Measurement of Ampère-class pulsed electron beams via field emission from carbon-nanotube cathodes in a radiofrequency gun

Pulsed field emission from cold carbon-nanotube cathodes placed in a radiofrequency resonant cavity was directly measured. The cathodes were located on the backplate of a conventional 1+1/2 -cell resonant cavity operating at 1.3-GHz and resulted in the production of bunch train with maximum average current close to 0.7 Ampère. The measured Fowler-Nordheim characteristic, transverse emittance, and pulse duration are presented and, when possible, compared to numerical simulations. The implications of our results to the promise of high-average-current electron sources are briefly discussed.This work was funded via U.S. Department of Energy (DOE) Contract DE-SC0004459 with Radiabeam Technologies, LLC. Fermilab is operated by the Fermi Research Alliance, LLC. for the DOE under Contract DE-AC02-07CH11359