Browsing by Author "Shimizu, Hiroshi"

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    Emittance measurement of high-brightness microbeams
    (Japanese Journal of Applied Physics, 1994) Musyoki, Stephen; Ishizuka, Hiroshi; Nakahara, Yuriko; Kawasaki, Sunao; Shimizu, Hiroshi; Watanabe, Akihiko; Shiho, Makoto
    Arrays of microtriodes have recently become available due to the development of microfabricated field-emission electron sources. Computer simulation has shown that the brightness of beams emitted by them is significantly higher than that of the common microbeams, and possible application of the accelerated beam to free electron lasers has been discussed. Experimentation on beam generation has started, but methods for diagnosing the beam have not yet been established. Difficulty is predicted, because of the high brightness, in applying the conventional methods of emittance measurement. In this paper we propose a new method that determines the emittance without using apertures. The cross section of a converging beam is elongated by a quadrupole lens, and parameters of the emittance ellipse are obtained from the beam size on a screen when changing either the strength or the axial position of the quadrupole lens.
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    A new method of emittance measurement for electron beams from the Micro-emitter
    (1994) Ishizuka, Hiroshi; Nakahara, Yuriko; Kawasaki, Sunao; Musyoki, Stephen; Shimizu, Hiroshi; Watanabe, Akihiko; Shiho, Makoto
    Recently a new type of cathode called Micor-emitter has been put in progress. This cathode is a microfabricated field emitter having the characteristics of very low emittance and high brightness. We cannot measure the emittance of the cathode with conventional methods like the pepper-pot method. The reasons are: (1) the angle between the electron orbit and the axis is very small and (2) we cannot focus the electron beam in the vacuum or on the surface of the material since the current density of the cathode is extremely high. For the emittance measurement for such low emittance and high brightness cathode, we need to expand the beam, and measure the beam's cross section without any slits or apertures. We studied and proposed a new emittance measurement method for the Micro-emitter.