285 research outputs found
Using the scanning electron microscope on the production line to assure quality semiconductors
The use of the scanning electron microscope to detect metallization defects introduced during batch processing of semiconductor devices is discussed. A method of determining metallization integrity was developed which culminates in a procurement specification using the scanning microscope on the production line as a quality control tool. Batch process control of the metallization operation is monitored early in the manufacturing cycle
GSFC Preferred Parts List PPL-15
A listing is presented of preferred electronic parts, part upgrading procedures, part derating guidelines, and part screening procedures to be used in the selection, procurement, and application of parts for Goddard Space Flight Center space systems and ground support equipment
A survey of particle contamination in electronic devices
The experiences are given of a number of National Aeronautics and Space Administration (NASA) and Space and Missile System Organization (SAMSO) contractors with particle contamination, and the methods used for its prevention and detection, evaluates the bases for the different schemes, assesses their effectiveness, and identifies the problems associated with each. It recommends specific short-range tests or approaches appropriate to individual part-type categories and recommends that specific tasks be initiated to refine techniques and to resolve technical and application facets of promising solutions
Theology, News and Notes - Vol. 56, No. 02
Theology News & Notes was a theological journal published by Fuller Theological Seminary from 1954 through 2014.https://digitalcommons.fuller.edu/tnn/1165/thumbnail.jp
Beam Based Alignment of Interaction Region Magnets
In conventional beam based alignment (BBA) procedures, the relative alignment
of a quadrupole to a nearby beam position monitor is determined by finding a
beam position in the quadrupole at which the closed orbit does not change when
the quadrupole field is varied. The final focus magnets of the interaction
regions (IR) of circular colliders often have some specialized properties that
make it difficult to perform conventional beam based alignment procedures. At
the HERA interaction points, for example, these properties are: (a) The
quadrupoles are quite strong and long. Therefore a thin lens approximation is
quite imprecise. (b) The effects of angular magnet offsets become significant.
(c) The possibilities to steer the beam are limited as long as the alignment is
not within specifications. (d) The beam orbit has design offsets and design
angles with respect to the axis of the low-beta quadrupoles. (e) Often
quadrupoles do not have a beam position monitor in their vicinity. Here we
present a beam based alignment procedure that determines the relative offset of
the closed orbit from a quadrupole center without requiring large orbit changes
or monitors next to the quadrupole. Taking into account the alignment angle
allows us to reduce the sensitivity to optical errors by one to two orders of
magnitude. We also show how the BBA measurements of all IR quadrupoles can be
used to determine the global position of the magnets. The sensitivity to errors
of this method is evaluated and its applicability to HERA is shown
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Effect of wakefields on first order transport in the SLC linac
The limitation in increasing the beam current in the SLC linac comes from the emittance growth caused by wakefields. Simulations of the beam transport that model the wakefield dynamics are being done to study methods to control this growth. To verify the theoretical estimates of the wakefield strengths assumed in these simulations, data were taken which are sensitive to their effect on the first order linac transport. Specifically, the dependence of single beam loading and betatron motion on beam current was measured in the range of 0--5.10{sup 10} to 3.5--10{sup 10} electrons per bunch. This paper presents these data together with comparisons to results from simulations. 5 refs., 7 figs
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