Bruce A. Banks

Science Application International Corporation, Cleveland, Ohio

Grace C. Dill and Ryan J. Loftus

Alphaport, Incorporated, Cleveland, Ohio

Kim K. de Groh and Sharon K. Miller

Glenn Research Center, Cleveland, Ohio

Comparison of Hyperthermal Ground Laboratory 

Atomic Oxygen Erosion Yields With Those in

Low Earth Orbit

NASA/TM—2013-216613

December 2013
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Bruce A. Banks

Science Application International Corporation, Cleveland, Ohio

Grace C. Dill and Ryan J. Loftus

Alphaport, Incorporated, Cleveland, Ohio

Kim K. de Groh and Sharon K. Miller

Glenn Research Center, Cleveland, Ohio

Comparison of Hyperthermal Ground Laboratory 

Atomic Oxygen Erosion Yields With Those in

Low Earth Orbit

NASA/TM—2013-216613

December 2013

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135
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Level of Review: This material has been technically reviewed by technical management. 
NASA/TM—2013-216613 1 

Comparison of Hyperthermal Ground Laboratory Atomic Oxygen 

Erosion Yields With Those in Low Earth Orbit 

Bruce A. Banks 

Science Application International Corporation 

Cleveland, Ohio 44135 

Grace C. Dill and Ryan J. Loftus 

Alphaport, Incorporated 

Cleveland, Ohio 44135 

Kim K. de Groh and Sharon K. Miller 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Abstract 

The atomic oxygen erosion yields of 26 materials (all polymers except for pyrolytic graphite) were 

measured in two directed hyperthermal radio frequency (RF) plasma ashers operating at 30 or 35 kHz 

with air. The hyperthermal asher results were compared with thermal energy asher results and low Earth 

orbital (LEO) results from the Materials International Space Station Experiment 2 and 7 (MISSE 2 and 7) 

flight experiments. The hyperthermal testing was conducted to a significant portion of the atomic oxygen 

fluence similar polymers were exposed to during the MISSE 2 and 7 missions. Comparison of the 

hyperthermal asher prediction of LEO erosion yields with thermal energy asher erosion yields indicates 

that except for the fluorocarbon polymers of PTFE and FEP, the hyperthermal energy ashers are a much 

more reliable predictor of LEO erosion yield than thermal energy asher testing, by a factor of four.

1.0 Introduction 

The reaction of low Earth orbital (LEO) atomic oxygen with hydrocarbon and halocarbon polymers 

has been a spacecraft durability concern for decades (Ref. 1). One of the most important characteristics of 

a polymer relating to its LEO durability is its atomic oxygen erosion yield which is the volume lost per 

incident atomic oxygen atom, given in cm3

/atom. The measurement of this value is most reliably 

performed by space experiments. However, because of the high cost, infrequent opportunity, and length 

of time to perform space experiments, ground laboratory systems have been developed which produce 

atomic oxygen in an effort to simulate the LEO environment. Due to the variety and complexity of the 

differences between the LEO atomic oxygen environment and ground laboratory simulations, differences 

exist which have not allowed the development of a simple relationship or proportionality between the 

LEO and ground laboratory erosion yields. Two of the most significant differences between most ground 

laboratory and LEO environments are the energy and directionality of the atomic oxygen. 

A comparison between the erosion yields measured in an isotropic thermal energy (~0.04 eV) plasma 

asher and LEO directed hyperthermal (~4.5 eV) atomic oxygen was conducted using the results of the 

Materials International Space Station Experiment 2 (MISSE 2) (Refs. 2 and 3). These results indicated 

that the ratio of erosion yields relative to Kapton H polyimide were greater for 38 out of the 39 polymers 

tested in the thermal asher than in LEO. Testing has also been conducted with white Tedlar (TiO2 pigment 

particle-filled polyvinylchloride) in LEO and in a directed hyperthermal energy asher (where the energy 

was greater than thermal energy but less than the sputter threshold of SiO2 which is thought to be 

