THE U N I V ERS I T Y OF MICHIGAN COLLEGE OF ENGINEERING Department of Electrical Engineering Space Physics Research Laboratory Scientific Report No. MS-4 ENGINEERING DESIGN FOR A BAYARD-ALPERT IONIZATION GAUGE PRESSURE MEASUREMENT IN THE UPPER ATMOSPHERE J.R. Caldw'e l IORA ProJect 04304. under contract with: NATIONAL AERONAUTICS AND SPACE ADMINISTRATION GODDARD SPACE FLIGHT CENTER CONTRACT NO. NASr-15 GREENBELT, MARYLAND administered through: OFFICE OF RESEARCH ADMINISTRATION ANN ARBOR May 1965

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Table of Contents Page List of figures v 1. Introduction 1 1.1 Thermosphere Probe 1 1.2 General Description of TEEPEE 2 Bayard-Alpert Ionization Gauge Experiment 2. Experiment Requirements 2 3. Electronic Design 2 3.1 Westinghouse WX4250 Characteristics 5 3.2 Electrometer Amplifier 5 3.3 Grid Bias Supply 9 3.4 Filament Supply 9 3.5 Regulator Amplifier 9 3.6 Regulator System 10 3.7 Filament Switching Circuit 10 3.8 Breakoff Device and Filament Timers 10 3.9 Gauge Wall Temperature 11 3.10 Total Power Requirment 11 4. Mechanical Assembly 11 4.1 Orifice and Gauge 11 4.2 Shield and Header 13 4.3 Deck and Amplifier Assembly 13 4.4 Breakoff Device 16 4.5 Experiment Weight 16 5. Calibration Procedure 16 6. Environmental Tests 20 7. Accuracy of Collector Current Measurement 20 8. Flight Performance 20 9. Results 20 iii

List of Figures Figure Page 1. Experiment Assembled for Flight 3 2. Experiment Block Diagram 4 3. WX4250 Collector Current vs. Collector Voltage 6 4. WX4250 Collector Current vs. Grid Voltage 7 5. WX4250 Before and After Flight Modification 8 6. Determination of Experiment Dimensions 12 7. Header, Miniature Plug, and Shield 14 8. Filament Emission Regulator and Breakoff Timer Deck 15 9. Grid Supply and Filament Burnout Switch Deck 15 10. Experiment Assembled for Flight Viewed from Amplifier End 17 11. Breakoff Device Installed Except for Snap-ring 18 12. Sealed Orifice and Breakoff Device Cams 19 13. Gauge Calibration 21 14. Vibration Levels 22 15. NASA 6.09 Telemetry Record 23 16. Electrometer Amplifier Block Diagram 24 17. Electrometer Amplifier Schematic 25 18. Bayard-Alpert Experiment Function Diagram 26 19. Filament Emission Regulator and Breakoff Timer Schematic 27 20. Grid Supply and Filament Burnout Switch Schematic 28 v

