PROJECT(Sanitized) PROGRAM

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A002500040014-6
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 9
• Document Creation Date: December 28, 2016
• Document Release Date: April 15, 2002
• Sequence Number: 14
• Publication Date: March 3, 1965
• Content Type: MEMO

Approved `Fef l ase 2002/06/17: CIA-RDP78B0 7 . 25000400`14'- i~
March 3rd, 1965
STATINTL
PROJECT
PROGRAM
STATINTL
I Lion of Basic Ex erimental 5et
The photosensitive dipole suspension ca
nta ins
ions
; or (b
photo dipoles.
(a) photo-
Window 2 i s
quartz or silica STATINTL
laminated with transparent
conductive coating 3013.
is Window 3
glass, laminated with the MPC transparent conductive coating
The window 2 passes ultraviolet light in
sans `r t i ve dipole to the photo-
suspension 1.
The ultraviolet light is supplied b an ultraviolet may y projector
y be one of three types:
1? High pressure mercury lamp
2. Xenon flash
3 Photoflash bulb
The flash lamp 11 is pulsed by control
Ultraviolet band pass 5.
filter 16 tran
m
s
its ultraviolet 1 ight
and absorbs visible light. A quartz or silica
ultraviolet light, lens 21 transmits
and is used to focus an image from plate 20
onto the electrosensitive dipole suspension. For ce
menu the image rtarn experi-
plate 20 may be removed so that the entire field
of the VARAD cell is illuminated uniformly. The
design such as a number of holes or a plate 20 may
letter such as 11xII
punched into a thin metal plate. This design is ima
gad u
Declass Review by NIMA/DOD Pon the
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plane of the suspension. Mechanical shutter 19 is a standard
photographic shutter mechanism. A lamp 10 emits visible light,
the intensity of which is maintained constant by a constant vol-
tage transformer 15. Ultraviolet absorption filter 17 and 18
pass visible infrared 1 ight.
The effect of the filters is that the cell is illuminated
by ultraviolet light only from source 11 and by visible light
only from source 10. Only visible light passes through the
f i l t e r 1 7 . The photocell 12 thus senses a change in the trans-
mission of visible light as influenced by the addition of ultra-
violet light. The ultraviolet light itself cannot pass through
to the photocell 12 because it is blocked by filter 17.
In investigating the effect of photo-ions, a steady DC
biasing voltage is applied via terminals 27 to the transparent
conductive coatings in sheets 2 and 3 and a pulse of UV light
impinged on the layer 1. The ions produced will separate in the
electric field. Isolating resistors 25 and 26 enable a square DC
pulse to be applied to the transparent conductive coatings from
terminals 2L. through capacitors 22 and 23. The current pulse to
the cell is measured across known resistor 30 by a CRT scope.
The pulsing of the UV light and the square wave DC can be re-
petitive. If a single pulse is employed 31 must then be a Memo-
scope.
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11 Experimental Investigations
Arrange to radiate the cell 1 with a pulse of ultra-
violet light. This pulse could be provided from:
(a) A flash bulb
(b) A Xenon flash source
(c) An ultraviolet light provided with a camera shutter.
Photo-ions may comprise fluid or solute molecules, which
when illuminated by ultraviolet light produce the positive and
negative ions from molecules originally neutral. Under the
applied DC field these migrate to opposite faces of the cell
walls close to the transparent conductors.
The separation of the ions is detected by a pulse of cur-
rent which can be measured as a voltage pulse across resistor
30; the isolating resistors 25 and 26 maintain a DC biasing
voltage across the cell I if required.
From a preceding analysis, the energy content of the ultra-
violet light pulse required to produce photo-ions which shield
an applied electric field of given intensity is known. A square
wave DC pulse can be triggered by the light pulse and applied
to the cell 1 at the same time. As the ions pass through the
layer toward the transparent conductors, the electric field in-
tensity across the dipole layer decreases.
