A new type of rocket-borne neutral atom analyzer

A new-type analyzer for measurement of energetic neutral atoms (ENAs) in an energy range of 4-40 keV is described. Incoming ENAs are ionized by electr on stripping at passage of an ultrathin carbon foil. After post-acceleratio n (by 3 kV), the particles are guided to a time-of-flight (TOF) section ove r a wide energy-per-charge bandwidth by means of electrostatic deflection w ithout any potential sweeping for electrodes. Then, their velocity is measu red by the TOF technique, with which species can also be identified, becaus e the particle energies are limited to a certain range by the electrostatic deflector and acceleration upon entering the TOF section. A unique feature in the present analyzer is in the rejection method of extreme ultraviolet (EUV) contamination. In contrast to conventional usage of serrated electrod es for EUV attenuation, one of the electrostatic deflection plates is machi ned to be so flat that EUV photons are guided to a photon trap regardless o f wavelength. The TOF device can also be used in a coincidence mode for noi se suppression. The present instrument was flown on a sounding rocket, and has successfully measured ENAs precipitating into the low-latitude upper at mosphere from the magnetosphere. (C) 2000 American Institute of Physics. [S 0034- 6748(00)02008-6].