Flash lamp with ballistic piston compressor for absorption spectroscopy measurements in ultraviolet regio

Cleaver, H. E.

English

NASA Technical Reports Server

General Disclaimer 
One or more of the Following Statements may affect this Document 
 
 This document has been reproduced from the best copy furnished by the 
organizational source. It is being released in the interest of making available as 
much information as possible. 
 
 This document may contain data, which exceeds the sheet parameters. It was 
furnished in this condition by the organizational source and is the best copy 
available. 
 
 This document may contain tone-on-tone or color graphs, charts and/or pictures, 
which have been reproduced in black and white. 
 
 This document is paginated as submitted by the original source. 
 
 Portions of this document are not fully legible due to the historical nature of some 
of the material. However, it is the best reproduction available from the original 
submission. 
 
 
 
 
 
 
 
Produced by the NASA Center for Aerospace Information (CASI) 
https://ntrs.nasa.gov/search.jsp?R=19710024750 2020-03-11T22:02:14+00:00Z
0
co
i
ce
f--J
O
APPROVED FOR PUBLIC RELEASE;
DISTRIBUTION UNLIMITED
NOLTR 71 -130
%/ A S 'fi (/^- iZO-7,? ^/
om"^
ELECTRONIC CIRCUITRY FOR A HIGH
INTENSITY FLASHLAMP
If
1
By
Harry E. Cleaver
71 Illl Y 1971
sk p 19?' Q,
,
0
1- --
sACCESSION NUMB
	 ti '^+	 (THRU)
O	 -	 (^
-'7
	 (COD EJ
J
UQ (NASA CR	 MX OR AD NUMBER ► 	 (CATEGORY)-^-- ..... 	 .....
NAVAL ORDNANCE LABORATORY, WHITE OAK, SILVER WHIM, !MARYLAND
Z	
1-m *e t—a 2 e 4 -r/ /1/0. C- 7 7,J'7-^g
TO C	 a
AM SA
UNCLASSIFIED
NOLTR 71-130
ELECTRONIC CIRCUITRY FOR A HIGH INTENSIFY FLASHLAMP
Prepared bar:
Harry E. Cleaver
ABSTRACT: (U) A Gartcn-Charat ! "lashlamp was used with the NOL
Ballistic Piston Compressor fox , absorption spectroscopy measurements
in the ultraviolet region. This report details the power circuits
needed to produce the high pulse currents required in the operation
of the flashlamp,
t
/4	 Atq"' le , sue?e 1
Approved by:	 A. B. DIETEMANN, Chief
Chemical Engineering Division
Chemistry Research Department
U. S. NAVAL ORDNANCE LABORATORY
MITE OAK, MARYLAND
i
UNCLASSIFIED
UNCLASSIFIED
t
NOLTR 71-130
	
