Shin, Y.-M. Fagerberg, G. Figora, M. Green, A.T. JACoW Geneva, Switzerland 978-3-95450-180-9 10.18429/JACoW-NAPAC2016-WEPOA40 English 785-788 WEPOA40 ion cathode electron gun emittance Contribution to a conference proceedings 2017 2017-01 http://dx.doi.org/10.18429/JACoW-NAPAC2016-WEPOA40 https://jacow.org/napac2016/papers/wepoa40.pdf We have been constructing a S-band RF-injector system for field-emission tests of a CNT-tip cathode. A pulsed S­band klystron is installed and fully commissioned with 5.5 MW peak power in a 2.5 micro­second pulse length and 1 Hz repetition rate. A single-cell RF­gun is designed to produce with 0.5 - ­ 1 pC electron bunches in a photo-emission mode within a 50 fs­ - 3 ps at 0.5-­ 1 MeV. The measured RF system jitters are within 1 % in magnitude and 0.2° in phase, which would induce 3.4 keV and 0.25 keV of energy jitters, corresponding to 80 fs and 5 fs of temporal jitters, respectively. Our PIC simulations indicate that the designed bunch compressor reduces the TOA­jitter by about an order of magnitude. Emission current and beam brightness of the field-emitted beam are improved by implanting CNT tips on the cathode surface, since they reduce the emission area, while providing high current emission. Once the system is completely commissioned in field-emission mode, the CNT-tip cathode will be tested in terms of klystron-power levels to map out its I-V characteristics under pulse emission condition.