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In extreme ultraviolet (EUV) lithography, plasmas are used to generate EUV light. Unfortunately, these plasmas expel high-energy ions and neutrals which damage the collector optic used to collect and focus the EUV light. One of the main problems facing EUV source manufacturers is the necessity to mitigate this debris. A magnetic mitigation system to deflect ionic debris by use of a strong permanent magnet is proposed and investigated. A detailed computational model of magnetic mitigation is presented, and experimental results from an EUV source confirm both the correctness of the model and the viability of magnetic mitigation as a successful means of deflecting ionic debris. [ABSTRACT FROM AUTHOR]

In this paper a detailed description of different passive shields for Extremely Low Frequency (ELF) applications is presented. The first part of the paper analyzes ferromagnetic and conductive materials by means of simulations and measurements. This step is mainly devoted to the identification of physical characteristics such as the relative permeability of the analyzed ferromagnetic materials. All the simulations are performed with a standard Finite Element (FE) code assuming linear behavior of the tested materials. The results are then used in the design of many shielding configurations and, finally, three different multilayer shield compositions are tested and presented. The second part of this paper outlines guidelines to assure a good shielding efficiency in the actual installation of a multilayer shield. The orientation of the shield as well as the possible decay of the shielding performance due to the discontinuity among the different slabs is investigated by means of experimental measurements. It is observed that the conductive part of the multilayer shield has to be faced to the source to have better performance. Moreover, it is important to assure the electrical conduction between the separate slabs. In this paper the conduction among different plates is conveniently obtained connecting them by straight bars of aluminum. In the third part of the paper the multilayer shield is tested under actual working conditions. A MV/LV substation was reproduced in the laboratory using a 630 kVA transformer working at its rated power. Several configurations were tested and the most significant results are presented. It is highlighted that, if the proper layout is not employed, the performance of the actual shield can be very different from the one of the material. [ABSTRACT FROM AUTHOR]