Investigation of a plasma delivery system for optical figuring process

Nan YU, Renaud JOURDAIN, Marco CASTELLI, Adam BENNETT, Jiang GUO, Chengyu MA, Fengzhou FANG*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Plasma figuring process enables the correction of metre-scale optical surfaces, which has advantages such as rapid convergence to ultra-precision accuracy level, no subsurface damage, ease of upscale thanks to the conditions of operation at atmospheric. Such attributes make plasma figuring a highly competitive technology. To maintain a stable discharge of plasma for long period, a robust Plasma Delivery System (PDS) is required for large optics manufacturing. A dedicated PDS, mainly based on an L-type radio frequency (RF) network and an inductively coupled plasma (ICP) torch, had been previously proposed and designed. This study addresses the requirement for improving the robustness and securing the performance of the plasma etching. Due to the complexity of interactions of PDS parameters, single variable optimization is conducted for adjusting the impedance of the plasma torch. The PDS optimization is analysed based on ignition power demand, test repeatability and reflected power values. The results show that reflected power values are controllable within 10 W, when the RF power is supplied from 200 W up to 800 W. Finally, plasma processing is carried out on fused silica glass, using the optimum parameters of the PDS.

Original languageEnglish
Pages (from-to)518-525
Number of pages8
JournalChinese Journal of Aeronautics
Issue number4
Early online date1 Sept 2020
Publication statusPublished - Apr 2021

Keywords / Materials (for Non-textual outputs)

  • Inductively coupled plasma
  • Plasma delivery system
  • Plasma etching
  • Radio frequency network


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