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In this paper we analyze fast ion motion in the Divertor Tokamak Test device. DTT is planned to be heated through a mix of 45 MW heating power, including 15 MW negative-ion-based Neutral Beam heating (NNBI) which is currently being developed by Consorzio RFX in Padova, Italy. An issue for DTT is that a Toroidal Field (TF) ripple with a maximum value of about 0.42% (with respect to the on-axis magnetic field $$B_0$$) is expected on the low-field side (LFS), and this ripple interacts with fast ions through rather well-known phenomena of ripple-precession resonances, in addition to prompt losses ofmore » ions which do not complete a full orbit in the poloidal plane. We will show that, with the planned geometry of NNBI, prompt losses are negligible, and ripple-precession losses amount to a maximum 0.15%. The calculations are performed with the guiding center code ORBIT using two different equilibria, and a beam with energy 400 keV and injection angle $$\alpha_{inj} = 40^{\circ}$$ (measured w.r.t. the first wall), which corresponds to a pitch of injected particles $$\lambda = v_{\parallel}/v \approx \sin{\alpha_{inj}} = 0.65$$. Main resonances are of the form $$\omega_b - n N \omega_d = 0$$, $$\omega_b$$ and $$\omega_d$$ being the bounce and precession frequency, respectively, $N=18$ the ripple periodicity and $$3 \le n \le 6$$ are the toroidal wavenumbers of the resonances. Although collisionless interaction with the TF ripple does not pose a serious threat to the NNBI project, an open question remains whether the presence of these resonances will interact with fast particles accelerated by \alfven eigenmodes, and if stochastization of the resonances is possible in DTT, as it was observed in the past in TORE SUPRA.« less

Collisional particle transport is examined in several toroidal plasma devices in the presence of perturbations typical of modes leading up to a disruption, of saturated tearing modes, or of unstable Alfvén modes. The existence of subdiffusive transport for electrons is found to occur in some cases at very low mode amplitudes and to also exist even for ions of high energy. Orbit resonances can produce long time correlations and traps for particle trajectories at perturbation amplitudes much too small for the orbits to be represented as uniformly chaotic. Here, the existence and nature of subdiffusive transport is found to dependmore » on the nature of the mode spectrum and frequency as well as the mode amplitudes.« less