Picosecond pulsed 532 nm laser system for roughening and secondary electron yield reduction of inner surfaces of up to 15 m long tubes

Elena Bez (Lead / Corresponding author), Marcel Himmerlich, Benoit Beaudou, Ana Karen Reascos Portilla, Stefan Wackerow, Martino Rimoldi, Stephan Pfeiffer, Markus Wiesendanger, Fetah Benabid, Mauro Taborelli, Amin Abdolvand, Paolo Chiggiato

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Abstract

Laser-induced surface structuring is a promising method to suppress electron mulitpacting in the vacuum pipes of particle accelerators. Electrons are scattered inside the rough surface structure, resulting in a low Secondary Electron Yield (SEY) of the material. However, laser processing of internal pipe surfaces with a large aspect ratio is technologically challenging in terms of laser beam guidance and focusing. We present a 532 nm ultrashort-pulse laser setup to process the inner parts of 15 m long beam vacuum tubes of the Large Hadron Collider (LHC). Picosecond pulses at a repetition rate of 200 kHz are guided through an optical fiber toward an inchworm robot traveling inside the beam pipe. The system was installed, characterized, and tested for reliability. First surface treatments achieved the required scan precision. Cu2O-dominated nano-features were observed when processing at high average laser power (5 W) and slow scanning speed (5 mm s−1) in nitrogen flow, and the maximum SEY of copper was decreased from 2.1 to 0.7.
Original languageEnglish
Article number103007
Number of pages11
JournalReview of Scientific Instruments
Volume94
Issue number10
DOIs
Publication statusPublished - 9 Oct 2023

Keywords

  • vacuum tubes
  • Power transmissions
  • Robotics
  • Laser ablation
  • Optical fibers
  • Photonic crystal fibers
  • Particle accelerators
  • Large Hadron Collider
  • Ultrafast lasers
  • Copper

ASJC Scopus subject areas

  • Instrumentation

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