SELENIUM RECTIFIERS

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600270732-9
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 4
• Document Creation Date: December 22, 2016
• Document Release Date: September 19, 2011
• Sequence Number: 732
• Publication Date: January 3, 1950
• Content Type: REPORT

Sanitized Copy Approved for Release 2011/09/19: CIA-RDP80-00809A000600270732-9
50X1-HUM
CLASSIFICATION CONFIDEdTIALCQNV`OENTI ft
CENTRAL INTELLI,ENCE AGENCY REPORT
COUNTRY
SUBJECT
HOW
PUBLISHED
WHERE
PUBLISHED
DATE
PUBLISHED
LANGUAGE
FOREIGN DOCUMFNTS OR RADIO BROADCASTS CD NO.
Scientific - Electrical equipment
Monthly periodical
Moscow
Feb 1947
TM11 DO0 11IT COLTAIIII IL/OQ.ATICN A791CT1N0 001 7ATIOI1L 0171111E
OY TO1 U*ITL0 31A711 510011 VIA ?1.1111 01 130101171/ ACT 10
0. I. C.. LI AN0 01. AL A1i1010. ITO T1A111IIOIOI 01 TML 1930LOIIOI
0I ITT *XT`T/ IN ANT 171111 00 AN UNAU00011/3O 311401 13 3/0.
1107000 IT LAS. I17I000C010N Of 0011 0611 13 710N111710.
SOURCE Elektricheetvo, No 2, 1947,
50X1-HUM
DATE OF
INFORMATION 1947
DATE DIST. 3 Jan 1950
NO. OF PAGES 4
SUPPLEMENT TO
REPORT NO.
THIS IS UNEVALUATED INFORMATION
SEMIUAI
V.G. V.G. Sonar, Capri Tech Sol
Moecuw Power Eng Inst i>seni Molotov.
re
uce the electroconductivity of the semiconductor. Electroforming (a slow in-
crease in the rectifier's blocking resistance under high inverse currents) to
explained by ion conductivity, namely, a displacement of ions of an impurity in
the semiconductor, which decreases the concentration of holes in the boundary
layer of the semiconductor.
The technology of producing selenium rectifiers to reduced to three basic
problems: 1) decreasing the direct resistance; 2) increasing the blocking
CLASSIr1"''TION ^ONFIDh TIAL
tad T LIMIKIBUTTON
ARMY JA AIR FBI
- ~-
Selenium
rectifiers are used. widely in plants, power stations, radii ou-
tions, railroads, airplanes, ships and in many other special installations. In
the USSR, industrial selenium -ectifiere were first developed by I. kihrietov in
1937. Selenium rectifiers were studied at the Leningrad Pbyeicotechnical
Institute, Acedeny of Sciences TESR, by A.Z. Levinzon and in the Scientific Re-
search Institute of Cinematography (NIEFI)= selenium rectifiers studied also by
the author together with N. Penin and. L. Sazhin and by S.B. Yuditakdy in the All-
Union Electrical Engineering Institute. Selenium rectifiers are mass-produced
in plants of the electrical industry.
The present-day theory of the rectifying action of selenium rectifiers
was developed by B. Davydov in 1938 and later by W. Schottky. The theory was
improved by A.F. Io9^;, who suggested that the increased resistance of the boun-
dary layer in a selenium rectifier in the absence of current was mainly due, not
to the contact potential differ/ance, but to the transition of the boundary layer's
conductivity from hole to electron. Ioffe'a research on the electrodoiduotlvity
of semioonluctore in strong electric fields was used to explain the lueak=+on
Woveno in selenium rectifiers. The theory of the rectifying action, however, is
not yet complete; it does not explain such important processes as aging and
electroforming.
The author has advanced a theory concerning the lonle nature of those Vro-
ceaees. Aging (a slow irreversible increase in the rectifier's direct resistance)
is explained by diffusion and variation in ion concentration of impurities or
defects of the lattice; these factors decrease the oencentratiou of holes and
d
Sanitized Copy Approved for Release 2011/09/19: CIA-RDP80-00809A000600270732-9
 Sanitized Copy Approved for Release 2011/09/19: CIA-RDP80-00809A000600270732-9
CONFIDINTIAL
ruaieubuce; and 3) obtaining s durable rectifier. The resistance of the selenium
the selenium layer; 2) removing metallic impurities from the selenium to increase
its electroconductivity; 3) adding halogen admixtures to the selenium to increase
its electroconductivity; and 4) heat-treating the selenium layer to increase its
slectroconiuctivity. The high resistance of the boundary layer between selenium
and the contact electrode was practically eliminated by nickel-plating the steel
-
I for th
alu4num A4
s
e contact lee
layor between selenium and the cathode was made a minimum only in the Inactive
part where practically no space charge exists fr inverse currents. T,
.16 reels_
ance of the active part of the selenium boundary layer (the blocking layer) is
made an optimum to obtain, on the one rani, and small direct resistance a i, on
the other, a high blocking resistance. The resistance of the selenium boundary
layer is made an optimum by the following methods: 1) selection of the material
for the cathode (use of cadmium alloys); 2) heat treatment to remove halo
ens
g
from the surface of the selenium layer; and 3) deposition of various substances.