21 July 1971
Electronic Circuitry for a High Intensity Flashlamp (U)
(U) The work described in this report was conducted primarily
under Task IR-167, Sp ectroscop ic Studies of High Preseure Ga,,es ..
The flashlamp was obtained from the Plasma Physics Section of the
Naval Research Laboratory on an indefinite loan 'basis. This work
was also funded in part by the National Aeronautics and Space
Administration.
ROBERT ENNIS
Captstin, USN
Comi3ander
C t c.t ^ t ^" ^^  t ^ ^ f. ...^+^-tom; ._
ALBERT LiG 1BODy
By directs n
,.
4
ii
TITCLASSIFIED
UNCLASSIFIED
NOLTR 71-130
CONTENTS
Page
Introduction .......«	 1
Physical Characteristics ...............««.......«,......
	 1
04.rcait Description	 4
Performance and Conclusions ............«.,..«,..........	 6
ILLUSTRATIONS
Figure	 Page
•	 1 Half Section of Flashlamp Assembly 	 2
2 Flashlamp and Power Pack Housing, Front View .......	 3
3 Flashlamp and Power Pack: Housing, Rear Vier ...«...«
	 5
LE Flashlamp Capacitor Discharge Circuit .....««...,...
	 7
REFERENCES
(1) Samson, J. A., "Techniques of Vacuum Ultraviolet Spectroscopy",
Wiley and Sons, New York, 1967, Unclassified.
(2) Charatis, G., and Hershey, T., University of Maryland Institute
for Fluid Dynamics and Applied Mathematics Technioai Note BN-361,
1a64, Unclassified.
(' )Halos, G. , and Hammond, G. , NOLTR 7015, if 	 Opacity Measurements
with a Ballietic Piston Compressor ", 21 Nov 1969, Unclassified,
iii
UNCLASSIFIED
UNCLASSIFIED
NOLTR 71-130
INTRODUCTION
Absorption spectroscopy experiments with the NOL ballistic piston
compressor require the use of a background light source of high
brightness temperature. For experiments in the ultraviolet part of
the spectrum, the brightness temperature must be extremely high to
overcome the rapid decrease in transmisc;ion of optical cot-liponents and
air with decreasing wavelength. Conventional ultraviolet sources,
such as high pressure hydrogen or deuterium lamps, are not bright
enough for wavelelgths less than 2000 A. and high energy, transient
discharges must be used for these vacuum-ultraviolet wavelengths.
A device that satisfies all the requirements of high brightness
temperature, line-free continuum spectra, reproducibility, ease of
operation and compactness is the Garton-Charatis flashlamp (references
1 and 2). An improved prototype version of the lamp was obtained by
NOL from the Naval Research Laboratory Plasma Physics Section for
evaluation with the NOL compressor. S pectroscopic observations with
the aid of this lamp are described in reference 3. Electronic
circuitry has been developed to synchronize the lamp firing with the
peak of the compression cycle of the compressor,
PHYSICAL CHARACTERISTICS
The lamp consists of a 6.3 cm .long capillary of 5mm bore in a
phenolic cylinder. The tungsten electrodes at each end of the
capillaryalso have 5mm diameter holes through which the light
generated by the sliding spark discharge in the capillary passes to
the ultraviolet transmitting Suprasil II windows at each end of
the lamp. Further details of lamp construction are shown in Figure 1.
The lamp is filled with air at approximately 5mm Hg pressure.
The application of 5000 volts across the electrodes is sufficient
to cause electrical breakdown in the capillary and the resulting
discharge is characterized b y a peak current density of approximately
1.4 x 103 amp/cma , and a brightness temperature of 30,OOOK in the
visible portion of the spectrum. The plasma generated in the
capillary consists of a mixture of air and high density ionized
organic material ablated from the capillary walls.
When used with the NOL compressor, the lamp is mounted willh the
capillary axis horizontal and aligned with the axis of the viewing
ports in the compressor test section. Vertical alignment is achieved
by rotating the large nuts on the threaded rods at each side of the
lamp mounting brackets. In Figures 2 and 3 the lamp and mounting
brackets are shown attached to the energy storage pack housing.
The peak brightness temperature of the lamp is maximized when
the electrical characteristics of the lamp minimize the self-inductance
1
UNCLASSIFIED
N
7
W
J_
•- Q
VN
Y
Dl
i
D
n
L
J
QZ0
W
CC
<dG
u J
0 O W
W Z W ZCl, _j
	
