Injection Kicker Research Articles

Simulation and measurement of beam-induced heating of ceramic vacuum chambers

In this article, we summarize recent theoretical and experimental studies of the impedance and beam-induced heating of titanium-coated ceramic vacuum chambers used in the NSLS-II injection kickers. The impedance was calculated using the field matching theory assuming planar approximation and compared with the mpedanceake2 code. For the coating thickness of a few microns, we demonstrated that the beam-induced power is dissipated in the titanium coating and that the longitudinally averaged two-dimensional power density is approximated by an analytical expression, thus allowing the use of a simplified model of the power density as input for the code to simulate the temperature distribution with realistic nonuniform thickness of the Ti coating. For a few values of the NSLS-II beam current, we measured the beam-induced heating of two ceramic chambers using thermal sensors installed along the chamber and compared the measurement results with the simulations. Published by the American Physical Society 2024

Operational experience of a low beam coupling impedance injection kicker magnet for the CERN SPS ring

The CERN SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam power deposition was considered an issue. There are two types of these magnets in the SPS: MKP-S (small aperture) and MKP-L (large aperture) versions. The MKP-L magnets are very lossy from a beam impedance perspective: this would be an issue during SPS operation with the higher intensity beams needed in the future for HL-LHC. Hence, a beam screen has been developed, which is inserted in the aperture of each MKP-L module. The screen consists of silver fingers applied to alumina U-shaped chambers: the fingers have been optimized to achieve both adequately low beam induced power deposition and good high voltage (HV) behaviour. A surface coating, with a low secondary electron yield, is applied to the inner surface of the alumina chambers to reduce dynamic vacuum. The low-impedance MKP-L has been extensively HV tested in the lab before installation in the SPS. This paper briefly presents the design and focuses on the operational experience in the SPS, including heating and vacuum.

Conceptual design of multipole injection kicker magnets for the ILSF storage ring

The standard injection scheme of the Iranian Light Source Facility(ILSF) is composed of 2 septum and 4 kicker magnets installed in a 7-meter-long straight section. Further tuning of the 4 kicker devices to reduce perturbations has proven to be almost impossible since it requires having 4 identical magnets, electronics and Ti-coated ceramic chambers. Different from pulsed dipole kicker magnets used in a conventional local-bump injection, a single nonlinear or multipole kicker provides a nonlinear distribution of magnetic fields, which has a maximum value off the axis where the injected beam arrives and a zero or near-zero value at the center where the stored beam passes by. So, here the designs of different multipole kickers, including sextupole, octupole and a nonlinear kicker, have been investigated and compared.

Online bunch-by-bunch position monitoring and analysis at the Taiwan Photon Source

The online bunch-by-bunch position monitor has been established through the utilization of a high-speed analog-to-digital converter, synchronized meticulously with the accelerator's radio frequency. This implementation serves the purpose of refining the alignment of the four injection kickers. A substantial volume of data needs to be managed when dealing with the motion of the bunches. To untangle the intricacies of bunch motion, an independent component analysis has been employed. This method efficiently segregates the bunch motion into discrete sources. The resulting bunch motion is a direct outcome of the linear combination of these distinct sources. Consequently, this approach significantly simplifies the overarching data analysis procedure. Throughout the injection phase, the predominant factors influencing the oscillation of filled bunches originate from three distinct sources. Firstly, there is a contribution arising from the mismatch among the four kickers during their activation period. Additionally, the damped betatron oscillation and the oscillation generated by wake fields constitute the other sources of bunch motion. To comprehend the tune variation in these sources, an examination is conducted through a numerical analysis of fundamental frequencies. Specifically, the tune associated with the betatron oscillation is contingent upon the amplitude of said oscillation. In contrast, the tune corresponding to the wake-field oscillation displays comparably minor fluctuations during both the growing and damping phases.

Toward transparent injection with a multipole injection kicker in a storage ring

Achieving transparent Top-Up injection, characterized by stored beam position perturbations lower than 10% of the root mean square (rms) size of the stored beam, is very challenging for third-generation storage ring-based synchrotron light sources. The standard bump-based injection scheme used at SOLEIL 2.75-GeV storage ring for daily operation relies on two pulsed septum magnets and four pulsed dipole kickers installed in a 12-m-long straight section. Perfect tuning of the kickers to meet the perturbation tolerances is impossible since it would require at least four identical magnets, Ti-coated ceramic chambers, and electronics. On the way toward transparent injection, the four kickers can be replaced by a single pulsed magnet, benefiting from a field-free region in the stored beam path. This Multipole Injection Kicker (MIK), developed in the frame of a collaboration between SOLEIL and MAX IV, and currently installed in the MAX IV 3-GeV storage ring, has proven to meet the transparency specifications. A copy of the MIK has been installed in a short straight section of the SOLEIL storage ring in January 2021. Perturbations of less than 2% of the rms size of the stored beam were measured using the newly installed high-performance diagnostics. In this article, a start-to-end model of the MIK-based injection is presented as well as major challenges inherent in designing such an innovative magnet. Then, the results of the MIK commissioning are presented in depth along with the high-performance diagnostics, which are essential when such levels of beam stability are to be achieved.

