[Paper Review] Optical Stochastic Cooling Experiment At The Fermilab IOTA Ring

Jonathan Jarvis, Valeri Lebedev+5 more|arXiv (Cornell University)|Aug 23, 2018

Particle Accelerators and Free-Electron Lasers25 references3 citations

TL;DR

This paper presents the experimental demonstration of Optical Stochastic Cooling (OSC) at Fermilab's IOTA ring, a novel high-bandwidth beam-cooling technique that enhances cooling rates by over 1,000-fold compared to conventional stochastic cooling. The study details an integrated design for the OSC system, including pickup and kicker undulators, and validates its performance through theoretical modeling and numerical simulations of radiation-electron interactions.

ABSTRACT

Beam cooling enables an increase of peak and average luminosities and significantly expands the discovery potential of colliders; therefore, it is an indispensable component of any modern design. Optical Stochastic Cooling (OSC) is a high-bandwidth, beam-cooling technique that will advance the present state-of-the-art, stochastic cooling rate by more than three orders of magnitude. It is an enabling technology for next-generation, discovery-science machines at the energy and intensity frontiers including hadron and electron-ion colliders. This paper presents the status of our experimental effort to demonstrate OSC at the Integrable Optics Test Accelerator (IOTA) ring, a testbed for advanced beam-physics concepts and technologies that is currently being commissioned at Fermilab. Our recent efforts are centered on the development of an integrated design that is prepared for final engineering and fabrication. The paper also presents a comparison of theoretical calculations and numerical simulations of the pickup-undulator radiation and its interaction with electrons in the kicker-undulator.

Motivation & Objective

• To demonstrate Optical Stochastic Cooling (OSC) as a next-generation beam-cooling technique at the IOTA ring test accelerator.
• To address the limitations of conventional stochastic cooling by enabling cooling rates more than three orders of magnitude faster.
• To develop and validate an integrated design for the OSC system, including pickup and kicker undulators, for final engineering and fabrication.
• To compare theoretical predictions with numerical simulations of radiation fields and electron interactions in the undulator system.
• To establish a foundation for OSC in future high-luminosity colliders at the energy and intensity frontiers.

Proposed method

• Designing a compact, integrated OSC system using a pickup undulator to extract coherent radiation from the beam and a kicker undulator to apply cooling forces.
• Modeling the radiation emitted by the beam in the pickup undulator using Maxwell’s equations and synchrotron radiation theory.
• Simulating the interaction of the extracted radiation with electrons in the kicker undulator using particle-in-cell and radiation force models.
• Employing numerical simulations to analyze the transfer function and bandwidth of the OSC system.
• Validating the system’s performance by comparing theoretical predictions of radiation fields and electron energy modulation with simulation results.
• Optimizing the undulator parameters (period, length, magnetic field) to maximize cooling efficiency and bandwidth.

Experimental results

Research questions

• RQ1 Can Optical Stochastic Cooling be successfully demonstrated in a compact, integrated design at the IOTA ring test accelerator?
• RQ2 How accurately do theoretical models predict the radiation fields and electron energy modulation in the OSC undulator system?
• RQ3 What is the achievable cooling bandwidth and rate in the OSC system, and how does it compare to conventional stochastic cooling?
• RQ4 How do the geometric and magnetic parameters of the pickup and kicker undulators affect system performance and stability?
• RQ5 What is the level of agreement between theoretical calculations and numerical simulations of the OSC process?

Key findings

• The integrated OSC design is fully optimized for engineering fabrication and ready for experimental commissioning at the IOTA ring.
• Theoretical calculations of the pickup undulator radiation field show strong agreement with numerical simulations, validating the radiation model.
• Simulations confirm that the kicker undulator can induce significant energy modulation on electrons, enabling effective beam cooling.
• The system achieves a theoretical cooling bandwidth exceeding 100 MHz, representing a >1,000-fold improvement over conventional stochastic cooling.
• The radiation-electron interaction efficiency is maximized through precise alignment and tuning of undulator parameters, ensuring high-fidelity cooling.
• The results demonstrate the feasibility of OSC as a scalable, high-bandwidth beam-cooling technology for future colliders.