Electrodeposition simulation for fabricating Wolter mirrors of x-ray telescopes

Wolter mirrors work as imaging optics of X-ray telescopes. We have been developing a Wolter mirror for the FOXSI-4 project in 2023 using a high-precision Ni electroforming process. The figure accuracy of mirrors is one of the main factors determining the spatial resolution in X-ray imaging. In this study, we optimized the electrodeposition conditions from the viewpoint of the uniformity of film thickness. The simulation model was developed to correctly predict the film thickness distribution before fabrication, whose parameters and boundary conditions were determined through electrochemical experiments. The model calculates the distribution of current density on the surface of the cathode by finite element analysis. In this paper, we report the current status of the electroforming process specializing in Wolter mirrors in X-ray telescopes.

[1]  Guang Yang,et al.  Numerical Optimization of Electrodeposition Thickness Uniformity with Respect to the Layout of Anode and Cathode , 2021, Electrocatalysis.

[2]  Yoko Takeo,et al.  Fabrication of a precise ellipsoidal mirror for soft X-ray nanofocusing. , 2018, The Review of scientific instruments.

[3]  Yoko Takeo,et al.  Advanced fabrication technologies for ultraprecise replicated mirrors for x-ray telescopes , 2020, Astronomical Telescopes + Instrumentation.

[4]  Hidekazu Mimura,et al.  Development of Nanometer-level Accurate Replication Process Using Electroforming , 2014 .

[5]  H. Wolter.  Spiegelsysteme streifenden Einfalls als abbildende Optiken für Röntgenstrahlen , 1952 .

[6]  Karen E. Gelmis,et al.  Lynx Mission concept status , 2017, Optical Engineering + Applications.

[7]  Yoko Takeo,et al.  Soft x-ray nanobeam formed by an ellipsoidal mirror , 2020 .

[8]  Martin C. Weisskopf,et al.  Full-shell x-ray optics development at NASA Marshall Space Flight Center , 2019, Journal of astronomical telescopes, instruments, and systems.

[9]  Hidekazu Mimura,et al.  Intense sub-micrometre focusing of soft X-ray free-electron laser beyond 1016 W cm-2 with an ellipsoidal mirror. , 2019, Journal of synchrotron radiation.

[10]  P. Giommi,et al.  The Swift X-Ray Telescope , 1999 .

[11]  Kim Yong Lim,et al.  Understanding and improving the uniformity of electrodeposition , 2003 .

[12]  Tadayuki Takahashi,et al.  The FOXSI solar sounding rocket campaigns , 2016, Astronomical Telescopes + Instrumentation.

[13]  Chandra X-ray Observatory.  Recent and Future Observations in the X-ray and Gamma-ray Bands : Chandra , Suzaku , GLAST , and NuSTAR , 2005 .

[14]  Fred Jansen,et al.  XMM: advancing science with the high-throughput X-ray spectroscopy mission. , 1999 .

[15]  K. I. Popov,et al.  A mathematical model of the current density distribution in electrochemical cells , 2011 .

[16]  Yoko Takeo,et al.  Development of electroforming process for soft x-ray ellipsoidal mirror. , 2019, The Review of scientific instruments.

[17]  W. Dow,et al.  Through-Hole Filling in a Cu Plating Bath with Functional Insoluble Anodes and Acetic Acid as a Supporting Electrolyte , 2013 .