The day before I returned to Canada, I took a day trip to Lausanne. Why? Well, a friend of a friend of a friend works in the physics department at the École Polytechnique Fédérale de Lausanne (EPFL) and offered to give me a tour! The opportunity to visit a physics lab is one I will never pass up, so I took the train to go see what type of research happens in Lausanne. | I could see Lake Geneva from the top of a hill near the train station in Lausanne. |
The École Polytechnique Fédérale de Lausanne is one of two Swiss Federal Institutes of Technology, the other being ETH Zurich (I saw the outside of ETH during my visit to Zürich last October). What makes these two universities special is that they are directly controlled by the Swiss federal government, while all other universities in Switzerland are controlled by their respective cantonal governments.*
The modern-day EPFL can trace its roots back to a private school under the name École spéciale de Lausanne, which was founded in 1853. In 1869, the school became the technical department of the public Académie de Lausanne, which became the University of Lausanne in 1890. In 1969, the department was separated from the rest of the university and became a federal institute under its current name.
The three main missions of EPFL are: education, research, and technology transfer at the highest international level. In pursuit of these missions, EPFL is organized into seven schools, with each school formed of institutes that group research units around common themes.
When I visited EPFL, I was at the School of Basic Sciences, which includes the Swiss Plasma Center. It is here that the TCV Tokamak resides.
*Instead of states, like the United States is divided into, European countries are typically divided into cantons. To explain the difference between states and cantons would take up quite a bit of room, so if you’re interested, see here for more detail.
A tokamak is a magnetic confinement device that is a leading candidate for a practical fusion reactor. Fusion? Like a bomb?? Yes and no. Though the words ‘fusion’ and ‘fission’ are associated with atomic bombs, fusion and fission are just terms for two different molecular reactions that release energy. These reactions can be used for a variety of applications—be that destructive bombs or clean (emission-free) energy—and the application depends on how large of a reaction takes place. Imagine people doing cannonballs into a pool. The five-year-old kid jumping into the water produces a much smaller wave than an adult, even though both actions are called ‘cannonballs.’ (For a scientific explanation on how the size of a reaction is determined, see here)
A leading contender for a stable fusion reactor design is the tokamak. A tokamak is a torus (doughnut) shaped device that uses a powerful magnetic field to contain hot plasma, which is the fourth state of matter (the others being solid, liquid, and gas). Tokamaks were designed in the 1950s by Soviet physicists, but it took until the 1970s for the design to become popular globally. This life-size scale model shows the layers inside the TCV Tokamak at EPFL. The plasma (center) is surrounded by various magnet systems to keep the plasma on track. |
Construction of the ITER complex started in 2013 and is expected to finish its construction phase in 2025. There are now seven member entities funding and running the project: the European Union, India, Japan, China, Russia, South Korea, and the United States. The TCV Tokamak. Only one person is allowed inside at a time to do repairs. |
The TCV Tokamak at EPFL is one of the five tokamaks currently funded under Horizon 2020. During my tour of EPFL, I learned that the EU had two reasons to discontinue funding for the majority of tokamaks: first, save money; second, increase collaboration. So far, both reasons have proved successful. There were scheduling challenges to accommodate the experiments from many more research groups on a single tokamak (especially since some of the five tokamaks are closed for upgrades), but my host explained that the increased collaboration has proven fruitful for research groups overall.
Of the five tokamaks, TCV conducts experiments over the shortest time interval. What does this mean? In a tokamak, fusion occurs when a current is sent through the plasma. However, the current makes the plasma susceptible to various instabilities that can disturb the plasma confinement. Because of this disruption to the confinement, the current cannot be run continuously and must be “pulsed” over short time intervals (though continuous operation is a future goal). The WEST tokamak has the record for longest pulse at 6.5 minutes; JET is about 40 seconds, and ASDEX Upgrade is about 10 seconds. The MAST tokamak was tied with TCV at about 1-2 seconds but can last about 5 seconds now after upgrades. When ITER is complete, it will have pulse durations of 400-600 seconds, or about 6-10 minutes.
For nuclear reactors, longer pulse durations (with a goal of continuous operation) is preferable for sustained energy production. For research, short pulse duration is fine. Most things vary on timescales of less than 1 second in plasma; after 10-20 seconds, there are very little changes in the behavior of the plasma. For scientists, this means they can learn almost everything they need to from short pulses durations.
Thank you, Tim and Alice, for giving me a tour of EPFL! :)
I plan to do a post on the projects I completed during my internship at CERN now that it is officially over. Keep your eyes peeled for that update, coming soon!