1. INTRODUCTION The Space Physics Research Laboratory has used thermionic ionization gauges to measure pressure in the upper atmosphere since the time the V-2 rocket was made available to universities for research. In 1949 Bayard and Alpert made significant improvements in the thermionic ionization gauge, and recently, a rugged version of the improved gauge was made available for rocket-borne instrumentation. The Space Physics Research Laboratory attempted its first Bayard-Alpert gauge measurement in the upper atmosphere in January, 1962. Two Bayard-Alpert gauges, an Omegatron and a Langmuir probe were mounted in a 13-Inch Spherel which was ejected into the atmosphere from NASA sounding rocket 4.18. The second stage extinguished early, however, and no useful scientific data were obtained. 1.1 THERMOSPHERE PROBE Although only one 13-Inch Sphere was attempted, it proved to be the forerunner of a series of experiments referred to as thermosphere probes or TEEPEES. The TEEPEE houses a variety of direct-measuring thermospheric probes in a cylindrical package designed for ejection away from the sounding rocket, enabling measurements to be made in a cleaner environment than that immediately surrounding the vehicle. The first three TEEPEES carried Omegatrons and Langmuir probes successfully into the upper atmosphere. TEEPEE IV and TEEPEE VI, launched in January and July respectively of 1964, each carried a BayardAlpert ionization gauge in addition to an Omegatron and Langmuir probe. TEEPEE IV (NASA 6.09) was launched at Wallops Island, Virginia and TEEPEE VI (NASA 6.10) was launched at Fort Churchill, Manitoba. The following pages describe the construction and performance of the TEEPEE Bayard-Alpert gauge experiments. Nagy, Spencer, Niemann and Carignan, Measurements of Atmospheric Pressure, Temperature, and Density at Very High Altitudes, Univ. of Mich., ORA Final Scientific Report 02804-7-F, August 1961. 2Taeusch, Carignan and Niemann, The Thermosphere Probe Experiment, Univ. of Mich., ORA Report 04304-3-S, February 1964. -1 -

1.2 GENERAL DESCRIPTION OF TEEPEE BAYARD-ALPERT IONIZATION GAUGE EXPERIMENT The Bayard-Alpert experiment shown in figure 1 occupied one end of the TEEPEE. The sealed gauge orifice is centered above the flange (TEEPEE end-plate) and below the end-plate the experiment electronics package can be seen. Figure 2 is a diagram of the fundamental parts of the experiment. Filament, grid and collector voltages for the ionization gauge (Westinghouse WX4250) were provided by a filament supply, grid supply and zener diode respectively; the filament was isolated from ground except for the zener path and the collector was essentially at ground. The emission current path is shown as "I " and the collector current as "I ". The collector current was measured with an electrometer amplifier designated "E.A.", the emission current being held constant by a control circuit consisting of the gauge, filament supply and an amplifier. 2. EXPERIMENT REQUIREMENTS The expected pressure range for the experiment was 10 to 10-4 torr. A nominal emission current of 5 milliamperes was specified which was to be held during flight to within 1% of the mean value existing during N2 calibration over the given pressure range and over a TEEPEE battery variation from +32 to +27 volts. The expected collector current for the given pressure range and emission current was 5 x 100 to 5 x 10- amperes. The collector current measurement was to be divided into 8 linear ranges with measurements to be kept full scale by automatic range sensing and switching during flight. The gauge was to be sealed at a pressure of 10- torr or lower before flight and opened to the atmosphere on the upleg at approximately 250 kilometers to avoid gauge contamination or damage due to the rocket engine gases or the earth's surface pressure. One further requirement was that if emission current should be lost, the electronics would automatically switch to an alternate filament. 3. ELECTRONIC DESIGN The following paragraphs describe the characteristics of the Westinghouse WX4250 gauge and the circuit design for the associated electronics. -2 -

nt Assembled for Flight. -3 -

AMPLIFIER FILAMENT ~\ ICOLLECTOR SUPPLY I CONTROiL"~ WX4250 Figure 2. Experiment Block Diagram. -4 -

