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Low Level Rf Control Of Microphonics In Superconducting Spoke Loaded Cavities
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Book Synopsis Low-Level RF Control of Microphonics in Superconducting Spoke-Loaded Cavities by :
Download or read book Low-Level RF Control of Microphonics in Superconducting Spoke-Loaded Cavities written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents the results of cw RF frequency control and RF phase-stabilization experiments performed with a piezoelectric fast tuner mechanically coupled to a superconducting, 345 MHz, Ë = 0.5 triple-spoke-loaded cavity operating at 4.2K. The piezoelectric fast tuner damped low-frequency microphonic-noise by an order of magnitude. Two methods of RF phase-stabilization were characterized: overcoupling with negative phase feedback, and also fast mechanical tuner feedback. The Ë = 0.5 triple-spoke-loaded cavity RF field amplitude and phase errors were controlled to ±0.5% and ±30 respectively.
Book Synopsis Determination of Low Level RF Control Requirements for Superconducting Cavities from Microphonics Measurements by :
Download or read book Determination of Low Level RF Control Requirements for Superconducting Cavities from Microphonics Measurements written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In lightly beam loaded superconducting accelerators the rf power requirements are dictated by the maximum amount of microphonics that the system must be able to control and by the energy content of the cavity. In previous machines, such as heavy-ion boosters, the energy content of the cavities was relatively small and one could afford to specify a large control window and still use low power ((almost equal to)100 W) rf sources. In newer accelerators that are being contemplated--such as the CEBAF 12 GeV upgrade or RIA--the energy content of the cavity is quite large requiring rf sources in excess of 10 kW. Conservatism in the control window specification would be quite costly; on the other hand loss of lock could have adverse effect on machine availability or beam property or even, in some cases, result in activation. We present a model to estimate the requirements to be placed on the rf control system based on the properties of the cavities, the frequency tuning system, and the characteristics of the accelerator.
Book Synopsis Digital Low-level Radio Frequency Control and Microphonics Mitigation of Superconducting Cavities by : Nathanael Robert Usher
Download or read book Digital Low-level Radio Frequency Control and Microphonics Mitigation of Superconducting Cavities written by Nathanael Robert Usher and published by . This book was released on 2007 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Low Level Radio Frequency Control of RIA Superconducting Cavities by : Michael John O'Farrell
Download or read book Low Level Radio Frequency Control of RIA Superconducting Cavities written by Michael John O'Farrell and published by . This book was released on 2005 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Electro-Mechanical Interactions in Superconducting Spoke -Loaded Cavities by :
Download or read book Electro-Mechanical Interactions in Superconducting Spoke -Loaded Cavities written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Electronic Damping of Microphonics in Superconducting Cavities by :
Download or read book Electronic Damping of Microphonics in Superconducting Cavities written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In previous applications of high-velocity superconducting cavities the accelerated beam currents were sufficiently high that the microphonics-induced frequency excursions were significantly less than the loaded bandwidth, and the power absorbed by the beam dominated the total power requirement. In new applications (CEBAF Upgrade, RIA) the beam currents will be sufficiently low that the RF power requirements will be dominated by the control of the cavity fields in the presence of microphonics. Active electronic damping of microphonics by modulation of the cavity field amplitude has been occasionally used in the past in small, low-velocity, low-gradient superconducting structures; its application to much larger, high-velocity, high-gradient structures could result in a substantial reduction of the RF power requirements. This paper presents an analytical study of various schemes for electronic damping and presents formulae that quantify the reduction of microphonics as a function of RF field amplitude modulation.
Book Synopsis Microphonics Measurements in SRF Cavities for RIA. by :
Download or read book Microphonics Measurements in SRF Cavities for RIA. written by and published by . This book was released on 2003 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phase stabilization of the RIA drift tube cavities in the presence of microphonics will be a key issue for RIA. Due to the relatively low beam currents (lte 0.5 pmA) required for the RIA driver, microphonics will impact the rf power required to control the cavity fields. Microphonics measurements on the ANL Beta=0.4 single spoke cavity and on the ANL Beta=0.4 two-cell spoke cavity have been performed many at high fields and using a new "cavity resonance monitor" device developed in collaboration with JLAB. Tests on a cold two-cell spoke are the first ever on a multi-cell spoke geometry. The design is essentially a production model with an integral stainless steel housing to hold the liquid helium bath.
