Some thoughts regarding Particulate Contamination Requirements

Document #:

LIGO-T1300511-v1

Document type:

T - Technical notes

Abstract:

Currently the best reference defining the required particulate cleanliness levels for the vacuum chambers and sensitive cavity optics for Advanced LIGO is T080067-v1, “Protecting installed core optics from particulates” . In T080067-v1, reasonable and conservative limits and approximations were employed as prudent, with the caveat that they be feasible. We have since found that these particulate contamination levels may not be feasible to achieve in the LIGO vacuum chambers with our current cleanliness protocols and infrastructure.

The purpose of this memo is to look for relief, by revisiting these requirements and taking out conservatism. This memo complements (does not invalidate) T080067. This is also not (yet) to be taken as a restatement of requirements, but rather a discussion of what might be acceptable, and what measurements are needed to improve our understanding of what is (or is not) acceptable.

Files in Document:

• T1300511-v1 some thoughts on particulate contamination...pdf (505.9 kB)

Other Files:

• T1300511-v1 some thoughts on particulate contaminatio...docx (137.5 kB)
• T1300511-v1 surface cleanliness requirements.nb (216.8 kB)

Topics:

• System Engineering

Authors:

• Dennis Coyne

Notes and Changes:

- need to add considerations for single large particles in the center of the beam -> show that this is not as restrictive as the integral of the area weighted PDF
- need to consider the requirements for the PRC as well as the TMs
- consider non-unity albedo?

Related Documents:

• LIGO-T080067: Protecting installed core optics from particulates