Investigations of X-ray metallic capillaries

Abstract

In our previous contributions [R. Mroczka, G. Żukociński, A. Kuczumow, J. Alloys Compd. 362 (2004) 88–95; R. Mroczka, G. Żukociński, A. Kuczumow, Geometrical description of the X-ray capillary and total reflection mirror surfaces with assumed reflection features, J. Alloys Compd. 382 (2004) 311–319], we solved the problem of analytical description of capillaries with designed reflection features. Now, the numerical program for ray tracing simulations was written, fully basing on our original analytical calculation of trajectories. All parameters essential for X-ray capillary optics system, such as point and extended X-ray sources, different ranges of photon energy, geometrical parameters of capillaries, variable surface roughness, different kinds of materials (mainly metals), location of target in relation to capillary, were tested. Profiles of output photon beam on the target were obtained. Here, some results of simulations, such as the influence of the photon energy, the capillary sizes and the internal wall smoothness on the efficiency of propagation were presented. All simulations were helpful in making decisions about the optimal shapes and parameters of capillaries that were manufactured in our laboratory. In the preliminary experimental work, the electrochemical manufacturing of capillaries with the metallic (Cu and Ni) walls was described. The cathode wire was coated with copper layer in controlled electrolytic process. It led to precise formation of the parabolic shape of a core part. Subsequently, a thin layer of nickel was coated in electroless way and electrochemically passivated. Then, a thin copper layer and subsequently, thick nickel one were electroplated, forming the body part of the capillary. The adjustment of the internal walls of the capillaries to the designed shape was controlled with the electron microscope and it was proved that it could be kept within ±1 μm scatter on a distance of several centimeters along the main axis. The roughness (rms) of the internal capillary walls was controlled by the atomic force microscope. The roughness was kept in the range of 3.5–5 nm and was in the low limit of allowed levels. The production will be optimized in the future.