3.1 WESTINGHOUSE WX4250 CHARACTERISTICS Figure 3 shows WX4250 collector current versus collector voltage for a grid voltage of 90 volts and emission currents of 1 and 5 milliamperes, and figure 4 shows collector current versus grid voltage for a collector voltage of 15 volts and emission currents of 1 and 5 milliamperes. The thermal properties of the filament were such that if a step of current was applied to it, a period of time was required to establish a constant emission current; in quantitative terms, the half-power frequency response was approximately 2 cps, an important factor in the choice of experiment tumble rate and emission current regulator design. The filament power required to produce an emission current of 5 milliamperes at a grid voltage of 90 volts was approximately 6 watts (2 amperes @3 volts). Figure 5 shows the WX4250 gauge before flight modification (lower right) and after processing for flight (upper left). 3.2 ELECTROMETER AMPLIFIER To measure collector current, a linear electrometer amplifier with 100% feedback was used. Eight current ranges (1.6 x 10-9, 5 x 10-9, 1.6 x 10-8.............. 5 x 10-6 amps full scale) were chosen to provide adequate resolution. To make the amplifier output compatible with the 0 to 5 volt telemetering input requirement and to save a phase inverter, the output signal was chosen to be 5 volts for zero input current and 0 volts for full scale current. An automatic range selector switched a proper impedance into the feedback loop to provide the desired sensitivity and frequency response. The switching criterion was derived from the output signal in such a way that switching towards lower sensitivity occurred instantly when the output voltage became negative. Switching towards a more sensitive range occurred only when the rising and falling output signal consistently attained a peak value greater than 3.4 volts during a period of 5 seconds. This arrangement was necessary to prevent the amplifier from switching continuously due to the cyclic pressure variations in the gauge that result from the tumbling motion of the instrument after ejection into the atmosphere. The rise time in each range was approximately 4 milliseconds. The noise at the output for the most sensitive range was approximately 10-11 amperes and was caused mainly by the gauge filamentto-collector capacitance which allowed the noise current to be drawn from the AC filament power supply. Figure 16 is a diagram -5 -

.3x10' PRESSURE 1 x 107 TORR GRID VOLTAGE: 90 VOLTS Iz 0 IE MA I. * *. 0 V -.1 0" 0 5 10 15 20 25 30 COLLECTOR VOLTAGE (VOLTS) Figure 3. WX4250 Collector Current vs. Collector Voltage. -6 -

PRESSURE a 1x10' TORR 1.3x108 COLLECTOR VOLTAGE 15 VOLTS.2x10- CO 0Q I.~~~~~~~~~~~~~~~IZ 1MA 0UJ ~ ~ ~0 0 0 100 200 300 GRID VOLTAGE (VOLTS) Figure 4. WX4250 Collector Current vs. Grid Voltage. -7 -

Figure 5. WX4250 Before and After Flight Modification. -8 -

of the complete amplifier system. Figure 17 is a schematic of the amplifier electronics excluding the power supply and switching circuitry. 3.3 GRID BIAS SUPPLY Power versus size requirements dictated that a DC-to-DC converter be used to provide the 90 volt @ 5 milliamperes grid bias rather than a battery supply. The actual output voltage required was 105 volts since the supply was in series with a 15 volt zener diode of opposite polarity. The supply voltage was regulated by temperature compensated zener diodes in the primary. The output ripple voltage was.1%. 3.4 FILAMENT SUPPLY Since changes in pressure in the Bayard-Alpert gauge caused changes in the temperature of the filament, and thus, changes in the emission current, a filament supply was required which could be controlled to hold the emission current constant. In addition, it was necessary to isolate the supply from ground because of the adopted biasing scheme for the gauge. Again a choice of a battery or DC-to-DC converter existed, the converter being chosen for its convenience; the converter shown in figure 19 was the supply. The filament voltage was directly proportional to the voltage applied at the emitter follower and the gain was.14. The half-power frequency response was greater than 1 kc. To minimize filament hum transmitted to the electrometer amplifier through the gauge by the AC filament, a hum balance network was used in referencing the secondary to ground. The AC filament was used rather than a DC filament because the filtering required to significantly reduce the AC ripple became the source of an undesired phase shift as explained in paragraph 3.6. 3.5 REGULATOR AMPLIFIER The regulator amplifier was used to sense a change in emission current. A decreasing emission current produced an increasing output voltage which when applied to the filament supply reduced the emission current change; an increasing emission current caused a decreasing output voltage. The output voltage was nominally 22 volts for 5 milliamperes of emission current, the actual voltage being adjustable to enable a particular setting of emission current to be made at a mid-range pressure of about 10-6 torr. The transfer impedance of the amplifier was 105 ohms and its half-power frequency response was greater than 10 kc. -9 -

