Conveners
B: High-Intensity Ring Design
- Robert Williamson
B: High-Intensity Linacs
- Okuno Hiroki (RIKEN)
B: Benchmarking and Experiments
- Kiersten Ruisard (Oak Ridge National Laboratory)
B: Space-Charge Modelling
- Ji Qiang
Description
Machine Design and Numerical Modelling of Beam Dynamics
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Robert Williamson30/09/2026, 11:00
Lead talk session B-4.
This talk outlines the key challenges of high-intensity ring design through the lens of the design and operation of ISIS, that of high-intensity machines worldwide, and particularly the design of the MW class neutron source ISIS-II. ISIS is the high-intensity pulsed neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation centres on a rapid...
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Takaaki Yasui (KEK)30/09/2026, 11:20B-4. High-Intensity Ring Design
In designing high-intensity proton synchrotrons, discussions often focus on the magnitude of the tune shift, that is, the linear effects of space charge. This is because the strength of space charge is generally considered to be characterized by the magnitude of the tune shift. Consequently, space-charge mitigation has traditionally been almost synonymous with tune-shift mitigation. Typical...
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Austin Hoover (Oak Ridge National Laboratory)30/09/2026, 11:35B-4. High-Intensity Ring Design
This talk will describe planned experiments to validate theoretical and computational models of space charge effects in the SNS Accumulator Ring (AR). I will discuss the potential to leverage the world-leading bunch intensity (2.25e14), flexible energy range (800-1300 MeV), four-dimensional phase space painting, and longitudinal bunch compression in the AR to push the tune shift to large...
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Joshua Appleby (University of Oxford)30/09/2026, 11:50B-4. High-Intensity Ring Design
In the design of future accelerators that push the high intensity frontier, such as ISIS-II, an outstanding question remains on how the choice of bare tune affects the space charge limit. As the bare tunes reflect the transverse focusing of each plane, different accelerator types, with different focusing schemes, such as synchrotrons or fixed-field alternating gradient accelerators (FFA’s),...
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Robert Williamson30/09/2026, 12:05
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Okuno Hiroki (RIKEN)01/10/2026, 08:30
Lead talk session B-1.
Designing next-generation high-intensity linacs requires a detailed understanding of collective beam physics and the technological constraints that limit reliable MW-class operation. As beam currents enter the strongly space-charge-dominated regime, emittance growth, halo formation, and beam loss become tightly coupled to injector dynamics, neutralization processes,...
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Jibong Hyun (QST)01/10/2026, 08:50B-1. High-Intensity Linacs
Longitudinal beam control using RF bunchers is widely employed in accelerators. However, the nonlinear RF fields in bunchers distort the longitudinal phase-space distribution, can lead to emittance growth. In this presentation, we report a self-linearization phenomenon observed for a 125 mA, 5 MeV deuteron beam in the Linear IFMIF Prototype Accelerator (LIPAc). In this mechanism, distortions...
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Abhishek Pathak (Fermi National Accelerator Laboratory)01/10/2026, 09:05B-1. High-Intensity Linacs
The PIP-II 800 MeV, CW-capable superconducting-RF H⁻ linac at Fermilab must deliver at least 1.2 MW to LBNF/DUNE while holding uncontrolled beam loss below the hands-on-maintenance limit of ~1 W/m, a challenge rooted in its deliberately non-equipartitioned, strongly space-charge-dynamics, where the transverse tune depression reaches η ≈ 0.65 in the HWR and SSR1 spoke sections and space charge...
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Dong-O Jeon (Institute for Basic Science)01/10/2026, 09:20B-1. High-Intensity Linacs
Parametric instabilities have been long known as a major space-charge halo mechanism and studied intensively. With realistic distributions, for the first time we confirm that high-order parametric instabilities other than the envelope instability are not manifested in actual linear accelerators. Moreover, the effect of the envelope instability is weaker for the realistic distributions than for...
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Okuno Hiroki (RIKEN)01/10/2026, 09:50
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Kiersten Ruisard (Oak Ridge National Laboratory)02/10/2026, 08:30B-2. Benchmarking and Experiments
Lead talk session B-2.
Beam Dynamics in the SNS Linac and Beam Test Facility:
The SNS Linac is currently the highest-power superconducting linac. This talk will describe operational challenges of the SNS H- linac, with a focus on what we do and don't understand about beam dynamics. R&D projects aimed at improving our understanding will be discussed, with a focus on the Beam Test Facility...
