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  • Cryolines | Another day, another spool

    Having wedged his body and equipment into the cramped space between the ceiling and the massive pipe, a worker is busy welding two cryolines spools. A few metre [...]

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  • Image of the week | Bearings unveiled

    The construction teams are in the last stages of preparing the Tokamak pit for the first major operation of ITER machine assembly: the lowering of the cryostat [...]

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  • Technology | Perfecting tritium breeding for DEMO and beyond

    While ITER will never breed tritium for its own consumption, it will test breeding blanket concepts—the tools and techniques that designers of future DEMO react [...]

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  • Fusion world | Japan and Europe complete the assembly of JT-60SA

    The JT-60SA fusion experiment in Naka, Japan, is designed to explore advanced plasma physics in support of the operation of ITER and next-phase devices. After s [...]

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  • Manufacturing | Thermal shield milestone in Korea

    Six years after the start of fabrication, Korean contractor SFA has completed the last 40° sector of vacuum vessel thermal shield. The stainless steel panels, c [...]

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Of Interest

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The story of a JET pulse

Culham Centre for Fusion Energy (CCFE)

JET came to life with the first plasma on 25 June 1983. Here is a view of the the JET Diagnostic Hall, which was turned into a temporary control room for the occasion. JET's director Paul Rebut is seen here discussing with Michel Huguet, who was to head the ITER Joint Work Site (JWS) at Naka. Leaning on the railing, is Juergen Dietz, who was head of In-Vessel Division at the Garching ITER JWS in the early years of the ITER Engineering Design Activities. (Click to view larger version...)
JET came to life with the first plasma on 25 June 1983. Here is a view of the the JET Diagnostic Hall, which was turned into a temporary control room for the occasion. JET's director Paul Rebut is seen here discussing with Michel Huguet, who was to head the ITER Joint Work Site (JWS) at Naka. Leaning on the railing, is Juergen Dietz, who was head of In-Vessel Division at the Garching ITER JWS in the early years of the ITER Engineering Design Activities.
In 30 years of operations JET has produced over 80,000 pulses. Although an everyday occurrence during experimental campaigns, how a pulse is prepared and processed deserves its own special story.

So what is meant by the term? A pulse is the name given to the time a plasma is held in the JET vessel. To create fusion in a future power station a plasma, or very hot electrically charged gas, has to be sustained inside the tokamak vessel whilst optimising three specific conditions: temperature, density and confinement time. This is called the fusion triple product and two isotopes of hydrogen, deuterium and tritium, are used to make the reaction occur.

A comics rendition of a countdown to plasma at JET: the first shift of the day is just starting and 15 pulses are planned. (Click to view larger version...)
A comics rendition of a countdown to plasma at JET: the first shift of the day is just starting and 15 pulses are planned.
Unlike future stations when the plasma will need to run for several hours or continuously, on JET, each pulse typically lasts around 40 seconds. Although this may seem like a short amount of time, the 80,000 or so plasmas already created in the machine since 1983 have provided crucial information for plasma science by focusing on its behaviour and improving its performance. The pulses have all contributed to an extensive knowledge bank of data (with over 100 TeraBytes of data collected to date) and their analysis plays a key part in the long-term goal of fusion electricity on the grid.

Like all good stories —the story of a pulse has a distinct beginning, middle and end, a strong setting and involves many people in this case engineers, scientists and computer experts who all have fascinating parts to play.

Read the whole story on CCFE website.


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