We devised and built a light, compact and transportable X-ray polarized source based on the Bragg diffraction
at nearly 45 degrees. The source is composed by a crystal coupled to a small power X-ray tube. The angles of
incidence are selected by means of two orthogonal capillary plates which, due to the small diameter holes (10
μm) allow good collimation with limited sizes. All the orders of diffraction defined by the crystal lattice spacing
are polarized up to the maximum order limited by the X-ray tube voltage. Selecting suitably the crystal and the
X-ray tube, either the line or the continuum emission can be diffracted, producing polarized photons at different
energies. A very high degree of polarization and reasonable fluxes can be reached with a suitable choice of the
capillary plates collimation.
We present the source and test its performances with the production of nearly completely polarized radiation
at 2.6, 5.2, 3.7 and 7.4 keV thanks to the employment of graphite and aluminum crystals, with copper and calcium
X-ray tubes respectively. Triggered by the very compact design of the source, we also present a feasibility study
for an on-board polarized source, coupled to a radioactive Fe55 nuclide and a PVC thin film, for the calibration
of the next generation space-borne X-ray polarimeters at 2.6 and 5.9 keV.