3.6 REGULATOR SYSTEM Referring to figure 2, when the feedback loop was opened at "A" and a small signal (with sufficient positive bias to produce a quiescent emission current of 5 milliamperes) was applied at the filament supply input and compared with the amplifier output, the measured voltage gain of the system was 150 and the two signals were 1800 out of phase at frequencies near DC. At 40 cps the gain was 1 and the phase shift was 3300; the phase shift consisted of 90~ in the gauge, 1800 in the amplifier, and 600 in the amplifier input filter. Rectification in the filament supply would have added phase shift possibly causing an oscillation, and therefore was, avoided. The emission current regulator performance was a function of the type of gas introduced to the gauge, being better than +1% for N2 and worse than +1% for 02 over the given pressure range. Performance during flight is described in paragraph 8. 3.7 FILAMENT SWITCHING CIRCUIT The filament switching circuit measured the emission current produced by the gauge "number one" filament. If the emission current fell from 5 milliamperes to less than 1 milliampere for a period lasting more than 6 seconds the circuit shut off "number one" filament and turned on "number two" filament. Relays were used to switch the two-ampere filament current to minimize power dissipated in the switch and to provide good isolation of the filaments from ground. The WX4250 has three filaments but it was felt that the advantage gained by having a third filament available was less important than the disadvantages resulting from the complexity required to keep the number of relay contacts to a minimum and still insure that no two of the three filaments could be on simultaneously. Figure 20 includes the switching circuit schematic. 3.8 BREAKOFF DEVICE AND FILAMENT TIMERS A pyrotechnic device was used to break away the seal over the gauge orifice. The pyrotechnics were detonated electrically by a 100 second electronic timer which was started in flight by a mechanical timer at +94 seconds. At +89 seconds the TEEPEE was ejected from the nose cone and the 105 second wait before breakoff provided some insurance against contamination of the gauge by third stage residual exhaust. The electronic timer circuit is shown in figure 19. The mechanical timer, which was -10 -

used because it was "g" actuated and provided a lift-off starting time, also kept power off the filaments until +94 seconds since it was found during pre-flight vibration tests that the filaments were stronger when "cold". 3.9 GAUGE WALL TEMPERATURE Thermistors (100K @ 25 C) were used to monitor the gauge wall temperature, one thermistor being taped to the glass envelope opposite each filament. 3.10 TOTAL POWER REQUIREMENT The current drain for the package was.55 amperes for a battery voltage of 28 volts, making the power requirement about 15 watts. 4. MECHANICAL ASSEMBLY The shape and size of the experiment was determined by the WX4250 gauge and the available electrometer amplifier (an existing Space Physics Research Lab package) as shown in figure 6. Little choice remained but to package the remaining electronics into hollow-cylinders to utilize the space around the gauge. The following paragraphs describe the Bayard-Alpert experiment assembly. 4.1 ORIFICE AND GAUGE The orifice and gauge assembly was prepared by NASA personnel at the Goddard Space Flight Center as described below. The orifice, shown in figure 1 and 5, was machined from Kovar and cleaned by firing it at 10000C in wet hydrogen for one hour. Following the cleaning the glass seal was made over the orifice, some glass work was done to prepare for the attachment of the gauge, and the piece was annealed and cleaned chemically. Meanwhile the gauge was calibrated as described later. After calibration the gauge was glassed to the orifice piece and the assembly was annealed again. During this annealing the gauge was back-filled with hydrogen to a pressure of 1/3 atmosphere and the outside of the assembly was purged with forming gas. Then the gauge was connected to a Varian vac-ion system through the stem, baked for 72 hours at 400~C and degassed at 40 milliamperes until the Varian monitor indicated a pressure in the gauge of about 5 x 10-9 torr. Finally the stem was sealed by applying a torch to it for short periods to minimize the pressure -11 -

