Study on the Fabrication Process of X-ray Focusing Mirrors.

Area of Science:

• X-ray astronomy
• Materials science
• Precision engineering

Background:

• The eXTP satellite requires high-quality X-ray focusing mirrors for deep space observations.
• Reducing mirror thickness and using multi-layer nesting are crucial for weight reduction and enhanced effective area.
• Mirror manufacturing presents challenges in quality, efficiency, and shell separation from mandrels.

Purpose of the Study:

• To investigate and optimize the replication process for X-ray mirrors.
• To address challenges in mirror shell separation and demolding.
• To develop an automatic demolding device and verify the X-ray performance of the replication mirrors.

Main Methods:

• Investigated ultraprecision machining, polishing, coating, electroforming nickel, and demolding processes.
• Applied a diamond-like carbon (DLC) release layer between gold (Au) and nickel-phosphorus (NiP) alloy.
• Utilized molecular dynamic simulation and tensile testing to analyze adhesion strength.
• Developed an automatic demolding device with force feedback.

Main Results:

• Identified factors causing difficult separation and release of mirror shells.
• Demonstrated significantly lower adhesion strength of Au-C compared to Au-NiP.
• Successfully developed and implemented an automatic demolding device.
• Reduced the mirror's half-power diameter (HPD) from 48 inches to 25 inches, exceeding production targets.

Conclusions:

• The optimized replication process, including the DLC release layer and automatic demolding, successfully addresses mirror fabrication challenges.
• The improved X-ray mirror performance, evidenced by the reduced HPD, meets and surpasses the stringent requirements for the eXTP satellite.
• This research contributes to advancements in the manufacturing of high-precision optics for space-based X-ray astronomy.