IPAC2016 - List of Authors (Zhao, Z.)

Paper	Title	Page
MOPMY016	Quadrature Directional Coupling Method for Precise RF Power Measurement	549
SUPSS096	use link to see paper's listing under its alternate paper code
	B. Du, G. Huang, L. Lin, Y.T. Liu, Z. Zhao USTC/NSRL, Hefei, Anhui, People's Republic of China
	The directional coupler is used in the RF transmission and distribution system of accelerator, to measure the forward and backward power. Due to the finite directional isolation of the coupler (20-30dB normally), the crosstalk exists between the bi-directional coupling output signals. For the typical isolation of 26dB, if the bi-directional crosstalk signals are in- or anti- phase, the error of input or reflected power measurement is 10% in case of total reflection, whilst the error of reflected power measurement is 100% in case of VSWR 1.1. A method of quadrature directional coupling measurement is developed to solve the isolation problem. A pair of directional couplers with 90° phase difference are employed to measure the RF power. The influence of the directional crosstalk would be reduced significantly by processing the measurement data. The prototype of quadrature directional couplers is constructed to verify this method. The results showed that the measurement accuracy of quadrature coupler pair after data process is better than 2% for forward measurement, even if the error of single coupler is over 6%. The paper also analyses the error caused by non-ideal quadrature.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY016
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WEPOY001	First Field Integral Measurement Campaign for Air Coil	2991
	Z. Zhao, B. Du, Q.K. Jia USTC/NSRL, Hefei, Anhui, People's Republic of China S. Karabekyan, J. Pflüger, M. Yakopov XFEL. EU, Hamburg, Germany
	For the operation of the air coils, which are needed for the undulator segments of the European x-ray free-electron laser (E-XFEL), precise conversion constants are needed to properly convert excitation current to steering strength. This paper describes the measurement of all 200 air coils, needed for this purpose using the short moving wire (MW) system. A LabView program was developed to measure the distribution of first field integral of both vertical (B_y) and horizontal (B_z) magnetic field components in the median plane of an air coil automatically. The program is an adaptation of the existing program, which was used to characterize magnetic properties of the phase shifters (PS). Before doing the measurements the new program automatically finds the centers of B_y and B_z components, which are found to match with the geometrical centers with sufficient accuracy. After the measuring procedure is complete, the results are presented as graphics output and final tables. It shows that the measurement results can fully meet the design requirements of E-XFEL. For all measurements the excitation current of the coils was set to 1 Ampere.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY001
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

MOPMY016

Quadrature Directional Coupling Method for Precise RF Power Measurement

549

SUPSS096

use link to see paper's listing under its alternate paper code

B. Du, G. Huang, L. Lin, Y.T. Liu, Z. Zhao
USTC/NSRL, Hefei, Anhui, People's Republic of China

The directional coupler is used in the RF transmission and distribution system of accelerator, to measure the forward and backward power. Due to the finite directional isolation of the coupler (20-30dB normally), the crosstalk exists between the bi-directional coupling output signals. For the typical isolation of 26dB, if the bi-directional crosstalk signals are in- or anti- phase, the error of input or reflected power measurement is 10% in case of total reflection, whilst the error of reflected power measurement is 100% in case of VSWR 1.1. A method of quadrature directional coupling measurement is developed to solve the isolation problem. A pair of directional couplers with 90° phase difference are employed to measure the RF power. The influence of the directional crosstalk would be reduced significantly by processing the measurement data. The prototype of quadrature directional couplers is constructed to verify this method. The results showed that the measurement accuracy of quadrature coupler pair after data process is better than 2% for forward measurement, even if the error of single coupler is over 6%. The paper also analyses the error caused by non-ideal quadrature.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOY001

First Field Integral Measurement Campaign for Air Coil

2991

Z. Zhao, B. Du, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China
S. Karabekyan, J. Pflüger, M. Yakopov
XFEL. EU, Hamburg, Germany

For the operation of the air coils, which are needed for the undulator segments of the European x-ray free-electron laser (E-XFEL), precise conversion constants are needed to properly convert excitation current to steering strength. This paper describes the measurement of all 200 air coils, needed for this purpose using the short moving wire (MW) system. A LabView program was developed to measure the distribution of first field integral of both vertical (B_y) and horizontal (B_z) magnetic field components in the median plane of an air coil automatically. The program is an adaptation of the existing program, which was used to characterize magnetic properties of the phase shifters (PS). Before doing the measurements the new program automatically finds the centers of B_y and B_z components, which are found to match with the geometrical centers with sufficient accuracy. After the measuring procedure is complete, the results are presented as graphics output and final tables. It shows that the measurement results can fully meet the design requirements of E-XFEL. For all measurements the excitation current of the coils was set to 1 Ampere.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY001

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)