33/8 INCHES AMP GAUGE 6 INCHES INCHES Figure 6. Determination of Experiment Dimensions. -12 -

rise in the gauge and allowing the gauge to return to 5 x 10-8 torr between each heating. The intention was to seal the gauge at 10-7 torr or lower, which would allow a pressure of 10-8 torr or lower to be achieved after the gauge cooled, but the goal was not attained. After sealing, the pressure in the gauge was approximately 10-5 torr and after several hours of on-off operation the pressure fell to approximately 10-7 torr. The orifice with gauge attached is shown in figure 5. 4.2 SHIELD AND HEADER An aluminum shield placed around (but not touching) the gauge had several functions. It provided electrical shielding, it provided mechanical" support for the header, and it intercepted and conducted heat to the TEEPEE skin that was radiated from the filament instead of allowing it to be absorbed by the electronics packages (an air space was maintained between the shield and electronics packages). Wiring to the gauge pins was accomplished by using an arrangement whereby a miniature Cannon plug was mounted in the header and wired to the header terminals. Flexible leads were run from the header terminals to the gauge pins but the header itself was not attached to the gauge; both the gauge and shield were attached mechanically to the origice piece only, to allow the gauge freedom to expand. Figure 7 shows the header, miniature plug, and shield above the TEEPEE end plate with the sealed gauge stem protruding through the shield; the shield was split to allow removal of one half for inspection of the gauge structure and wiring after vibration tests. The orifice piece was held to the end plate of the TEEPEE by four screws and an "0" ring was placed between the orifice piece and end plate to maintain the inside of the TEEPEE at atmospheric pressure during flight. 4.3 DECK AND AMPLIFIER ASSEMBLY The two electronics decks shown in figures 8 and 9 were held in place by 4 threaded rods screwed into the TEEPEE end plate. Hex-nuts used to secure the decks were special pieces fabricated from standard stock. The amplifier was mounted on an adapter plate which in turn was screwed to the hex-nuts. The gauge collector connection to the amplifier was accomplished by running a 1 inch piece of flexible wire from the collector to a terminal under the adapter plate. Coax was run from the terminal to a female Sealectro "snap-on" coaxial connector mounted on the -13 -

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plate and the amplifier connector was a male Sealectro "snap-on" allowing the amplifier to be simply pulled away from the package once its power cable and mounting screws were removed. The completed foamed package (amplifier on top) ready for flight is shown in figure 10. 4.4 BREAKOFF DEVICE The breakoff device, designed at the Goddard Space Flight Center, mounted over the orifice as shown in figure 11. Inside the device were pyrotechnic motors which expanded when detonated and pushed against the cams shown in figure 12. The push caused the device to rotate rapidly and rise on the cams to strike a snap-ring secured to the orifice seal, breaking the seal. Ideally the orifice seal and breakoff device leave the orifice area so that they do not interfere with the experiment; also ideally, no gas escapes from the pyrotechnic motors to contaminate the experiment. 4.5 EXPERIMENT WEIGHT The weight of the experiment package including the TEEPEE end-plate was 6 3/4 pounds. 5. CALIBRATION PROCEDURE Calibration of the gauge was performed on an oil diffusion pump vacuum system in the Physics Branch of the Goddard Space Flight Center. The reference gauge was a GSFC ionization gauge. The flight WX4250, a back-up WX4250, the Space Physics Lab flight omegatron and the reference gauge were mounted on the same chamber of the vacuum system and the flight gauges were compared with the reference gauge for N from 10 9 to 10-4 torr (omegatron turned off at 10o torr) and for He and 0 from 10-9 to 10 torr. Before calibration the entire system was baked and the gauges were degassed; after the 0 calibration the gauges were again 2 degassed and the N2 calibration was re-run to test for gauge changes possibly caused by oxygen. No change in sensitivity was measured for the WX4250 gauges. The result of the calibration is shown in figure 13. -16 -

