  For modern high-intensity linear accelerators, the well-known envelope
instability and recently reported fourth-order particle resonance impose a
fundamental operational limit (i.e., zero-current phase advance should be less
than 90 deg). Motivated by the stability of spinning flying objects, we propose
a novel approach of using spinning beams to surpass this limit. We discovered
that spinning beams have an intrinsic characteristic that can suppress the
impact of the fourth-order resonance on emittance growth and the associated
envelope instability.
