Nonintrusive measurement of time-resolved emittances of 1-GeV operational hydrogen ion beam using a laser comb

We proposed and demonstrated a novel technique to measure time-resolved transverse emittances of the hydrogen ion (${\mathrm{H}}^{\ensuremath{-}}$) beam in a 1-GeV high-power accelerator. The measurement is performed in a nonintrusive manner by using a laser comb---laser pulses with controllable multilayer temporal structure. The technique has been applied to the transverse emittance measurement of a 1-GeV ${\mathrm{H}}^{\ensuremath{-}}$ beam in the Spallation Neutron Source high energy beam transport line. More than 20 time-resolved emittances have been simultaneously determined within a macropulse, a single minipulse, or a single bunch of the 1.4-MW neutron production ${\mathrm{H}}^{\ensuremath{-}}$ beam from a single measurement.