The properties of charged particle beams associated with the distribution of the particles in energy and in time can be grouped together under the category of longitudinal emittance. This article is intended to provide an intuitive introduction to the concepts longitudinal emittance; to provide an incomplete survey of methods used to measure this emittance and the related properties of bunch length and momentum spread; and to describe the detailed design of a 6 Ghz bandwidth resistive wall current monitor useful for measuring bunch shapes of moderate to high intensity beams. Overall, the article is intended to be broad in scope, in most cases deferring details to cited original papers. 37 refs., 21 figs.

Current interest in the measurement of infrared heat emission and absorption of structural materials is discussed. Distinctions between the emission characteristics of materials in the visible and heat radiation regions of the spectrum are made. The terminology of radiation exchange is reviewed from the standpoint of simplicity and usefulness in a standardized test suitable for use with structural materials as non-incandescent temperature radiators. Basic laws of radiation exchange are briefly reviewed. On the basis of the foregoing considerations, the plan of an apparatus construction for surface emittance measurement in the 0 to 300 F range is described.

In techniques presently available for the rapid determination of total emittance, the sample is generally exposed to surroundings that are at a different temperaturethan the sample's surface. When the infrared spectral reflectance of the surface is spectrally selective, these techniques introduce an error into the total emittance values. Surfaces of aluminum overcoated with oxides of various thicknesses fall into this class. Because they are often used as temperature control coatings on satellites, their emittances must be accurately known. The magnitude of the error was calculated for Alzak and silicon oxide-coated aluminum and was shown to be dependent on the thickness of the oxide coating. The results demonstrate that, because the magnitude of the error is thickness-dependent, it is generally impossible or impractical to eliminate it by calibrating the measuring device.

A study of emittance measurements using a slit pinhole type emittance meter is conducted using a 1 MeV, 18 ka electron beam. The beam is passed through titanium foils of varying thickness and the emittance is measured downstream. Two different types of emittance masks are used - one composed of tantalum bars with knife edges and another using cylindrical bars of elkonite. The prototype is used to measure the rms emittance and the projected phase space density of a nominal 1 MeV, 16 ka, 25 ns FWHM electron beam. Data is collected optically using an open shutter camera with polaroid film (time integrated). In addition, time resolved data is presented using a gated optical imaging ccd system on a 5 MeV IREB. This study sets a bound on the measurement accuracy to be expected when using this method of data collection and illustrates the effects of two different mask designs.

The three volumes in the PRINCIPLES OF ELECTRON OPTICS Series constitute the first comprehensive treatment of electron optics in over forty years. While Volumes 1 and 2 are devoted to geometrical optics, Volume 3 is concerned with wave optics and effects due to wave length. Subjects covered include:Derivation of the laws of electron propagation from SchrUdinger's equationImage formation and the notion of resolutionThe interaction between specimens and electronsImage processingElectron holography and interferenceCoherence, brightness, and the spectral functionTogether, these works comprise a unique and informative treatment of the subject. Volume 3, like its predecessors, will provide readers with both a textbook and an invaluable reference source.