Elimination of the central solenoid is a consideration for the design of toroidal confinement devices, which then require alternative methods for initiating the plasma current. A new method of non-inductive startup, referred to as transient coaxial helicity injection (Transient CHI) [1,2,3], has been successfully developed on the Helicity Injected Torus, experiment [4], and recently implemented on the National Spherical Torus Experiment [5]. In this method, a plasma current is rapidly produced by discharging a capacitor bank between coaxial electrodes in the presence of toroidal and poloidal magnetic fields, shown schematically in Fig. 1. An initial very small gas puff is introduced near the injector, which is ionized by the applied voltage.The initial poloidal field configuration is chosen such that the plasma rapidly expands into the chamber. When the injector current is rapidly decreased, magnetic reconnection occurs near the injector electrodes, with the toroidal plasma current forming closed flux surfaces. By selfconsistently increasing both the injector flux and the externally produced toroidal flux, the useful CHI-produced current on closed flux surfaces has been increased to 100 kA on HIT-II, and is retained during a subsequent inductive ramp. On HIT-II, CHI-started plasmas outperform discharges initiated by induction alone and consume less volt-seconds. [3] Transient CHI is successfully used on NSTX for an unambiguous proof-of-principle demonstration of closed-flux current generation, of up to 160 kA, without the use of the central solenoid. Significant improvements over the HIT-II results are (a) demonstration of the process in a vessel volume thirty times larger than HIT-II on a size scale more comparable to a reactor, (b) a multiplication factor of 60 between the injected current and the achieved toroidal current, compared to six in previous experiments, and (c) significantly more detailed experimental measurements, including, for the first time, fast time scale visible imaging of the entire process, showing discharge formation, disconnection from the injector, and the reconnection of magnetic field lines to form closed flux. In some discharges the generated current persists for an unprecedented, and unanticipated 400 ms (until external equilibrium coils are shut off).These significant results, which were obtained on a machine designed with mainly conventional components and systems, indicate favourable scaling with machine size.From helicity conservation, for a Taylor minimum energy state, λ inj ≥ λ tok , where λ inj =