Experiments with Dense Plasma in the Central Solenoid of Ambal-M
| Autor: | G. I. Shulzhenko, T. D. Akhmetov, V. S. Belkin, A. S. Krivenko, P. A. Potashov, Igor Bespamyatnov, Vladimir I. Davydenko, Yu. V. Kovalenko, V. Ya. Savkin, V. B. Reva, V. V. Razorenov, G. I. Dimov |
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| Rok vydání: | 2003 |
| Předmět: |
Nuclear and High Energy Physics
Materials science Ambipolar diffusion 020209 energy Mechanical Engineering Magnetic confinement fusion Solenoid Atmospheric-pressure plasma 02 engineering and technology Plasma 01 natural sciences 010305 fluids & plasmas Magnetic field Nuclear Energy and Engineering Physics::Plasma Physics Physics::Space Physics 0103 physical sciences 0202 electrical engineering electronic engineering information engineering Electron temperature General Materials Science Inductively coupled plasma Atomic physics Civil and Structural Engineering |
| Zdroj: | Fusion Science and Technology. 43:58-62 |
| ISSN: | 1943-7641 1536-1055 |
| Popis: | At present the axisymmetric ambipolar mirror trap AMBAL-M consists of a central solenoid which is attached to a plugging and MHD stabilizing end system and is filled from the other end by a plasma stream generated by a gas-discharge source. In the first experiments we obtained the plasma in the solenoid with ∼0.4 m diameter, density ∼6.10 12 cm -3 , electron temperature ∼50 eV, and ion energy ∼250 eV. In order to enhance the plasma flow from the source into the solenoid, the distance between the entrance throat of the solenoid and the plasma source was gradually decreased, and the plasma density was increased to ∼2.10 13 cm -3 . Installation of a second source from the opposite end of the machine allowed us to increase the plasma density up to ∼2.5.10 13 cm - 3 in the solenoid and up to ∼1.5.10 13 cm -3 in the mirror trap of the end system. For better propagation of the plasma stream from the second source into the trap the coil of the MHD-stabilizer semicusp was switched in the same direction as all other coils, thus the magnetic configuration consisted of a series of simple mirrors. However, the plasma remained MHD stable owing to its line-tying to conducting ends. When this line-tying broke during the fast cut-off of the source current, the density profile in the solenoid abruptly rearranged pointing to possible MHD activity, and independently of the initial shape it became almost flat up to the limiter. Further enhancement of the plasma density was achieved using hydrogen puffing into the solenoid plasma while only the first source was functioning. Two methods of gas puffing were used - through a ceramic tube to the solenoid axis and into a gas-box surrounding the plasma. Optimization of the hydrogen puffing rate led to the density increase up to ∼ 6.10 13 cm -3 without noticeable degradation of the ion temperature which remained at a high level of ∼200 eV (the ratio of the plasma pressure to the magnetic field pressure β∼0.1), which is provided by stochastic ion heating from electrostatic oscillations when the source is working. The obtained solenoid plasma density is the highest one achieved in ambipolar mirror traps. |
| Databáze: | OpenAIRE |
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