What is a Tokamak?
The most successful and promising fusion confinement device is known as a Tokamak. The word Tokamak is actually an acronym derived from the Russian words toroid-kamera-magnit-katushka, meaning “the toroidal chamber and magnetic coil.” This donut-shaped configuration is principally characterized by a large current, up to several million amperes, which flows through the plasma. The plasma is heated to temperatures more than a hundred million degrees centigrade (much hotter than the core of the sun) by high-energy particle beams or radio-frequency waves. Reference: http://ippex.pppl.gov/fusion/fusion4.htm Maintaining a stable “pinched” plasma in a magnetic field is very difficult at best. If a solid vessel is used to maintain the plasma and the plasma comes into contact with the vessel wall, then the plasma will immediately transfer heat to the vessel and cool off to below the required fusion temperatures. Likewise, the chance of the solid vessel vaporizing when coming into physical conta
Image courtesy of (link) A tokamak is a plasma-containment device shaped roughly like a doughnut. It contains toroidal and vertical coils that, along with the large current running through the plasma, generate the magnetic field that confines the plasma. The current through the coils is driven by an ohmic solenoid. The major radius of a tokamak is the distance between from the center of the solenoid to the center of the plasma. The minor radius is the radius of the plasma. The ratio of major radius to minor radius is typically 3. The tokamak is the most commonly studied plasma containment device. Below is a picture of the inside of the Tokamak Fusion Test Reactor (TFTR), a working tokamak at the Princeton Plasma Physics Laboratory from 1982-1997.
A tokamak is also a toroidal (donut-shaped) plasma magnetic confinement device. However, the tokamak is axially symmetric (see the picture below) and relies only on 2-dimensional shaping (in the cross section you would get by cutting through the donut). The tokamak also has field lines that wrap around the plasma surface (show below as white lines). However, the tokamak achieves its rotational transform through internal plasma currents that flow around the torus. This reliance on plasma currents implies that the tokamak is not a steady state system, but will require some level of current drive. Also, the presence of current in the plasma can drive instabilities and turbulence in the plasma. However, the tokamak can offer very good plasma confinement due to its high degree of symmetry. The stellarator requires careful optimization to achieve similar levels of plasma confinement as the tokamak.
The most successful and promising fusion confinement device is known as a tokamak. The word tokamak is actually an acronym derived from the Russian words toroid-kamera-magnit-katushka, meaning “the toroidal chamber and magnetic coil.” This donut-shaped configuration is principally characterized by a large current, up to several million amperes, which flows through the plasma. The plasma is heated to temperatures more than a hundred million degrees centigrade (much hotter than the core of the sun) by high-energy particle beams or radio-frequency waves. >> Inside of the Princeton Plasma Physics Laboratory Tokamak TFTR.
The most successful and promising fusion confinement device is known as a tokamak. The word tokamak is actually an acronym derived from the Russian words toroid-kamera-magnit-katushka, meaning “the toroidal chamber and magnetic coil.” This donut-shaped configuration is principally characterized by a large current, up to several million amperes, which flows through the plasma. The plasma is heated to temperatures more than a hundred million degrees centigrade (much hotter than the core of the sun) by high-energy particle beams or radio-frequency waves.
