For slowly evolving, discrete-time-dependent systems of difference equations (iterated maps), we believe the simplest means of demonstrating the validity of the averaging method at first order is by way of a lemma that we call Besjes' inequality. In this paper, we develop the Besjes inequality for identity maps with perturbations that are (i) at low-order resonance (periodic with short period) and (ii) far from low-order resonance in the discrete time. We use these inequalities to prove corresponding first-order averaging principles, together with a principle of adiabatic invariance on extended timescales; and we generalize and apply these mathematical results to model problems in accelerator beam dynamics, and to the Henon map.
This report summarizes the findings of the AF1 Topical Subgroup to Snowmass 2021, which investigates beam physics and accelerator education within the accelerator frontiers (AF). The report focuses primarily on opportunities for basic accelerator and beam physics, formulated into four grand challenges. In addition, the report also studies the current status of accelerator education, outreach and diversity issues. Physics limits of ultimate beams for future colliders are also briefly discussed.
The RAON accelerator of the Rare Isotope Science Project (RISP) has been developed to create and accelerate various kinds of stable heavy ion beams and rare isotope beams for a wide range of the science applications. In the RAON accelerator, the rare isotope beams generated by the Isotope Separation On-Line (ISOL) system will be transported through the post accelerator, namely, from the post Low Energy Beam Transport (LEBT) system and the post Radio Frequency Quadrupole (RFQ) to the superconducting linac (SCL3). The accelerated beams will be put to use in the low energy experimental hall or ac…
Many particle accelerators operate with very high beam power and very high energy stored in particle beams as well as in magnet systems. In the future, the beam power in high intensity accelerators will further increase. The protection of the accelerator equipment from the consequences of uncontrolled release of the energy is essential. This was the motivation for organizing a first school on beam losses and accelerator protection (in general referred to as machine protection). During the school the methods and technologies to identify, mitigate, monitor and manage the technical risks associat…
Multi-objective optimization is important for particle accelerators where various competing objectives must be satisfied routinely such as, for example, transverse emittance vs bunch length. We develop and demonstrate an online multi-time scale multi-objective optimization algorithm that performs real time feedback on particle accelerators. We demonstrate the ability to simultaneously minimize the emittance and maintain a reference trajectory of a beam in the electron beamline in CERN's Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE).
This paper gives an introduction of longitudinal beam dynamics for circular accelerators. After briefly discussing some types of circular accelerators, it focuses on particle motion in synchrotrons. It summarizes the equations of motion, discusses phase-space matching during beam transfer, and introduces the Hamiltonian of longitudinal motion.
This paper presents a list of Low Energy Beam Transport (LEBT) facilities for light-ion, high-intensity accelerators. It was put together to facilitate comparisons with the PXIE LEBT design choices. A short discussion regarding the importance of the beam perveance in the choice of the transport scheme follows.
The article considers a proton accelerator containing seven independent beams arranged on the accelerator radius. The current in each beam is one hundred milliamps. The initial part of the accelerator consists of shielded spiral waveguides assembled in the common screen. The frequency of the acceleration: three hundred megahertz, high-frequency power twenty-five megawatts, the length of the accelerator six meters. After reaching the proton energy of six megaelektronvolts the protons using lenses with the azimuthal magnetic field are collected in one beam. Further beam acceleration is performed…
After a 14 month shutdown accelerator modifications and upgrades are in place to allow us doubling of the Main Injector beam power. We will discuss the past MI high power operation and the current progress towards doubling the power.
Neutrino beams obtained from proton accelerators were first operated in 1962. Since then, neutrino beams have been intensively used in particle physics and evolved in many different ways. We describe the characteristics of various neutrino beams, relating them to the historical development of the physics studies and discoveries. We also discuss some of the ideas still under consideration for future neutrino beams.
The challenges in beam instrumentation and diagnostics for present and future particle accelerator projects are presented. A few examples for advanced hadron and lepton beam diagnostics are given.
Suppression of beam losses is essential for successful operation of high-intensity linac. Historically, the values of the field amplitudes and phases of the side-coupled, 805-MHz LANSCE linac modules are maintained using a well-known delta-t tuning procedure. Transverse matching of the beam with accelerator is performed through adjustments of beam ellipses in 4D phase space with accelerator lattice using matching quadrupoles. Control of the beam-energy ramp along the length of a proton linear accelerator is required to improve tune of accelerator and decrease beam losses. Time-of-flight measur…
This is the Snowmass Whitepaper on Beam Test Facilities for R&D in Accelerator Science and Technologies and it is submitted to two topical groups in the Accelerator Frontier: AF1 and AF6.
