Transport of Fusion Alpha Particles in ITER Scenarios

We predict the fusion-born alpha particle density in steady-state and hybrid (reverse shear) ITER scenarios with an integrated 1D transport model [1]. The model combines ``stiff'' critical gradient alpha-driven Alfv\'en eigenmode (AE) transport with a quasilinear approximation of microturbulent transport [2]. In an ITER baseline case [3], AE transport is found to redistribute alphas within the core but not propagate to the loss boundary. The remaining microturbulence at the edge causes negligible alpha-channel energy flux there (neglecting ripple loss). We set the AE stiff transport critical gradient threshold at $g_{AE}=g_{ITG}$, below which microturbulence can nonlinearly suppress AE transport [4], and the more stringent condition $g_{AE}=0$.\par \vskip6pt \noindent [1] R.E. Waltz and E.M. Bass, ``Prediction of the fusion alpha density profile in ITER from local marginal stability to Alfven eigenmodes,'' accepted for Nucl. Fusion\par \noindent [2] C. Angioni et al., Nucl. Fusion {\bf49}, 055013 (2009)\par \noindent [3] J.E. Kinsey et al., Nucl. Fusion {\bf51} 083001 (2011)\par \noindent [4] E.M. Bass and R.E. Waltz, Phys. Plasmas {\bf17}, 112319 (2010)