Optimal Compound Multi-Segment Cooling Method for High-Heat-Load X-Ray Mirrors

Zhen Wang; Yajun Tong; Xiaohao Dong; Fang Liu

doi:10.3788/AOS202242.2334003

Journals >Acta Optica Sinica >Volume 42 >Issue 23 >Page 2334003 > Article

Acta Optica Sinica
Vol. 42, Issue 23, 2334003 (2022)

Optimal Compound Multi-Segment Cooling Method for High-Heat-Load X-Ray Mirrors

Zhen Wang¹, Yajun Tong¹, Xiaohao Dong², and Fang Liu^1,*

Author Affiliations

¹Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China

²Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China

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DOI: 10.3788/AOS202242.2334003 Cite this Article Set citation alerts

Zhen Wang, Yajun Tong, Xiaohao Dong, Fang Liu. Optimal Compound Multi-Segment Cooling Method for High-Heat-Load X-Ray Mirrors[J]. Acta Optica Sinica, 2022, 42(23): 2334003 Copy Citation Text

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Fig. 1. Layout of FEL-I beamline in SHINE

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Absorbed power density distribution of M1 at energy of 7.0 keV with grazing angle of 1.9 mrad. (a) Spontaneous radiation; (b) FEL fundamental radiation; (c) third harmonic radiation; (d) total power

Fig. 2. Absorbed power density distribution of M1 at energy of 7.0 keV with grazing angle of 1.9 mrad. (a) Spontaneous radiation; (b) FEL fundamental radiation; (c) third harmonic radiation; (d) total power

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Fig. 3. Heat load distribution at each characteristic energy point in M1. (a) Meridian direction of reflector;(b) sagittal direction of reflector

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Fig. 4. Mirror cooling model and FEA model. (a) Mirror cooling structure; (b) enlarged view of mirror cooling structure; (c) FEA model of mirror cooling structure; (d) enlarged view of FEA model of mirror cooling structure

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Fig. 5. Temperature distribution after ray with energy of 7.0 keV incident on M1 mirror at grazing angle of 1.9 mrad

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Fig. 6. Thermal deformation of M1 mirror in meridian direction at each characteristic energy point

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Fig. 7. Thermal deformation after X-ray with energy of 7.0 keV incident on M1 mirror at grazing angle of 4.0 mrad under different cooling fin lengths

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Fig. 8. Residual height error after X-ray with energy of 7.0 keV incident on M1 mirror at grazing angle of 4.0 mrad under different cooling fin lengths

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Fig. 9. Schematic diagram of multi-stage compound cooling structure

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Device	Parameter	Value
Electron beam	Electron energy /Gev	8
	Bunch charge /pC	100
	Average current /mA	0.1
	Peak current /A	1000
	Pulse duration /fs	100
	Emittance /（μm·rad）	0.4
	Repetition rate /MHz	1
Undulator	Peak magnetic field /T	1
	Period /mm	26
	Undulator length /m	4
	Number of segments	42
	Distance between segments /m	1

Table 1. Parameters for accelerator used in simultaneous radiation simulation

Photon energy /keV	3.0	7.0	12.4	15.0
Bunch charge /pC	100	100	100	100
Electron energy /GeV	5	8	8	8
Pulse energy /μJ	930	1800	394	60
Source size（FWHM）/μm	49	48	50	50
Source divergence（FWHM）/μrad	5.5	2.7	1.7	1.3

Table 2. Light source parameters under different photon energies

Material	Density /（kg·m^-3）	Elastic modulus /GPa	Yield stress /MPa	Poisson ratio	Thermal conductivity /（W·m^-1·K^-1）	Thermal expansion coefficient at temperature of 300 K /（ $10^{- 6}$ K^-1）
Silicon	2329	112.4	120	0.28	148	2.50
Copper	8900	110.0	220	0.34	391	1.75
In/Ga	6350				28

Table 3. Material parameters in FEA

Energy /keV	Grazing angle /mrad	Total heat /W	Simulated S_R
3.0	4.0	18.90	0.17
5.0	4.0	28.60	0.12
7.0	4.0	38.20	0.15
7.0	1.9	37.10	0.16
12.4	1.9	9.23	0.29
15.0	1.9	1.72	0.70

Table 4. S_R of M1 mirror under different energies

Energy /keV	Grazing angle /mrad	Optimum cooling fin length /mm
3.0	4.0	156
5.0	4.0	109
7.0	4.0	53
7.0	1.9	148
12.4	1.9	64
15.0	1.9	65

Table 5. Optimum cooling fin lengths under different energies

Energy /keV	Grazing angle /mrad	Total heat /W	Simulated S_R
3.0	4.0	18.90	0.30
5.0	4.0	28.60	0.26
7.0	4.0	38.20	0.35
7.0	1.9	37.10	0.27
12.4	1.9	9.23	0.60
15.0	1.9	1.72	0.93

Table 6. S_R under different energies after comprehensive optimization

Energy /keV	Grazing angle /mrad	Before Optimization		After Optimization		Repetition rate ratio
Energy /keV	Grazing angle /mrad	Total heat /W	Repetition rate /kHz	Total heat /W	Repetition rate /kHz	Repetition rate ratio
3.0	4.0	0.63	33.3	1.89	100	3.0
5.0	4.0	0.57	20.0	1.57	55	2.8
7.0	4.0	0.48	12.5	3.06	80	6.4
7.0	1.9	0.62	16.7	1.86	50	3.0
12.4	1.9	0.37	40.0	3.07	333	8.3
15.0	1.9	0.43	250.0	0.86	500	2.0

Table 7. Nominal heat load and working repetition rate before and after optimization at S_R=0.96

Zhen Wang, Yajun Tong, Xiaohao Dong, Fang Liu. Optimal Compound Multi-Segment Cooling Method for High-Heat-Load X-Ray Mirrors[J]. Acta Optica Sinica, 2022, 42(23): 2334003

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