Book Synopsis Low Level RF Control for a Superconducting 3rd Harmonic Accelerating Cavity by : Alexander Eckhardt
Download or read book Low Level RF Control for a Superconducting 3rd Harmonic Accelerating Cavity written by Alexander Eckhardt and published by . This book was released on 2006 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Transient Microphonic Effects In Superconducting Cavities by : G. Davis
Download or read book Transient Microphonic Effects In Superconducting Cavities written by G. Davis and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A number of experiments were performed on an installed and operational 5-cell CEBAF cavity to determine the minimum time required to reestablish stable gradient after a cavity window arc trip. Once it was determined that gradient could be reestablished within 10 ms by applying constant power RF signal in and a voltage controlled Oscillator-phase locked loop based system (VCO-PLL), a second experiment was performed to determine if stable gradient could be reestablished using a fixed frequency RF system with a simple gradient based closed loop control system. During this test, instabilities were observed in the cavity forward power signal, which were determined to be microphonic in nature. These microphonic effects were quantified using a cavity resonance monitor and a VCO{_}PLL RF system. Two types of microphonic effects were observed depending on the type of arc event. If the arc occurred in the vacuum space between the warm and cold windows, the transient frequency shift was about 75 Hz peak-to-peak. If the arc occurred on the cavity side of the cold window the transient frequency shift was about 400 Hz peak-to-peak. The background microphonics level for the tested cavity was approximately 30 Hz peak-to-peak. Experimental results, analysis of the resultant klystron power transients, the decay time of the transients, and the implications with respect to fast reset algorithms will be presented.
Book Synopsis Electro-Mechanical Properties of Spoke-Loaded Superconducting Cavities by :
Download or read book Electro-Mechanical Properties of Spoke-Loaded Superconducting Cavities written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents experimental data characterizing the electro-mechanical properties of superconducting spoke-loaded cavities developed for high-intensity ion-linac applications, such as the cw ANL Advanced Exotic Beams Laboratory (AEBL) driver linac and the pulsed FNAL High Intensity Neutrino Source (HINS, now project X) proton driver linac. High-gradient cw operation at 4.2 K can produce violent boiling in the liquid helium coolant causing microphonic frequency noise. A spoke cavity designed to minimize the effects of helium pressure on RF eigenfrequency, the total microphonic induced RF frequency variations, were found to be on the level of the phase noise in the reference oscillator. To determine the pulsed cavity RF performance, the Lorentz transfer function was measured and used to predict the dynamic detuning in pulsed operation. There is good agreement between the predicted fit and the measured data, demonstrating the utility of the Lorentz transfer function, which can compl.
Book Synopsis Microphonics Detuning Compensation in 3.9 GHZ Superconducting RF Cavities by :
Download or read book Microphonics Detuning Compensation in 3.9 GHZ Superconducting RF Cavities written by and published by . This book was released on 2003 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanical vibrations can detune superconducting radio frequency (SCRF) cavities unless a tuning mechanism counteracting the vibrations is present. Due to their narrow operating bandwidth and demanding mechanical structure, the 13-cell 3.9GHz SCRF cavities for the Charged Kaons at Main Injector (CKM) experiment at Fermilab are especially susceptible to this microphonic phenomena. We present early results correlating RF frequency detuning with cavity vibration measurements for CKM cavities; initial detuning compensation results with piezoelectric actuators are also presented.
Book Synopsis Studies of Superconducting Cavities for Heavy Ion Accelerators by : Peter Hutson Ceperley
Download or read book Studies of Superconducting Cavities for Heavy Ion Accelerators written by Peter Hutson Ceperley and published by . This book was released on 1972 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Adaptive Feedforward Cancellation of Sinusoidal Disturbances in Superconducting Radio Frequency Cavities by : Tarek Hamdi Kandil
Download or read book Adaptive Feedforward Cancellation of Sinusoidal Disturbances in Superconducting Radio Frequency Cavities written by Tarek Hamdi Kandil and published by . This book was released on 2005 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Microphonics Control for Project X. by :
Download or read book Microphonics Control for Project X. written by and published by . This book was released on 2011 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proposed multi-MW Project X facility at Fermilab will employ cavities with bandwidths as narrow as 20 Hz. This combination of high RF power with narrow bandwidths combined requires careful attention to detuning control if these cavities are to be operated successfully. Detuning control for Projects X will require a coordinated effort between the groups responsible for various machine subsystems. Considerable progress in this area has been made over the past year. Detuning levels in the Project X cavities, specifically the Low and High [beta] 650 MHz elliptical types, can have a significant impact on the overall cost of the project. The narrow bandwidths, and the high RF Power requirements, and the large number of these cavities mean that careful attention to detuning control will be required if these cavities are to operate successfully. Limiting cavity detuning in Project X will require a coordinated effort between the groups responsible for various subsystems of the planned machine. Considerable progress towards this goal has been made by each of these groups over the past year.
