Author: Ramona Leewe
Publisher:
ISBN:
Category :
Languages : en
Pages : 102
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Book Description
RF cavities are resonators and the key structures in particle accelerators. An electromagnetic field within the cavities provides the acceleration field. Within linear particle accelerators, particle bunches travel along a beam pipe and through the aligned cavities. A positive electric field along the beam line results in an acceleration kick of the particle bunch. The speed of the traveling particle bunches is synchronized with the RF field withinthe cavities. Hence, tuning of the natural resonance frequency of an RF cavity is essential for accelerator structures to achieve efficient beam acceleration and to reduce power requirements. Operational cavities are typically tuned using phase comparison techniques. Phase measurement is subject to temperature drifts which renders this technique labor and time intensive. In this thesis, we developed two novel resonance frequency tuning schemes solely depending on the reflected power component of a cavity. The base for control scheme development is a mathematical model of the cavity in terms of the steady state signals. The first control scheme was derived through a Lyapunov analysis and incorporates a gradient estimator of the performance function. The second control scheme is based on sliding mode extremum seeking. Both systems are analyzed in terms of the stability; conditions are provided which guarantee stable system behavior up to twice the cavity bandwidth. A simulation study verifies the derived stability conditions. An experimental test bench, including a room temperature quarter wave cavity, was built to test the control schemes under various conditions. Although both control schemes show similar tuning results, a higher tuning accuracy is obtained by the sliding mode based control scheme. Hence, the latter was chosen to be implemented on two resonators, DTL tanks, of TRIUMF's ISAC I facility. The system was fully commissioned on both DTL tanks and has been in operation since April 2016. Reflected power, forward power, and tuning position are monitored and analyzed. Long term measurements showed the influence of environmental temperature variations. As the influence of environmental temperaturevariations can be neglected for reflected power measurements, the reflected power based tuning system provides a higher tuning accuracy compared to the traditional phase based tuning system. The start-up time and the need for human oversight are reduced significantly.
Author: Zahra Shahriari
Publisher:
ISBN:
Category :
Languages : en
Pages : 58
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Book Description
RF cavity resonators are one of the key structures in particle accelerators. They provide accelerating field for a beam of charged particles passing through them. An RF source transmits required power for acceleration to cavity through waveguides. Due to impedance mismatch, some amount of available power generated by the RF source reflects back from the cavity. To save power and provide the maximum accelerating field, it is desirable to minimize this reflected power by equalizing the frequencies of the cavity and source. A mechanical tuner mounted on top of the cavity moves a tuner plate in or out of the cavity, thereby changing cavity's resonance frequency. In this thesis, first a mathematical dynamic model of the cavity in terms of its transient and steady state signals is provided. Then based on the dynamic model, an extremum seeking (ES) algorithm is developed to automatically reach the minimum value of the reflected power and maintain this condition by keeping the resonance frequency of the cavity equal to the source frequency. The ES algorithm is derived through a Lyapunov-based analysis and uses only reflected power as feedback signal. A gradient estimation is performed to determine the direction of movement. The proposed ES controller is further compared with classical perturbation-based ES methods. Simulation and experimental results are presented to evaluate stability and the response behavior of the algorithms in reaching the minimum condition. While both algorithms successfully minimize reflected power in finite time, the results obtained from the Lyapunov-based algorithm are faster and smoother. However, if the cavity is not perfectly coupled and the minimum reflected power is greater than zero, the performance of the proposed controller degrades due to appearance of steady state oscillation. This problem can be solved by adding an initialization phase to the controller, to track the minimum value of reflected power and update the control law with the new value of the minimum.
Author: Helmut Wiedemann
Publisher: Springer Science & Business Media
ISBN: 3662029030
Category : Science
Languages : en
Pages : 457
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Book Description
Particle Accelerator Physics covers the dynamics of relativistic particle beams, basics of particle guidance and focusing, lattice design, characteristics of beam transport systems and circular accelerators. Particle-beam optics is treated in the linear approximation including sextupoles to correct for chromatic aberrations. Perturbations to linear beam dynamics are analyzed in detail and correction measures are discussed, while basic lattice design features and building blocks leading to the design of more complicated beam transport systems and circular accelerators are studied. Characteristics of synchrotron radiation and quantum effects due to the statistical emission of photons on particle trajectories are derived and applied to determine particle-beam parameters. The discussions specifically concentrate on relativistic particle beams and the physics of beam optics in beam transport systems and circular accelerators such as synchrotrons and storage rings. This book forms a broad basis for further, more detailed studies of nonlinear beam dynamics and associated accelerator physics problems, discussed in the subsequent volume.