20 eV). Results from exposure of white Tedlar indicated that the ratio of the erosion yield relative to 

Kapton H polyimide was less in the hyperthermal asher than in thermal energy ashers (Ref. 4). The 
NASA/TM—2013-216613 2 

differences between the thermal energy and hyperthermal results is thought to be due to the directed 

versus isotropic nature of the arrival of atomic oxygen, differences in energy dependence of erosion yield, 

and presence of inorganic pigment particles causing better shielding from erosion in the case of directed 

hyperthermal attack. 

The intent of this paper is to compare the results of directed hyperthermal asher erosion yields relative 

to Kapton H with those found from the results of the MISSE 2 and MISSE 7 experiments where the 

fluences were substantial enough (8.431021 and 4.181021 atoms/cm2

, respectively) to provide accurate 

erosion yields (Refs. 2 and 5). 

2.0 Apparatus and Procedures 

Two different directed hyperthermal RF plasma ashers, operating at different frequencies, were used 

to measure ground laboratory atomic oxygen erosion yields. The results were compared with erosion 

yields from isotropic thermal energy asher (13.56 MHz Structure Probe, Inc. Plasma Prep II) erosion 

yields (Ref. 3) and LEO flight data (Refs. 2 and 5). The two directed hyperthermal RF plasma ashers were 

a 35 kHz, LF-5 Axic plasma asher and a 30 kHz MCS, Model LF-6 plasma asher, both operated on air. 

Samples were placed in aluminum sample holders, which allowed exposure of a large central Kapton H 

sample and up to 21 smaller surrounding samples to simulate a portion of the MISSE 7 mission. The large 

central Kapton H fluence reference sample was 2.078 cm in diameter surrounded by up to 21 samples 

0.886 cm in diameter as shown in Figure 1. 

Two additional larger samples were also exposed in separate aluminum holders alongside the large 

sample holder plate in the 30 kHz hyperthermal asher as shown in Figure 2. 

The flux within the hyperthermal ashers varies slightly with sample location in each asher. Thus, to 

estimate the fluence that each sample was exposed to, based on the fluence of the central large Kapton H 

sample, a flux calibration test was conducted in each asher with Kapton H samples in all the sample 

locations and operated for several days (72 hr in the 35 kHz asher and 70.2 hr in the 30 kHz asher). This 

allowed the computation of flux maps which were used to compute the relative fluence for all 22 or 24 

sample positions for each asher based on the fluence of the central large Kapton H sample. 

Figure 1.—Sample holder plate used in the 35 kHz 

hyperthermal asher. 

Figure 2.—Sample holders for hyperthermal atomic 

oxygen exposure simulating a portion of the materials 

flown on the MISSE-2 flight experiment in the 30 kHz 

hyperthermal asher. 
NASA/TM—2013-216613 3 

The mass loss of 48 hr vacuum dehydrated Kapton H samples was used to obtain the Kapton H 

effective atomic oxygen fluence for the ground laboratory samples as described in ASTM E 2089-00 

(Ref. 6) utilizing a Sartorius microgram balance. Based on the estimated erosion of the various polymers 

from both LEO and thermal energy asher testing, stacked layers of thin samples were used when possible 

to ensure that erosion all the way through the sample layers would be less likely to occur. 

One of the goals of this investigation was to compare erosion yields more accurately by exposing 

samples to a significant Kapton H effective fluence as occurred in LEO. This approach was used because 

the erosion yields for most polymers that have significant ash content gradually diminishes with fluence 

due to shielding caused by the ash particles being exposed on the surfaces of the polymers (Refs. 4 and 7). 

