In pursuit of nuclear fusion as a viable and clean energy source for future use, scientists and engineers are continuously pushing the boundaries of science. Groundbreaking research leads to higher plasma pressures and temperatures, a better confinement and longer pulse durations. In that respect, the past couple of months have been a very succesful by shattering some of the previous fusion records, making sure to end the year 2016 with a bang.
60 seconds of non-inductive H-mode confinement in EAST, China
The Experimental Advanced Superconducting Tokamak (EAST) in Hefei, China, has achieved a steady-state, non-inductive H-mode plasma discharge which lasted over a minute. This discharge, which took place in November during the 11th EAST experimental campaign, broke the world record for longest non-inductive pulse for H-mode confined plasmas. By doing so, EAST doubled the previous confinement record, which was already in the hands of EAST when the machine managed to run a 32 second discharge in 2012. In order to achieve the sustained H-mode confinement which resulted in the new record, EAST relies on its ITER-like RF heating system as well as NBI and lower hybrid current drive systems.
70 seconds of non-inductive H-mode confinement in KSTAR, Korea
The Korea Superconducting Tokamak Advanced Research (KSTAR) of the National Fusion Research Institute (NFRI) in Daejeon, South Korea, managed to raise the bar even higher by breaking the brand new confinement record within a month time. The KSTAR team succeeded to keep a high-performance H-mode plasma stable for 70 seconds. The record-winning confinement has been achieved by operating the device in the so-called 'high poloidal beta scenario', which uses a high-power neutral beam in combination with several other techniques, including the use of a rotating 3D field to alleviate the accumulated heat fluxes on the plasma-facing components.
The record-winning machines: EAST on the left and Alcator C-Mod on the right.
2 atmosphere of plasma pressure in Alcator C-Mod, USA
A high confinement is key to reach plasma ignition, but plasma pressure, which is the product of plasma temperature and density, is just as important. During its last day of operation, the Alcator C-Mod tokamak at the Massachusetts Institute of Technology (MIT) has reached a plasma pressure of roughly 2 atmosphere, breaking the previous world record of 1.77 atmospheres, which dated from 2005 and was also set by Alcator C-Mod.
The record-winning discharge was achieved by using the high-magnetic-field approach, having a central magnetic field of about 5.7 T, which is more than double the magnetic field strength that is typically being used in other machines. The resulting temperature inside the tokamak reached over 35 million degrees Celsius, which is about twice the core temperature of the sun, during a pulse lasting two full seconds.
For more information, please refer to the press releases of the involved institutes: