The Fokker - Planck description of collisional ripple transport processes of fast ions is extended for tokamaks with the strong toroidal field (TF) ripple. The topology of superbanana orbits generated by TF ripple drift of banana guiding centers is analyzed in terms of adiabatic invariant. The transport coefficients of 4D in the phase space Fokker - Planck equation in the case of strong TF ripples are derived. This study is done in framework of generalization of the kinetic simulation of the fast ions in plasmas of present-day and next generation tokamaks.

The suppression of edge-localized modes by means of the externally applied resonant magnetic field perturbations (RMPs) and its effect on plasma transport is investigated actively on modern tokamaks. In present paper the modification of loss rates of fusion born alpha particles caused by application of RMPs in tokamak plasma is examined. This study has been performed by means of test-particle simulations. To simplify calculations we use magnetic field model with circular magnetic surfaces. The transport properties of alpha particles are investigated during 3 seconds time interval by tracing the test-particle ensemble. Each particle trajectory is calculated by means of integration of full orbit equations. Three regimes of particle losses are identified during the evolution of the particle ensemble. The formation of magnetic islands together with the stochastic magnetic layers at the plasma edge is the natural consequence of RMPs excitation. It is demonstrated that due to the formation of these resonant magnetic field structures the irregularities of energetic alpha particle orbits occur, and hence the substantial increasing of the losses from the plasma periphery is observed. RMPs slightly affect the first orbit losses of fusion alphas.

Technique of calculation the pitch-angle, energy and poloidal distributions of the flux of charged fusion products (CFPs) lost to the first wall of axisymmetric tokamak due to first orbit (FO) loss mechanism is developed. This technique extends the approach for evaluation the poloidal distributions of FO loss of CFPs in tokamaks proposed by [Kolesnichenko Ya.I. et al. Sov. J. Plasma Phys 2 (1976) 506]. The upgraded technique enables to calculate distributions of lost fast ions in wide class of tokamak magnetic configurations. Analytical model of the magnetic field used in this study [Yavorskij V.A. et al. Plasma Phys. Control. Fusion 43 (2001) 249] takes into account Shafranov shift, elongation, triangularity and up-down asymmetry. Usage of the drift constant of motion space allows substantial reducing the computational efforts for simulation the lost particles flux at a given point of the first wall. The developed approach is useful for simulation the pitch-angle and energy distributions of fast ions lost to the scintillator detector [Zweben S.J. et al. Nucl.Fusion 30 (1990) 1551] in present-day tokamaks [Kiptily V.G. et al. Nucl.Fusion 49 (2009) 065030] as well as for calculation of the CFP fluxes to the plasma-facing wall in future tokamak-reactors.

Індекс рубрикатора НБУВ: В333.631 в641

Рубрики:

Торсидальні (замкнуті) магнітні уловлювачі

Шифр НБУВ: Ж69121 Пошук видання у каталогах НБУВ 

Розглянуто початкову стадію розвитку нестійкості аксіально-несиметричних електростатичних коливань суцільного пучка електронної плазми, який обертається в зовнішньому магнітному полі. Показано, що експоненціальне наростання потенціалу призводить до перерозподілу щільності пучка під дією пондеромоторної сили. Рух електронів під дією пондеромоторної сили змодельовано числово. Результати моделювання наведено графічно у вигляді розподілу часток у поперечному перерізі пучка. Наведено якісну оцінку коефіцієнта зв'язку пучка, яка вказує на можливість охолодження електронної плазми, тобто збільшення потенційної енергії частинок в порівнянні з їх кінетичною енергією.