Beam halo is one of the crucial issues limiting the machine performance and causing radioactivation in high-intensity accelerators. A clear picture of beam-halo formation is of great importance for successful suppression of the undesired beam loss. We present numerical and experimental studies of transverse and longitudinal halos in the KEK Accelerator Test Facility. The fair accordance between predictions and observations in various conditions indicates that the Touschek scattering is the dominant mechanism forming the horizontal and momentum halos.
This report is a summary of two preparatory workshops, documenting the community vision for the national accelerator and beam physics research program. It identifies the Grand Challenges of accelerator and beam physics (ABP) field and documents research opportunities to address these Grand Challenges. This report will be used to develop a strategic research roadmap for the field of accelerator science.
We report on the development of multi-beam RF linear ion accelerators that are formed from stacks of low cost wafers and describe the status of beam power scale-up using an array of 120 beams. The total argon ion current extracted from the 120-beamlet extraction column was 0.5 mA. The measured energy gain in each RF gap reached as high as 7.25 keV. We present a path of using this technology to achieve ion currents >1 mA and ion energies >100 keV for applications in materials processing.
Accelerator and beam physics (ABP) is the science of the motion, generation, acceleration, manipulation, prediction, observation and use of charged particle beams. It focuses on fundamental long-term accelerator and beam physics research and development. Accelerator and beam physics research has resulted in important advances in accelerator science, yet support for this research is declining. NSF has terminated its program in accelerator Science and funding by DOE through GARD and Accelerator Stewardship has been steady or declining. The declining support for accelerator research will slow adv…
In this paper we describe the methods and tools used to characterize a 150 MeV proton scaling Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University Research Reactor Institute. Many of the techniques used are unique to this class of machine and are thus of relevance to any future FFAG accelerator. For the first time we detail systematic studies undertaken to improve the beam quality of the FFAG. The control of beam quality in this manner is crucial to demonstrating high power operation of FFAG accelerators in future.
We report the initial considerations of using linearly polarized optical transition radiation (OTR) to characterize the electron beams of laser plasma accelerators (LPAs) such as at the Univ. of Texas at Austin. The two LPAs operate at 100 MeV and 2-GeV, and they currently have estimated normalized emittances at ~ 1-mm mrad regime with beam divergences less than 1/γ and beam sizes to be determined at the micron level. Analytical modeling results indicate the feasibility of using these OTR techniques for the LPA applications.
Since the initial proposal in 1990s, the method of electron lenses has been successfully developed and employed at the high energy particle colliders, like Tevatron and RHIC. Here we propose a new set of electron multi beam elements (electron grids, electron lattices, electron grates and other) which employ many beams in various spatial configurations, with possible time varying currents. We present major principles of operation and generation of such systems and briefly discuss a set of possible applications in accelerators.
Fermilab's Integrable Optics Test Accelerator is an electron storage ring designed for testing advanced accelerator physics concepts, including implementation of nonlinear integrable beam optics and experiments on optical stochastic cooling. The machine is currently under construction at the Advanced Superconducting Test Accelerator facility. In this report we present the goals and the current status of the project, and describe the details of machine design. In particular, we concentrate on numerical simulations setting the requirements on the design and supporting the choice of machine param…
For the proper operation of Dalian Compact Light Source (DCLS) linac, measurement and control of the electron bunch is critical. In order to test control algorithms and high level physical applications, a virtual accelerator environment is constructed based on ELEGANT and SDDS toolkit. The required beam parameter measurement and orbit control tools are verified under this virtual environment. The design concept and current development status are presented.
The hose instability of the drive beam constitutes a major challenge for the stable operation of plasma wakefield accelerators (PWFAs). In this work, we show that drive beams with a transverse size comparable to the plasma blowout radius generate a wake with a varying focusing along the beam, which leads to a rapid detuning of the slice-betatron oscillations and suppresses the instability. This intrinsic stabilization principle provides an applicable and effective method for the suppression of the hosing of the drive beam and allows for a stable acceleration process.
