Use of ion processing to improve the quality of fullerene-coated field emitters
The efficiency of tip field emitters covered by activated fullerene coatings is studied in a wide range of emission currents and residual gas pressures. Main mechanisms behind the influence of the gaseous medium and ion bombardment on the emitter efficiency are determined. The feasibility of improving the homogeneity of the fullerene coating by potassium ion bombardment is demonstrated. From data on the emitter performance in a technical vacuum, a previously unknown effect is discovered: the structure of activated fullerene coatings is reproduced under intense ion bombardment. It is found that intense bombardment by residual gas ions increases a limiting current extracted from fullerene-coated tip field emitters.
The purpose of this study is to investigate the accuracy of dose predicted by cone convolution algorithm. This work describes an experimental verification of two dose calculation algorithms available on the Philips Pinnacle3 (version 8.0) commercial radiotherapy treatment planning system (TPS): Collapsed cone convolution and Fast convolve. Both experiment and TPS were tested for 6 MV photon beam, the fields were 5cm×5cm and 10cm×10cm respectively. Dosimetry was performed with thermoluminescent dosimeters. At the end of this article, we analyzed the difference between calculation and experiment