NAKAMURA, Takeshi

Accelerator Division

SPring-8 / Japan Synchrotron Radiation Research Institute(JASRI)

mail: nakamura@spring8.or.jp

http://acc-web.spring8.or.jp/~nakamura/

Research Fields

Beam Instabilities

    Measurement
        Multi-bunch instabilities
            HOM, resistive-wall, Fast-ion
        Single-bunch instabilities
            Head-tail, mode-coupling

    Analysis
        Broad-band impedance of vacuum components
        Wake field of vacuum comonents
        Resistive-wall impedance with thin conductive sheet

    Simulation
        CISR:    Multi-bunch instabilities driven by HOM  ( longitudinal,   transverse )
        SISR:    Single-bunch instabilities by broad-band geometric impedance

    Cure
        Bunch-by-bunch feedback
            Signal processor ( FPGA, 12-bit ADC x 4 or 6 =>  508.58MS/s )
            Effect of noise on beam size
            Monitor, kicker
            Single-loop two-dimensional feedback
            Time Domain Least Square Fitting Method for FIR filter coefficients
            Analog de-multiplexer by square wave mixing (EPAC04)

        Chromaticity modulation by synchrotron frequency

Chromatic effect
        Energy spread measurement by chromaticity
        Effect of chromaticity for multi-bunch instabilities

Longitudinal Dynamics
    Beam loading
    Robinson Instability + low level feedback  ( calculation, experiment )

Free Electron Lasers and a bit of transverse dynamics

Note

    Beam Instabilities at Light Sources     (Journal of the JSSR)    (in Japanese)

Codes

    ELFIN (ELectron-Laser Field INteraction)

    SISR (Single-bunch Instability in Storage Ring)

        Simulation code for single-bunch instability in storage rings
        using wake functions (calculated by codes, models, .. )

   CISR (Coupled-bunch Instability in Storage Ring)
        Simulation code for coupled-bunch instability in storage rings driven by resonator impedance. It's written in C++.

For Internal Users

Thanks feedback to:   NAKAMURA, Takeshi