Patent Number: 045049645
Section: description

DETAILED DESCRIPTION X-ray system 2 in FIGS. 1 and 2 includes a pair of electrodes 4 and 6 spaced by an axial gap 8 therebetween. Electrode 6 is a cylindrical member having a plurality of circumferentially spaced axial passages such as 10 and 12 therethrough. A plurality of laser sources such as 14 and 16 direct laser beams axially through the axial passages such as 10 and 12 such that a cylindrical array of laser beams impinge on electrode 4 in an annular pattern as shown at 18. Electrode 6 may alternatively have an annular passage therethrough, in place of plural passages such as 10 and 12. Electrode 4 is a target electrode of a given substance, for example aluminum, for producing plasma vapor in response to laser impingement thereon. Upon closing switch 20, a large storage capacitor 22, charged from voltage source 24, discharges electrode 4 across axial gap 8 to electrode 6. This passes high current through the plasma annulus in gap 8, causing magnetic field pinching of the plasma radially inwardly. This radial inward pinching of the plasma further heats the plasma and causes X-ray emission from the pinched plasma. Referring to FIG. 2, the annular pattern of the plasma before pinching is shown at 18, and the constricted pinched plasma is shown at 26. The X-rays are emitted through an axial passage 28 in the target electrode 4 coaxially aligned with the centrally pinched plasma 26. Alternatively, the X-rays may be emitted back through a central axial passage 30 through the other electrode 6. The axial emission orientation of the X-rays enables placement of a masked semiconductor substrate 32 normal to the axial direction of emission for impingement by the X-rays. An additional laser beam from another laser source 34 may be directed through central axial passage 30, regardless of which direction X-rays are emitted. This additional central laser beam impinges on the radially inwardly pinched central plasma 26 in gap 8 and further heats the pinched plasma. In an alternative, a single laser source may be used with a beam splitter, such as mirror or prism means, to provide a plurality of circumferentially spaced laser beams. It is recognized that various modifications are possible within the scope of the appended claims.