The diamond amplifier (DA) is a new device for generating high-current, high-brightness electron beams. Our transmission-mode tests show that, with single-crystal, high-purity diamonds, the peak current density is greater than $400\mathrm{mA}/{\mathrm{mm}}^2$, while its average density can be more than $100\mathrm{mA}/{\mathrm{mm}}^2$. The gain of the primary electrons easily exceeds 200, and is independent of their density within the practical range of DA applications. We observed the electron emission. The maximum emission gain measured was 40, and the bunch charge was $50\mathrm{pC}/0.5{\mathrm{mm}}^2$. There was a 35% probability of the emission of an electron from the hydrogenated surface in our tests. We identified a mechanism of slow charging of the diamond due to thermal ionization of surface states that cancels the applied field within it. We also demonstrated that a hydrogenated diamond is extremely robust.

• Received 11 March 2010

DOI:https://doi.org/10.1103/PhysRevLett.105.164801