Mod-01 Lec-39 Thermonuclear fusion reactors

So, in the previous lecture I talked about the reaction rates and the reaction rate is R. If you write n x n y and sigma v average value of that n x n y are the concentrations number of nuclei of x of y per unit volume and sigma is the cross section for that particular

reaction in those particular conditions, and v is the relative speed between the two interacting nuclei, and this we saw that the sigma v itself is a function of v and since the velocities are distributed according to Maxwell Boltzmann distribution in the plasma. So, you have to integrate over all varieties of velocities involved and we saw that only

a small part contributes in this integration, because when you do integration using this Maxwell Boltzmann probability distribution for relative velocities. This distribution itself if you write in terms of energy, you get two terms one dominated by this distribution of velocities, another dominated by the barrier penetration probability and then one rises with temperature with a velocity, and one falls with velocity, and the product is contributed

only by a small range in these relative velocities, and then we can integrate and get this sigma v. We also saw that as temperature increases in the beginning this whole thing increases and therefore, the reaction rate increases but, if one goes to very high temperatures which are not very relevant for fusion reactors

then but, in principle it is there that this thing may come down. Now that reaction rate can be calculated for any given concentration of x plus y at a given temperature one can look at different possible constituents which can be used in a fusion reactor. And turns out that for making a fusion reactor the most attractive proposition is what you called