An assembly for adjusting gas flow patterns and gas-plasma interactions including a toroidal plasma chamber. The toroidal plasma chamber has an injection member, an output member, a first side member and a second side member that are all connected. The first side member has a first inner cross-sectional area in at least a portion of the first side member and a second inner cross-sectional area in at least another portion of the first side member, where the first inner cross-sectional area and the second inner-cross-sectional area being different. The second side member has a third inner cross-sectional area in at least a portion of the second side member and a fourth inner cross-sectional area in at least another portion of the second side member, where the third inner cross-sectional area and the fourth inner-cross-sectional area being different.