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.
]
See also
* Edge-localized mode An edge-localized mode (ELM) is a disruptive instability occurring in the edge region of a tokamak plasma due to the quasi-periodic relaxation of a transport barrier previously formed during a transition from low to high-confinement mode. This phen ...
, an instability of H-mode
* Joint European Torus
The Joint European Torus, or JET, is an operational Magnetic confinement fusion, magnetically confined Plasma (physics), plasma physics experiment, located at Culham Centre for Fusion Energy in Oxfordshire, United Kingdom, UK. Based on a tokamak ...
(JET) operates in H-mode
* COMPASS tokamak
COMPASS, short for Compact Assembly, is a compact tokamak fusion energy device originally completed at the Culham Science Centre in 1989, upgraded in 1992, and operated until 2002. It was designed as a flexible research facility dedicated mostly t ...
can/could operate in H-mode
* KSTAR
The KSTAR (or Korea Superconducting Tokamak Advanced Research; ko, 초전도 핵융합연구장치, literally "superconducting nuclear fusion research device") is a magnetic fusion device at the Korea Institute of Fusion Energy in Daejeon, So ...
(South Korea) operates in H-mode
* EAST
East or Orient is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth.
Etymology
As in other languages, the word is formed from the fac ...
(China) operates in H-mode
* NSTX-U
The National Spherical Torus Experiment (NSTX) is a magnetic fusion device based on the ''spherical tokamak'' concept. It was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, ...
operates in H-mode
References
Plasma physics
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