In addition, multilayer samples tend to have higher erosion yields than single layer materials due to 

trapping of atomic oxygen as a layer becomes partially eroded (Ref. 8). To assure that the Kapton H 

effective fluence in the hyperthermal asher was a reasonably close simulation to the MISSE 2 and 7 

fluences, the fluence on the central Kapton H sample was measured at approximately the half-fluence 

point of the MISSE 2 and 7 missions to allow for a midway correction to the exposure duration. 

3.0 Results and Discussion 

3.1 MISSE 7 Materials Simulation 

The 72 hr atomic oxygen exposure of the sample plate to make a flux map for the MISSE 7 flight 

experiment resulted in a flux of 6.0691015 atoms/(cm2

 sec) and a fluence of 1.5731021 atoms/cm2 on the 

large central Kapton H sample. The resulting ratio of flux at each sample location relative to the large 

central Kapton H sample is given in Table 1. 

TABLE 1.—RATIO OF FLUX AT EACH SAMPLE LOCATION 

RELATIVE TO THE LARGE CENTRAL KAPTON H SAMPLE 

FOR THE 35 kHz ASHER FOR MATERIALS FLOWN ON 

THE MISSE 7 FLIGHT EXPERIMENT 

Sample position Flux relative to position 0 

0 1.000 

1 0.940 

2 0.995 

3 1.037 

4 1.034 

5 1.062 

6 1.001 

7 0.917 

8 1.006 

9 0.979 

10 0.999 

11 1.020 

12 0.861 

13 0.976 

14 1.031 

15 1.025 

16 0.968 

17 0.978 

18 0.952 

19 0.829 

20 0.917 

21 0.858 

22 0.873 

 
NASA/TM—2013-216613 4 

The results of a 190.3 hr exposure of most of the MISSE 7 materials in the 35 kHz directed 

hyperthermal asher are compared with LEO erosion yield results in Table 2. 

The central Kapton H sample received a fluence of 3.511021atoms/cm2

 which was 83.2 percent of 

the actual MISSE 7 experiment fluence. The uncertainties in the erosion yields are standard deviations 

computed using a propagation of error analysis as shown in Reference 9. 

TABLE 2.—COMPARISON OF THE LEO AND DIRECTED HYPERTHERMAL 35 kHz ASHER 

EROSION YIELDS AND THEIR STANDARD DEVIATION UNCERTAINTIES FOR 

SIMULATION OF THE MISSE 7 ATOMIC OXYGEN EXPOSURE 

Material Abbrev. Density, 

g/cm3

Mass fraction 

of polymer 

that is ash 

(Ref. 7) 

