HIGH-POWER TEST OF THERMIONIC RF-GUN AT THE POHANG ACCELERATOR LABORATORY

A one-cell RF-gun with a dispenser cathode was fabricated for high-bri ghtness applications at the Pohang Accelerator Laboratory, The gun was designed to withstand heavy beam loading and breakdown for long-pulse operation, After some RF-conditioning, the gun could be powered up to a nominal RF-power of 3.5 MW during 6 mu s. The gun produced an elect ron beam with an average current of 300 mA and energy up to 1 MeV, nor mally operated with a 6-mu s macropulse and 12-Hz repetition rate, The beam loading and the energy spectra were measured to confirm the gun' s performance, The beam emittance was measured and compared with simul ation results. The breakdown problem due to the field-emitted electron s and the backward electrons in the gun is discussed.