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Dr Tony Wood (Oak Ridge National Laboratory)02/10/2026, 08:50B-2. Benchmarking and Experiments
Research at the SNS Beam Test Facility uses comprehensive phase space diagnostics to support benchmarking of our particle-in-cell linac model. The BTF transports 2.5 meV, 50 mA H- beams a distance of 13 meters, through a transport line that includes 9.5 FODO cells. This talk will report on current benchmarking results. Very good agreement for the 90% core of the matched beam is demonstrated....
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Nilanjan Banerjee (Fermi National Accelerator Laboratory)02/10/2026, 09:05B-2. Benchmarking and Experiments
We have begun 2.5 MeV proton operations at the Integrable Optics Test Accelerator (IOTA) in Fermilab to study beam dynamics with an incoherent tune shift approaching 0.5 in a zero‑wakefield environment. We present a detailed comparison of predicted dynamics in bare IOTA (dipoles and quadrupoles only) from several simulation codes, including ImpactX, Lifetrac, MAD-X, PyORBIT, and Xsuite. We...
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Haroon Rafique (STFC)02/10/2026, 09:20B-2. Benchmarking and Experiments
PyORBIT has recently been ported to Python 3 and migrated to a Meson-based build system. This creates both an opportunity and a practical challenge for compiling PyORBIT together with the PTC libraries, which enable realistic lattice tracking, including nonlinear machine effects, within multi-particle space-charge studies.
This contribution will discuss ongoing work and experience with...
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Yichao Jing (Brookhaven National Lab)02/10/2026, 09:35B-2. Benchmarking and Experiments
At the Electron Ion Collider's Hadron Injector, the Alternating Gradient Synchrotron (AGS), space charge effects at injection remain a key factor that limits the polarized proton beam quality. Minimizing the emittance growth is essential for delivering high luminosity and minimizing polarization loss during acceleration. In this paper, we present Xsuite simulations of beam dynamics during AGS...
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Kiersten Ruisard (Oak Ridge National Laboratory)02/10/2026, 09:50
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Ji Qiang02/10/2026, 10:45B-3. Space-Charge Modelling
Lead talk session B-3.
Space Charge modelling of long bunches and data-driven approaches:
In this presentation, we will discuss challenges in space-charge modeling to support the design of new space-charge limited particle accelerator facilities. We will then review recent advances in space-charge modeling, such as the use of data-driven approaches and efficient methods for long bunches....
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Andreas Adelmann (Paul Scherrer Institut)02/10/2026, 11:05B-3. Space-Charge Modelling
Predictive modelling of high-intensity hadron and lepton beams requires self-consistent, first-principles simulations that remain scalable on heterogeneous HPC systems. This contribution presents OPALX as a unified, performance-portable framework for space-charge modelling across a wide range of accelerator regimes.
OPALX combines grid-based and grid-less methods in one toolchain: PIC with...
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Helena Alamprese (Michigan State University - FRIB)02/10/2026, 11:20B-3. Space-Charge Modelling
As next-generation particle accelerators aim for unprecedented beam intensities, modeling collective effects—particularly space charge—has become a dominant challenge. In low-energy, high-intensity hadron colliders, space charge has been demonstrated to cause tune shifts, emittance growth, halo formation, and particle losses. Consequently, accurate modeling is essential for machine design and...
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Oliver Boine-Frankenheim (TU Darmstadt and GSI)02/10/2026, 11:35B-3. Space-Charge Modelling
In hadron synchrotrons coherent bunch modes and their loss of Landau damping thresholds are important to determine active feedback requirements and bunch intensity limits. At low or medium energies space charge is the dominant collective force acting on the longitudinal bunch distribution. Usually simple g-factor or impedance models are applied, assuming a transversely constant force and a...
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Chad Mitchell02/10/2026, 11:50B-3. Space-Charge Modelling
ImpactX represents the next generation of the particle-in-cell code IMPACT-Z, featuring s-based symplectic tracking with collective effects, C++ parallelism with GPU acceleration, mesh-refinement (MR), openPMD standardized data I/O and a Python interface suitable for coupling to AI/ML workflows. Space charge models include FFT-based Integrated Green Function Poisson solvers (2D, 2.5D, and 3D),...
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Ji Qiang02/10/2026, 12:05
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Chen Xiao (GSI)B-1. High-Intensity Linacs
Intense uncoupled beams are conventionally transported through periodic focusing lattices composed of linear optical elements that provide radial confinement against defocusing space-charge forces. In such systems, interplane coupling has traditionally been regarded as an undesirable perturbation. Recently, however, the concept of matched transport in periodic quadrupole focusing channels has...
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