Experiments are to be initially made to detect voltage pulses
produced across the resistor 30 using a biasing voltage 27 pulse
impinged on the cell 1, without dipoles in suspension, using
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photo-ion solvents or solutions containing photo-ionic solutes.
Then the effect of adding the dipoles on visible light trans-
mittance will be observed.
A photocell can be used to trigger the circuit so that the
voltage can be applied to the VARAD cell at the same time that
the ultraviolet light pulse arrives. A second photocell 12
which is used to measure the intensity of the visible light
beam may alternatively be connected to the log amplifier circuit
and then to the Memoscope to detect and to show rapid variations
in the intensity of the visible light beam due to changes in
dipole alignment caused by the ultraviolet pulse.
Photo-Res onsive Di olar Sus ensions
Photo-responsive dipolar suspensions may be; (a) dipoles
in a fluid containing photo-ions produced by ultraviolet light;
and (b) photo-dipoles whose conductivity or Y potential difference
changes in ultraviolet light.
(a) The dipoles employed with the photo-ions may be
of three types:
(1) A dielectric or non-conducting dipole which may
for example, Include lead carbonate platelets; y
(2) A metallic dipole; and
(3) A herapathite dipole containing polyiodide chains.
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(b) The photo-dipole may be of two types:
(1) A semi-conducting needle, for example, silicon
or germanium; and
(2) Photo-voltaic whiskers which develop their own
potential difference along the needles when excited by ultra-
violet light. Zinc sulphide whiskers are an example.
Silicon needles become more conducting when actuated by the
ultraviolet light, while the zinc sulphide becomes conducting and
photo voltaic as well.
In a photo-ionic dipolar suspension, when the ultraviolet
light pulse arrives, in the presence of an electric field,
positive and negative ions are produced within the fluid, the
metallic dipoles take, on induced positive and negative charges
at opposite ends, and the photo-ions move to neutralize the
charged ends of the dipole. An electric current passes through
the dipole as the ions discharge the ends of the dipoles. Photo-
ions will decrease in number and, therefore, fewer will be avail-
able to travel to the opposite faces of the VARAD cell to neutralize
the electric field.
Thus the presence of metallic dipoles will have an effect
similar to that of increasing the recombination rate of the
dipoles and will tend to reduce the magnitude of the shielding
effect. This effect will tend to become more pronounced for
high concentrations of dipoles. In dilute suspensions where the
dipoles are far apart, there will be less tendency for this
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effect to occur. At the same time the discharge of the
charged ends of the dipole will decrease the turning torque
which is equivalent to the shielding effect. However, this
involves internal energy losses which may be objectionable.
On the other hand, with dielectric dipoles, no current
passes through the dipoles. Therefore, the photo-ions will
be available to neutralize the dipolar induced potential and
will tend to p reven i_ the dipoles from rrenc. L i n with the el cc:.-
tric. field. V ith dielc,.,talc dipoles it may not be necessary
to depend upon the shielding of the internal electric field
at the faces of the VARAD Panel but the shielding will occur
on the induced charges of the dipoles themselves by the attach-
ment of available local photo-ions. This would produce a more
rapid and complete shielding.
There will be an upper limiting frequency to dipole ion
shielding effect because the mobility of the ions is small, and
the AC field reversal can be so rapid that the ions cannot move
towards and away From the dipole ends quickly enough to shield
effectively.
Investigate a dipole suspension and photo-ion layer as
separate layers separated by a thin glass sheet. Under these
circumstances, the separation of the photo-ions will cause an
increase in the electric field and the dipoles in dipole layer
will increase their orientation. There will be an augmentation
rather than a decrease to orientation.
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Investigate the time required for the electric field
in the dipole layer to be shielded by the photo-ions. Make
this commensurate with the time required for the dipoles to
orient or disorient. This effect is obviously tied in with the
magnitude of the electric field, the viscosity of the fluid,
the size of the dipoles and the mobilities of the photo-ions
produced,
The photo-ions MU'; f not- re