Measurement of the orbit fluctuation caused by an insertion device with the amplitude modulation method

振幅変調法による挿入光源が引き起こす軌道変動の測定

中谷 健 ; 安居院 あかね; 吉越 章隆 ; 松下 智裕*; 高雄 勝*; 青柳 秀樹*; 竹内 政雄*; 田中 均*

Nakatani, Takeshi; Agui, Akane; Yoshigoe, Akitaka; Matsushita, Tomohiro*; Takao, Masaru*; Aoyagi, Hideki*; Takeuchi, Masao*; Tanaka, Hitoshi*

挿入光源(ID)が持つ誤差磁場による軌道変動のみを抽出する方法を開発した。これは、誤差磁場を変調させながら蓄積電子ビームの位置を測定して、得られた軌道変動をWavelet変換を用いた処理を行って、IDの誤差磁場変動に伴う軌道変動のみを抽出する方法である。この方法を用いて、原研軟X線ビームライン用挿入光源(ID23)の駆動によって引き起こされる静的な軌道変動と動的な軌道変動それぞれを定量的に測定した。

We have developed a new method to extract only the orbit fluctuation caused by changing magnetic field error of an insertion device (ID). This method consists of two main parts. (i) The orbit fluctuation is measured with modulating the error field of the ID by using the real-time beam position measuring system. (ii) The orbit fluctuation depending on the variation of the error field of the ID is extracted by the filter applying the Wavelet Transform. We call this approach the amplitude modulation method. This analysis technique was applied to measure the orbit fluctuation caused by the error field of APPLE-2 type undulator (ID23) installed in the SPring-8 storage ring. We quantitatively measured two kinds of the orbit fluctuation which are the static term caused by the magnetic field error and the dynamic term caused by the eddy current on the ID23 chamber.