Figure 10. Experiment Assembled for Flight Viewed Amplifier End. -17 -

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6. ENVIRONMENTAL TESTS The experiment package was designed to operate in ambient temperatures ranging from -15 C to +35 C and from battery voltages ranging from +27 volts to +32 volts without exceeding the +1% emission current stability or the collector current measurement accuracy limits stated in the next paragraph. In addition, the package was not to be damaged by battery voltages from +32 to +35 volts or by vibration levels as tabulated in figure 14. The unit was tested under the above conditions and the specifications were met. 7. ACCURACY OF COLLECTOR CURRENT MEASUREMENT The accuracy of the gauge collector current measurement depended on the electrometer amplifier drift (+10 mv.), the electrometer amplifier feed-back resistor tolerance (+2%), and the precision of the measurement of the electrometer amplifier output voltage. The worst error that could have resulted from the amplifier drift and feed-back resistor uncertainty was +3%. The estimated accuracy of the measurement of the amplifier output voltage after transmission through an FM/FM telemetry link with in-flight calibration was +1%. 8. FLIGHT PERFORMANCE Evaluation of the flight records indicated that the packages did not malfunction at any time during the flight. The emission current rose to +1% at apogee and fell to -1.8% at 10-4 torr, based on the emission current value that existed for the N calibration at 3 x 10-7 torr. The collector current measured varied from 3 x 10-9 amps at apogee to beyond full scale before loss of signal occurred on the down-leg. 9. RESULTS Due to a rocket instability, the jaws of the NASA 6.10 nose cone failed to open completely and TEEPEE VI never ejected, although the jaws did open wide enough to allow the experiment to function as described in paragraph 8. The data is considered to be questionable because of the unknown amount of local contamination within the nose cone and because the telemetry antennas were not able to deploy to give adequate signal strength. Good data was received from TEEPEE IV, however; figure 15 shows a portion of the raw telemetry data. The TEEPEE IV Bayard-Alpert gauge data, although not completely analyzed, are being compared with the Omegatron data from the same probe and are proving to be useful in establishing the variability of the sensitivity of the Bayard-Alpert gauge when exposed to the recombination processes and changing composition in the atmosphere. -20 -

-5 10 10 I I I II I t. i l l~ 1 i I l l l I I i l ~ OPERATING CONDITIONS GRID VOLTAGE: 90V -6 EMISSION CURRENT: 5MA 10 — COLLECTOR VOLTAGE:15V GAS:CURVE IS VALID FOR EITHER N2 OR 02 tU 0 10U1' Fg 10' U 0 PRESSURE (TORR) Figure 13. Gauge Calibration. -21

Frequency- Acceleration- Sweep RateAxis cps g peak Seconds/octave * Z 10 to 2000 1 40 Z 10 to 31 (1.4 g to 3g) 6 in/sec 20 31 to 120 3 120 to 500 7 500 to 2000 13 X 10 to 20 0.5 40 20 to 2000 1.0 X and Y 10 to 30 0.6 20 30 to 150 1.5 150 to 2000 5.0 Random Vibration levels Frequency- Acceleration- Total TimeAxis cps g2/cps Seconds Z 20 to 650 0.05 60 650 to 2000 0.05 to 0.23 X,Y 20 to 650 0.02 120 650 to 2000 0.02 to 0.93 Z 20 to 650 0.05 30 650 to 2000 0.05 to 0.23 *Z axis corresponds to gauge longitudinal axis. Figure 14. Vibration Levels. -22 -

