Investigation of impurity evolution in plasma streams generated by means of pulse plasma accelerators to provide Tokamak-Reactor fueling.
Tech Area / Field
- FUS-PLA/Plasma Physics/Fusion
8 Project completed
Senior Project Manager
Karabashev S G
TRINITI, Russia, Moscow reg., Troitsk
- VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Lawrence Livermore National Laboratory, USA, CA, Livermore\nPhillips Laboratory, USA, NM, Albuquerque
Project summaryTokamak reactors have been developed to near the reactor level of performance. In recognition of this success, the USA, Russia, Europe, and Japan are jointly developing an engineering design for the International Thermonuclear Experimental Reactor, ITER. The fueling system design Is the one of the problems to be solved In a frame of this project. Proven methods of fueling either deposit the fuel near the periphery, as with pellets, or carry too much energy Into the core, as with MeV range neutral beams.
LLNL Invented the Compact torus accelerator concept. Compact torus injection has been proposed as a method of fueling the core of a Tokamak. This concept is practically free from disadvantages mentioned above. One of the most stringent requirements to be met by a fueling system is the purity of the fuel-impurities must be restricted to very low levels to minimize dilution and contamination of the deuterium fuel, to maintain a high reactivity. It was found that a compact torus can pick up wall material, generally water and hydrocarbons or the electrode metal. In greater amounts than is permissible for fueling purposes, so compact torus purity is a critical issue. The compact torus may also play a role in high density fusion schemes such as magnetically insulated fusion. Magnetically insulated fusion is a form of pulsed fusion that has not been as extensively studied experimentally. In a success the effective neutron source can be constructed for fusion technology on a base of the proposed scheme. It offers the advantage over a steady state magnetic trap of much smaller size, therefore reduced development costs. In this case low influx of wall material is important as well for two reasons:
(1) Maintaining a high reactivity with low dilution and contamination by impurities, as in the Tokamak case discussed above.
(2) Efficient acceleration, without coupling energy into the walls by charge-exchange interactions with wall-evolved gas or metal.
The gas evolving from the wall and its diffusion into the plasma streams is supposed to be studied in a frame of the project.
To obtain the knowledge to control wall evolved gas requires both experimental and. theoretical investigations. Experimental data can be obtained with plasma guns to create plasma velocities in the 107 to 109 cm/s range (TRINITI, LLNL) and measuring the evolution of gas both in the gun itself, in downstream drift tubes, and. In a stagnation chamber. The numerical codes will be developed to simulate these processes (ITPC, LLNL). The acceleration procedure and best plasma-facing materials for plasma accelerator could be chosen to construct the real fueling system in a result of the study.
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