R). Credit: PPPL

Conference dinner

It was at another EPS-DPP conference in 1988 that the two men made their bet on a grassy hill overlooking the medieval city of Dubrovnik in what was then Yugoslavia and is now Croatia. The conference featured papers by PPPL and JET physicists predicting the success of their two experiments in deuterium-tritium (DT) operations on JET and PPPL’s Tokamak Fusion Test Reactor (TFTR). The wager was made at the conference dinner as they consumed “a fair bit of good wine,” according to Goldston, and the rest was history.

“The big-debated question was which machine would succeed first,” Jacquinot recalled in the 11-minute the video shown at the conference. “We were both convinced that we had a good chance to do it, and obviously a bet became unavoidable.”

Goldston, then head of physics for the TFTR, and Jacquinot, then head of the radio frequency division of JET, each bet that their experiment would be the first to achieve 10 million watts or megawatts of fusion power, sustained for over one second.

TFTR, which operated from 1982 to 1997, became the first fusion experiment in the world to achieve 10.7 million watts of fusion power, using the mixture of D-T, in 1994. That achievement has opened the door in the quest to develop fusion energy as a clean, green and plentiful source of electricity.

However, TFTR did not sustain this burst of energy for over one second, as the wager had stipulated. In 2021, JET, which also used D-T fuel, achieved a world record for fusion energy production of 59 megajoules in a single shot, more than two-and-a-half times JET’s previous record set in 1997.

The terms of the bet were that if TFTR won, Jacquinot, who is French, would provide a French dinner to the full TFTR team. Since the JET team was considerably bigger, Goldston offered to supply McDonald’s burgers to the JET staff it its tokamak won.

Goldston said he walked over to PPPL director Harold Furth’s table to run the bet by him, since the bet could be perceived as an official Lab commitment. Furth told him, “Rob, do any damn thing you want,” thereby both giving Goldston permission and denying any responsibility in the same sentence. Jacquinot said he did not dare go to Paul-Henri Rebut, then the JET director, since he feared Rebut would raise the conditions even further.

Jacquinot later became the director of JET and is currently a scientific advisor to the French High Commissioner for Atomic Energy and senior advisor to the ITER director-general. Goldston, a professor in the Princeton University Astrophysics and Astronomy Department since 1982, was director of PPPL from 1997 to 2008.


Jacquinot lost the napkin with the conditions of the deal, signed by Goldston, Jacquinot and witnesses. But when Goldston reminded him of the bet, there was no disagreement about the conditions, including the one-second duration requirement.

When Goldston looked into the cost of providing McDonalds dinners to the entire JET team of 1,000 people, he found the tab would be about $10,000. Goldston was skeptical that sending burgers all over Europe would be truly appreciated. He proposed instead to donate the $10,000 to the International Rescue Committee to benefit refugees from Ukraine. This idea was applauded by Jacquinot. They noted that the Kharkiv Institute of Physics and Technology was bombed by Russian forces in March and remembered a similarly-enjoyable EPS-DPP dinner in Kyiv.

Goldston said he would have liked to sample some French cuisine, which would have happened if the bet had been kept to achieving 10 megawatts of fusion power. “I was sort of thinking that would make it a fair fight,” Goldston said in an interview. “I wonder if Jean would have taken the bet just for 10MW, with no condition on how long? I can all but taste the French dinner!”


Plaque to recognize the JET team’s 2021 accomplishment of over 10 MW of fusion power production for a continuous period of over one second, fulfilling the conditions of a wager between Drs. Jean Jacquinot and Rob Goldston at the 1988 European Physical Society Division of Plasma Physics Conference in Dubrovnik. Credit: PPPL

In the video, Goldston presented Jacquinot and the JET team with a plaque produced at PPPL that will be hung in the JET lobby. It includes a graph of the bet-winning shot. The plaque reads, “In recognition of the JET team’s accomplishment of over 10 MW of fusion power production for a continuous period of over one second fulfilling the conditions of a wager between Drs. Jean Jacquinot and Robert Goldston at the 1988 European Physical Society Division of Plasma Physics Conference in Dubrovnik, Croatia.”

“I would like to praise the spirit of international cooperation and fair competition, which continues to be present in our field, and which has a good part of responsibility for the good progress that we have made,” Jacquinot said. “It is really a wonderful hallmark of the fusion program,” Goldston agreed.

About PPPL

PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit

About EUROfusion

The EUROfusion consortium coordinates experts, students and facilities from across Europe to realise fusion energy in accordance with the EUROfusion fusion roadmap. EUROfusion is co-funded via the Euratom Research and Training Programme.

The EUROfusion programme is preparing for experiments at the international ITER project and developing concepts for the European demonstration fusion power plant DEMO. The programme supports fusion education and training, and works with companies to develop the European fusion industry.

Plasma shot in the US tokamak TFTR (Tokamak Fusion Test Reactor). Credit: PPPL
Fusion shot in the JET tokamak, setting a world fusion energy record of 59 megajoules of fusion heat. Source: EUROfusion Consortium
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