JT-60

JT-60 (short for Japan Torus-60) is a large research tokamak, the flagship of the Japanese National Institute for Quantum Science and Technology's fusion energy directorate. As of 2023 the device is known as JT-60SA and is the largest operational superconducting tokamak in the world, built and operated jointly by the European Union and Japan in Naka, Ibaraki Prefecture. SA stands for super advanced tokamak, including a D-shaped plasma cross-section, superconducting coils, and active feedback control. JT-60 claimed that it held the record for the highest value of the fusion triple product achieved: 1.77×1028 K·s·m−3 = 1.53×1021 keV·s·m−3. The product quoted is not a valid fusion triple product since the plasmas did not satisfy the steady state of the Lawson criterion as discussed below. JT-60 also claimed without proof that it held the record for the hottest ion temperature ever achieved (522 megakelvins). In reality the TFTR machine at Princeton routinely measured higher ion temperatures during the 1993-1996 campaign, as discussed below.