Author: Alexander Scheinker
Publisher: Springer
ISBN: 3319507907
Category : Technology & Engineering
Languages : en
Pages : 129
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Book Description
With this brief, the authors present algorithms for model-free stabilization of unstable dynamic systems. An extremum-seeking algorithm assigns the role of a cost function to the dynamic system’s control Lyapunov function (clf) aiming at its minimization. The minimization of the clf drives the clf to zero and achieves asymptotic stabilization. This approach does not rely on, or require knowledge of, the system model. Instead, it employs periodic perturbation signals, along with the clf. The same effect is achieved as by using clf-based feedback laws that profit from modeling knowledge, but in a time-average sense. Rather than use integrals of the systems vector field, we employ Lie-bracket-based (i.e., derivative-based) averaging. The brief contains numerous examples and applications, including examples with unknown control directions and experiments with charged particle accelerators. It is intended for theoretical control engineers and mathematicians, and practitioners working in various industrial areas and in robotics.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 4
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Book Description
A method for tuning rf cavities that has fewer rf reflected power conditions and is easier for accelerator operators to use is presented. This method will also prepare the rf cavity tuning for future higher beam currents. The results and installation methods are discussed.
Author: H. Henke
Publisher: Atlantica Séguier Frontières
ISBN: 9782863321157
Category : Particle accelerators
Languages : en
Pages : 942
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Book Description
Author: S. I. Kurokawa
Publisher: World Scientific
ISBN: 9789810238810
Category : Science
Languages : en
Pages : 742
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Book Description
This volume comprises the proceedings of the 8th Joint School on accelerator physics. On this occasion, the US, CERN, Japan and Russia Particle Accelerator Schools collaborated to present the topic "Beam Measurements." The aim was to provide an introduction to the principles of beam dynamics and measurements in circular particle accelerators. This was achieved by a series of lectures under the heading of "single-particle dynamics," "beam measurements" and then "multi-particle dynamics," along with practical courses on feedback and data processing, maps and simulation, diagnostic and microwave measurements. The resulting proceedings represent a unique summary of the currently available knowledge on beam measurements applied to circular particle accelerators.
Author: H. Schlüter
Publisher: Springer Science & Business Media
ISBN: 9401706336
Category : Science
Languages : en
Pages : 580
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Book Description
This book draws together three areas of work on plasma technologies: advanced efforts based on wave generated, high frequency plasmas, plasma assisted ion implantation, and electron beam generated plasma. It lays a foundation for the application of sources in industry and various research areas
Author:
Publisher:
ISBN:
Category : Nuclear physics
Languages : en
Pages : 802
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 3
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Book Description
A tuning system is described that is being used to match the source frequency of a high-power klystron on the resonant frequency of the prototype single-cell cavity for the 7-GeV Advance Photon Source (APS) storage ring. Typically a water-cooled piston tuner is required to adjust the reactive component of the cavity's impedance to minimize reflected power back to the RF drive source. As the cavity watts expand due to RF heating, the resonant frequency decreases. Adjusting the source frequency to follow the cavity resonant frequency is a convenient method used to condition the cavity (for vacuum) at high power levels, in this case, 1 MV gap voltage at 100 kW power level. The tuning system consists of two coupling ports, a phase detector, a digitizing I/O system, and a DC coupled FM-modulated RF source. Proportional Integral Derivative (PID) loop parameters for the Experimental Physics and Industrial Control System (EPICS) software are calculated, and data is presented showing the damped response to peturbations on the loop. The timing system presented here does not need water-cooling, has no moving parts to wear out, and has an inherently faster response time. Its one limitation is the digitizing sampling rate. The only limitation in tuning range is the bandwidth of the RF source.
