Study on Radiation from Microbunch Electrons

1.Studies on microbunch FEL were carried out using a linac facility of the Research Laboratory for Nuclear Science(LNS)at Tohoku University and that of Kyoto University Research Reactor Institute(KURR)。We have clarified that the amplification of radiation of the TEM ei D200锡D2 mode occurred in an open cavity of the cylindrical symmetry and studied fundamental properties such as the tuning characteristics and the spectral distribution of the out-put intensity。Fundamental information was obtained to develop the FEL of higher power.2。We have constructed systems of spectrophotometric measurement using coherent transition radiation as the light source。At KURR the intensity of the coherent source in the millimeter wave region was more intense than high pressure mercury lamp by 3to4orders of magnitude.By observation of the absorption spectrum of N I D22西耶D2O gas，the usefulness of the spectroscopic system was confirmed in the low energy region from3to several tens of wavenumber。At LNS a rapid-scanning interferometer was constructed which can be scanned in70seconds to observe a spectrum with a resolution of 0.5wavenumber.3。We constructed two kinds of bunch shape monitors using a rapid-scanning interferometer and a polychromator.The former type covers the wavenumber region from 15µm to 5 mm with the maximum resolution of 0.25 wavenumber and the observation of the bunch shape takes about5s.The polychromator type covered the wavelength range from 0.2 to 4 mm with the resolving power of 10 and it can measure the bunch shape in about one second.Using the two systems，it has been demonstrated that fast monitors of bunch shape have been successfully developed for the sub-millimeter region，or pico-second region in time scale.It will be easy to extend the region of monitoring to visible and UV region，or femto-second region。

1. Studies on microbunch FEL were carried out using a linac facility of the Research Laboratory for Nuclear Science (LNS) at Tohoku University and that of Kyoto University Research Reactor Institute (KURR). We have clarified that the amplification of radiation of the TEMィイD200ィエD2 mode occurred in an open cavity of the cylindrical symmetry and studied fundamental properties such as the tuning characteristics and the spectral distribution of the out-put intensity. Fundamental information was obtained to develop the FEL of higher power.2. We have constructed systems of spectrophotometric measurement using coherent transition radiation as the light source. At KURR the intensity of the coherent source in the millimeter wave region was more intense than high pressure mercury lamp by 3 to 4 orders of magnitude. By observation of the absorption spectrum of NィイD22ィエD2O gas, the usefulness of the spectroscopic system was confirmed in the low energy region from 3 to several tens of wavenumber. At LNS a rapid-scanning interferometer was constructed which can be scanned in 70 seconds to observe a spectrum with a resolution of 0.5 wavenumber.3. We constructed two kinds of bunch shape monitors using a rapid-scanning interferometer and a polychromator. The former type covers the wavenumber region from 15 μm to 5 mm with the maximum resolution of 0.25 wavenumber and the observation of the bunch shape takes about 5 s. The polychromator type covered the wavelength range from 0.2 to 4 mm with the resolving power of 10 and it can measure the bunch shape in about one second. Using the two systems, it has been demonstrated that fast monitors of bunch shape have been successfully developed for the sub-millimeter region, or pico-second region in time scale. It will be easy to extend the region of monitoring to visible and UV region, or femto-second region.