Description: Implementing graphene foils in existing neutral atom detector designs will increase their angular and energy resolution, and also improve their mass discrimination and usable energy range. Graphene atomic uniformity and low mass density offer natural advantages over amorphous carbon foils in time-of-flight instruments. We expect that Phase II will yield flight-ready prototype foils available for rocket or pathfinder missions with substantial improvements in instrument performance. Graphene foils can also enable improved designs, for instance with lower mass or lower power consumption. Graphene is potentially useful in very low energy neutral atom detection, e.g. E4cm2) -SLG on nanohole arrays with hole coverage of >99% -a method for attaching single-layer graphene to mesh without adhesive -bilayer graphene membranes with >95% coverage on commercial mesh -Lyman alpha blocking of 99.8% using aluminum nanohole arrays Our Phase II effort will continue to improve microgrids, nanogrids and graphene for LENA detectors. In particular, we will 1. Fabricate bilayer graphene (BLG) on microgrids as a better-performing foil for existing LENA instrument designs. 2. Fabricate pristine SLG on nanogrids, extending TOF detectors to <200eV. 3. Investigate surface modification of graphene to enable detection of <10eV neutral atoms. 4. Make prototype samples for other NASA and non-NASA applications. Compared with existing foils, our proposed SLG structure reduces scattering, improves low energy signal, and improves energy resolution. The structure reduces the serial losses and increases the effective collection area.

Benefits: Neutral atom detector foils and particle detector foils The graphene foils we report in Phase I have excellent energy resolution and low energy signal compared with existing foils.We have shown prototype grids which appear suitable for supporting bilayer graphene in an instrument-usable configuration. Graphene antistatic and emissive coatings on particle beam and EUV filters Present antistatic coatings and contamination blocking filter coatings are made from >5nm thick amorphous carbon. Graphene has higher conductivity than amorphous carbon, but is only 0.3nm thick. This represents a considerable improvement in electron scattering cross section, thermal emissivity, and mass density. Nanohole arrays for EUV filters Presently the wavelength range 50-120nm has no viable narrow-band filter. Imaging of EUV spectral lines needs wavelength-selectable bandpass filters. Availability of solar-blind bandpass EUV filters will enable imaging of, for instance, elemental plasma processes in planetary atmospheres. Miscellaneous Instrument Graphene Foils Cooled instruments require a membrane to separate environmental contaminants without otherwise affecting detection or beam optics. For example, cryodetectors, such as X-ray microcalorimeters, require contamination blocking elements to prevent UHV or spacecraft contaminants from adsorbing onto the detector and causing soft X-ray opacity. Currently, these barrier foils are 50nm-100nm thick.

Nanohole arrays for EUV filters and High-Harmonic-Laser Order Selectors Presently the wavelength range 50-120nm has no viable transmission filters except for broad-band elemental In and Sn foils. Detection of spectral lines, and generation of laser lines, needs wavelength-selectable bandpass filters in this wavelength range. Synchrotrons and Free-electron lasers rely on the elemental properties of foils for harmonic rejection, greatly limiting the utility of synchrotrons in the 50-120nm wavelength range. The proposed nanohole arrays can improve the selectability and performance of spectral filters in this range of wavelengths. Miscellaneous Instrument Graphene Foils Instruments such as X-ray microcalorimeters and electron beam systems, require a membrane to separate environmental contaminants without otherwise affecting detection or beam optics. For example, cryogenic detectors, such as X-ray microcalorimeters, require contamination blocking elements to prevent UHV or spacecraft background contaminants from adsorbing onto the detector and causing soft X-ray opacity. Currently, these barrier foils are 50nm-100nm in thickness, and are highly absorbing for X-rays <300eV. Graphene is a promising low mass contamination barrier, since is less than 1nm thick.