Abstract

Space plasma instruments often rely on ultrathin carbon foils for incident ion detection, time-of-flight (TOF) mass spectrometry, and ionization of energetic neutral atoms. Angular scattering and energy loss of ions or neutral atoms in the foil can degrade instrument performance, including sensitivity and mass resolution; thus, there is an ongoing effort to manufacture thinner foils. Using new 3-layer graphene foils manufactured at the Los Alamos National Laboratory, we demonstrate that these are the thinnest foils reported to date and discuss future testing required for application in space instrumentation. We characterize the angular scattering distribution for 3-30 keV protons through the foils, which is used as a proxy for the foil thickness. We show that these foils are ∼2.5-4.5 times thinner than the state-of-the-art carbon foils and ∼1.6 times thinner than other graphene foils described in the literature. We find that the inverse relationship between angular scattering and energy no longer holds, reaffirming that this may indicate a new domain of beam-foil interactions for ultrathin (few-layer) graphene foils.

Highlights

  • Ultrathin carbon foils are commonly used in space plasma instrumentation, for example, time-of-flight (TOF) ion mass spectrometers (e.g., NASA Van Allen Probes/HOPE, Cluster/CODIF, JUNO/JADE) (Funsten et al, 2013; Möbius et al, 1998; Rème et al, 1997; and McComas et al, 2017) and energetic neutral atom (ENA) imagers (e.g., NASA IBEX/IBEX-Hi, TWINS) (Funsten et al, 2009; McComas et al, 2012)

  • Using new 3-layer graphene foils manufactured at the Los Alamos National Laboratory, we demonstrate that these are the thinnest foils reported to date and discuss future testing required for application in space instrumentation

  • Ultrathin carbon foils are commonly used in space plasma instrumentation, for example, time-of-flight (TOF) ion mass spectrometers (e.g., NASA Van Allen Probes/HOPE, Cluster/CODIF, JUNO/JADE) (Funsten et al, 2013; Möbius et al, 1998; Rème et al, 1997; and McComas et al, 2017) and energetic neutral atom (ENA) imagers (e.g., NASA IBEX/IBEX-Hi, TWINS) (Funsten et al, 2009; McComas et al, 2012)

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Summary

INTRODUCTION

Ultrathin carbon foils are commonly used in space plasma instrumentation, for example, time-of-flight (TOF) ion mass spectrometers (e.g., NASA Van Allen Probes/HOPE, Cluster/CODIF, JUNO/JADE) (Funsten et al, 2013; Möbius et al, 1998; Rème et al, 1997; and McComas et al, 2017) and energetic neutral atom (ENA) imagers (e.g., NASA IBEX/IBEX-Hi, TWINS) (Funsten et al, 2009; McComas et al, 2012). These instruments exploit several useful properties of the interaction physics of atoms and molecules as they traverse an ultrathin foil. We compare the angular scattering measurements to Meyer’s theory, which is commonly used to describe foil–beam interactions, and show that graphene foils are in a new domain of physics

Synthesis of graphene foils
Apparatus used to measure scatter distribution
Description of acquired data
DATA ANALYSIS
Annular bin method
Comparison of analysis techniques
RESULTS AND DISCUSSION
Graphene foils in relation to Meyer’s theory
CONCLUSION AND FUTURE STUDIES
Full Text
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