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MOPRI034 | Development of temporal response measurement system for transmission-type spin-polarized photocathodes | 670 |
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Spin polarized electron beam is essential for "International Linear Collider". In Nagoya University, transmission-type spin-polarized photocathodes have been developed, and the quantum efficiency of 0.5 % and the polarization of 90 % were achieved*,**. Recently, we succeeded in making the active layer several times thicker with keeping the spin polarization on the GaAs/GaAsP strain-compensated superlattice photocathode***. Increasing the thickness of the active layer is very advantageous for high quantum efficiency, but might be disadvantageous for pulse response. In order to investigate the pulse response, we have developed a pulse length measurement system by using an RF deflecting cavity. In the measurement, magnetic field induced on the beam axis kicks electron pulse transversely and the pulse length is projected to the transverse plane, which is measured by knife-edge method. The pump laser pulses are provided by a Ti:sapphire laser oscillator. By using a pulse stretcher, the pulse width of the pump laser can be changed in the range between 130 fs and 20 ps. In the poster session, we will describe the details of the measurement system and the most recent experimental results.
* T. Nakanishi, The XXI International LINAC Conference(1998) ** Xiuguang Jin, Japanese Journal of Applied Physics 51 (2012) 108004 *** Xiuguang Jin, Applied Physics Express 6 (2013) 015801 |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI034 | |
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MOPRI035 | Development of the Photocathode LiTi2O4 and Evaluations of the Initial Emittance | 673 |
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In UVSOR, the X-ray free electron laser (XFEL) based on linear accelerator with high pulse repetition about 1MHz has been designed as a candidate for the next radiation sources. We thought a combination of superconducting RF cavity and photocathode is an optimal electron gun for the new accelerator. For this electron gun, we propose a back-illuminated multi-alkali* photocathode with transparent superconductor LiTi2O4**. The reason for using LiTi2O4 is to reflect RF by using feature of penetration depth of superconductor, which is defined from London equation. This feature protects optical components from RF damage. However, LiTi2O4 is a new material and properties are not clear. We have measured the basic properties of this photocathode, such as magnetic susceptibility measurement and photoelectron spectrometry, etc. In this conference, we will explain the detail of the concept and advantage of this cathode, and show the result measured about the basic properties of this photocathode focusing on the initial emittance measurement.
* A. V. Lyashenko et al. JINST 4 P07005 (2009) ** Kumatani et al. APL 101 (2012) 123103″ |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI035 | |
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TUPRI042 | Numerical Study of the Microbunching Instability at UVSOR-III: Influence of the Resistive and Inductive Impedances | 1656 |
SUSPSNE061 | use link to see paper's listing under its alternate paper code | |
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At high charge, relativistic electron bunches circulating in storage rings undergo an instability, the so-called microbunching or the CSR (Coherent Synchrotron Radiation) instability. This instability is due to the interaction of the electrons with their own radiation and leads to the formation of microstructures (at millimeter scale) in the longitudinal phase space. Thanks to a new type of detector, based on superconducting thin film YBCO, it is now possible to observe directly these microstructures and follow their temporal evolution*. These experimental observations open a new way to make severe comparisons with theory. Here we present results of the modeling of the dynamics at UVSOR-III using a one dimensional Vlasov-Fokker-Planck equation. We show that to obtain a relatively good agreement between numerical simulations and experiments, we have to take into account several types of impedance such as the shielded CSR impedance but also the resistive and inductive impedances.
* First Direct, Real Time, Recording of the CSR Pulses Emitted During the Microbunching Instability, using Thin Film YBCO Detectors at UVSOR-III, IPAC2014 |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI042 | |
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WEPRO011 | Design Study of Pulsed Multipole Injection for Aichi SR | 1962 |
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Since March of 2013 the user operation has been started with the top-up injection mode of the storage ring at Aich SR.The accelerators of Aichi SR consisted with a 50 MeV linac, an 1.2 GeV full energy booster and the storage ring. The operation current of the storage ring is 300 mA and the injection rate is up to 1 Hz. The single bunch injection scheme is employed and the electron beam can be injected into the arbitrary bucket of the storage ring. Up to now, the stabilitiy of 0.2 % for the stored beam current was achieved, however, the coherent oscillation of stored beams due to injection kikers is also obserbed. In order to introduce the new injection scheme into Aichi SR and to suppress that coherent oscillation, we have designed the pulsed multipole injection system. The system consists of the sextupole-like pulsed magnet and the micro-sec responce power supply. In the paper, we will report the results of beam tracking calculations with our designed magnet and power supply. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO011 | |
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