Operating Conditions to sustain burning plasma in stellarator/heliotron-type fusion reactor

Self-burning plasma have been extrapolated from the LHD experiments taking into account a dynamic behavior of the plasma profiles evolution. Possible self-burning solutions can be found under the feasible pellet fueling conditions at the present pellet injection technology. A deep fueling into the core plasma contributes to the efficiency improvement of the particle fueling and burning ratio, although it will be required to inject a pellet at a very high speed (>10 km/s) which cannot be achieved without pushing past the limit of the current pellet injection technology. Fuel dilution is enhanced due to the source profile effects of the α particle which is generated in the core plasma and fuel which must be inject from the peripheral. In order to mitigate the fuel dilution below an acceptable level, enough fuel re-circulation is required even if it leads to suppression of burning ration.