February 2016 might become a milestone month in the history of nuclear fusion. Last week, German scientists were able to create hydrogen plasma in a stellarator reactor, and now Chinese scientists claim they have performed the longest sustained reaction in a tokamak.
The Chinese team from the Hefei Institute of Physical Science were able to produce hydrogen plasma at 50 million Kelvin (49.999 million degrees Celsius, 89.999 million degrees Fahrenheit) and held it for an incredible 102 seconds. If the success is confirmed, it will be the longest sustained fusion reaction.
The Chinese lab performed the experiment in the Experimental Advanced Superconducting Tokamak (EAST), a donut-shaped nuclear fusion reactor that was invented by Soviet scientists. The tokamak is the most common design for a nuclear fusion reactor, and EAST is one of the precursors of ITER, a full-scale nuclear fusion power plant currently being built in France. ITER is funded by an international collaboration of countries.
EAST was designed to test what exactly happens in a reactor when the hydrogen is fusing for a long time. The hydrogen plasma needs to be heated up to incredibly high temperatures for long enough to harness the energy produced by the fusion reaction. The team working on EAST has previously maintained nuclear fusion in the reactor for 30 seconds. The goal for EAST is to reach 1,000 seconds (17 minutes).
Interior of the reactor with the plasma in purple. The plasma needs to be kept in suspension by powerful magnetic fields. Hefei Institute of Physical Science, Chinese Academy of Sciences
For comparison, the Wendelstein 7-X (W7X) stellarator last week was able to heat a cloud of hydrogen plasma to a temperature of about 80 million Kelvin and the reaction lasted for about 0.25 seconds. The German team believes now that the proof-of-concept tests are completed, they will be able to produce continuous fusion for up to 30 minutes.
A peer-reviewed paper regarding the latest Chinese effort has not been published yet, so we’ll have to wait to find out if and how they achieved this result. If all is confirmed, it could spell great news for nuclear fusion, as two different technologies are both progressing full speed towards the common goal of plentiful, cheap, clean energy.
3