Cold Electron Source with an Electron Multiplier Illuminated by Ultraviolet Photons

A shelved structure for the support of an electron optical column affords advantages both to the designer and the user. A lens may be removed for cleaning for example, without demounting the remaining lenses. A custom device for another example, may be placed on a shelf, substituting for the standard lens perhaps so that some specialized research may be undertaken. Especially advantageous is a shelved arrangement if the column assembly is designed to hang from a supporting structure such as a gas borne floating platform, as is the case with the system described below.As shown on the schematic, a floating platform (I) supports the electron source apparatus (2) and a U-shaped column support shelf (3). The column support shelf acts as a key for locating and supporting three struts (4) which with nuts (5) support the condenser shelf (6), the objective shelf (7), the upper projector shelf (8), and the lower projector shelf (9).

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SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109768 ◽

1978 ◽

Vol 36 (1) ◽

pp. 524-525

Author(s):

T. Koshikawa ◽

Y. Fujii ◽

E. Sugata ◽

F. Kanematsu

Keyword(s):

Electron Emission ◽

Secondary Electron ◽

Secondary Electron Emission ◽

Life Time ◽

Activation Process ◽

Beam Diameter ◽

Activation Temperature ◽

Electron Multiplier ◽

Activation Condition ◽

Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

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First H+ Charge-Exchange Images in the Stim.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092487 ◽

1976 ◽

Vol 34 ◽

pp. 504-505

Author(s):

Wm. H. Escovitz ◽

T. R. Fox ◽

R. Levi-Setti

Keyword(s):

Charge Exchange ◽

Neutral Component ◽

Channel Electron Multiplier ◽

Electron Multiplier ◽

Neutral Particles ◽

Charged Beam ◽

Scanning Transmission ◽

Contrast Mechanism ◽

Ion Microscopy ◽

Beam Component

Charge exchange, the neutralization of ions by electron capture as the ions traverse matter, is a well-known phenomenon of atomic physics which is relevant to ion microscopy. In conventional transmission ion microscopes, the neutral component of the beam after it emerges from the specimen cannot be focused. The scanning transmission ion microscope (STIM) enables the detection of this signal to make images. Experiments with a low-resolution 55 kV STIM indicate that the charge-exchange signal provides a new contrast mechanism to detect extremely small amounts of matter. In an early version of charge-exchange detection (fig. 1), a permanent magnet installed between the specimen and the detector (a channel electron multiplier) sweeps the charged beam component away from the detector and allows only the neutrals to reach it. When the magnet is removed, both charged and neutral particles reach the detector.

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Optical Properties of HVEM Accelerators

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100114529 ◽

1975 ◽

Vol 33 ◽

pp. 180-181

Author(s):

A. Strojnik ◽

J.W. Scholl ◽

V. Bevc

Keyword(s):

Optical Properties ◽

Electron Accelerator ◽

Systematic Investigation ◽

Electron Source ◽

High Brightness ◽

The Past ◽

Wide Range ◽

Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

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