The Second Criterion for a thermonuclear reactor and some possible ways to lower it

The Lawson Criterion (the First Criterion) only considers bremsstrahlung loss from a plasma and neglects all other energy losses from the whole fusion reactor, that makes it much lower than that required of an actual fusion reactor. Thus an important parameter ηH - the overall heating efficiency of the fusion reactor must be added to the criterion. It is defined as ηH = (3nKT+Pbτ)V/Wf, where Wf is the total energy of reactor consumption per pulsed period; n, τ, T and V are the density, confinement time, temperature and volume of its plasma, respectively; Pb is the bremsstrahlung power. Only a fraction of Wf is injected into its plasma, namely Wp, and only a fraction of Wp is valid, which is equal to (3nKT+Pbτ)V. The rest of Wp are invalid, which are dissipated in heat conduct, cyclotron radiation, particle escape, etc. If the fraction of the nuclear reaction energy retained as thermal energy in the plasma is C, and the efficiency of energy conversion is η. Then the energy gain and breakeven conditions for a fusion reactor is η(3nKT+Pbτ+(1-C)Prτ)≥(3nKT+Pbτ-CPrτ)/ηH (1) where Pr is the nuclear power released in a plasma per unit volume. Thus a space of three dimensions can be composed of plasma temperature T, the product of density n and confinement time τ, and ηH from the eq.(1). The breakeven conditions for the actual fusion reactor are given by a surface in this space. It is called the Second criterion for realizing the breakeven. The Lawson Criterion expressed in the nτ-T space of two dimensions is a special example of the Second Criterion. The aim of investigating the fusion reactor criterion is to explore and to search for some ways to lower it. Some possible ways to lower this criterion are presented in this paper. 3 refs