Experimental studies of low energy proton irradiation of thin vacuum deposited Aluminum layers

T. Renger, M. Sznajder, U.R.M.E. Geppert

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degradation studies especially for thin foils

simultaneous irradiation to simulate the solar elm. and particle radiation:• photons 40nm < < 2500nm𝜆• electrons + protons 1…100keV

changes in the thermo-optical and elastic material properties

• measurement of αS and ε

• mass spectroscopy to evaluate the outgassing processes

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The Complex Irradiation Facility (CIF)

> Experimental studies of low energy proton irradiation of thin vacuum deposited Aluminium layers > T. Renger > 04.04.2014

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For this special experiments:

• Low energy protons

• Thermal conditioning of the sample

• 7.5 µm Upilex-S® foil covered on both sides with 100 nm Al

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100 keV proton / electron dual beam irradiation system

> Experimental studies of low energy proton irradiation of thin vacuum deposited Aluminium layers > T. Renger > 04.04.2014

Target mounting

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thermal conditioning: 80 K to 470 K

> Experimental studies of low energy proton irradiation of thin vacuum deposited Aluminium layers > T. Renger > 04.04.2014

Test parameters

Sample T [K] E [keV] D [p+ cm-2] ts [days]

A1 300.0 2.5 4.3 x 1017 3.5

A2 300.0 6.0 5.9 x 1017 4.8

B1 323.0 2.5 7.8 x 1017 4.8

B2 323.0 2.5 8.2 x 1017 5.0

B3 323.0 2.5 1.3 x 1018 7.9

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See next talk by M.Sznajder

Picture of the sample and the spot

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Microscope pictures of sample B3(unirradiated and irradiated region)

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Microscope pictures of sample A1 and A2

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A1 (2.5 keV; 4.3 x 1017 p+cm-2; 300.0 K) A2 (6.0 keV; 5.9 x 1017 p+cm-2; 300.0 K)

> Experimental studies of low energy proton irradiation of thin vacuum deposited Aluminium layers > T. Renger > 04.04.2014

SRIM simulation: Polyimide covered with 100 nm Al-layer

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2.5 keV protons 6.0 keV protons32.8 % pass through the Al-layer

> Experimental studies of low energy proton irradiation of thin vacuum deposited Aluminium layers > T. Renger > 04.04.2014

Microscope pictures of sample B1, B2, and B3

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Average bubble radius:B1: 0.17 ± 0.05 µm (7.8 x 1017 p+cm-2; 2.5 keV; 323.0 K)

B2: 0.2 ± 0.05 µm (8.2 x 1017 p+cm-2; 2.5 keV; 323.0 K)

B3: 0.25 ± 0.05 µm (1.3 x 1018 p+cm-2; 2.5 keV; 323.0 K)

> Experimental studies of low energy proton irradiation of thin vacuum deposited Aluminium layers > T. Renger > 04.04.2014

Height profile of sample B3

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B3:1.3 x 1018 p+cm-2 2.5 keV323.0 K

> Experimental studies of low energy proton irradiation of thin vacuum deposited Aluminium layers > T. Renger > 04.04.2014

Conclusion

• Molecular Hydrogen bubbles populate Aluminum surfaces under interplanetary space conditions, depending on energy and dose of incident protons and temperature of the surface

• The change of morphology of a thin Al-layer depends on the energy of protons. If it is higher then the critical energy, the protons pass through the Al-layer and other effects appear.

• The average bubble size increases with higher proton doses.

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