An x-ray source comprising a housing, in which a target in the form of an ionized cloud based on metal vapour is provided. The ionized cloud can be excited by means of an electron beam for emitting monochromatic x-rays. The low atom density advantageously produces only a little braking radiation. The robustness of the plasma with respect to the inevitable thermal energy input is also advantageous with respect to the solid target materials. The cloud can be filled at any time with target material which can be vaporised by means of an electric arc. A method for producing x-rays with the above-mentioned x-ray source is also provided. The use of an x-ray source for emitting monochromatic x-rays for x-raying a body is further provided.