= J
co a.
	 a
i
J
`m
WN
CL
J
N
QJ
U-
U-
0
O
N
V
W
N
Li-J
Q
_O
LL_
N
C
C
L
Z
NOLTR 71-130
oc
W
V
Q
a
V) oc
Z
1	 Q
O}J
<
ceQ
fl
O
LL!
V (^
Q
V V VO vi oc
+— 0 V
2
FLASHLA
FRONT -
W INDOV0
CONNEC
BLOCKS
COAXIAI
CABLE
HYDROG
THYRATRI
EXTERNAL
TRIGGER
INPUT
CONNEC
BLOCKS
CAPACIT(
BANK
NOLTR 71-130
FIG. 2 FLASH LAMP AND P(DWER PACK HOUSING, FRONT VIEW
3
UNCLASSIFIED
NOLTR 71-130
of the discharge circuit. To achieve this, the lamp can be connected
to the energy storage capacitors by multiple parallel coaxial cables.
CIRCUIT DESCRIPTION
The energy storage capacitor bank shown in Figure 4 consists of
two six microfarad, 7500 volt capacitors connected in para' lel. The
voltage level impressed on the capacitors is monitored using a
resistance voltage divider and a Fairchild Model 7050 digital volt-
meter. Resistor values in the voltage divider were chosen to allow
the most accurate readings possible from the digital voltmeter by
operating in the up-scale portion of the range selected. With the
voltmeter operating on its 15 volt range, the LOW monitor terminal
is used when measuring capacitor voltages up to 5000 volts. Above
5KV the HIGH monitor terminal should be used with the voltmeter still
on the 15 volt range. An exact voltage measurement was not as
important in the experiments described in reference 3 as was the
ability to reproduce a given voltage level.
Energy stored in the capacitor bank is delivered to the flashlamp
by using a 5C22 hydrogen thyratron as -he switching dev,ce. 5C22
thyratrons are high plate voltage, high peak current tubes designed
for pulsing service. The grid drive circuit may be operated at zero
bias, as it is in this design, and requires a 200 volt minimum pu..se
to fire the tube.
Lead wires carrying the high discharge currents are shown as
darkened lines in Figure 4. A heavy braided-wire conductor is used
to connect those parts of the circuit to a coaxial cable connector
block. Lead lengths were kept as short as possible.
A one megoliT, high voltage resistor is connected across the
flashlamp terminals. It serves as a bleeder resistor to prevent
static voltage buildup on the flashlamp electrodes caused by leakage
currents.
A commercially available 10,000 volt power supply is used to
charge the capacitor bank. The output voltage is adjusted from 0 to
10KV by controlling U"he a.c. voltage input to the power supply with
an autotransformer. The output tarminais of the power su pply are
isolated from the capacitor bank by eight 10OK0 resistors, Capacitor
bank charging currents and charging rates are also controlled by
these resistors.
5C22 thyratron tubes require a cathode heating time of at least
five minutes before high voltage is applied to the plate. To allow
for this warmup time, two thermal relays connected in series provide
a five minute delay before power can be applied to the autotransformer
and high voltage power supply.
Pulses used to fire the thyratron are generated in the triggering
sect:.-.1n and c-,upled to the grid of the 5C22 by a 1:10 step-up
r	 A
i
4
UNCLASSIFIED
VACUUM
CONNECTIC
HEIGHT
ADJUSTING
NUTS
COAXIAL
CABLF
F LA SH LAM P
REAR WINDOW
HEIGHT
ADJUSTING
NUTS
THREADED
SUPPORT
ROD
HIGH
VOLTAGE
ADJUST
^i
NOLTR 71-130
4
FIG. 3 FLASHLAMP AND POWER PACK HOUSING, REAR VIEW
5
UNCLASSIFIED
NOLTR 71.130
transformer. The triggering section is powered by a voltage doubler
circuit that provides 76 volts LC maximum to charge a 0.01 of
capacitor. Although the voltage level on the capacitor is variable,
it must be above the level required to produce the 200 volt minimum
grid drive pulse. Grid drive pulses above the '200 volt minimum
will shorten the turn-on time of the tube. When the 2N1885 silicon
controlled rectifier (SCR) is triggered on, the 0.01 of capacitor
discharges through the primary of 'the pulse transformer and the
necessary grid drive pulse is developed. The IN538 diode across the
priri.ary of the pulse transformer suppresses the neeative transient
voltage swing generated by the transformer.
The 1.1 megohm resistor controls the charging rate for the 0.01
of capacitor. It also isolates the SCR from the power source and
causes current flow through the SCR to drop below the level required
to maintain conduction once the capacitor has discharged. When the
current falls below the holding level, the SCR will automatically
turn off and may then be recycled.
The triggering section may be operated manually by a switch on th..,
front panel or remotely by the circuits designed to synchronize lamp
firing with the peak of the compression cycle of the compressor.
PERFORMANCE AND CONCLUSIONS
Oscilloscope displays of the flashlamp light pulse were made with
an RCA 7200 photomultilier tube (S19 responae) in a vacuum mono-
chromator set at 1900 . Measurements were made with the capacitor
bank charged to 5KU. There was a time delay from thyratr•on triggering
to peak light intensity of 14 f 1 1^ seconds. The light pulse exhibited
a rise time of about 5 i^ seconds followed by a slower exponent ialdecay yielding a pulse half-width of about 10p, seconds,
When the autotransformer was left untouched between shots and the
lamp fired at a constant value of the digi-cal voltmeter display, the
peak intensity of the light pulse was reproducible to fl%. Most of
this variation is attributable to changes in window transmission and
capillary properties from shot to shot, so we conclude that variations
in the discharge circuit performance are negligible.
No detectable deterioration in thyratron operation has occurred
in more than 300 firings, and no other circuit component has required
replacement. The flashlamp circuitry has exceeded all design
requirements and, coupled with the lamp itself, constitutes a valuable
addition to the set of NOL Ballistic Piston Compressor accessories.
6
UNCLASSIFIED
NOLTR 71-130
n
	
