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PLATINIUM-LINED

ADIABATIC SOLUTION CALORIMETER

Capability: Liquid or crystalline samples up to 2.7 cm3 in volume are dissolved in 300±15 cm3 of any solution reactant that does not attack platinum. Minor modifications permit the introduction of gaseous samples in a flow system. For exothermic or endothermic reactions of 200 J or more, enthalpies of solution may be measured between 293 and 363 K for both rapid and slow reactions, with a precision of 0.02%.

Calorimeter temperatures are measured with a quartzoscillator sensor with digital printout. The adiabatic shield temperature is controlled automatically to eliminate heat transfer to the calorimeter from its environment. The data are processed by a time-shared computer. The calorimeter is calibrated by supplying a known amount of electrical energy to the calorimeter resistance heater before and after the chemical reaction measurements.

Applications: Used to determine enthalpies of reaction at or near room temperature, for the purpose of obtaining enthalpies of formation, enthalpies of solution, and related thermodynamic properties of substances.

Availability: Because of the complexity of the instrumentation and the procedures of operation, use of the facility is limited to qualified members of the NBS staff or other scientists, after specific training of perhaps two months. The facility may be used indirectly through cooperative or contractual research agreements.

Literature:

[1] E. J. Prosen and M. V. Kilday, An adiabatic solution calorimeter and measurements of a standard reaction for solution calorimetry, J. Res. Nat. Bur. Stand. (U.S.) 77A, 179 (1973). [2] M. V. Kilday and E. J. Prosen, The enthalpy of solution of low quartz (a-quartz) in aqueous hydrofluoric acid, J. Res. Nat. Bur. Stand. (U.S.) 77A, 205 (1973).

Contact: Dr. G. T. Armstrong, Chief, Thermochemical Measurements and Standards Section, Chemistry Building, Room B350, Phone 301-921-2131.

ROTATING

PLATINUM-LINED, ADIABATIC BOMB CALORIMETER

Capability: Solid or liquid samples are reacted with oxygen at three megapascals (about 30 atm) pressure in a 100 cm3 combustion bomb. The type of sample is limited only in that the products of the reaction must not be any chemical species that attacks platinum. A uniform concentration of aqueous products is assured by continuous rotation of the calorimeter. Amounts of sample are normally such as to cause 2500 J to be liberated as heat in the reaction. Under optimum conditions, the energy of reaction can be determined between 298 K and 323 K with a precision of better than 0.005%. Calorimeter temperatures are measured potentiometrically with a platinum resistance thermometer as the sensor. The adiabatic shield temperature is controlled automatically to minimize heat transfer to the calorimeter from its environment. Determination of the amount and products of reaction can be determined by measurement of the amount of CO2 gas formed, and by analysis of aqueous solution constituents.

Applications: Used to determine enthalpies of reaction at or near room temperature, for the purpose of obtaining enthalpies of formation, enthalpies of solution, and related thermodynamic properties of sub

stances.

Availability: Because of the complexity of the instrumentation and the procedures of operation, use of this facility is limited to qualified members of the NBS staff or other scientists, after specific training of perhaps two months. The facility may be used indirectly through cooperative or contractual research agreements.

Literature:

[1] W. H. Johnson and E. J. Prosen, The enthalpies of combustion and formation of the monochlorobenzoic acids, J. Res. Nat. Bur. Stand. (U.S.) 78A, 683 (1974).

Contact: Dr. G. T. Armstrong, Chief, Thermochemical Measurements and Standards Section, Chemistry Building, Room B350, Phone 301-921-2131.

COMPUTER

CENTRAL

COMPUTER FACILITIES

The NBS Central Computer Facilities are available on a fee-for-service basis to support Government programs. In addition to Federal agencies, certain state and local government agencies, non-profit organizations, universities and private organizations, may qualify for use of the facilities. Service can be provided to non-Federal agencies on joint projects or for work that cannot be done effectively in the private sector. Arrangements can often be made to process work through remote terminals.

Facility Overview: The main computer in the NBS Central Facility is a UNIVAC 1108. The present operating system, EXEC 8, is a general purpose executive designed to operate in a multiprogramming environment which provides for a variety of user options. Access to the main computer is provided to both onsite users and those at remote terminals connected via telecommunications. Software support includes FORTRAN, COBOL, ALGOL, XBASIC, MIRADS (a generalized data base management system), and OMNITAB (a computer language developed at NBS for statistical and numerical analysis).