MISSE 7 

erosion yield, 

cm3

/atom 

35 Hz hyperthermal 

asher erosion yield, 

cm3/atom 

Ratio of 35 Hz 

hyperthermal 

asher to LEO 

erosion yield 

White Tedlar PVF 1.624 0.295 1.480.05 

E-25 

2.320.04 

E-25 

1.57 

White Tedlar w/ 0.5 mil 

Kapton H cover 

PVF 1.624 0.295 1.540.05 

E-25 

2.330.04 

E-25 

1.52 

White Tedlar w/ 1.0 mil 

Kapton H cover 

PVF 1.624 0.295 1.670.05 

E-25 

2.270.04 

E-25 

1.36 

Kapton H PI (H) 1.427 0.00284 3.000.03 

E-24 

3.000.03 

E-24 

1.00 

Polyvinyl chloride PVC 1.34 0.0033 1.740.03 

E-24 

5.150.03 

E-24 

2.96 

Polyethylene PE 0.918 0.0203 3.740.03 

E-24 

2.510.03 

E-24 

0.671 

Polymethylpentene PMP 0.833 0.00043 4.450.03 

E-24 

3.120.03 

E-24 

0.700 

Polyethersulfone PES 1.37 0.0025 2.790.03 

E-24 

3.050.03 

E-24 

1.094 

Aluminized-fluorinated 

ethylene propylene 

Al-FEP 2.144 0.0668 1.810.03 

E-25 

3.900.03 

E-24 

21.548 

Kapton HN PI(HN) 1.435 0.00441 3.010.03 

E-24 

2.620.03 

E-24 

0.869 

Kapton HN w/0.5 mil 

Kapton H cover 

PI(HN) 1.435 0.00441 2.850.03 

E-24 

2.260.03 

E-24 

0.795 

Kapton HN w/1.0 mil 

Kapton H cover 

PI(HN) 1.435 0.00441 2.200.03 

E-24 

2.780.03 

E-24 

1.264 

Polyamide-imide Torlon 1.42 0.0234 1.740.03 

E-24 

2.740.03 

E-24 

1.574 

Polyvinyl alcohol PVOH 1.28 0.000534 3.140.03 

E-24 

5.960.03 

E-24 

1.898 

Cellulose Nitrate CN 1.4 0.0020 7.340.06 

E-24 

8.290.06 

E-24 

1.130 

Polyimide 

(AO resistant) 

CORIN 1.36 0.1724 3.050.04 

E-26 

4.160.03 

E-25 

13.632 

Urethane LCP 

mesh 

1.4 0.0782 4.610.06 

E-25 

3.280.06 

E-25 

0.712 

Pyrolitic Graphite PG 2.22 0.00154 4.150.45 

E-25 

4.050.03 

E-25 

0.976 

Polytetrafluoroethylene PTFE 2.1503 0.0427 1.420.04 

E-25 

6.980.03 

E-24 

49.218 

 
NASA/TM—2013-216613 5 

3.2 MISSE 2 Materials Simulation 

A 70.2 hr atomic oxygen exposure in the 30 kHz hyperthermal asher of the sample plate samples and 

two additional large samples all loaded with Kapton H was used to make a flux map for simulation of the 

MISSE 2 flight exposure. This resulted in an average flux of 2.731015 atoms/(cm2

 sec) and a fluence of 

6.901020 atoms/cm2

 on the large central Kapton H sample. The fluence on the central Kapton H sample 

represents a fluence of 67.4 percent of the MISSE-2 fluence. The resulting ratio of flux at each sample 

location relative to the large central Kapton H sample is given in Table 3. 

TABLE 3.—RATIO OF FLUX AT EACH SAMPLE LOCATION 

RELATIVE TO THE LARGE CENTRAL KAPTON H SAMPLE 

FOR THE 35 kHz ASHER FOR MATERIALS FLOWN 

ON THE MISSE 2 FLIGHT EXPERIMENT 

Sample position Flux relative to position 0 

0 1.000 

1 1.153 

2 1.135 

3 0.867 

4 0.934 

5 1.019 

6 0.964 

7 0.935 

8 0.848 

9 0.765 

10 0.809 

11 0.907 

12 0.982 

13 0.951 

14 0.916 

15 1.083 

16 1.011 

17 0.905 

18 0.935 

19 0.961 

20 0.880 

21 0.826 

22 0.865 

Large sample 1 0.935 

Large sample 3 1.072 

 
NASA/TM—2013-216613 6 

The erosion yield results from exposure of a portion of the MISSE-2 materials in the 30 kHz directed 

hyperthermal asher for 1284 hr are compared with LEO erosion yield results in Table 4.

TABLE 4.—COMPARISON OF THE LEO AND DIRECTED HYPERTHERMAL 30 kHz ASHER EROSION YIELDS 

AND THEIR STANDARD DEVIATION UNCERTAINTIES FOR SIMULATION OF THE 

MISSE 2 ATOMIC OXYGEN EXPOSURE 

Material Abbrev. Density 

(g/cm3

) 

(Ref. 2) 

Mass fraction 

of polymer 

that is ash 

(Ref. 7) 

LEO erosion 

yield, cm3/atom 

(Ref. 2) 