Selenium is the basic material for the production of rectifiers.- The tech=
nology of factory purification of selenium for rectifiers was perfected in the
d33SR by B. Levi (NIUIF, Scientific Research Institute of Fertilizers and Insecto-
fungicides). Important refinements in the technology were devised later by S.
Golyai (NIOGAZ). The author, together with K. Aetakhov, B. Levi, ani N. Peni,n,
studied the influence of impurities in selenium upon the properties of selenium
lished that the majority of impurities in quantities of 0.1 percent or more -
act unfavorably upon the reetifier,s characteristics, namely, increasing the
direct resistance, decreasing the 'block 3 resistance and intensifying aging.
The harmful impurities include: zinc, cadmium, mercury, tin, lead, arsenic,
nickel, iron, sulfur, tellurium, and oxygen. Copper, silver, and antimony im-
purities were especially harmful, increasing the direct resistance and intensi-
fying aging even in quantities of 0.001 percent. The beneficial effect of ex-
tremely small quantities of :hlorine, bromine, and iodine (thousandths of a
percent) in reducing the direct resistance use also established. At the same
time, it was determined that too large a halogen content not only decreases the
blocking resistance, but also lovers the breakdown voltage.
The selenium used in the USSR for rectifiers contains thousandths of a per-
cent of chlorine and has no copper, silver, or antimony in it; th, total of other
metallic impurities does not exceed 0.01 percent (nonvolatile residue).
The contact electrode of a selenium rectifier is produced from sheets of
steel or aluminum from 0.8 to 1.5 millimeters thick. These sheets are out and
stamped so that the surface of the disk is perfectly flat in order that a thin
uniform selenium layer may be deposited.
The sandblasting which follows guarantees good mechanical contact and the
proper electrical contact of the selenium with the metallic electrode. The
disks are then nickel-plated (1 or 2 microns thick), which ensures low direct
resistance of the newly produced rectifiers and affords protection against aging.
The technological process for thin nickel-plating of steel and aluminum disks
for cnatwot electrodes was developed by the author together with A. Gopius.
Fusion is used to deposit the selenium on the contact electrode: the
contact electrode is heated to approximately 250 degrees centigrade and the
selenium is fused on; the rapidly cooled disks with the fused vitreous selenium
are then pressed to obtain a thin Uniform selenium layer. The disks are pressed
while the selenium is heated to 110-120 degrees centigrade at a pressure of
several tens of kilograms per square centimeter. The selenium is held under
pressure until the surface section of the layer crys?allizes. The selenium is
0.07 to 0.1 millimeters thick after pressing. Spec:el presses, which ensure con-
stant uniform pressure, are used in this process. The selenium is protected from
contamination by special chrome-plated matrices.
The selenium layer is heat-treated in furnaces at a temperature of around
215 degrees centigrade. The selenium surface is left uncovered during this prec-
ese. Chlorine is partially volatilized from the upper part of the selenium
- 2 -
CONFIDWTIAL
C QNE; E HAL
Sanitized Copy Approved for Release 2011/09/19: CIA-RDP80-00809A000600270732-9
 Sanitized Copy Approved for Release 2011/09/19: CIA-RDP80-00809A000600270732-9
layer, thus '.ncreasing the blocking resistance of the rectifier. The eleotro
contuctivity of selenium in the layer is considerably increased because of the
increase in the number of defects of the crystal-lattice in connection with
the fact that the teeperature during heat-tc!enaing is close to the temperature
of fusion (217 degrees centigrade) for eels l-um. Using Z-ray analysis, G.'Zhdanov
and in. Shaawin showed. that the parax tere of the selenium lattice do not a ge ray
more in heat-treatment than in aging of the rectiziere. Spacial furnaces with
accurate automatic temperature regulation are used. for heat-treatment.
Sulfur is deposited on the selenium surface after heat-treatment. The
disks are held in sulfur vapors at a temperature of about 150 degrees centigrade
for several tons of minutes. The sulfur dissolves into the surface of the
selenium layer end thus increases its resistance.
A metal Spray gun using compressed air, which shoots the fused. metal on ;
the selenium, is used for covering the rectifier disks with the cathode. Alloys
resistance during electrofnrming. These rectifiers also have the highest ratio
of blocking to direct voltage and thus are met officie.t. However, rectifiers
with thallium cathodes or with cathodes having alight thallium impurity age more
rapidly than the usual rectifiers.
Electroforming at the plants producing selenium rectifiers is carried out
after metal plating by passing a high inverse current through the rectifiers
(current density of several tens of milliamperes per square centimeter) for a
length of time from several tens of minutes to several hours. The rectifier's
rating as to blocking voltage is increased 1.5 to 2 times in this process.
