H. Momota

N.Y. Shabrov

Y. Tomita

National Institute for Fusion Science (NIFS-Repository)

§12. Adiabatic lnvariance Analysis of D 3He Fusion Products in an Axisymmetric Field Reversed Configuration Shabrov, N.Y. (Moscow State Technical Univ.) Tomita, Y, Momota, H. Field reversed configuration (FRC) is a very attractive candidate as a lo\v radioactivity o ·'He fueled commercial fusion reactor. Since energy balance for such reactor is significantly determined by fusion products, we will study the tnotion of high energy fusion products in an axisymmetric FRC. An appreciable fraction of particles in an FRC are stochastic [ 1]. Also, one can observe passtng and trapped particles trajectories. Passing particles intersect the middle plane z=O every bounce whereas trapped particles is confined in one-half of the system with z>O or z<O during a bounce. The presence of stochastic behavior in particle motion and availability of passing and trapped particles could be significant in distribution function calculations, diffusion and equilibriutn studies. Action integral around one gyro-oscillation would be appropriate for analyzing particles behavior in an FRC 1 = fv~dr [2]. It is an adiabatic invariant in the case of reactor n1agnetic field when bryro-frequency of particle oscillations exceeds much more than a bounce tJ·equency. Nun1erical investigations of action integral - J are introduced. An availability of boundary values of J between stochastic and regular, passing and trapped particles is obtained. A simple analytical model of bounce oscillation was considered for the detennination of boundary ./. This model is based on averaging over gyro-period . The distinctive features of it ts the conservation of .J over a bounce. Boundaries between particles populations as a function of angular momentum - P8 and action integral - J have been investigated (fig. 1 ). Those boundaries are considered in velocity space too. The analysis of boundaries allows us to estimate the part of fusion products that lost fron~ the system immediately after their birth. Also stochastic/regular and trapped/passing fractions of particles could be calculated. This calculations was made for fusion protons under the assumption that the plasma density and temperature are almost constant along magnetic lines inside the separatrix. J ' -... .... ............... .... 0.03 -. .......___ ~------- I '" -- -I " /\ \ , 0.02-::. trapped /// \ \\ -1 / ~ t ..,,...... \ ~ {- stochastii-\- regu Jar 0.01 --j \ ~ passing 3 \\ 0.00-torTTIIIIII IIIII 111!11 II II 0.00 0.04 0.08 0.12 0.16 angular momentum Fig. I . The boundaries between main populations of fusion protons on dimensionless J-P e plane . References 1) Finn J.M., Plasma Phys. 21 (1978) 405. 0.20 [2] Kim, J.-S., Cary, J.R., Phys. Fluids 26 ( 1983) 2161 . 287 

Adiabatic Invariance Analysis of D3He Fusion Products in an Axisymmetric Field Reversed Configuration

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