30 kHz 

hyperthermal 

asher erosion 

yield, cm3

/atom 

Ratio of 30 kHz 

hyperthermal asher 

to LEO erosion 

yield 

Acrylonitrile butadiene 

styrene 

ABS 1.05 0.0458 1.090.03 E-24 2.500.06 E-24 2.29 

Cellulose acetate CA 1.2911 0.00283 5.050.13 E-24 9.270.25 E-25 0.18 

Poly-(p-phenylene 

terephthalamide) 

PPDT 1.4422 0.00372 6.280.16 E-25 3.350.08 E-24 5.33 

Polyethylene 

(low oxygen) 

PE 0.918 0.0203 3.740.09 E-24 3.660.09 E-24 0.98 

Polyvinyl fluoride PVF 1.3792 0.00285 3.190.08 E-24 4.830.12 E-24 1.51 

Crystalline 

polyvinylfluoride 

w/white pigment 

PVF 1.6241 0.295 1.010.04 E-25 1.820.07 E-25 1.80 

Polyoxymethylene; 

acetal; 

polyformaldehyde 

POM 1.3984 0.00902 9.140.28 E-24 5.580.17 E-24 0.61 

Polyacrylonitrile PAN 1.1435 0.00184 1.410.05 E-24 3.410.11 E-24 2.42 

Polystyrene PS 1.0503 0.00042 3.740.10 E-24 3.650.10 E-24 0.98 

Polymethyl 

methacrylate 

(Impact. Mod.) 

PMMA 1.1628 0.00028 5.600.15 E-24 7.520.19 E-24 1.34 

Polyethylene oxide PEO 1.147 0.00112 1.930.05 E-24 1.390.04 E-23 7.19 

Poly(p-phenylenebenzobisoxazole), 

balanced biaxial film 

PBO 1.3976 0.0109 1.360.08 E-24 7.600.45 E-25 0.56 

Epoxide or epoxy EP 1.115 0.0304 4.210.11 E-24 5.040.14 E-24 1.20 

Polypropylene PP 0.9065 0.00184 2.680.07 E-24 6.850.18 E-24 2.56 

Polybutylene 

terephthalate 

PBT 1.3318 0.0629 9.110.24 E-25 2.100.05 E-24 2.30 

Polysulfone PSU 1.2199 0.00348 2.940.09 E-24 2.460.08 E-24 0.84 

Polyeurethane PU 1.2345 0.00664 1.560.05 E-24 1.980.06 E-24 1.27 

Polyphenylene 

isophthalate 

PPPA 0.72 0.0476 1.410.04 E-24 3.050.09 E-24 2.16 

Pyrolytic Graphite PG 2.22 0.00154 4.150.45 E-25 3.620.39 E-25 0.87 

Polyetherimide PEI 1.2873 0.00105 3.310.08E-24 2.740.07 E-24 0.83 

Polyamide 6 PA 6 1.1233 0.00388 3.510.09 E-24 3.770.10 E-24 1.07 

Polyamide 66 PA 66 1.2252 0.00459 1.800.23 E-24 3.650.46 E-24 2.03 

Polyimide PMDA PI (H) 1.4273 0.00284 3.000.07 E-24 3.000.07 E-24 1.00 

 
NASA/TM—2013-216613 7 

3.3 Comparison Between 30 and 35 kHz Hyperthermal Ashers, Thermal Energy Asher, 

and LEO Results 

A comparison of the erosion yields for two different hyperthermal ashers, a thermal energy asher, and 

the LEO environment is given in Table 5. The table only lists those materials that have been tested in 

multiple environments. 