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K tE 19-1183 11-63 -820gr R317 I 9 + 20R.2 2 -22 + BIAS - * FIL - 20R.22 - 22 + BIAS-,FIL@ ~< ~~ grid POWER CONVERTER; CALIBRATE yrid~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~u I AMPLIFIER ELECTRONICS pro PW _______* 1K * out ~~Mwht R~i~rOU feedback Iluf blk + -I~) + R~~~~~~ pur F cato EXTERNAL ext RANGE CONTROLcont gry AUTOMATIC r) RANGE SELECTOR R301- C?51 - C355S 2 r^__ ~AAA^____^R308 C354 C356 RANGE AMPS FS. RESISTOR SHUNTCAP INPUTCAP 3 4 n 1 5x10C6 1x106 1000 - ~22 ~02 \ 3D~ ~VV^~> 2 1.6xlo' 3.16x10 330 C302 ~I3 5x10o-7 1X10o/ O 0022 RANGE RANGE~(1~ 4 1l6x10-" 3.16x10^ 33 1~V^ P IDOWNI!Wl15p 4^ -^y^- 5 5x10 l- I XlO ' 6 1~~~.Gxl 3~1631x108 NO.2 BIDIRECTIONAL rng 7 5x109 1 x109 LEDX MOTOR -1530 5 ^^~ 8~1.6x10-9 3.16x109 LD27AWG COIL TOR THE SANN ARBRSICHIGESAN C AOAOYELCTO E t FE mierSIT Bloc Diagr am. ANN~~~~~~~~ ARBOR,' MICIGN B E14 Figure 16. Electrometer Amplifier Block Diagram.^^^^^ Ipi^Q

1'75 mg __2~ 20me^1 3^~~~~~~~~~~~~~~~~~~~~~~ F^ ^~1 l L~ ~ redt1 K K R1327 — 2.2.t.8K Figur 17. C105E ' R128 3. ma - C1-02______ -— ~' CR0 1.;17^e,047uf 2 N930 CK58 2N26A2 0103A TK587 w QlO2A Ri w OUT IN IR113__ _8.21K I ~ 56K R129-13.K gr2 Rile 3.9R ~ * ~ * ~ 34.7 K R131 i-blu_15K >_82K__1_4 D102-V' 62K 1 12T1022 -m^'! R120I 1- 30 BIA O R1R120 d.blu R125A C0lO 2123 mRl12. Figure -~ A 17BO. Elcrmete AACHmpAl e S cemt i ^ ________ DIM. ENDINQ.000 ~. 10.0 _______ 30 M G RUN. 145

K&~E 1.11aS,1U ~M_ ~28V,28V 8 OV _- nco RYA TEST REGULATOR AMLFER~~ 105V AMPL ~ AM ___ I _ E 100 SECOND BIAS MON G BREAKOFF TIMER 3K 1152 p 1) IF L MONI RY SQUIB2 ' ~I~ CO- ~ W 250 I CONTROL le -m In RAYMOND TIMER;22 NOM FILAMENT SUPPLY TEST 28V X —~- B-A- -pr E-x rAMPL — F D. B IAS I N G 11 3 6E ^~SCR 8EAM SENSOR / " -RE, I BI'AS ING ~^ ~3^____-FILAMENT TURNON 15.47 j~ ^ I |l' ) I I TELEMETRY 105 <) 1 - J |ov... ___. a______. RA Rj l~^~^< 1 -~ ~~~~:,o I FA MN SPACE PHYSICS RESEARCH LABORATORY~ BAYARD-A LPERT T FIL. ' ' F^ ~ ' DEPARTMENT OF ELECTRICAL ENGINEERING EXPERIMENT TP- 6 7'20 -11~ IUNIVERSITY OF MICHIGAN -515-64 I_______ IANN ARBOR MICHIGAN -_ E139,~o DT, Figure 18. Bayard-Alpert Experiment Function Diagram.

