An InGaN photocathode with a negative electron affinity (NEA) surface is suitable for industrial use because of features such as a long quantum efficiency lifetime, availability with a visible laser as an excitation light source, and the presence of a transmission-type structure. The first objective is the development of an InGaN photocathode electron gun that can be mounted on a scanning electron microscope (SEM) and the evaluation of the electron beam size at the emission point, maximum emission current, and transverse energy of the electron beam, which are important factors for realizing a high probe current in the SEM. The second objective is the evaluation of emission current stability, while the third objective is the generation of a pulsed electron beam and multi-electron beam from the InGaN photocathode. The parameters of the electron beam from the photocathode electron gun were an emission beam radius of 1 μm, transverse energy of 44 meV, and an emission current of up to 110 μA. Using a high beam current with low transverse energy from the photocathode, a 13 nA probe current with 10 nm SEM resolution was observed with 15 μA emission. At 15 μA, the continuous electron beam emission for 1300 h was confirmed; at 30 μA, the cycle time between the NEA surface reactivations was confirmed to be 90 h with 0.043% stability. Moreover, a 4.4 ns pulsed e-beam with a 4.7 mA beam current was generated, and a 5 × 5 multielectron beam with 12% uniformity was then obtained. The advantages of the InGaN photocathode, such as high electron beam current, low transverse energy, long quantum efficiency lifetime, pulsed electron beam, and multi-electron beam, are useful in industries including semiconductor device inspection tools.
In order to apply failure diagnosis of a rotating machine, normal and abnormal vibrations of a rotating-element bearing were formulated by Herzian contact theory and the results of numerical simulation were applied to decide the existence of a defect. In this paper, firstly three dimensional dynamics of a rotating-element bearing under thrust load were considered and motion equations of bearing elements were developed. And then, in order to consider abnormal vibrations by bearing defects, defects were classified to the three types of impulse train and these impulse trains were added to the motion equations. Moreover, some numerical simulations were conducted by Runge-Kutta method and compared with experimental examples. In the result, it was found that thrust vibrations of a rotating-element bearing has one eigen frequency and this eigen frequency does not change largely by rotating speed and presence of a defect. Using these characteristics, the new method of failure detection was applied to a rotating-element bearing at low speed and the effectiveness of this diagnosis method was confirmed by an example.
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