TABLE 5.—COMPARISON OF THE EROSION YIELDS FOR TWO DIFFERENT HYPERTHERMAL ASHERS, 

A THERMAL ENERGY ASHER, AND LEO 

Material Abbrev. LEO 

erosion 

yield, 

cm3

/atom 

(Ref. 2) 

Ratio of thermal 

energy asher 

erosion yield to 

LEO erosion 

yield (Ref. 3) 

Ratio of 30 kHz 

hyperthermal 

asher erosion 

yield to LEO 

erosion yield 

Ratio of 35 kHz 

hyperthermal 

asher erosion 

yield to LEO 

erosion yield 

Acrylonitrile butadiene styrene ABS 1.09 E-24 6.2 2.29 ------ 

Cellulose acetate CA 5.05 E-24 2.1 0.18 ------ 

Poly-(p-phenylene 

terephthalamide) 

PPDT 6.28 E-25 24.0 5.33 ------ 

Polyethylene (low oxygen) PE 3.74 E-24 1.8 0.98 0.671 

Polyvinyl fluoride PVF 3.19 E-24 1.6 1.51 

Crystalline polyvinylfluoride 

w/white pigment 

PVF 1.01 E-25 37.1 1.80 1.57 

Polyoxymethylene; acetal; 

polyformaldehyde 

POM 9.14 E-24 2.8 0.61 ------ 

Polyacrylonitrile PAN 1.41 E-24 3.6 2.42 ------ 

Polystyrene PS 3.74 E-24 1.2 0.98 ------ 

Polymethyl methacrylate 

(Impact. Mod.) 

PMMA 5.60 E-24 1.9 1.34 ------ 

Polyethylene oxide PEO 1.93 E-24 9.3 7.19 ------ 

Poly(p-phenylenebenzobisoxazole), balanced 

biaxial film 

PBO 1.36 E-24 2.8 0.56 ------ 

Epoxide or epoxy EP 4.21 E-24 2.4 1.20 ------ 

Polypropylene PP 2.68 E-24 4.6 2.56 ------ 

Polybutylene terephthalate PBT 9.11 E-25 6.2 2.30 ------ 

Polysulfone PSU 2.94 E-24 1.3 0.84 ------ 

Polyeurethane PU 1.56 E-24 9.3 1.27 ------ 

Polyphenylene isophthalate PPPA 1.41 E-24 5.9 2.16 ------ 

Pyrolytic Graphite PG 4.15 E-25 1.2 0.87 0.976 

Polyetherimide PEI 3.31 E-24 1.2 0.83 ------ 

Polyamide 6 PA 6 3.51 E-24 2.8 1.07 ------ 

Polyamide 66 PA 66 1.80 E-24 4.7 2.03 ------ 

Polyimide PMDA PI (H) 3.00 E-24 1.0 1.00 1.00 

Polyimide PMDA PI (HN) 2.81 E-24 1.1 ---- 0.869 

Fluorinated ethylene propylene FEP 2.00 E-25 7.2 ---- 21.548 

Polytetrafluoroethylene PTFE 1.42 E-25 7.9 ---- 49.21 

Averages 5.82 1.80 10.83 

Averages excluding FEP and PTFE 5.67 1.80 1.02 

 
NASA/TM—2013-216613 8 

The 30 kHz hyperthermal asher produced the closest average erosion yield approximation to LEO 

results. If one eliminates the fluorocarbon polymers FEP and PTFE, then the 35 kHz hyperthermal asher 

produces much closer erosion yield predictions to LEO results. The hyperthermal asher erosion yield of 

crystalline polyvinyl fluoride with white pigment particles is much closer to the LEO erosion yield values 

than the thermal energy asher value. This is thought to be due to the directed nature of the hyperthermal 

asher atomic oxygen which allows pigment particles to protect the underlying PVC matrix polymer 

(Refs. 7 and 10). 

