Target windows for isotope systems

A target for an isotope production system, the target comprising:

• a body configured to encase a target material and having a passageway for a charged particle beam;
• and
• a target window between a high energy particle entrance side and a target material side, the target window comprising a plurality of foil members in a stacked arrangement, wherein sides of different ones of the plurality of foil members engage one another, at least two of the plurality of foil members having different material properties.

An isotope production system comprising:

• an accelerator including an acceleration chamber;
• and
• a target system located inside, adjacent to or a distance from the acceleration chamber, the accelerator configured to direct a particle beam from the acceleration chamber to the target system, the target system having a body configured to hold a target material and a target window within the body between a high energy particle entrance side and a target material side, the target window comprising a plurality of foil members in a stacked arrangement, wherein sides of different ones of the plurality of foil members engage one another, at least two of the plurality of foil members having different material properties.