FIG. 7.

(a) Basic electrical schematic of a resonant tank for establishing large circulating currents and an intuitive model with nearly identical impedance vs frequency characteristics. (b) Impedance vs frequency for a handheld coil with various resonances. (c) Analysis of the role of voltage and power constraints on optimizing the number of turns in an idealized tank circuit. (d) Measured Q-factor values of resonant tanks with comparable inductance and resonance frequencies but different inductor design. (e) Photographs of the coils measured in (d). Tank i is a simple 8 turn copper tubing coil. Tank ii incorporates 4 parallel copper tube conductors into an 8 cm diameter two turn solenoid. Tank iii incorporates two parallel litz wires (42 × 10 × 10/44 AWG) surrounded by flexible Teflon tubing for flow.