Electron Accelerator

TARLA is Turkey’s first continuous wave (CW) superconducting electron accelerator infrastructure. It provides electron beams in the energy range of 1–40 MeV for research purposes. The system is composed of three main sections: the electron gun, the injector line, and the superconducting cryomodules.

⚙ Electron Gun

This section is where electrons are generated using a thermionic DC source operating under high voltage. The system produces electrons with an energy of approximately 250 keV. The electron bunch is generated at a tungsten dispenser cathode with grid modulation, resulting in a bunch length of about 600 ps. The electron gun represents the first and most critical step in determining beam quality.

⚙ Injector Line

Electrons exiting the electron gun at around 250 keV undergo control and conditioning processes before being injected into the main accelerator section. The injector line is specifically designed to shape the time structure of the beam, adjust its trajectory, and optimize its optical parameters. The main components include:

• Two RF normal conducting cavities, which compress the bunches in time to form short and uniform pulses required for efficient acceleration in superconducting cavities.
• Magnetic elements for steering and focusing:
  • A 15° dipole magnet used for preliminary beam diagnostics.
  • A 75° dipole magnet for beam characterization and bunch length measurements via a deflector cavity.
  • Solenoid magnets that focus the beam and ensure a stable and focused beam profile.
• Beam diagnostics systems: Equipment for measuring bunch length, beam current, and emittance.

This line is crucial for enhancing beam quality and defining its temporal structure before transferring it to the superconducting cryomodules for energy gain.

❄ Superconducting Cryomodules

Electrons from the injector are accelerated to higher energies in the superconducting acceleration structures. Key features include:

• Each cryomodule contains two TESLA-type superconducting RF cavities, which apply electromagnetic fields to increase the energy of the beam.
• The cavities are cooled to ~2 Kelvin using liquid helium to maintain superconductivity.
• Electron beams can be accelerated up to approximately 40 MeV.
• Operating in CW mode, these modules are vital for delivering high-quality beams.

⚙ Bunch Compression System

The electron beam at TARLA is compressed into short, high-density bunches suitable for time-resolved applications. The bunch compression system, located between two cryomodules, consists of quadrupole and dipole magnets that manipulate the temporal structure of the beam.

Since the Free Electron Laser (FEL) relies on a high-brightness electron beam, precise control of bunch length is essential. This system allows for both temporal and spatial compression of the beam, resulting in a compact and optimized electron bunch.

📊 Electron Beam Technical Specifications