Plasma channel undulator excited by high-order laser modes

Area of Science:

• Plasma physics
• Laser-driven acceleration
• Advanced photon sources

Background:

• Compact ultraviolet and X-ray sources are desirable for broader access beyond large-scale synchrotron and free-electron laser (FEL) facilities.
• Existing plasma undulator and accelerator concepts suffer from broad radiation bandwidth, limiting source brightness and FEL instability.
• Reducing the cost and size of accessing advanced photon sources is a key research driver.

Purpose of the Study:

• To investigate a novel plasma undulator design for generating compact, high-brightness ultraviolet and X-ray sources.
• To overcome the limitation of broad radiation bandwidth in existing plasma-based photon sources.
• To assess the feasibility of developing table-top free-electron lasers (FELs) using plasma undulators.

Main Methods:

• Multi-dimensional particle-in-cell (PIC) simulations were employed to model plasma undulator dynamics.
• A plasma channel was used to guide a mixture of high-order laser modes.
• Phase locking techniques and longitudinal tapering were utilized to enhance undulator properties.

Main Results:

• The proposed plasma undulator design generates radiation with a few percent bandwidth, a significant improvement over previous methods.
• Achieved undulator strengths approach unity with periods below a millimeter.
• Electron currents reached 0.3 kA in the beam-loaded regime, demonstrating potential for FEL applications.
• Polarization control was demonstrated through careful selection of laser mode phases.

Conclusions:

• A novel plasma undulator design, utilizing beating laser modes in a plasma channel, significantly reduces radiation bandwidth.
• This design enables enhanced control over undulator parameters like strength, period, and polarization.
• The demonstrated electron currents and controlled bandwidth suggest a viable pathway towards realizing table-top free-electron lasers (FELs).