Improving Touschek lifetime and synchrotron frequency spread by passive harmonic cavity in the storage ring of SSRF

Phimsen, Thanapong; Jiang, Bingyan; Hai-yan, Hou; Tian, Shun-Qiang; Zhang, Manzhou; Zhang, Qing-Lei; Zhao, Zhentang

doi:10.1007/s41365-017-0259-y

Cited by 13 publications

(2 citation statements)

References 13 publications

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“…According to the Nyquist stability criterion, if the Nyquist plot of positive frequencies doesn't cross the left-hand side of the (-1, 0j) point on the real axis, then the closed-loop system is stable with no poles in the right half-plane. The loop delay time T is around 1-2 µs [12] since the klystron's control function has a minor impact on this model's beam dynamics. Since the delay function is approximately e −sT ≈ 1 − sT ≈ 1 and the zero-mode oscillation frequency of SSRF is around 4.8 kHz, the model omits delay for simplicity.…”

Section: Influence Of Loop Parameters On System Performancementioning

confidence: 99%

Stability analysis of double-harmonic cavity system in heavy beam loading with its feedback loops by a mathematical method based on Pedersen model

Shen,

Gu,

Jiang

et al. 2024

J. Phys.: Conf. Ser.

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With the high beam current in storage ring, it is necessary to consider the instability problem caused by the heavy beam loading effect. It has been demonstrated that direct RF feedback (DRFB), autolevel control loop (ALC) and phase-lock loop (PLL) in the main cavity can lessen the impact of the beam effect. This paper regarded the beam, main cavity, harmonic cavity and feedback loops as double harmonic cavity system, and extended the transfer functions in the Pedersen model to this system. Some quantitative evaluations of simulation results have been got and conclusions have been drawn. In the case of a passive harmonic cavity, the optimization strategy of the controller parameters in the pre-detuning, ALC and PLL, as well as the gain and phase shift of DRFB were discussed. Meanwhile, it also involved the impact of the harmonic cavity feedback loop on the system stability at the optimum stretching condition when an active harmonic cavity was present. The research results can be used as guidelines for beam operation with beam current increasing in the future.

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Section: Influence Of Loop Parameters On System Performancementioning

confidence: 99%

Stability analysis of double-harmonic cavity system in heavy beam loading with its feedback loops by a mathematical method based on Pedersen model

Shen,

Gu,

Jiang

et al. 2024

J. Phys.: Conf. Ser.

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show abstract

“…Its advantages include minimal beam energy loss, extremely stable performance away from performance limits, easy handling of higher order modes (HOMs), and the ability to adjust the load quality factor in a flexible manner. Based on the above benefits, one attractive design for improving the beam lifetime is to lengthen the bunches using a passive third harmonic superconducting cavity without an external high-power source, as the voltage in a passive cavity is excited by the beam [6]. Table 1 lists the synchrotron radiation installation with improved beam lifetime through harmonic cavities.…”

Section: Introductionmentioning

confidence: 99%

RF design and frequency sensitivity analysis of a 1500 MHz passive third harmonic superconducting cavity for the SILF

Yuan¹,

Ma²,

Sun³

et al. 2023

J. Inst.

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To reduce Touschek scattering in the beam and extend the lifetime of the beam in the Shenzhen Innovation Light-source Facility (a fourth-generation light source), a 1500 MHz passive third harmonic system will be used. The present work is devoted to the RF design and frequency sensitivity analysis of the 1500 MHz passive third harmonic superconducting cavity, optimizing the RF parameters of the cavity, and giving a frequency scheme for the cavity in fabrication. The reliability of the cavity during operation is taken as the main goal for the optimization of the geometrical parameters, and its structural and RF parameters are obtained with E peak/E acc of 2.17, B peak/E acc of 5.12 mT/(MV/m) and G · R/Q of 25052 at 2 K. A pair of fluted beam pipes are used to propagate the higher order modes (HOMs) of the harmonic cavity, allowing a smooth transition of the first dipole mode to the absorber located at room temperature area. For the frequency sensitivity analysis, the frequency variations of the cavity in fabrication are obtained by multi-physics coupling simulation in the paper, which gives the target frequency of the cavity between welding and preloading. After electron beam welding (EBW), the resonant frequency of the cavity should be maintained at 1500.096 MHz, and the pre-tuning target frequency is 1497.456 MHz. The slow tuning range is ±400 kHz, the fast-tuning range is 600 Hz, and the maximum allowable tuning force is 15 kN.

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Analysis and optimization of high-power pulse transformer for SXFEL

Liu

Matsumoto

et al. 2019

NUCL SCI TECH

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Improving Touschek lifetime and synchrotron frequency spread by passive harmonic cavity in the storage ring of SSRF

Cited by 13 publications

References 13 publications

Stability analysis of double-harmonic cavity system in heavy beam loading with its feedback loops by a mathematical method based on Pedersen model

Stability analysis of double-harmonic cavity system in heavy beam loading with its feedback loops by a mathematical method based on Pedersen model

RF design and frequency sensitivity analysis of a 1500 MHz passive third harmonic superconducting cavity for the SILF

Analysis and optimization of high-power pulse transformer for SXFEL

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