Tokamaks - Toroidal coils with plasma pinch (plasma column) inside, for the long time are considered as the most perspective candidates for the role of the future fusion reactors. Originally, conception of tokamak was published in 1950th by Igor Tamm and Andrei Sakharov - fathers of Soviet nuclear weapons, and since then many experimental models were built worldwide, with many billion dollars spent, with less than moderate results . Even now, there is no industry grade fusion reactor built. On this background, on April 28 news appeared that in the compact tokamak ST-40, built by private UK company Tokamak Energy, first plasma achieved.
Image: Tokamak Energy - Founder Alan Sykes and ST-40 profile in 1:1 scale
Since its foundation in 2009, Tokamak Energy (located near to the largest in the world JET Tokamak) received 35 million dollars for researches, which is nothing as compared to ITER's (International Tokamak project) 20 billion.
What can they do at all?
The main problem of fusion is not just to obtain fusion reactions, but that reactor would be of reasonal size. There are amny concepts of fusion and avery one will work, if to build 1 kilometer reactor with terawatt power, but this is not for the real life. Plasma scientists and engineers are looking for such configurations, when its size is minimal.
In theory, spheroidal tokamaks allow to achieve plasma column of minimal size with the same fusion power
Image: Tokamak Energy - tokamak will be confined in the vacuum vessel - cryostat, with copper magnetic system from toroidal and poloidal coils, compressing the plasma column and keeping it off toroidal camera walls.
ST-40 - experimental machine, one of intermediate stages to real reactor prototype ST185, planned in 2025.
Spheroidal tokamak with plasma pinch radius 0,4 meter and toroidal vacuum camera is a real dwarf, compared to its sister machines. ST185 mus have plasma parameters Q>1 (1.. 2 etc) where Q is ratio of fusion power to energy, spent for plasma creation and heating. Today's record is Q=1.2 for tokamak JT60-U with plasma volume tens times more. The neighboring to the ST40 tokamak JET with plasma volume 40 times more, achieved only Q=0.7
If projected ST-40's parameters will be confirmed experimentlly, it will be enormopus disruption for tokamaks.
Image: Tokamak Energy - toroidal vacuum camera ST-40
For further reading: http://www.world-nuclear-news.org/NN-Tokamak-Energy-turns-on-ST40-fusion-reactor-28041701.html