Generation of rotational transform in a toroidal confinement device with tilted coils

Experimental evidence was obtained, by means of an electron beam, that rotational transform can be generated in a toroidal configuration constructively similar to a tokamak, but solenoid-free and featuring six tilted toroidal-field coils. The coils are planar and, in fact, circular, hereby the device name CIRCUS [1]. In addition, the coils are interlinked to each other, which helps reducing the aspect ratio but is not strictly required. Comparisons between calculations and field-line mapping measurements will be presented, as well as predictions for devices featuring more coils, resulting in more axisymmetric plasmas. These are expected to operate at lower plasma current than a tokamak of comparable size and magnetic field, which might have interesting implications for disruptions and steady-state operation. Additionally, the toroidal magnetic ripple is less pronounced than in an equivalent tokamak in which the coils are not tilted.\\[4pt] [1] A. W. Clark et al., \textit{Fusion Eng.~Des.~} \textbf{89}, 2014