A high peak current, flat longitudinal phase space electron beam is desirable for efficient x-ray free electron laser (FEL) radiation in next generation light sources. To attain such a beam requires the extensive design of the linear accelerator (linac) including both linear and nonlinear effects. In this paper, we propose a lumped longitudinal beam dynamics model for fast optimization of the electron beam longitudinal phase space through the accelerator. This model is much faster than available tracking programs and also shows good agreement with the fully three-dimensional element-by-element…
We briefly give some of the characteristics of the beam-driven, plasma-based particle accelerator known as the plasma wakefield accelerator (PWFA). We also mention some of the major results that have been obtained since the birth of the concept. We focus on high-energy particle beams where possible.
High energy and high beam power accelerators are extensively used for the neutrino physics research. At present, the leading operational facilities are the Fermilab Main Injector complex that delivers over 0.75 MW of 120 GeV protons on the neutrino target, and the J-PARC facility in Japan which recently approached 0.5 MW of the 30 GeV proton beam power. Here we present the status and planned upgrades of the Fermilab and J-PARC accelerators and proposals for the next generation accelerator-based facilities, their challenges and required and ongoing accelerator R&D programs aimed to address corr…
The PIP2IT accelerator was assembled in multiple stages in 2014 - 2021 to test concepts and components of the future PIP-II linac that is being constructed at Fermilab. In its final configuration, PIP2IT accelerated a 0.55 ms x 20 Hz x 2 mA H- beam to 16 MeV. To determine location of the beam loss in the accelerators low-energy part, where radiation monitors are ineffective, a method using oscillating trajectories was implemented. If the beam is scraped at an aperture limitation, moving its centroid with two dipole correctors located upstream and oscillating in sync, produces a line at the cor…
For modern high-intensity linear accelerators, the well-known envelope instability and recently reported fourth-order particle resonance impose a fundamental operational limit (i.e., zero-current phase advance should be less than 90 deg). Motivated by the stability of spinning flying objects, we propose a novel approach of using spinning beams to surpass this limit. We discovered that spinning beams have an intrinsic characteristic that can suppress the impact of the fourth-order resonance on emittance growth and the associated envelope instability.
A superconducting RF accelerator test facility is currently under construction at Fermilab. The accelerator will consist of an electron gun, 40 MeV injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, and multiple downstream beam lines for testing diagnostics and performing beam experiments. With 3 cryomodules installed this facility will initially be capable of generating an 810 MeV electron beam with ILC beam intensity. The facility can accommodate up to 6 cryomodules for a total beam energy of 1.5 GeV. This facility will be used to test SRF cryomodules under…
The performance of high beam power accelerators is strongly dependent on appropriate injection, acceleration and extraction system designs as well as on the way interactions of the beam with machine components are handled. The experience of the previous ICFA High -Brightness Beam workshops has proven that it is quite beneficial to combine analyses and discussion of these issues in one group. A broad range of topics was presented and discussed at the Working Group C sessions at the HB2012 Workshop. Highlights from the talks, outstanding issues along with plans and proposals for future work are …
C. B. Schroeder, E. Esarey, C. Benedetti, and W. P. Leemans {Phys. Rev. ST Accel. Beams 13, 101301 (2010) and 15, 051301 (2012)} have proposed a set of parameters for a TeV-scale collider based on plasma wake field accelerator principles. In particular, it is suggested that the luminosities greater than 10^34 cm-2s-1 are attainable for an electron-positron collider. In this comment we dispute this set of parameters on the basis of first principles. The interactions of accelerating beam with plasma impose fundamental limitations on beam properties and, thus, on attainable luminosity values.