Online optimization of NSLS-II dynamic aperture and injection transient

The goal of the NSLS-II online optimization project is to improve the beam quality for the user experiments. To increase the beam lifetime and injection efficiency, we have developed a model-independent online optimization of nonlinear beam dynamics using advanced algorithms, such as Robust Conjugate-Gradient Algorithm (RCDS). The optimization objective is the injection efficiency and optimization variables are the sextupole magnet strengths. Using the online optimization technique, we increased the NSLS-II dynamic aperture and reduced the amplitude-dependent tune shift. Recently, the sextupole optimization was successfully applied to double the injection efficiency up to above 90% for the high-chromaticity lattice being developed to improve the beam stability and to increase the single-bunch beam intensity. Minimizing the beam perturbation during injection is the second objective in this project, realized by online optimization of the injection kickers. To optimize the full set of kicker parameters, including the trigger timing, amplitude, and pulse width, we upgraded all kicker power supplies with the capability of tunable waveform width. As a result, we have reduced the injection transient by a factor of 29, down to the limit of 60 μm.

Investigation of RF heating for the multipole injection kicker installed at SOLEIL

During the commissioning of the new Multipole Injection Kicker (MIK) pulsed magnet at SOLEIL synchrotron, an anomalously high heating of the MIK chamber and flanges was found. To better manage the heat load, fans directed toward the MIK were added to improve the air-cooling flow. This allowed the nominal current to be reached in all operation modes while keeping reasonable temperatures on the MIK. Post-installation investigations subsequently showed that the initial estimate of the maximal heat load was in agreement with the measured temperature in several operation modes both with and without the additional fans. In this article, we present the complete study, starting from the impedance calculation to thermal simulations, and comparison with the measured data with beam.

A double dipole kicker for off and on-axis injection into ALBA-II

Injection into the ALBA-II storage ring will be performed off-axis in a 4 meters straight section with a single multipole kicker. We present a novel topology for the coils of the injection kicker, named double dipole kicker (DDK). The resulting magnetic field is the superposition of two opposite dipoles, generated by four inner and four outer conductor rods. When the eight rods are powered, the dipole term cancels and the remaining multipole field is used for off-axis injection. Alternatively, when the four inner rods are switched off, an almost pure dipole is produced, that is useful for on-axis injection during the commissioning. A prototype of DDK is presently under design to be installed and tested in the existing ALBA storage ring. The positioning of the rods is calculated in order to maximize the kick efficiency in mrad/kA and minimise the disturbance to the orbit and the emittance of the stored beam. A metallic coating with optimised thickness along the inner ceramic vacuum chamber should provide compensation for the eddy currents induced field in order to minimize the disturbance to the stored beam while ensuring sufficiently low heat dissipation by the beam image currents.

Multi-objective optimization of longitudinal injection based on a multi-frequency RF system for fourth-generation storage ring-based light sources

In the fourth-generation storage ring light sources (4GLSs), associated with the extremely strong nonlinearities inherent in the multi-bend achromat design, the dynamic acceptance is usually small and it is difficult to implement traditional off-axis local-bump injection. To release the requirement on dynamic acceptance, on-axis longitudinal injection schemes have been explored. In this paper, we present a multi-objective optimization of longitudinal injection with a multi-frequency RF system, based on the parameters of the Southern Advanced Photon Source, a 4GLS proposed in China. We show that by treating the optimal bunch lengthening condition as an optimizing objective rather than a condition that must be satisfied, a plethora of feasible candidate solutions can be found, showing different trade-offs among multi-objectives. From these candidate solutions, one can find an optimal RF parameter setting that is most adapted to a specific 4GLS physics design and the available technical level of injection kicker. Especially, it would be feasible to realize longitudinal injection within a static bucket enabled by a double-frequency RF system, suggesting an attractive longitudinal injection option for 4GLSs.

Iron lamination and interlaminar insulation for high-frequency pulsed magnets.

In high-frequency pulsed magnets, such as kickers in particle accelerators, it is essential to reduce eddy currents that could be induced in the magnet core during excitation not to distort and attenuate the magnetic field pulse. A novel iron lamination scheme with additional interlaminar insulation is proposed for the magnet core of such pulsed magnets. A laminated steel sheet core is formed by alternately stacking thin steel and insulation sheets. For application to matched kicker magnets for accelerators, test magnets with the new and conventional iron lamination were designed, assembled, and extensively evaluated. The pulsed magnetic field waveforms of two test magnets with the new lamination successfully matched to below 0.1% over the entire pulse duration, which was significantly better than those with the conventional lamination. Among the applications of the developed high-frequency pulsed magnets, beam injection kickers for the coming next generation light sources and future colliders, where suppression of the transient stored-beam oscillation during beam injection is crucial, are considered to be promising.

