Conveners
THFA WGs flash talks: Flash Talks
- Liangting Sun (Institute of Modern Physics, Chinese Academy of Sciences)
We present PyFFA, a Python-based simulation framework developed for high-intensity beam dynamics studies in circular accelerators with unfixed closed orbits. The code features multi-particle tracking with self-consistent 2.5D Particle-In-Cell (PIC) space charge calculations and supports multi-turn painting injection for long bunches in accelerators such as FFA machines and cyclotrons.
The High-Luminosity upgrade of the Large Hadron Collider targets a yearly integrated luminosity of $300\,\text{fb}^{-1}$. Following several hardware upgrades, the bunch intensity is foreseen to be raised to $2.2 \cdot 10^{11}$ protons per bunch. The resulting beam loading poses a challenge for the main radio frequency (RF) system of the LHC. The limited RF capture voltage and an enlarged...
Coupled-bunch instabilities will occur with long-range wakefields. And it’s an effective way to adjust the chromaticity to suppress transverse coupled-bunch instabilities. There are some theoretical studies showing that strong space charge can weaken the suppression effect of chromaticity. In this paper, transverse coupled-bunch instabilities with space charge are simulated and analysed using...
The CERN Proton Synchrotron Booster (PSB) operates at two nominal extraction energies, 1.4 GeV and 2 GeV, each presenting distinct achievable beam intensities. To mitigate longitudinal instabilities, the PSB RF system employs a combination of double-harmonic voltage and multi-harmonic cavity feedback loops. When operating with single-harmonic voltage and open cavity loops, a fast instability...
The challenge of delivering FLASH irradiation to large volume targets within 100 ms using 3D pencil beam scanning (PBS) persists. A novel scanning scheme based on a rapid-cycling synchrotron (RCS) is proposed. This work introduces a longitudinal localized kick driven fast extraction method used in the scheme. By applying stripline kicker pulses to specific longitudinal segments of the bunch...
Controlling induced radioactivity remains crucial for high-intensity proton accelerators. This study analyzes radiation hotspots in a Rapid Cycling Synchrotron (RCS) using extensive dose measurements (2018-2025). We identified hotspots (>5 mSv/h) exhibiting either transient ("peaking-then-decreasing") or persistent ("increasing-then-stabilizing") behavior. Strategic measures - orbit...
CSNS-II superconducting Section Beam Loss Measurement Electronic Design
The CSNS-II linear accelerator upgrade will adopt superconducting accelerator structures, with the beamline enclosed in low-temperature modules. Detection of beam loss can only be done on the outer surface of the low-temperature modules. The CSNS-II accelerator plans to use a parallel plate multi-electrode ionization...
This study explores the use of Bayesian optimization in reducing CSNS RCS beam loss. Bayesian optimization is a global optimization framework ideal for complex, black-box functions. By building a probabilistic model of the objective function, often a Gaussian process, it selects new sampling points based on predicted uncertainty, efficiently finding the optimum with limited resources. It has...
Longitudinal ion beam stacking in a storage ring using a barrier rf system combined with beam cooling has been successfully demonstrated in several experiments. Based on the bunching effect observed in the pulsed electron beam cooling experiment at HIRFL-CSRm, we propose a new beam stacking scheme using only pulsed electron beam, in which the barrier voltage and cooling process can be achieved...
We propose an end-to-end deep learning method for reconstruction of proton synchrotron longitudinal phase space distributions from 1D beam current projections. Unlike iterative tomographic approaches, our model bypasses complex physics computations by establishing a direct sequence-to-image mapping. The architecture integrates sinusoidal positional encoding to capture multi-turn temporal...
This paper presents an overview of the beam intensity measurement system for the C-band photocathode electron gun platform, detailing the observed phenomena during measurements and the associated experimental investigations. The system’s design, operational principles, and key components are introduced, followed by an analysis of critical measurement results and unexpected behaviors, such as...
At the J-PARC Main Ring, a project is in progress to upgrade the beam power to 1.3 MW for the neutrino oscillation experiment. Control of the optics and beam orbit relative to the magnetic center of the accelerator components is crucial to suppress beam losses in intense beams. We need to reduce the determination error of the beta function from the current value of 2% to less than 1%....