Radio Frequency Quadrupole (RFQ) accelerators often need to face the challenges of space charge effects from high beam currents. This study investigated how to reach RFQ beam dynamics designs with not only high beam transmission and short structure length but also high beam quality simultaneously. To avoid beam instabilities induced by emittance transfer, a so-called el/et (ratio of the longitudinal and transverse emittances) = 1.0 design guideline is being proposed. The application of this design guideline integrated with the BABBLE/NFSP design method for a high current, high frequency, high …
This article introduces an analytical formalism for the calculation of the evolution of beam moments and the transverse emittance for beams which are externally injected into plasma wakefield accelerators. This formalism is then applied to two scenarios with increasing complexity - a single beam slice without energy gain and a single beam slice with energy gain, both propagating at a fixed co-moving position behind the driver. The obtained results are then compared to particle-in-cell (PIC) simulations as well as results obtained using an semi-analytic numerical approach (SANA). We find excell…
The 750-keV low-energy beam transport of the Los Alamos Neutron Science Center (LANSCE) linac consists of two independent beam lines that facilitate simultaneous injection of H+ and H- beams into the linear accelerator. The efficiency of beam transport within this structure is largely controlled by the effects of space-charge neutralization. In this paper, we report a series of experiments that were performed to determine the level, as well as the required timescale for the onset of beam space charge neutralization. Measurements performed along the structure indicate significant variation of n…
Circular particle accelerators at the energy frontier are based on superconducting magnets that are extremely sensitive to beam losses as these might induce quenches, i.e.\ transitions to the normal-conducting state. Furthermore, the energy stored in the circulating beam is so large that hardware integrity is put in serious danger, and machine protection becomes essential for reaching the nominal accelerator performance. In this challenging context, the beam halo becomes a potential source of performance limitations and its dynamics needs to be understood in detail to assess whether it could b…
A Compact laser plasma accelerator (CLAPA) is being built in Peking University, which is based on RPA-PSA mechanism or other acceleration mechanisms. According to the beam parameters from preparatory experiments and theoretical simulations, the beam line is preliminarily designed. The beam line is mainly constituted by common transport elements to deliver proton beam with the energy of 1~50MeV, energy spread of 0~1% and current of 0~108 proton per pulse to satisfy the requirement of different experiments. The simulation result of 15MeV proton beam with an energy spread of 1%, current of 1x108 …
Commissioning at the SCRF accelerator at the Fermilab Accelerator Science and Technology (FAST) Facility has included the implementation of a versatile bunch-length monitor located after the 4-dipole chicane bunch compressor for electron beam energies of 20-50 MeV and integrated charges in excess of 10 nC. The team has initially used a Hamamatsu C5680 synchroscan streak camera to assess the effects of space charge on the electron beam bunch lengths. An Al-coated Si screen was used to generate optical transition radiation (OTR) resulting from the beam's interaction with the screen. The chicane …
Beam injections to KEKB and Photon Factory are performed with pulse-to-pulse modulation at 50 Hz. Three very different beams are switched every 20 ms in order to inject those beams into KEKB HER, LER and Photon Factory (PF) simultaneously. Human operators work on one of those three virtual accelerators, which correspond to three-fold accelerator parameters. Beam charges for PF injection and the primary electron for positron generation are 50-times different, and beam energies for PF and HER injection are 3-times different. Thus, the beam stabilities are sensitive to operational parameters, and…
Beam loading is the phenomenon which limits the charge and the beam quality in plasma based accelerators. An experimental study conducted with a laser-plasma accelerator is presented. Beam loading manifests itself through the decrease of the beam energy, the reduction of dark current and the increase of the energy spread for large beam charge. 3D PIC simulations are compared to the experimental results and confirm the effects of beam loading. It is found that, in our experimental conditions, the trapped electron beams generate decelerating fields on the order of 1 GV/m/pC and that beam loading…
Beam-driven collinear wakefield accelerators (CWAs) that operate by using slow-wave structures or plasmas hold great promise toward reducing the size of contemporary accelerators. Sustainable acceleration of charged particles to high energies in the CWA relies on using field-generating relativistic electron bunches with a highly asymmetric peak current profile and a large energy chirp. A new approach to obtaining such bunches has been proposed and illustrated with the accelerator design supported by particle tracking simulations. It has been shown that the required particle distribution in the…
Radio-frequency linear accelerators are used as injectors for synchrotrons and as stand-alone accelerators for the production of intense particle beams, thanks to their ability to accelerate high beam currents at high repetition rates. This lecture introduces their main features, reviewing the different types of accelerating structures used in linacs and presenting the main characteristics of linac beam dynamics. Building on these bases, the architecture of modern proton linear accelerators is presented with a particular emphasis on high-energy and high-beam-power applications.
