Sausage instability in a proton-beam transport through wall-confined plasma channel in Nagaoka ETIGO-I

Transport of an intense pulsed proton beam with an energy of 800-keV has been studied through a wall-confined, z-discharged plasma channel (1-m long) in the Nagaoka ETIGO-I. The transport efficiency increases with increasing channel current or decreasing channel pressure. Reasonable agreement is obtained between the experiment and the existing theories. Changing the timing between the channel current and the beam injection, we have found that there exists a relevant timing for the beam injection. In some cases, the beam ceases to be transported through the channel due to the presence of some plasma instabilities. The non-transport region has been clarified in a parameter space.