A gated-time-of-flight top-hat electrostatic analyzer for low energy ion measurements

Daniel J Gershman; Levon A Avanov; Glyn Collinson; Corey J Tucker; Alexander Barrie; Dennis J Chornay; Nikolaos P Paschalidis; Douglas Rowland; Thomas E Moore

doi:10.1063/5.0139022

A gated-time-of-flight top-hat electrostatic analyzer for low energy ion measurements

Rev Sci Instrum. 2023 Aug 1;94(8):083304. doi: 10.1063/5.0139022.

Authors

Daniel J Gershman¹, Levon A Avanov^{1

2}, Glyn Collinson^{1

3}, Corey J Tucker^{1

4}, Alexander Barrie^{1

5}, Dennis J Chornay^{1

2}, Nikolaos P Paschalidis¹, Douglas Rowland¹, Thomas E Moore¹

Affiliations

¹ NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
² Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA.
³ Department of Physics, Catholic University of America, Washington, District of Columbia 20064, USA.
⁴ Science Systems and Applications Inc., Greenbelt, Maryland 20771, USA.
⁵ Aurora Engineering, Greenbelt, Maryland 20771, USA.

PMID: 38065138
DOI: 10.1063/5.0139022

Abstract

When incorporated into a top-hat electrostatic analyzer, a gate electrode enables the separation of ions by their mass-per-charge with modest mass resolution (M/∆M ∼ 10). Gated-time-of-flight (TOF) instruments avoid the energy straggling and angular scattering effects prevalent in foil-based detection systems, providing more pristine measurements of three-dimensional distribution functions of incident ions. Gated-TOF implementations are ideal for measuring the properties of low-energy (i.e., <100 eV) thermal ions in various space environments. We present an instrument prototype capable of separating H+, He+, O+, and O2+ in Earth's ionosphere and demonstrate that in addition to providing species determination, precise operation of the gate electrode provides an electronically adjustable geometric factor that can extend a single instrument's dynamic range by several orders of magnitude.