Speaker
Mr
Yutaro Umeda
(Osaka Prefecture University)
Description
In the design of fusion reactors for high power and long pulse operation, vast heat flux will be expected and perfectly detached plasma must be produced and sustained much more reliably. In a linear divertor plasma simulator TPD-SheetIV[1], so-called long leg divertor configuration is constructed by connecting the rectangular duct to the entrance of the V-shaped divertor and studied its effect on the formation of detachment of divertor plasma experimentally. In order to study the neutral behavior in detail and understand the basic mechanism of detached plasma, simulation study with DEGAS 2 Monte Carlo code [2] is conducted[3].
In our experiment, the hydrogen atomic and molecular ion currents (H+, H2+, H3+) are measured by omegatron mass analyzer located behind the target plate in TPD-SheetIV. It was found that by fine adjustment of gas puffing into divertor, the production amount of the molecular ion changes dramatically[4]. With the increasing of contact gas flow, density ratio of molecular ions (H2+, H3+) becomes dominant than that of atomic ion. This experiment result indicates that molecular ions make important rolls in the detachment plasma formation. The Generating mechanisms of molecular ions are complicated, and they are dependent on the plasma conditions. Excited atoms are generated by molecular ions, and H alpha is released from excited atoms. Therefore, H alpha is indicator of the amount of molecular ions. In [5], contribution of H excitation and H2 dissociation for H alpha is compared with Collisional Radiative model (CR model). In this work, the CR model is also applied to TDP-SheetIV detached divertor experiment and studied the atomic and molecular process. In the conference, the calculation result by using the model will be discussed.
This work is partially performed with the support and under the auspices of the NIFS Collaborative Research Program
References:
[1] A.Tonegawa, et al., Jpn J. Appl. Phys. **45**, 8208 (2006).
[2] D. Stotler et al., Contrib. Plasma Phys. **34**, 392 (1994).
[3] H.Matsuura et al., Fusion Sci Tech. **68**, 76 (2014)
[4] S. Tanaka, et al., Fusion Sci. Tech. **63**, 420 (2013).
[5] H.Matsuura et al., J.Plasma Fusion Res. SER. **8**, 450 (2009)
Primary author
Mr
Yutaro Umeda
(Osaka Prefecture University)
Co-authors
Mr
Akira Tonegawa
(Tokai University)
Mr
Hiroto Matsuura
(Osaka Prefecture University)
Mr
Takaaki Iijima
(Tokai University)
Mr
Yuta Tanaka
(Tokai University)