By averaging the ratio of all the hyperthermal asher erosion yields to the LEO values for each 

polymer (except for FEP and PTFE) and using Kapton H as a reference with an erosion yield of 

3.0010–24 cm3

/atom, then one can find a constant which allows one to estimate LEO erosion yield values 

based on hyperthermal or thermal energy asher erosion yields. Combining the data from the two 

hyperthermal energy ashers, the predicted LEO erosion yields averaged a factor of 0.256 times the values 

measured in the hyperthermal ashers. For thermal energy ashers, the predicted LEO erosion yields 

averaged a factor of 0.172 times the values measured in the thermal energy ashers. The magnitude of the 

ground laboratory-to-LEO proportional constants of 0.256 and 0.172 is not as important as the fractional 

variation between the predicted LEO erosion yields and the actual measured LEO erosion yields. If one 

compares the standard deviation of the ratio of predicted-to-measured atomic oxygen erosion yields for 

those materials that were tested in the two hyperthermal ashers and the thermal energy asher (Ref. 3), then 

an approximate determination can be made as to which type of asher is the most reliable predictor of LEO 

erosion yield as shown in Figure 3. 

If one compares the hyperthermal energy atomic oxygen erosion yields to the LEO values, one would 

find that the LEO erosion yields, for the materials tested, are on the average lower (by a factor of 0.256) 

than the hyperthermal asher values. Thus, for some material of unknown erosion yield, the LEO erosion 

yield would be the hyperthermal energy asher measured erosion yield multiplied by 0.256 to obtain the 

estimate of the LEO value. Similarly, the LEO erosion yields predicted based on the thermal energy asher 

data need to be multiplied by 0.172 to obtain an estimate of the LEO values. However, some LEO erosion 

yield values will be higher or lower than the predictions. The fractional standard deviation in predicted 

erosion yield (predicted LEO erosion yield divided by measured LEO erosion yield) for all materials 

tested in the hyperthermal ashers was found to be 2.41, and for thermal energy asher predictions 1.37. 

Thus, using either type of asher, the fractional uncertainty in predicted LEO erosion yield is over 

100 percent. However, if one excludes the fluoropolymers FEP and PTFE, then the fractional standard 

deviation in predicted erosion yield for the hyperthermal ashers was found to be only 0.375 and for 

thermal energy asher predictions 1.42. 

(a) (b) 

Figure 3.—Comparison of the fractional standard deviation uncertainty of the ratio of predicted erosion yields to LEO 

measured erosion yields: (a) all data, (b) all data excluding the results for FEP Teflon and PTFE. 
NASA/TM—2013-216613 9 

Ideally, the most accurate prediction would be the lowest fractional uncertainty in the ratio of 

predicted-to-measured LEO erosion yields. As can be seen from Table 5 and Figure 3(a), the 

hyperthermal asher results for FEP and PTFE are more than an order of magnitude higher than all other 

polymers causing the hyperthermal asher to appear to be a poor predictor of LEO erosion yields. If one 

excludes FEP and PTFE results from the data, as shown in Figure 3(b), the hyperthermal asher appears to 

be a much more reliable (by a factor of ~3.8 better) predictor of LEO erosion yield than thermal energy 

asher testing. The reason why FEP and PTFE hyperthermal erosion yields are anomalous compared to the 

other polymers is not well understood. 

The results indicate that the hyperthermal asher data (excluding FEP and PTFE) were able to predict 

the LEO erosion yields within a fractional standard deviation of 37.5 percent whereas the thermal energy 

asher data predicted LEO results within 142 percent. Thus, the prediction of LEO erosion yields can be 

estimated by multiplying the erosion yield measured in a hyperthermal asher by 0.256 to obtain an 

average uncertainty of 37.5 percent. It should be pointed out that the erosion yield of most polymers is 

somewhat fluence and ash content dependent, thus, for significantly different fluences or ash fill contents, 

the predicted LEO erosion yields would be expected to be different. 

