Study on Structural Stability of Long Cantilever Target Assembly in High Power Laser Facility

Yuanqi He; Jianqiang Zhu

doi:10.3788/CJL220947

Journals >Chinese Journal of Lasers >Volume 50 >Issue 10 >Page 1001003 > Article

Chinese Journal of Lasers
Vol. 50, Issue 10, 1001003 (2023)

Study on Structural Stability of Long Cantilever Target Assembly in High Power Laser Facility

Yuanqi He^1,2 and Jianqiang Zhu^1,*

Author Affiliations

¹Key Laboratory of High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China

²Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

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DOI: 10.3788/CJL220947 Cite this Article Set citation alerts

Yuanqi He, Jianqiang Zhu. Study on Structural Stability of Long Cantilever Target Assembly in High Power Laser Facility[J]. Chinese Journal of Lasers, 2023, 50(10): 1001003 Copy Citation Text

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Fig. 1. Structural diagram of NIF cryogenic target assembly

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Fig. 2. Preliminary design of damping target assembly. (a) Assembly drawing; (b) scheme 1; (c) scheme 2

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Fig. 3. Continuous beam model with spring damping support

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Fig. 4. Schematic of damping structure

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Fig. 5. Schematics of arrangement of vibration damping components. (a) 3-Y type; (b) 3-inverted Y type; (c) 4-X type

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Fig. 6. Contour diagrams for simulation results of wires. (a) Suspension response deformation; (b)natural frequency; (c) wire mass

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Fig. 7. Response deformation of suspension end versus diameter

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Fig. 8. Simulation results when wire diameter is 0.8 mm . (a) Natural frequency; (b) static deformation

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Fig. 9. Final structure of damping target assembly

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Fig. 10. PSD displacement of test bench under vibration source 1

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Fig. 11. Layout of test bench

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Fig. 12. Measurement results under vibration source 1. (a) Time domain result of original target assembly; (b) frequency domain result of original target assembly; (c) time domain result in scheme 1 when wire diameter is 1.2 mm; (d) frequency domain result in scheme 1 when wire diameter is 1.2 mm

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Fig. 13. Measurement results under vibration source 2. (a) Time domain result of original target assembly; (b) frequency domain result of original target assembly; (c) time domain result in scheme 1 when wire diameter is 1.2 mm; (d) frequency domain result in scheme 1 when wire diameter is 1.2 mm

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Fig. 14. Measurement results in scheme 2 when wire diameter is 1.2 mm. (a) Vibration source 1, time domain; (b) vibration source 1, frequency domain; (c) vibration source 2, time domain; (d) vibration source 2, frequency domain

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Frequency /Hz	1	3	4	5	7	9	20-100
PSD displacement /（ $m \cdot H z^{- \frac{1}{2}}$ ）	$1.0 \times 10^{- 6}$	$1.4 \times 10^{- 6}$	$4.0 \times 10^{- 6}$	$4.0 \times 10^{- 6}$	$8.0 \times 10^{- 7}$	$5.0 \times 10^{- 7}$	$8.0 \times 10^{- 8}$

Table 1. Parameters of refrigerator operating vibration source

Project	Section size	Length	Material
Base	$ϕ 40$ mm	24 mm	Pure copper
Copper platen	$ϕ 4$ mm	124.5 mm	Pure copper
Copper clamp	6 mm×8 mm	22 mm	Pure copper
Si arm	6 mm×1 mm	63.5 mm	Si
Thermal sleeve	$ϕ$ 6 mm	7 mm	Au and Al

Table 2. Main structure parameters of target assembly

Type of vibration damping component	First natural frequency /Hz	Second natural frequency /Hz
Original target assembly without vibration damping component	57.3	57.9
3-Y type	88.2	90.5
3-inverted Y type	88.2	90.5
4-X type	91.4	94.0

Table 3. Natural frequencies of different damping target assemblies

Global damping coefficient	Maximum response deformation of suspension end /（10^-3 mm）	Convergence time /s	Optimization efficiency /%
0.01	5.62	2.73	-
0.02	6.36	2.03	25.6
0.03	5.99	1.68	38.5
0.04	5.75	1.49	45.4
0.05	6.09	1.28	53.1

Table 4. Simulation results under variable global damping

Target assembly	Natural frequency /Hz	Response deformation under vibration source 1 /m	Response deformation optimization rate /%	Convergence time under vibration source 2 /s	Convergence time optimization rate /%
Original target assembly	57	$9.64 \times 10^{- 5}$	-	2.86	-
Target assembly with wire diameter of 0.8 mm	138	$6.36 \times 10^{- 6}$	93.4	2.05	28.3
Target assembly with wire diameter of 1.0 mm	153	$7.68 \times 10^{- 6}$	92.0	2.11	26.2
Target assembly with wire diameter of 1.2 mm	163	$4.20 \times 10^{- 6}$	95.6	2.09	26.9

Table 5. Comparison of vibration response characteristics between original target assembly and target assembly in scheme 1

Target assembly	Natural frequency /Hz	Response deformation in vibration source 1 /m	Response deformation optimization rate /%	Convergence time under vibration source 2 /s	Convergence time optimization rate /%
Original target assembly	57.3	$9.64 \times 10^{- 5}$	-	2.86	-
Target assembly with wire diameter of 0.8 mm	138.0	$6.09 \times 10^{- 6}$	93.7	1.28	55.2
Target assembly with wire diameter of 1.0 mm	153.0	$9.89 \times 10^{- 6}$	89.7	1.26	55.9
Target assembly with wire diameter of 1.2 mm	163.0	$5.54 \times 10^{- 6}$	94.3	1.28	55.2

Table 6. Comparison of vibration response characteristics between original target assembly and target assembly in scheme 2

Target assembly	Vibration source 1		Convergence time under vibration source 2 /s	Natural frequency /Hz
Target assembly	Root mean square value of deformation /m	Response frequency /Hz	Convergence time under vibration source 2 /s	Natural frequency /Hz
Original target assembly	$1.67 \times 10^{- 5}$	34	3.32	33.8
Target assembly with wire diameter of 0.8 mm	$1.37 \times 10^{- 6}$	110, 185	2.45	113.0
Target assembly with wire diameter of 1.0 mm	$1.71 \times 10^{- 6}$	130, 216	1.24	120.0
Target assembly with wire diameter of 1.2 mm	$1.04 \times 10^{- 6}$	99, 180	1.13	178.0

Table 7. Measurement results of target assembly in scheme 1 and original target assembly

Target assembly	Vibration source 1		Convergence time under vibration source 2 /s	Natural frequency /Hz
Target assembly	Root mean square value of deformation /m	Response frequency /Hz	Convergence time under vibration source 2 /s	Natural frequency /Hz
Original target assembly	$1.67 \times 10^{- 5}$	34	3.32	33.8
Target assembly with wire diameter of 0.8 mm	$3.26 \times 10^{- 6}$	109, 185	1.25	110.7
Target assembly with wire diameter of 1.2 mm	$1.38 \times 10^{- 6}$	110, 186	0.76	183.0

Table 8. Measurement results of target assembly in scheme 2 and original target assembly

Yuanqi He, Jianqiang Zhu. Study on Structural Stability of Long Cantilever Target Assembly in High Power Laser Facility[J]. Chinese Journal of Lasers, 2023, 50(10): 1001003

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