  A method to achieve High-Brightness Self-Amplified Spontaneous Emission
(HB-SASE) in the Free Electron Laser (FEL) is described. The method uses
repeated non-equal electron beam delays to de-localise the collective FEL
interaction and break the radiation coherence length dependence on the FEL
cooperation length. The method requires no external seeding or photon optics
and so is applicable at any wavelength or repetition rate. It is demonstrated
using linear theory and numerical simulations that the radiation coherence
length can be increased by approximately two orders of magnitude over SASE with
a corresponding increase in spectral brightness. Examples are shown of HB-SASE
generating transform-limited FEL pulses in the soft X-ray and near
transform-limited pulses in the hard X-ray. Such pulses may greatly benefit
existing applications and may also open up new areas of scientific research.
