the thermal energy attributable to the anode target 164 is effectively removed from the electron collector assembly 110 and the vacuum vessel 112 in addition to the embodiments discussed above it is to be understood that the electron collector assembly may take on various alternative embodiments as well for example in addition to the first plate having a plurality of protrusions protruding from its first side the second plate may similarly have a plurality of thermally emissive protrusions protruding from its second side furthermore though the electron collector assembly described hereinabove largely comprises two separate plates and an inner member that are joined together it is to be understood that the electron collector assembly may alternatively comprise two plates and an inner member that are substantially integral with each other or even a single substantially monolithic plate in an exemplary embodiment comprising a single monolithic plate for example the plate itself may comprise an electrically conductive metal and be thermally emissive such a monolithic plate may have a plurality of thermally emissive protrusions protruding from a first side a second side or both the first and second sides and an internal conduit sandwiched between the first and second sides of the plate the internal conduit allowing a heat absorbing cooling fluid to flow therethrough in an exemplary embodiment comprising a single monolithic plate for example the plate itself may comprise an electrically conductive metal and be thermally emissive such a monolithic plate may have a plurality.