Page 4 - Plasma and Fusion Research,ISSN 1880-6821

Plasma and Fusion Research: Regular Articles
Volume 13, 3402098 (2018)
Fig. 6
Simulation result with an additional set of mirror coils, as shown in Fig. 5, clearly affecting FRC merging dynamics.
is shown in the red line of Fig. 5. The magnetic field gra- dient is increased towards the central confinement region. Figure 6 shows the simulation results of FRC dynamics using the modified magnetic profile by the additional mir- ror coils. In this case, the collided FRC does not bounce off completely unlike the case shown in Fig. 4; more im- portantly, merged FRC is successfully formed at 85 μs in the simulation without the bouncing and the merged FRC clearly have higher temperature. These simulation results suggest that the additional mirror coils shall help merging process of FRC’s and may improve confinement property.
5. Summary
FRC collisional merging experiments have been started in FAT-CM. Experimental results and numerical simulations agree that there is a significant increase in the excluded flux of the merged FRC, compared to the sin- gle translated FRC. The simulation indicates that this in- crease is due to an efficient conversion of the translating FRC kinetic energy into the merged FRC thermal energy; it is similar to what was observed in C-2. The simulation also indicates that the structure of the confinement mag- netic field is important for the merging process of FRCs, and final merged FRC state with higher temperature was successfully obtained by the additional mirror coils in the simulation.
Acknowledgements
The authors gratefully acknowledge the work of past and present member of our laboratory. This work was partially supported by JSPS KAKENHI Grant Number 16K06939.
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have inadequate field profile for effective FRC merging so that the collided FRCs do not merge but rather bouncing off axially.
To improve the FRC merging, a set of mirror coils is added at z = ±1.13 m in the simulation, whose field profile
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