The physics of divertors in tokamaks is reviewed, primarily from an experimental point of view, although where possible simple analytic modelling is included. The paper covers the four main subject areas at issue in divertor research: (1) the wide dispersal of plasma power exhausted from the main plasma, (2) the production of sufficiently high gas pressures in the vicinity of pump ducts to enable the removal of fuel and helium (`ash') gas from the system, (3) the elimination or reduction of impurity production and (4) the screening of impurities produced, or intentionally added, at the plasma boundary from the plasma core. A simple analytic model, the `two-point' model, is introduced early in the paper and provides a framework for comparison of the experimental results, drawn from many machines, with simply derived expectations. Conclusions regarding the direction of future research priorities are made.

https://iopscience.iop.org/article/10.1088/0741-3335/39/6/001/pdf

Experimental divertor physics

Impurities continue to be a concern for future fusion devices, and ongoing efforts are made to study their generation, confinement, and control. Techniques for analysis of concentrations, power losses, and confinement of impurities are surveyed, and experimental examples illustrating typical observations in tokamak plasmas are presented. The use of impurities for diagnosing plasma properties is outlined briefly.

https://iopscience.iop.org/article/10.1088/0029-5515/24/12/008/pdf

Impurities in tokamaks

Over the past several years, tokamak neutral beam injection experiments have evolved from the brute force study of the effects of global discharge characteristics (Ip, ne, Pheat, etc.) on energy confinement to the appreciation that there are effects more subtle, yet controllable, that may influence confinement dramatically. While this evolution from first to second generation experiments is derived from an empirical understanding of ‘‘low’’ and ‘‘high’’ energy confinement modes and how to achieve them operationally, the underlying physics is still unknown. Several theories with different physical bases appear to describe the global scaling of the low confinement mode discharges quite well. On the other hand, little agreement has been found between theoretical and experimentally deduced values of local transport coefficients. While it is known operationally how to achieve any one of several types of high confinement mode discharges, here too, the underlying physics of the transport associated with these m...

/pdf/a-review-of-energy-confinement-and-local-transport-scaling-1k18sajpl2.pdf

A review of energy confinement and local transport scaling results in neutral‐beam‐heated tokamaks

https://iopscience.iop.org/article/10.1088/1361-6587/aa6959/pdf

A review of radiative detachment studies in tokamak advanced magnetic divertor configurations

An electrowetting display device includes a black matrix that includes a plurality of openings corresponding to pixels, respectively, a first extension portion extending in a driving direction of an electrowetting layer, the driving direction being a direction in which motion of the electrowetting layer is induced when a voltage difference is applied between a common electrode and a pixel electrode, and a partition wall that partitions the pixels. The first extension portion includes first and second areas respectively extending in opposite directions to each other and a third area having a width substantially the same as a width of the partition wall. The first area has a width less than about half of a first length corresponding to a length extending between both sides of each pixel in the driving direction, and the second area has a width less than the width of the first area.

Electrowetting display device

A projection is formed on a pump body of an electroosmotic flow pump so as to face a communication hole of a micro fluid chip. When the projection and the communication hole are fitted together, a first flow path of the pump and a second flow path of the micro fluid chip are communicated and the pump is fixed to the micro fluid chip. At the same time, the connection between the first flow path and the second flow path is sealed to prevent leakage of liquid gas, etc. to the outside.

Electroosmotic Pump System and Electroosmotic Pump

High density, single-null poloidal divertor results in doublet III☆

An electroosmotic flow pump (10A) is filled with a driving liquid (15) exhibiting electroosmotic phenomenon, and a transport liquid (31) capable of noncontact movement through a valve (33) as the driving liquid (15) moves. Since only the driving liquid (15) can pass through an electroosmotic material (16), even a transport liquid (31) not exhibiting electroosmotic phenomenon can be transported by utilizing the electroosmotic flow pump (10A). Consequently, the electroosmotic flow pump (10A) can transport any transport liquid (31) stably so long as the driving liquid (15) exhibits electroosmotic phenomenon.

Masana Nishikawa

Papers

Electroosmotic Pump System and Electroosmotic Pump

High density, single-null poloidal divertor results in doublet III☆

Liquid-Transport Device and System

Thermomechanical behavior of graphite and coating materials subjected to a high heat flux

Development of general methodology of safety analysis and evaluation for fusion energy systems (GEM-SAFE)☆