In one embodiment, an x-ray tube 15 can be used closer to a sample. An angle A1 between an anode axis 02 and an electron-beam axis 01 can be ≥10° and ≤80° and an angle A2 between the anode axis 02 and an x-ray axis 03 can be ≥10° and ≤80°. In another embodiment, a cap 20 on an anode 12 can block x-rays emitted in undesired directions. The cap 20 can include an internal cavity 24, an electron-beam hole 21, an anode hole 22, and an x-ray hole 23. In another embodiment, an electrical connection between an x-ray tube 15 and a power supply 18 can be reliable and easy to manufacture. The anode 12 can include a hole 31 at an end of the anode 12 sized and shaped for insertion of an electrical connector 32.