High-confinement mode, or H-mode, is an operating mode possible in toroidal

magnetic confinement fusion Magnetic confinement fusion is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of fusion energy research, along with ...

devices mostly

tokamaks A tokamak (; russian: токамáк; otk, 𐱃𐰸𐰢𐰴, Toḳamaḳ) is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being ...

, but also in

stellarator A stellarator is a plasma device that relies primarily on external magnets to confine a plasma. Scientists researching magnetic confinement fusion aim to use stellarator devices as a vessel for nuclear fusion reactions. The name refers to the ...

s.How Fritz Wagner "discovered" the H-Mode
In this mode the plasma is more stable and better confined. It was discovered by

Friedrich Wagner Friedrich E. Wagner (born November 16, 1943, sometimes abbreviated as Fritz Wagner) is a German physicist and emeritus professor who specializes in plasma physics. He was known to have discovered the high-confinement mode (i.e. H-mode) of mag ...

in 1982 during neutral-beam heating of the plasma at ASDEX. It has since been reproduced in all major toroidal confinement devices and is planned in the operation of ITER. Its self-consistent theoretical description was a topic of research in 2007. It was still considered a mystery with multiple competing theories (e.g. predator–prey model) in 2016.''First results of NSTX-U research operations presented''
Oct 2016.

History

Prior to the H-mode’s discovery, all tokamaks operated in what is now called the or low-confinement mode. The is characterized by relatively large amounts of turbulence, which allows energy to escape the confined plasma. Moreover, it was observed that as the heating power applied to an plasma increased, the confinement decreased. However, it was discovered in 1982 on the ASDEX tokamak that if the heating power applied using neutral beams was increased beyond a certain critical value, then the plasma spontaneously transitioned into a higher-confinement state. This new state was called the and the old lower-confinement state was in turn called the Due to its improved confinement properties, quickly became the desired operating regime for most tokamak reactor designs.

References

Plasma physics {{plasma-stub

History

See also

References