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We have constructed ion optics which, when interfaced with a channel electron multiplier (CEM), make possible quantitative measurements of positive and negative ion fluxes. We describe the design and operation of a detection system using these optics and present a calibration of the CEM for low energy (0.2–8.7 keV) positive and negative oxygen ions.

Absolute detection efficiencies for singly and multiply charged positive ions have been measured for a channelplate and for two different channel electron multipliers (CEM). The efficiencies were measured for impact energies between approximately 0.25 and 25 keV and for ion masses ranging from 14 to 132. The maximum efficiencies were found to be the same for all ions investigated and were approximately 58% for a channelplate and 89% for the CEMs. For a channelplate it is shown that the detection efficiencies for heavier ions scale to a single curve if plotted versus the impact energy divided by the square root of the ion mass. Data taken from the literature imply that lighter ions scale differently. Polynomial fitting parameters to the present efficiency curves are provided.

The response of a large area (4.6×13 cm) multianode channel electron multiplier array (CEMA) detector to energetic neutrons was investigated. The measured neutron detection efficiencies of the chevron microchannel plate (MCP) were 1.7×10−3 and 6.4×10−3 counts/neutron, respectively, for 2.5 MeV‐DD and 14 MeV‐DT neutrons. The apparently higher efficiency observed for the 14 MeV neutrons is attributed to neutron‐induced background gamma radiation.

We report direct measurements of the sensitivity of a channel electron multiplier to electrons with different spin orientations. Four regions of the multiplier cone were examined using polarized electrons at 100‐eV incident energy. Pulse counting and analog modes of operation were both investigated and in each case the observed spin effects were less than 0.5%.

The movable Faraday cup assembly of the varian LEED optics system has been modified by the addition of a channel electron multiplier. Signal‐to‐noise was increased by several orders of magnitude, rendering the assembly suitable for the measurement of energy distributions of photoelectrons with an angular resolution as small as ±2°.

The initial results of absolute proton efficiency measurements made in an auroral particle study by sounding rockets are given. The measurements were made at several counting rates from 1000 to 40,000 counts/sec on rocket-borne equipment. The results agree with those of Egidi et al. (1969) in the high energy range and show a disagreement at low energies.

A commercial quadrupole mass filter has been modified to accept a channel electron multiplier. The modification is relatively simple and inexpensive. The resulting mass filter is very sensitive (gain > 107) and compact.

A spiral type continuous channel multiplier was used for pulse counting heavy positive ions. The shape of the output pulses was studied. The pulse risetime was found to be very long and composed of numerous after‐pulsing as revealed by the ``staircase'' appearance of the pulse. As a consequence, the count rate capability is greatly hampered. Detection of the positive ions by a catcher foil and collection of the secondary electrons lead to a smooth pulse clean of any after‐pulsing and to a greatly improved count rate capability.

The effects of a longitudinal magnetic field on the performance of a channel electron multiplier are studied and the gain variation due to the magnetic field is explained by considering hopping and gyrating motion of electrons.

The possibility of using the channel electron multiplier in the analog continuous current mode is pointed out. By combining this mode with the usual pulse counting mode, one can extend the dynamic range of the channel multiplier over several decades.

Considerable differences in the current gain have been found in a channel electron multiplier when used as a detector of 100 keV N1+ ions, depending on the point of impact at the channel entrance. These differences occur at high current gains which are usually considered near to saturation. In contrast to the current gain, the detection efficiency shows no significant variation with the point of impact, suggesting that at least one of the electrons from the primary interaction of the ion with the secondary surface is multiplied by the channel to provide a detectable pulse.