Matching and transport of beams in a continuously twisted quadrupole channel

Twisted quadrupole (stellarator) focusing can reduce dispersion in the bends of a recirculating accelerator such as the Spiral Line Induction Accelerator (SLIA). Envelope oscillations caused by guide field/stellarator transitions add free energy to the beam which can couple into the beam emittance. This effect can be reduced by phase space matching of the beam at the transitions. Experimental results are presented on the coupled 4D problem of envelope matching into a straight helical quadrupole channel. These results are compared with envelope code predictions. Expected benefits from such matching in a few-turn accelerator system are discussed.<>