Two methods of using the X pinch as a source of X-ray radiation for the radiography of dense plasmas and other objects
are presented. These methods do not use pinholes, instead taking advantage of the small source size (<1 mm, and in some
cases <1 pm) and short X-ray emission duration (< 2 ns , and < 20 ps in some cases) of the X pinch radiation. Detailed
measurements of the emission characteristics of X pinches made using different wire materials and in different energy
ranges using a set of X-ray diagnostics with high temporal and spatial resolution are presented. Several applications of
the X pinch are discussed.
We present a system for diagnostic imaging of x-ray sources using a compound refractive lens. Such a system can be built at a low cost, yet image at resolutions of 2 μm or better. The essential components of the system are the source to be imaged, a compound refractive lens and imaging detector (either electronic or film). In addition, spatial and spectral filters can be added to improve resolution and a laser alignment system can be used to rapidly align the source, lens and camera.
X pinch radiation produced by electron beams accelerated in the X pinch minidiode ranging in energy from 10 to 100 keV has been studied and used to image a variety of different objects. The experiments have been carried out using the XP pulser (470 kA, 100 ns) at Cornell University and the BIN pulser (280 kA, 120 ns) at the P.N. Lebedev Physical Institute. This electron-beam-generated x-ray source's geometric, temporal and spectral properties have been studied over different energy ranges between 10 and 100 keV. The imaging was carried out in a low magnification scheme, and spatial resolution of a few tens of μm was demonstrated.
The X pinch plasma emits subnanosecond bursts of x-rays in the 3 - 10 keV energy range from a very small source. As such, it has been used for high-resolution point-projection imaging of small, dense, rapidly changing plasmas, as well as submillimeter thick biological samples. The very small x-ray source size of the X pinch provides high spatial coherence of the x-rays, enabling the X pinch to be used for imaging low absorption, low contrast objects with excellent spatial resolution by incorporating wave-optics effects. The reverse procedure has been used to determine the X pinch x-ray source size: well-defined micro-fabricated slits were imaged by point-projection radiography, and the detailed patterns were compared with wave-optics calculations of the expected image patterns on film as a function of x-ray source size and energy band. In addition, an x-ray streak camera was used to study the X pinch source size as a function of time. Dynamic shadow images of a boron fiber with a tungsten core and glass fiber sheathed in plastic were compared with a time-integrated radiographic image. Source sizes as small as 1.2 μm (full width at half maximum, assuming a Gaussian spatial intensity profile for the source) have been inferred.
The application of the X pinch x-ray source for phase-contrast x-ray radiography of low absorption materials is demonstrated. The X pinch is a source of radiation in the 1-10 keV x-ray band with extremely small size and short pulse duration. The small source size provides high spatial coherence of the imaging x-ray beam, enabling it to be used to image low absorption, low contrast objects with excellent spatial resolution. Images with spatial resolution better than 3 micrometers of exploded, insulated 25 micrometers W wire and biological objects are presented. The advantages of the X-pinch over other x-ray sources are discussed.
Several methods of using the X pinch as a source of x-ray radiation for the radiography of dense plasmas and other objects are presented. These methods do not use pinholes, instead taking advantage of the small source size and short x-ray emission duration of the X pinch radiation. Detailed measurements of the emission characteristics of X pinches made using different wire materials and in different energy ranges using a set of x-ray diagnostics with high temporal and spatial resolution are presented. Several applications of the X pinch are discussed.
The results are presented of investigations of extremely dense plasmas generated from exploding wires using a new method, monochromatic x-ray backlighting. In this method, shadow images of a bright, dense plasma can be obtained with high spatial resolution using monochromatic radiation from a separate plasma, permitting a major reduction in the required backlighting source power. The object plasma is imaged utilizing x-ray optical elements with spherically bent mica crystals. In particular, shadow images of exploding Al wire plasmas in the 1s2-1s3p line radiation of He-like Al XII were obtained. The images confirm the existence of a low density 'corona' around the wire at an early stage of the wire explosion process, with a dense core at the original wire position. Test experiments were also done with laser produced backlighter plasmas. Spatial resolution of 10 microns was demonstrated. The scheme described here is useful for backlighting extended high density plasmas, and could be a less costly alternative to using x-ray lasers for such purposes.
This paper describes a 1 kW average power soft x-ray source for application to sub-micron lithography. This source will be capable of 1 second resist exposure times, assuming 15 mJ/cm2 resist sensitivity, with feature sizes < 0.18 micron. The source is based on the X-Pinch, a pulsed plasma soft x-ray source which was initially developed at Cornell University for lithography. Experiments have been performed to characterize the radiation emitted from magnesium (Mg) wire X-Pinch plasmas using an 80 ns, < 500 kA pulse. Applied Pulsed Power has designed and is building a 1 kW average power soft x-ray source using the X-Pinch and a 40 pulse/second (pps), 500 kA/pulser. This system is designed to deliver 25 mW/cm2, after the attenuation due to a protective beryllium (Be) foil filter and the lithography mask, to a wafer located 56 cm from the source. This paper summarizes the experimental results and discusses the implications of these test results for microlithography applications. The design of the 1 kW source is described, including the pulser, 40 pps wire array loader, and the debris shielding. Results of initial system testing are presented.