  Thermonuclear fusion reactivity is a pivotal quantity in the studies
pertaining to fusion energy production, fusion ignition and energy break-even
analysis in both inertially and magnetically confined systems. Although nuclear
fusion reactivity and thereafter the power density of a magnetic confinement
fusion reactor and the fulfillment of the ignition criterion are quantitatively
determined by assuming the ion speed distribution to be Maxwellian, a
significant population of suprathermal ions,with energy greater than the
quasi-Maxwellian background plasma temperature, is generated by the fusion
reactions and auxiliary heating in the fusion devices. In the current work
3-parameter Dagum speed distribution has been introduced to include the effect
of suprathermal ion population in the calculation of total fusion reactivity.
The extent of enhancement in the fusion reactivity, at different back-ground
temperatures of the fusion fuel plasma, due to the suprathermal ion population
has also been discussed.
