An extensive series of experiments in the Extrap mode has been carried out on Extrap T1-U in an attempt to obtain hot, collisionless discharges. Using no external axial magnetic field, performance has been limited to low temperatures and low currents at high loop voltages kV, leading to energy confinement times of only a few s or Alfvén times. The discharge length is typically of the order of greater than 100 Alfvén times. Imposing a weak axial field at peak current) the temperature could be increased to at toroidal currents . Energy confinement times up to 15 Alfvén times were then obtained. The poor confinement is attributed to the weak axial magnetic field, generating strong instability-induced fluctuations and related radial transport in the core plasma. A turbulence core plasma transport model is suggested, based on theoretical evidence of linear instability in the kinetic regime. Self-generation of axial magnetic field is observed when the magnetic X-points, generated by the plasma current and an external octupole field, approach or pass beyond the wall. Edge transport appears to be dominated by line radiation and heat conduction to the wall along open field lines.