Relationship between spatial coherence of synchrotron radiation and emittance

Area of Science:

• Optics and Photonics
• Particle Accelerators

Background:

• Gaussian beams are frequently approximated for synchrotron radiation analysis.
• Investigating brightness, flux, and qualitative properties often relies on this approximation.

Purpose of the Study:

• Compare analytical calculations of Gaussian beam spatial coherence with numerical calculations for synchrotron radiation.
• Evaluate the validity of the Gaussian beam approximation for synchrotron radiation.

Main Methods:

• Performed analytical calculations for first-order spatial coherence of Gaussian beams.
• Conducted exact numerical calculations for synchrotron radiation spatial coherence.

Main Results:

• Synchrotron radiation demonstrates lower spatial coherence compared to Gaussian beams.
• Differences arise from beam profile, wave phases, and polarization characteristics.
• The Gaussian beam approximation is shown to be limited.

Conclusions:

• Synchrotron radiation's coherence is inherently lower than that of Gaussian beams.
• Measuring synchrotron radiation's beam size and spatial coherence allows for direct determination of photon beam emittance.
• This method bypasses the need for detailed Twiss parameters of the storage ring.