Special panels which automatically maintain the current within the necessary
limits are used for electroforming. In order to limit the direct current and
avoid excess beating, the rectifiers are placed in opposition and connected to
the alternating-current circuit through an effective resistance. The great
influence of the cathode material, magnitude, current, and temperature in the
electroforming process indicates the important role of the ions of the cathode
metal in this process. Under the action of the strong electric field, they pene-
trate into the barrier layer and change Ito electrocamductivity.
After molting, the rectifiers are tooted. All neuly produced rectifiers
are tested for electrical strength and rated with respect to direct and blocking
voltages. In the USSR, selenium rectifiers are rated on direct current with a
direct-current density of 50 milliamperes per square centimeter (or 4G micro-
aiaperea per square centimeter) and inverse current density of 4 milliarTeres
per square centimeter (or 2 microamperes per square centimeter). A test voltage
of 50 volts is used.
In a brief discussion of the vacs"tm method of producing selenium recti-
fiers, it ic, stated that work Is being done on this method in the USSR, but
that the equipment outlay required for the method is enormous and that further
improvement of the method is necessary.
The NISFI has proposed a new set of selenium rectifiers of diameters of
5, 10, 20, 30, 50, 80, and 130 millimeters. This set Is distinguished by the
small number of different sizes. Moreover, parallel connection of two recti-
fiers will not replace a rectifier of larger diameter.
Selenium rectifiers are widely used for the folloving-purposes:
1. Charging Batteries -- Selenium rectifiers are used in garages, and air-
ports to charge starter batteries for automobiles, aircraft, and other machines
LO Sanitized Copy Approved for Release 2011/09/19: CIA-RDP80-00869A000600270732-9
 Sanitized Copy Approved for Release 2011/09/19: CIA-RDP80-00809A000600270732-9
7. ? Supplying Electromagnets of Various Unite -- Selenium rectifiers are
used to supply the electromagnetic plates of grinding machines. They are also
used to supply driving electromagnets, for example, oil switches.
A low-power direct-current generator has been designed with permanent
magnets and selenium rectifiers in the main circuit. Despite a certain loss of
efficiency, the new system is more reliable and does not require much mainte.
nance.
8. Current and Voltage Stabilizers and Regulators -- The author designed
an economical static voltage regulator using selenium rectifiers and magnet-
ically saturated coils.
9. Magnetic Amplifiers -- Selenium rectifiers have recently been used
in magnetic amplifiers of various automatic regulation equipment.
10. Grid Control of Ionic Rectifiers -- Selenium rectifiers are used to
obtain the negative bias voltage on the grids of thyratrone or controlled
mercury rectifiers. I.L. gaganov designed static magnetically saturated regu-
latory for grid control of power rectifier and inverter unite.
Selenium rectifiers are also used for signaling and automatic blocking
on railroads, supplying telephone and telegraph communication lines and series
connection of rectifiers In the line to double their carrying capacity, supplying
equipment used in testing cable insulation, supplying X-ray equipment, detection
in hIgh-frequency circuits, electrostatic gas purification, cathodic corrosion
protection, telecontrol, arc quenching in direct-current circuits etc.
In conclusion, it is specified that the production of selenium rectifiers
6. Measuring Instruments -- Special measuring selenium rectifiers have
been designed (NIEFI) with increased stability of resistance and decreased
capacitance for operation at 10 kilocycles.
none without using rotating exciters.
5. Supply of Radar Installation,- and. Radio Communication Equipment --
Despite the low efficiency of selenium rectifiers, they are often use-.. Instead
of ionic devices because of their prolonged and continuous operation and high
volts. ioienium rectifiers have been deveioped for currents up to 1,000 amperes
in the USSR. Westinghouse of England developed 15,000-ampere rectifiers in 1945.
The current is regulated in many designs by changing the number of turns or the
transformer winding. Rectifiers Immersed in oil may be operated for prolonged
periods when installed directly near the bath. Selenium rectifiers are used In
electrolysis shops for plating copper, zinc, cadmium, chrome, nickel, etc. Se-
lenium rectifiers have been designed in the N1:9FI to supply bntha for silver
regeneration in (;!Ile-copying processes.
3. Supply for Electric Arcs -- Several types of selenium rectifiers have
been designed in the T13SR to supply electric arcs with currents from 3 to 50
amperes at vo?tages from 20 to 60 volts. A selenium rectifier was designed with
economical ferrorosonance stabilization of the current for an are projector of
2-2.5 kilowatts' power. A regulated selenium rectifier has also been designed
to supply the electric are used in spectral analysis.
4. Excitation of Electric Generators -- S. Yuditskiy devised a system of
excitation and compounding of synchronous generators by means of seleniemt, reeti-
is 1:?4ri ~~, r?,~ : J
Sanitized Copy Approved for Release 2011/09/19: CIA-RDP80-00809A000600270732-9