K&fE 191U 1153 T6~1ND6145 39K ~FIL MON +28 FIL PW PW GND II 27 180K C3 < ~ t i180K 515K S C 4 K R 1% ',, 3.6 R4 T5 Il I C;^ 1f D 21.2 K 17 5 T |H E R M T20 ~- '~2N1132 - R5- V R24 SQUIB 1 01 1 A T19 -FD300 SQUIB 20 D4 T2QU j 1, 21180 /25 12K 2_,_ 1 ~QUIB GNO/ 2 R2 Iblu 4E20 RC N2851 TOP VIE7 W5727D 3 UNIVERSITY OFMICHIG5Q 2 top GND i ~ 180/25 1u 1 1N645 K R N BR22 TH.~E ~M QGNo.TiD S e.01/50 ~ 28 PW 2 6 6.8 K 1N645 23 3 D11^- ~ RS~~l~ 9D6 bottom RYA T Dli^~~~ R9 luK~: ~4 ~ ~~IN2851L 1 jump 0 FD3 00 L 1.2K n RYB b\k 7- R7 012 5727D T li E 2N930 20v 47/2 R A ~ ^05 - -)~ ~ ~ ^ ~1-6 DB ^ ^~ ~ RYB20 6.8K 56K RD R10 Rll _-~^~~~~~~ I~,VV^^ ^ ~i ~15K 15K 3.3K N3.4K TI ~ ~ ~ ~ ~ ~ ~ ~ ~ Ri R1 2 R15 R18 D9l 2.4 I — 820 D12 6 8K FSP143 ' ~ R14 D 07 "!^ I 6.8K 3.9K 3.3K 6 1K.68/25 L__. _J - R13 R16 -R17 - D13 R20 CC7 _ ~ ^ ~ ' I" ~'^^~^~22M BEAM MON -105v + 105v '.-' \GOLDEN "G" ENGINEER J C _ DRAFTSMAN CB ~ o^_^^ ^ SPACE PHYSICS RESEARCH LABORATORY DEPARTMENT OF ELECTRICAL ENGINEERING AND BREAKOFF TIMER TOP VIEW 5727D UNIVERSITY OF MICHIGAN PANN ARBOR, MICHIGAN B- E141 LAST USED R C D L Figure 19. Filament Emission Regulator and Breakoff Timer Schematic.

K &C 19-1133 11-63* BIAS MON *28PW PW GND GND +105 -105 1N645 3 30 r -s 07 R6 Q~ ~ ~~3 Q 1 ~ 01/50~ C~ I - R2 D I 1N645 C 39K I ---) D 6 i R 1 D 2___ _____j2N657 7 eI _____ -c A ____ FD01/0 og 1 g )i 56 /75 0 4 __ 5 C 3L 1 K R5 5729_ - 330 ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ co gr l e o6 2 ~ 0 _ i i Q ^ l 3N8 2N9 D^ ^16 k R14 0 (D 6C4 1^ ______ ^A (8)\/~~0 R R8 <10K ~ ' 6.8I 0\/^ ^~~~~~~~~~~~ ~ ~~~~ ~ ~~~~~R12 120 /15^ D16I ^\ X^ -^ T ^ ^~~~ ~ ~~~~~~~~~~~~~~~~~~~6 3~" K^ I' ' ~V^~^~< ~ VV~~ 0~~~~ ~ ~~~~~~~~~~~~~~~~15II TOP VIEW OF 5729B lOOK 1OK 56K R9 ^ ^R10 R 1 1 ~~~ = CANNON DAM-15P ~~-~Q7 —i ~ ~~-~ ~~1 -— ~~~1~~~~-~~~ ~~~~ TEST/TIMED RYA RELA RYB +28 PW~ MON ENGINEER JC DRAFTSMAN CB SPACE PHYSICS RESEARCH LABORATORY BIAS SUPPLY AND FILAMENT 7-0-84 DEPARTMENT OF ELECTRICAL ENGINEERING BURNOUT SWITCH - 25-6 UNIVERSITY OF MICHIGAN TP 6 5-13-64 ANN ARBOR, MICHIGAN BE 14 DA2 LAST USE B Rt CtL Figure 20. Grid Supply and Filamen~t Burnout Switch Schematic.

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