Back recursive estimation of unknown frequency sinusoidal disturbance in superconducting RF cavities

Area of Science:

• Physics
• Electrical Engineering
• Control Systems

Background:

• Superconducting radio frequency (SRF) cavities are susceptible to detuning caused by microphonic disturbances.
• Accurate estimation and compensation of these disturbances are crucial for stable SRF cavity operation.
• Existing methods may struggle with the dynamic and unknown frequency nature of microphonics.

Purpose of the Study:

• To propose a novel back recursive estimation (BRE) scheme for SRF cavities.
• To model and estimate microphonic disturbances accurately.
• To ensure the stability and robustness of the estimation error.

Main Methods:

• Modeling microphonics as an unknown frequency sinusoidal disturbance.
• Utilizing an auxiliary filter to excite disturbance properties and estimate frequency within an observer framework.
• Rearranging sinusoidal disturbances into a series of dynamics using virtual disturbances.
• Calculating the back recursive signal based on the correlation between virtual and equivalent input disturbances.

Main Results:

• Asymptotic stability of the estimation error is achieved using a Lyapunov function.
• Robustness of the estimation is demonstrated in the presence of external bounded disturbances.
• Simulations confirm the effectiveness of the proposed BRE method.

Conclusions:

• The proposed BRE scheme offers an effective solution for mitigating microphonic detuning in SRF cavities.
• The method provides guaranteed stability and robustness for the estimation error.
• This advancement contributes to improved performance and reliability of SRF cavity systems.