SYSTEMS CODE COMPARISON OF INTERNAL AND EXTERNAL PF COIL CITS.

System studies are performed to examine the tradeoffs of placing the poloidal field (PF) coils external to the toroidal field (TF) coils or internal to the TF coils in Compact Ignition Tokamaks (CITs). This study compares the size requirements for internal and external PF CIT options having the same performance levels and compares performance capabilities of internal and external CITs of the same size. It is found that the internal PF systems are slightly smaller (about 5 cm) than comparable-performance external PF CITs. The primary difference in the radial builds of the internal and external CITs results from the movement of the ohmic heating (OH) solenoid. At the same major radius, the all-internal PF case can achieve about 10% larger field-on-axis levels (a physics performance parameter) than the external PF CIT. For the internal PF CIT, the power supply requirements are dominated by the TF coil (90%), whereas for the external PF coil case, the TF and PF coil circuits have roughly equal contributions to the power supply requirements.