Efficiency of a Traveling Wave Direct Energy Converter with High-Density Beam for Applications to Aneutronic Fusion Experiments

Due to the appeal of aneutronic fusion, a variety of reactor concepts have been proposed in past. In most cases, to achieve a positive net power balance these reactor concepts rely on a significant re-circulation of the energy produced to maintain a non-equilibrium configuration (unlike ignited plasmas). The availability of a direct conversion process with high efficiency is then critical for determining the feasibility of a reactor (particularly when the ``almost true aneutronic'' reaction like $p-^{11}B$ is considered). A Traveling Wave Direct Energy Converter (TWDEC, [1]) is considered for the energy conversion of a high-density beam formed by the fusion products (MeV-range $\alpha $-particles). As in [2], a PIC code is utilized for a realistic beam model. The study is focused on the possibility of obtaining high-efficiency coupling between a modulated high-density ``bunched'' beam, accounting also for a neutralizing electron environment, and the TWDEC electrode collector structure.\\[4pt] [1] Momota\textit{ et al.} (1999) Fus. Tech., 35, 60\\[0pt] [2] Y.Yasaka \textit{et al.} (2009), Nucl. Fus., 49, 075009