Book Synopsis Active Vibration Modeling and Control in Radio Frequency (RF) Cavities by : Mahsa Keikha
Download or read book Active Vibration Modeling and Control in Radio Frequency (RF) Cavities written by Mahsa Keikha and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microphonic interference, created primarily by environmental and mechanical vibrations, has the potential to impact the performance of superconducting radio frequency (RF) cavities of electron linear accelerators (e-LINACs), such as the accelerator of the Advanced Rare IsotopE Laboratory (ARIEL) currently under construction at TRIUMF, Canada's particle accelerator center. In the e- LINAC, electrons are accelerated up to 50MeV along a linear beamline via an oscillating electric field generated by multi-cell RF cavity resonators. Delivering a high-quality beam requires that the amplitude and phase of the accelerated particles be precisely controlled so that bunched particles receive the same amount of energy from the multi-cell RF cavities. There should be no unwanted variation in the desired resonance frequency. However, microphonic interference can cause deformations in the shape of the cavity that creates a shift in resonance frequency. To design a controller that can reduce or suppress microphonic interference, one must first have an appropriate model of such a cavity. Yet, creating an analytical model of mechanical vibrations in a multi-cell cavity has historically proven to be an extremely complex task. Further challenges in controlling TRIUMF's nine-cell niobium RF cavity arise from its boundary conditions. Access to the cavity is restricted to either end because the cavity is suspended within a Helium bath, limiting the application of forces only to the cavity ends. This thesis outlines the development of an active vibration control to cancel out specific mechanical modes of e-LINAC multi-cell RF cavity. This work involved several steps: First, the development of a control system is presented for active noise cancellation of a conventional multi-cell cavity. To this end, an analytical RF model for a multi-cell structure was developed when the cavity is under acceleration mode. Next, two different approaches were employed for mechanical vibration analysis. In the first approach, the cavity is modeled as a pseudo-rigid cylindrical beam system that accounts for the bending and stretching of the cavity's flexible structure. From there, an observer-based controller was designed to suppress the longitudinal vibrations of the flexible structure system. Proof of its controllability, demonstrated via simulations, is presented herein. In the second step, the multi-cell cavity's dynamic equations were modeled by utilizing a cylindrical shell structure. It is verified through comparison with ANSYS software that the latter dynamics is close to the dynamics of a nine-cell cavity. This resulted in a unified solution for cylindrical shell systems with generic boundary conditions. From this model, an observer-based LQG controller--a combined Kalman filter and LQR controller--was developed, and its performance was tested through simulation analysis.
Book Synopsis Analysis of Electronic Damping of Microphonics in Superconducting Cavities by :
Download or read book Analysis of Electronic Damping of Microphonics in Superconducting Cavities written by and published by . This book was released on 2008 with total page 65501 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Low Temperature Baking on the RF Properties of Niobium Superconducting Cavities for Particle Accelerators by :
Download or read book Effect of Low Temperature Baking on the RF Properties of Niobium Superconducting Cavities for Particle Accelerators written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Radio-frequency superconducting (SRF) cavities are widely used to accelerate a charged particle beam in particle accelerators. The performance of SRF cavities made of bulk niobium has significantly improved over the last ten years and is approaching the theoretical limit for niobium. Nevertheless, RF tests of niobium cavities are still showing some ''anomalous'' losses that require a better understanding in order to reliably obtain better performance. These losses are characterized by a marked dependence of the surface resistance on the surface electromagnetic field and can be detected by measuring the quality factor of the resonator as a function of the peak surface field. A low temperature (100 C-150 C) ''in situ'' bake under ultra-high vacuum has been successfully applied as final preparation of niobium RF cavities by several laboratories over the last few years. The benefits reported consist mainly of an improvement of the cavity quality factor at low field and a recovery from ''anomalous'' losses (so-called ''Q-drop'') without field emission at higher field. A series of experiments with a CEBAF single-cell cavity have been carried out at Jefferson Lab to carefully investigate the effect of baking at progressively higher temperatures for a fixed time on all the relevant material parameters. Measurements of the cavity quality factor in the temperature range 1.37 K-280 K and resonant frequency shift between 6 K-9.3 K provide information about the surface resistance, energy gap, penetration depth and mean free path. The experimental data have been analyzed with the complete BCS theory of superconductivity. The hydrogen content of small niobium samples inserted in the cavity during its surface preparation was analyzed with Nuclear Reaction Analysis (NRA). The single-cell cavity has been tested at three different temperatures before and after baking to gain some insight on thermal conductivity and Kapitza resistance and the data are compared with different models. This paper describes the results of these experiments and comments on existing models to explain the effect of baking on the performance of niobium RF cavities.