High intensity proton beam impact at 440 GeV/c on Mo and Cu coated CfC/graphite and SiC/SiC absorbers for beam intercepting devices

Beam Intercepting Devices (BIDs) are essential protection elements for the operation of the Large Hadron Collider (LHC) complex. The LHC internal beam dump (LHC Target Dump Injection or LHC TDI) is the main protection BID of the LHC injection system; its main function is to protect LHC equipment in the event of a malfunction of the injection kicker magnets during beam transfer from the SPS to the LHC. Several issues with the TDI were encountered during LHC operation, most of them due to outgassing from its core components induced by electron cloud effects, which led to limitations of the injector intensity and hence had an impact on LHC availability. The absorbing cores of the TDIs, and of beam intercepting devices in general, need to deal with high thermo-mechanical loads induced by the high intensity particle beams. In addition, devices such as the TDI — where the absorbing materials are installed close to the beam, are important contributors to the accelerator impedance budget. To reduce impedance, the absorbing materials that make up the core must be typically coated with high electrical conductivity metals. Beam impact testing of the coated absorbers is a crucial element of development work to ensure their correct operation.In the work covered by this paper, the behaviour of several metal-coated absorber materials was investigated when exposed to high intensity and high energy proton beams in the HiRadMat facility at CERN. Different coating configurations based on copper and molybdenum, and absorbing materials such as isostatic graphite, Carbon Fibre Composite (CfC) and Silicon Carbide reinforced with Silicon Carbide fibres (SiC-SiC), were tested in the facility to assess the TDI's performance and to extract information for other BIDs using these materials. In addition to beam impact tests and an extensive Post Irradiation Examination (PIE) campaign to assess the performance of the coatings and the structural integrity of the substrates, extensive numerical simulations were carried out.

“Spiral COSAMI” — A Multi-Undulator Compact Source for Actinic Mask Inspection in the extreme ultraviolet range

A compact electron storage ring provides a bright, stable and reliable source of extreme ultraviolet (EUV) radiation for metrology applications in semiconductor industry. The COSAMI concept (COmpact Synchrotron for Actinic Mass Inspection) applied design principles and technology of modern diffraction limited light source storage rings to an EUV facility operating at 13.5 nm wavelength. Since floor space is an important issue in an industrial environment, we propose a lattice configuration where three (or more) recirculation turns are stacked vertically. We present a facility, called Spiral-COSAMI, which simultaneously serves multiple (three or more) EUV beamlines within about the same floor space of the original COSAMI, and using the same type of injector and the same set of diagnostics, radio-frequency and pulsed magnet devices. The increased period of revolution of the multiple turns mitigates the problem of ion trapping and relaxes specifications of injection kickers.

Fast injection and extraction kicker system design for High rEpetition rate Muon Source at CSNS

A non-parasitic muon production facility (HEMS, abbreviation of High rEpetition rate Muon Source) at China Spallation Neutron Source (CSNS) is proposed. HEMS will extract a 500 MeV proton beam from a proton storage ring with a circumference of 80 m to bombard a target on a linear section at a repetition rate of 100 Hz. After bombarding the target, the beam will be injected back into the proton storage ring. The proton beam will be extracted and injected repeatedly to the proton storage ring 20 times within 20 ms. For injection and extraction kicker system, the repetition rate of pulser should be as high as 1 kHz. In addition, to achieve a large kick angle with a high magnet gap aperture in a relatively small beam lattice, kicker pulser is required to generate a large excitation current. The primary challenge is to build a high repetition rate, high current, and fast injection and extraction kicker system. To achieve these requirements, a 6.25 Ω impedance matching kicker system, mainly composed of a twin-C transmission line kicker magnet and inductive adder, is developed. In this paper, we report the conceptual design of the kicker magnet and kicker pulser for HEMS.

Injection and Extraction Kickers for the Advanced Light Source Upgrade Project (ALS-U)

Injection and Extraction Kickers for the Advanced Light Source Upgrade Project (ALS-U)

Influence of Injection Kicker Post-pulses on Storage of Ion Stack in NICA Collider

Influence of Injection Kicker Post-pulses on Storage of Ion Stack in NICA Collider

Beam Induced Power Deposition in CERN SPS Injection Kickers

Beam Induced Power Deposition in CERN SPS Injection Kickers

Feasibility Study of Using Multipole Injection Kicker (MIK) and Sextupole for TPS Injection

Feasibility Study of Using Multipole Injection Kicker (MIK) and Sextupole for TPS Injection

Impedance and Thermal Studies of the LHC Injection Kicker Magnet Upgrade

Impedance and Thermal Studies of the LHC Injection Kicker Magnet Upgrade

Deployment and Commissioning of the CERN PS Injection Kicker System for Operation with 2 GeV Beams in Short Circuit Mode

Deployment and Commissioning of the CERN PS Injection Kicker System for Operation with 2 GeV Beams in Short Circuit Mode

The fast non-ferric kicker system for the Muon [formula omitted] Experiment at Fermilab

We describe the installation, commissioning, and characterization of the new injection kicker system in the Muon g−2 Experiment (E989) at Fermilab, which makes a precision measurement of the muon magnetic anomaly. Three Blumlein pulsers drive each of the 1.27-m-long non-ferric kicker magnets, which reside in a storage ring vacuum (SRV) that is subjected to a 1.45 T magnetic field. The new system has been redesigned relative to Muon g−2’s predecessor experiment, and we present those details in this manuscript.