[en] The important physics considerations involved in the current TNS tokamak design are divided into four parts: (1) PLASMA DYNAMICS: The minimum β required for ignition is shown to be insensitive to the transport scaling used (with β approximately 5%). It is also argued that particle diffusion alone may set an upper limit to the β-value achievable in a tokamak. (2) PLASMA HEATING: The theory of lower hybrid (LH) heating of a tokamak plasma is presented with applications to the current TNS models. (3) PLASMA SHAPING AND MHD: The double layer field shaping coil and the doubly indented ''peanut'' systems are analyzed from the standpoints of stability, control, and external power demands. (4) PLASMA BOUNDARY PHYSICS: The behavior of potential limiter materials under thermonuclear burn conditions is examined. A combination of Be-Ni and carbon are shown to best satisfy current TNS requirements, with carbon serving in the high load regions. The surface physics involved along the first wall is shown to have a strong impact on the efficiency of any vacuum pumping system