  VOR, the versatile optimal resolution chopper spectrometer, is designed to
probe dynamic phenomena that are currently inaccessible for inelastic neutron
scattering due to flux limitations. VOR is a short instrument by the standards
of the European Spallation Source (ESS), 30.2 m moderator to sample, and
provides instantaneous access to a broad dynamic range, 1 - 120 meV within each
ESS period. The short instrument length combined with the long ESS pulse width
enables a quadratic flux increase, even at longer wavelengths, by relaxing
energy resolution from $\Delta$E/E = 1% up to $\Delta$E/E = 7%. This is
impossible both on a long chopper spectrometer at the ESS and with instruments
at short pulsed sources. In comparison to current day chopper spectrometers,
VOR can offer an order of magnitude improvement in flux for equivalent energy
resolutions, $\Delta$E/E = 1-3%. Further relaxing the energy resolution enables
VOR to gain an extra order of magnitude in flux. In addition, VOR has been
optimised for repetition rate multiplication (RRM) and is therefore able to
measure, in a single ESS period, 6 - 14 incident wavelengths, across a
wavelength band of 9 \AA{} with a novel chopper configuration that transmits
all incident wavelengths with equivalent counting statistics. The
characteristics of VOR make it a unique instrument with capabilities to access
small, limited-lifetime samples and transient phenomena with inelastic neutron
scattering.
