UMIST linear system
Encyclopedia
The ULS is a gas target divertor simulator located on the former UMIST
campus of the University of Manchester
. It enables physicists to study the recombination processes of a detached plasma
in a hydrogen
target chamber.
Research on detached plasma and on its recombination modes is of primary importance in order to design an appropriate divertor region in a future nuclear fusion
power plant, where huge amounts of energy
will be deposited by the fast-moving particle
s generated in the main reactor. The major goal of the ULS as for many other linear divertor simulators, is to reproduce the same temperature
and density
conditions of the SOL (Scrape Off Layer) of a tokamak
in a linear environment and therefore to make easier the study of its properties.
In the past few years, ULS has been used with great insight to analyze the molecular activation
and the electron-ion recombination modes, and to determine the conditions for their activation: diffusive processes
have also been considered. However, research on these subjects is still ongoing and our understanding of the elementary processes involved in a detached plasma is still far from being satisfactory.
UMIST
The University of Manchester Institute of Science and Technology was a university based in the centre of the city of Manchester in England. It specialised in technical and scientific subjects and was a major centre for research...
campus of the University of Manchester
University of Manchester
The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...
. It enables physicists to study the recombination processes of a detached plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
in a hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
target chamber.
Research on detached plasma and on its recombination modes is of primary importance in order to design an appropriate divertor region in a future nuclear fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
power plant, where huge amounts of energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
will be deposited by the fast-moving particle
Subatomic particle
In physics or chemistry, subatomic particles are the smaller particles composing nucleons and atoms. There are two types of subatomic particles: elementary particles, which are not made of other particles, and composite particles...
s generated in the main reactor. The major goal of the ULS as for many other linear divertor simulators, is to reproduce the same temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
and density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
conditions of the SOL (Scrape Off Layer) of a tokamak
Tokamak
A tokamak is a device using a magnetic field to confine a plasma in the shape of a torus . Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape...
in a linear environment and therefore to make easier the study of its properties.
In the past few years, ULS has been used with great insight to analyze the molecular activation
Plasma recombination
Plasma recombination is a process by which ions of a plasma capture the free energetic electrons to form new neutral atoms.Recombination usually take place in the whole volume of a plasma , although in some cases it is confined to some special region of it...
and the electron-ion recombination modes, and to determine the conditions for their activation: diffusive processes
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
have also been considered. However, research on these subjects is still ongoing and our understanding of the elementary processes involved in a detached plasma is still far from being satisfactory.
Further reading
- Kay, Michael J. (1998) A Study of Plasma Attenuation and Recombination in the Gas Target Chamber of a Divertor Simulator. UMIST Ph.D. thesis