Multilayer Overview Current application Optimization of Multilayers Model

Multilayer Overview • Current application • Optimization of Multilayers • Model Designs for GRI

Grazing Incidence Optics: Past/Present/Future Chandra and XMM Monolitic and replicated Wolter 1 optics Hero, High-energy replicated optics Single layer coated; Ir, Au In. Focus, International Focusing Optics Collaboration, Pt/C HEFT, High Energy Focusing Optics, W/Si Nu. STAR, XEUS, Constallation-X

High Energy Focusing Telescope (HEFT) 6 m focal length Depth-graded W/Si Multilayers Energy range 20 – 70 ke. V Effective Area: ~70 cm 2 @ 40 ke. V Over-constrained optics: 1. 2’ HPD Field of view: 17’ @ 20 ke. V Collaboration: California institute of technology, Lawrence Livermore National Lab. , Columbia University, Danish National Space Center

The HEFT Optics Parameters: Number: 3 Type : Conical Approximation optic Size : 24 cm x 40 cm Material : W/Si, multilayers Energy range : 5 – 69 ke. V

Multilayers: HEFT Production • Thermally slumped AF 45 borosilicate glass • Mirror thickness, 0. 3 mm • Mirror length = 10 cm • Mirror radii: 4 cm < R < 12 cm

Multilayers: Design Power law:

Multilayers: Optimization, The Figure Of Merit • • A(E) effective area – A(E) = 2 pra. L * [R(E, a)]2 reflectivity matrix, calculated with Nevot-Croce formalism • Winc(a, ) angular weigthing function – Very CPU intensive • WE energy weigthing function = E(ke. V)/100 + 0. 7 P. H. Mao et al, Applied Optics 38, p. 4766 -4775, 1999 a

Multilayers: Optimization Power law: • • Constants a and b are uniquely determined by Dmin and Dmax For a given max and min graze angle for a group Dmin and Dmax are determined by the Bragg equation • Multilayer recipes are optimized over: number of bilayers N high Z fraction G power law index c

Model Designs for GRI • Double reflection Radius = 0. 1 – 1. 0 m Optimized E range = 20 – 500 ke. V • • Modified Radius = 0. 17 – 0. 56 m Double reflection Optimized E range = 40 – 500 ke. V Single reflection Radius = 0. 09 – 0. 44 m Optimized E range = 80 – 200 ke. V Common Parameters: Substrate thickness = 0. 2 mm Mirror length = 0. 6 m Focal length = 150 m Material Combination = W/Si Substrate = Si Radial Obs. Factor = 20%

Design 1 a: Double reflection R = 0. 1 – 1. 0 m a = 0. 57’ – 5. 73’

Design 1 a Total mass = 2057 kg Number of shells = 1144 Aeff @ 20 ke. V 200 ke. V cm 2 13900 2023

Design 1 b: modified double reflection R = 0. 17 – 0. 56 m a = 1. 02’ – 3. 22’ Design 1 a Design 1 b Total mass = 824 kg Number of shells = 582 Aeff @ 20 ke. V 200 ke. V cm 2 3653 1568

Design 2: Single Reflection R = 0. 09 – 0. 45 m a = 1. 03’ – 5. 125’

Design 2 Aeff cm 2 @ Mass kg 20 ke. V 200 ke. V Design 2 190 2716 1160 Optionally: Same design can be used at F = 75 m, as a real focusing System, but with a slight loss in effective area. Total mass = 190 kg Number of shells = 433

Conclusions • Mass versus Effective area – Real focusing system or single reflection • Material combinations – W/Si chosen as a baseline – Pt/C, Pt/Si. C, WC/Si. C, ( Cu/Si. C) Aeff cm 2 @ Mass kg 20 ke. V 200 ke. V Design 1 a 2057 13900 2023 Design 1 b 824 3653 1568 Design 2 190 2716 1160 • Substrate technology – For arcsec performance new developments in substrates are needed – Inherited technology from XEUS, Constallation-X

Grp 1 2 S Emin Emax dmin dmax N c Gamma Thick FOM 1 Si W Si 50 200 53. 9 495. 9 50 0. 160 0. 287 0. 360 2 Si W Si 50 200 46. 9 431. 7 63 0. 179 0. 314 0. 393 13. 47 3 Si W Si 50 200 40. 9 375. 8 97 0. 190 0. 333 0. 517 17. 90 4 Si W Si 50 200 35. 6 327. 1 151 0. 195 0. 344 0. 691 22. 22 5 Si W Si 50 200 30. 9 284. 8 187 0. 213 0. 371 0. 755 26. 72 6 Si W Si 50 200 26. 9 247. 9 332 0. 207 0. 376 1. 145 30. 22 7 Si W Si 50 200 23. 4 215. 8 647 0. 205 0. 370 1. 925 33. 03 8 Si W Si 50 20. 4 187. 9 1010 0. 202 0. 372 2. 601 32. 74 9. 96