1
tx^
A
40
OZ
lJ Z
La
ce Ln
< 0
M
W uIXZ <
V
uj
,j
ua 0
Zn Z
8
Ind
0
> LU
CA Z
OC
00
> z	 C;
CI-
0 93- IL u
—Jill
Z)
>
;:.	
^,
<
F
His
N
cc CNI LLJz W 04m"i U-
N
^o
Uj
0
^y^ Q h
cc Z
m	
rL
00
cn10CL
LA
LU
/3.
r-Y^ 	 T i)D
11
UNCLA^JIFIED
" o , vmtt k
4
5'N 0	 1 . t^07.	 I
DOCUMENT CONTROL DATA - R & D
' Y.orr hr"'
Naval Ordnance Laboratory Unclassified
White Oak, Silver Spring, Md. 2-10910
None
Electronic Circuitry for a High Intensity Flashlamp
4	 11 L `. C"'  11 i' A N G' L	 N , -) 1 L	 f ftpjrt ._Yi, d mk Io., :, x N e	 Jot v	 1 I
Ai 	 t w:^ ",*,), k I tr^, t too It, t-, ;,t^jjjj, I	 ^tm I id l,	 josr
Htrry E. Cleaver
o:,	 kR L 51 Q k t	 CD A A L I C, I AL	 N ,
- ,	 C, o-	 A " L ^j t b-	 or 
I 
-j
	
0E-	 o.L	 -'i
21 July 1971 7- 7	 3
ea	 C :)N r ol A C T (_1 R Iy vr A N 1	 0 4 C,1 Qk-o%Q;1NA ttW'. FIL^C)Vo! I	 NV-iMbU,44R51
15,	 r NO NOLTR 71-130MAT-03L-OOO/ZRO11-01-01 	 Prob 167
-A HE 9? FiL rl a^ha I	 tj0f!;) (Atq	 ,their t1ill 'bers that woo- be assigned
ii'ls rr'Pvrto
None
AI's	 g715 I o4i uu T iOt4 5 T A I C M L N r
approved for public release; distribution unlimited.
I I	 '-Vj P'P L A E N A A	 T C I"	 S P ON 5 1: 1 P N N C, tA^ L 0 1 A Yo',	 A 1: 1 0 v I T 
r%1Chief of Naval Mater.L4
 ."A.0
Washington ., D. C.
A 1_1 ^' t o-- A
A Garton-Charatis flashlamp was used with the NOL Ballistic Piston
Compressor for absorption spectroscopy measurements in the ultraviolet
region.	 This report details the power circuits needed to produce the
high pulse currents required in the operation of the flashl&mp.
DD, FORM. ' 1473 (PA^-2E 	 I I 7TNrT.Aq0TVTVT1
4
- UNCLASSIFIED
4t°e^^rxk} ! I^t^wXt^^`^lxr+n
"4 IL9N
	
A L
-
ILwNiK	 C
►tOLC N a0LL 140L  1%
Flashlamp
Capacitor Disoharge Circuit
ballistic Liston Compressor
L
-1
DD FORM 14^ Nov ss 73 (e acK >	 TiN(!T.ARRTFTFT)
( P AGE 2)	 Security Classification
0


Electronic circuitry for a high intensity flashlamp

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server