Measurements Of X-ray Production Research Articles

Reverse field injection for the gradient B drift transport of a high-current electron beam

Reverse field injection was used to inject a 0.9-MeV electron beam produced in a ring diode into a drift tube. The annular beam then was transported distances of up to 183 cm by gradient B drift in an applied magnetic field. The electron beam struck a tantalum target at the end of the drift tube, producing bremsstrahlung x-rays. An electron beam current of 1.1 MA was inferred from measurements of x-ray production in the target. This implies an injection efficiency of 69%.

Characterization and optimization of a laser generated plasma source of soft X rays

An investigation into the feasibility of using a laser-generated plasma source of soft X rays as a laboratory based instrument for biological imaging and microlithography is presented. A preliminary characterization of the source has been carried out with carbon, copper and aluminum targets with specific interest in generating a monochromatic source of soft X rays in the ‘water window’. Measurements of X-ray production with respect to angular distribution, effects of cratering and different focusing conditions are reported. Initial conclusions on the optimization of the source for use in biological imaging are drawn.

Gradient B drift transport of high current electron beams

A 1-MeV, 200-kA electron beam was transported 89 cm in a low pressure background gas via gradient B drift in the 1/r azimuthal magnetic field of a current carrying wire. The electron drift velocity was measured and found to be in good agreement with theory. Measurements of x-ray production in the target indicated high transport efficiency.

Universal cross sections forK-shell ionization by low-velocity protons: Importance of relativistic and energy-loss effects

When Z1 << Z2, inner-shell ionization of a target atom of atomic number Z2 by a projectile of atomic number Z1 occurs predominately via removal of an inner-shell electron to the target atom continuum (direct ionization). Electron capture contributes then insignificantly to the ionization, and thus the predictions of perturbative-in-Z1/Z2 theories of direct ionization can be tested through comparison with measured ionization cross sections. We present such a comparison with the recently reported data1 for K-shell ionization of the Z2 = 22, 26, 28, and 30 elements by 60–150 keV protons (Z1=1). These ionization cross sections were inferred from x-ray production measurements using Krause’s fluorescence yields.2