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Beyond single-fluid magnetohydrodynamics, multi-scale plasmas have been widely employed in recent studies on toroidal plasmas. To comparatively investigate two-fluid plasmas in a single machine, we devised an efficient method for designing an optimal set for comprehensively supporting existing toroidal field coils (TFCs) linked to a torus chamber. Electromagnetic forces acting on the TFCs and the strain in the TFCs were precisely calculated by using a three-dimensional (3D) finite element analysis method. Based on the obtained results, various additional support components to be attached to specific weak places of the TFCs were determined. Experimental studies revealed that the strain observed in the TFCs was reduced to considerably less than its yield strain by using the additional support components. The value of the strain was consistent with those of 3D simulations. The aid of additional support components to existing TFCs allows modern comparative studies such as those on two-fluid plasmas in the same machine, in which tokamak edges as well as reversed-field pinches with low densities and distinct safety factors are considered. The results can provide insight into the two-fluid plasma mechanism, thus aiding future fusion plasma development. • An efficient method was developed for designing a minimum set for supporting existing toroidal field coils (TFCs). • Forces as well as the strain in the TFCs are calculated by using a three-dimensional finite element analysis method and consistent with measurements. • Obtained results can provide guidelines for the development of additional support components for TFCs of any other existing toroidal machines. • Comparative studies between circular cross-section tokamaks and RFPs in the same machine with relatively low density will promote our understandings for two-fluid toroidal plasmas. [ABSTRACT FROM AUTHOR]