4.0 Summary 

The atomic oxygen erosion yields of 25 materials were measured in either of two directed 

hyperthermal RF plasma ashers operating at 30 and 35 kHz on air. The 30 kHz hyperthermal asher 

exposed 23 materials to ~5.691021 atoms/cm2

 representing a fluence of 67.4 percent of the MISSE 2 

experiment and the 35 kHz hyperthermal asher exposed 19 materials to 3.511021atoms/cm2

 which was 

83.2 percent of the actual MISSE 7 experiment fluence. The direct comparison of hyperthermal erosion 

yield values to LEO values is somewhat compromised because of the difference in fluence between the 

asher and LEO exposures. This compromised comparison is due to the erosion yield of the polymers 

being somewhat dependent on fluence. This would be most compromising for the high ash content 

polymers. All the erosion yields were compared to LEO erosion yield values and for 26 of the materials, 

hyperthermal erosion yields were compared to thermal energy erosion yields. 

Comparison of the hyperthermal asher prediction of LEO erosion yields with thermal energy asher 

erosion yields indicates that, except for the fluorocarbon polymers PTFE and FEP, the hyperthermal 

energy ashers are a much more reliable (by a factor of ~4 better) predictor of LEO erosion yield than 

thermal energy asher testing. 

References 

1. Leger, L.J., Spiker, I.K., Kuminecz, J.F., Ballentine, T.J., and Visentine, J.T., “STS Flight 5 LEO 

Effects Experiment - Background and Description of Thin Film Results,” AIAA-83-2631-CP, 

October, 1983. 

2. de Groh, K.K., Banks, B.A., McCarthy, C.E., Rucker, R.N., Roberts, L.M. and Berger, L.A., 

“MISSE 2 PEACE Polymers Atomic Oxygen Erosion Experiment on the International Space 

Station,” Journal of High Performance Polymers 20 (2008) 388–409. 

3. Stambler, A.H., Inoshita, K.E., Roberts, L.M., Barbagallo, C.E., de Groh, K.K., Banks, B.A., 

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Space Environment,” (conference held May 19–23, 2008 in Toronto, Canada) Ed. J.I. Kleiman, AIP 

Conference Proceedings 1087, pp. 51–66, 2009; also NASA/TM—2011-126904. 

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Fill on the Atomic Oxygen Erosion of Polymers and Paints,” Proceedings of the 12th International 

Symposium on Materials in the Space Environment (ISMSE 12), Noordwijk, The Netherlands (ESA 

SP-705, February 2013). 
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5. Yi, G.T., de Groh, K.K. Banks, B.A., Haloua, A., Imka, E.C., and Mitchell, G.G., “Overview of the 

MISSE 7 Polymers and Zenith Polymers Experiments After 1.5 Years of Space Exposure,” 

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12),” Noordwijk, The Netherlands (ESA SP-705, February 2013); also NASA/TM—2013-217848, 

2013. 

6. ASTM E 2089-00, “Standard Practices for Ground Laboratory Atomic Oxygen Interaction 

Evaluation of Materials for Space Applications,” June 2000. 

7. Banks, B.A., Simmons, J.C., de Groh, K.K., Miller, S.K., “The Effect of Ash and Inorganic Pigment 

Fill on the Atomic Oxygen Erosion of Polymers and Paints,” Proceedings of the “12th International 

Symposium on Materials in the Space Environment (ISMSE 12),” Noordwijk, The 

Netherlands (ESA SP-705, February 2013). 

8. de Groh, K.K., Banks, B.B., Mitchell, G.G., Yi, G.T., Guo, A., Ashmead, C.C., Roberts, L.M., 

McCarthy, C.E. and Sechkar, E.A., “MISSE 6 Stressed Polymers Experiment Atomic Oxygen 

Erosion Data,” Proceedings of Proceedings of the “12th International Symposium on Materials in 

the Space Environment (ISMSE 12),” Noordwijk, The Netherlands (ESA SP-705, February 2013). 

9. McCarthy, C.E., Banks, B.A., and de Groh, K.K., Miller, S.K., “MISSE 2 PEACE Polymers 

Experiment Atomic Oxygen Erosion Yield Error Analysis,” NASA/TM—2010-216903, Nov. 2010. 

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