High quantum energy efficiency X-ray tube and targets

An end window x-ray tube comprising:

• an evacuated housing that is sealed;
• an end window anode disposed in said housing comprised of a target of a thin foil or a plurality of thin foils;
• a cathode disposed in said housing which emits an electron beam, which proceeds along a beam path in said housing to strike said anode in a spot, generating a beam of x-rays which exits the housing through the end window;
• wherein said electron beam is focused above, below or onto the target by a focusing lens;
• a power supply connected to said cathode providing a selected electron beam energy to produce a bright beam of x-rays characteristic of the target foil or foils;
• and wherein the thickness of the target foil or foils is less than two times the electron penetration depth of the electrons striking the target producing predominantly bremsstrahlung x-rays.

An x-ray transmission tube comprising:

• (a) a sealed, evacuated housing,
• (b) an end-window anode disposed in said housing comprising a target of at least two different foils layered sequentially one on the other, each of the different foils comprising a different material;
• (c) a cathode disposed in said housing emits an electron beam;
• wherein x-rays are produced when an electron beam impinges the foil closest to the source of the electron beam;
• wherein the energy spectrum of said x-rays is determined at least in part by the energy of the electron beam impinging on the target material;
• and
• (d) power supply means connected to said cathode for enabling the electron beam to be produced with either (i) a first preselected energy whereby to cause only the first foil to emit a characteristic emission with said line emission being characteristic of the first foil or (ii) a second preselected energy whereby to cause each of the first and second foils to produce a line emission with the line emission of the first foil being characteristic of the first foil and the line emission of the second foil being characteristic of the second foil.