Searcharxiv⌕ Search

arXiv subjects

Zhilong Pan

Publications and source records attributed to Zhilong Pan.

4 recordsLinked to original sources
arXiv2026

Weak-Strong Steady-State Microbunching Accelerator Light Source

We propose a phase space manipulation involving one energy modulation sandwiched by two dispersion sections which converts a bunched particle beam or bunch train to ultra-high-harmonic density modulation, while the energy modulation in principle can be arbitrarily weak. The same scheme can also be used for energy bunching, creating energy levels in a bunched beam. We further propose a mechanism invoking three laser modulators in a storage ring to longitudinally focus the electron beam both weakly and strongly, such that a microbunch train and its high-density-harmonics or energy bunching form and sustain turn-by-turn. We call this mechanism weak-strong steady-state microbunching (Weak-Strong SSMB). The longitudinal beta function can vary by seven orders of magnitude along such a ring, with the minimal value squeezed to 10 nm. An example application of Weak-Strong SSMB for kW coherent EUV radiation is presented. Extension to X-ray can be anticipated. An energy-leveled electron beam enables $\gamma$-ray frequency comb production. The ideas can be scaled to wavelengths like RF and THz, for bunch length and energy spread control, ultrashort X-ray and coherent THz generation. Our work establishes a new paradigm for longitudinal dynamics study, accelerator light source development, and opens great potential for accelerator physics and technology.

physics.acc-ph↗
arXiv2026

Echo Enhanced Strong Focusing for Coherent Short-Wavelength Radiation

Storage-ring-based fully coherent light sources, including steady-state microbunching (SSMB), as well as compact seeded FELs driven by laser plasma accelerators, typically have relatively large intrinsic energy spreads. Extending the spectral reach of these facilities toward the X-ray regime represents a major challenge, as existing seeded schemes require rather extreme parameters to generate appreciable microbunching at high harmonics. In this Letter, we propose an echo enhanced strong focusing scheme that employs transverse-longitudinal coupling together with the beam echo effect to simultaneously resolve the energy spread bottleneck and enable efficient high-harmonic generation. This approach substantially relaxes the requirements on both the intrinsic energy spread and the transverse emittance, paving the way for soft X-ray production using relatively weak laser modulation. Based on this scheme, we further present an SSMB storage ring capable of generating kW-level average power 6.7 nm soft X-ray radiation.

physics.acc-ph↗
arXiv2024

Steady-State Micro-Bunching based on Transverse-Longitudinal Coupling

In this paper, three specific scenarios of a novel accelerator light source mechanism called steady-state micro-bunching (SSMB) have been studied, i.e., longitudinal weak focusing, longitudinal strong focusing and generalized longitudinal strong focusing (GLSF). At present, GLSF is the most promising among them in realizing high-power short-wavelength coherent radiation with a mild requirement on the modulation laser power. Its essence is to exploit the ultrasmall natural vertical emittance of an electron beam in a planar storage ring for efficient microbunching formation, like a partial transverse-longitudinal emittance exchange at the optical laser wavelength range. Based on indepth investigation of related beam physics, a solution of a GLSF SSMB storage ring which can deliver 1 kW-average-power EUV light is presented. The work in this paper, such as the generalized Courant-Snyder formalism, the analysis of theoretical minimum emittances, transverse-longitudinal coupling dynamics, and the derivation of bunching factor and modulation strengths for laser-induced microbunching schemes, is expected to be useful not only for the development of SSMB but also for future accelerator light sources in general that demand increasingly precise electron beam phase space manipulations.

physics.acc-ph↗