X-ray emission from a compact hot plasma: applications to radiology and mammography

Hot electrons confined in a compact magnetized plasma (in a 1 litre chamber) and heated by electron cyclotron resonance were used to provide an intense reproducible x-ray emission. Since electrons were generated in situ, the use of filaments and high voltages at the base of the x-ray tubes was avoided. The source can be pulsed or operated in a highly stable continuous mode. The spatial and energetic characteristics of the hot electrons were determined via their bremsstrahlung by comparison with theoretical calculations. In this test x-ray source the average energy of the hot electron flux was in the range 10-40 keV, depending on the operating parameters: intermagnet distance (6-9 cm), power of the 2.45 GHz microwave (200-1000 W), chamber pressure (4 x 10(-5)-9 x 10(-5) Torr). The insertion of solid targets into the electron flux leads to various focal spot sizes, enabling application in radiology and mammography. The images of a mammographic phantom were obtained in a few seconds with good contrast (microcalcifications being successfully detected).