Purpose: To describe a concept of a compact electron accelerator for external radiation therapy with variable energy in the range of 6 - 20 MeV, based on linotron principle. Methods: Beam dynamics simulation using the CST and MAD-X code. Various optimization methods of multi-parameter problem. Results: Our accelerator differs from the Reflexotron in a number of essential details: a much more compact and more efficient C-band accelerating structure, optimized for the high capture efficiency, narrow energy and phase spectra, and low transverse emittance; magnetic mirror with fixed field based on…
A superconducting RF accelerator test facility is being constructed at Fermilab. The existing New Muon Lab (NML) building is being converted for this facility. The accelerator will consist of an electron gun, injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, multiple downstream beam lines for testing diagnostics and conducting various beam tests, and a high power beam dump. When completed, it is envisioned that this facility will initially be capable of generating an 810 MeV electron beam with ILC beam intensity. Expansion plans of the facility are underway …
Beam measurement is very important for accelerators. With the development of analog-to-digital conversion techniques, digital beam measurement becomes a research hot spot. IQ (In-phase & Quadrature-phase) analysis based method is an important beam measurement approach, the principle of which is presented and discussed in this paper. The State Key Laboratory of Particle Detection and Electronics in University of Science and Technology of China has devoted efforts to the research of digital beam measurement based on high-speed high-resolution analog-to-digital conversion, and a series of beam me…
The 3 MV Tandem Pelletron accelerator at the Spanish Accelerator Laboratory (CNA) has been recently upgraded to produce pulsed ion beams for neutron Time-Of-Flight (TOF) measurements. The upgrade has consisted of two actions: a pulsing system installed at the low energy part of the Tandem accelerator and a new line fully equipped. The pulsing system provides approximately one nanosecond pulse width of protons with variable repetition rates from kHz down to MHz. The new line is equipped with conventional devices and a pick-up for timing measurements with high resolution. The properties of the w…
The Integrable Optics Test Accelerator (IOTA) at the Fermilab Accelerator Science & Technology (FAST) Facility is beginning operations, with an experimental program aimed at developing technology to enable future high intensity particle beams. The results garnered from IOTA should allow for better control of beam losses, leading to higher safely achievable beam power. This will be particularly useful for future accelerator based neutrino experiments. Two of the R&D efforts at IOTA, Nonlinear Integrable Optics and Electron Column-based space charge compensation, are discussed here.
Protection of accelerator equipment is as old as accelerator technology and was for many years related to high-power equipment. Examples are the protection of powering equipment from overheating (magnets, power converters, high-current cables), of superconducting magnets from damage after a quench and of klystrons. The protection of equipment from beam accidents is more recent, although there was one paper that discussed beam-induced damage for the SLAC linac (Stanford Linear Accelerator Center) as early as in 1967. It is related to the increasing beam power of high-power proton accelerators, …
Laser-based electron acceleration is attracting strong interest from the conventional accelerator community due to its outstanding characteristics in terms of high initial energy, low emittance and high beam current. Unfortunately, such beams are currently not comparable to those of conventional accelerators, limiting their use for the manifold applications that a traditional accelerator can have. Besides working on the plasma source itself, a promising approach to shape the laser-generated beams is coupling them with conventional accelerator elements in order to benefit from both, a versatile…
We report on the development of a radio frequency (RF) linear accelerator (linac) for multiple-ion beams that is made from stacks of low cost wafers. The accelerator lattice is comprised of RF-acceleration gaps and electrostatic quadrupole focusing elements that are fabricated on 10-cm wafers made from printed circuit board or silicon. We demonstrate ion acceleration with an effective gradient of about 0.5 MV per meter with an array of 3 by 3 beams. The total ion beam energies achieved to date are in the 10 keV range with total ion currents in tests with noble gases of ~0.1mA. We discuss scali…
We present a method to compressed the 2D transverse phase space projections from a hadron accelerator and use that information to predict the beam transmission. This method assumes that it is possible to obtain at least three projections of the 4D transverse phase space and that an accurate simulation model is available for the beamline. Using a simulated model we show that, a procedure using a convolutional autoencoder can be trained to reduce phase-space information which can later be used to predict the beam transmission. Finally, we argue that although using projections from a realistic no…
We outline the design of beam experiments for the electron linac at the Fermilab Accelerator Science and Technology (FAST) facility and for the Integrable Optics Test Accelerator (IOTA), based on synchrotron light emitted by the electrons in bend dipoles, detected with gated microchannel-plate photomultipliers (MCP-PMTs). The system can be used both for beam diagnostics (e.g., beam intensity with full dynamic range, turn-by-turn beam vibrations, etc.) and for scientific experiments, such as the direct observation of the time structure of the radiation emitted by single electrons in a storage r…
The high-intensity rare-isotope accelerator (RAON) of the Rare Isotope Science Project (RISP) in Daejeon, Korea, has been designed to accelerate multiple-charge-state beams. The ion beams, which are generated by Electron Cyclotron Resonance Ion Source (ECR-IS), will be transported through the main Low Energy Beam Transport (LEBT) system to the Radio Frequency Quadrupole (RFQ). While passing the beams through LEBT, we should keep the transverse beam size and longitudinal emittance small. Furthermore, the matching of required twiss parameter at the RFQ entrance will be performed by using electro…