Univac 1108: The UNIVAC 1108 includes 262,144 thirty-six-bit words of 750 nanosecond core memory. Auxiliary high-speed (1,440,000 characters per second) drum storage of approximately 25-million characters capacity provides for efficient workload control and swapping of executive program files. Disk storage of approximately 925-million characters (FASTRAND mode) provides the needed capacity for on-line storage of application programs and data files. In addition, the system configuration includes eight seven-track tape drives (200, 556, 800 fpi), two nine-track NRZI tape drives (800 fpi), two nine-track PE tapedrives (1600 fpi), two printers, two card punches and two card readers. An IBM 1403-N1 printer is available off-line for printing from magnetic tapes prepared on the 1108.

Graphics Facilities: The Central Computer Facility provides off-line plotting on a CalComp 763 ZipMode Digital Plotter, Computer Output to Microfilm (or hard copy) using a Stromberg-Carlson 4020, and extended character printing. A Graphical Display System software package is available which permits optical output to a variety of display devices including the CalComp Plotter, the SC 4020 Microfilm Recorder, or the Line Printer.

Capacity to Handle Scientific Documents: An extended character input/output subsystem, presently operating off-line to the 1108, permits users to take full advantage of the information interchange facilities of the American National Standard Code for Information Interchange (ASCII). This provides character printing sufficient to handle documents at the normal level of complexity in notation, including half-line spacing for superscripts and subscripts, a repertory of Greek alphabetic characters and an assortment of special signs and symbols. Off-line paper tape facilities exist for entering ASCII punched paper tape as data via a 300 CPS optical scan paper tape reader.

Applications and Services: While the primary use of the central computer facility is as a laboratory tool for the technical staff of NBS and other agencies, an increasing level of support is provided to a variety of administrative and other data processing applications.

A consultant is available during working hours by phone or in the computer center for advice on details of system operation and problems owing to system and program interaction. New system development is frequently done for problem areas of general utility. Periodic training sessions are held to acquaint users with various system capabilities (both hardware and software).

Literature: Various manuals are available to NBS users in the storeroom in the Administration Building. Other-agency users may secure manuals through the Management Assistant's office (301) 921-3364. Use of Computer Facilities: Charges for the various computer services are on a cost-reimbursable basis and rate schedules are available.

Interested parties may contact Mr. R. A. Palladino, Management Assistant, Room A225, Administration Building, NBS, Washington, D.C. 20234 [telephone (301) 921-3364].

AUTOMATION LABORATORY

The Automation Laboratory is equipped with a computer controlled robot manipulator system with 6 degrees of freedom and a grip which allows it to pick up objects.

Capability: 750 mm reach; 4.5 kg load, 1 m/sec tip velocity; touch, force, and proximity sensors. Controlled from a PDP-11/45 minicomputer.

Applications: Research on evaluation of sensors and computer control techniques for advanced automa

tion systems such as industrial robots and numerically controlled machine tools.

Availability: NBS staff, Guest Workers, Research Associates.

Contact: John M. Evans, Jr., Office of Developmental Automation Control Technology, Technology Building, Room A128, Phone 301-921-2381.

ELECTRICAL MEASUREMENTS FACILITIES

NON-MAGNETIC FACILITY. The probe shown in the foreground travels along the axis of the 1000-turn precision solenoid to locate the axial position of each turn of wire and to compare the relative area enclosed by each turn. This measurement allows calculation of the magnetic field produced by a known current.

AUTOMATIC

NETWORK ANALYZER

Provides computer controlled rf stimulus for the calibration and measurement of passive quantities such as impedance, reflection coefficient, and attenuation and active quantities such as power and voltage. This is a commercially available item which has been modified into a special high accuracy system by NBS personnel.

Capability: The automatic network analyzer provides for discrete frequencies in the range of 0.1 to 18 GHz as an rf stimulus, applies these signals to the device under test, measures their characteristics, mathematically manipulates the data if necessary and outputs the data. The data output is available as a tabulation on a teletype or high-speed printer, a plot or diagram on an electrostatic plotter, or may be viewed as polar or rectangular plots on an oscilloscope. The measured data is in complex form and may be reflection coefficient, impedance, renormalized impedance, VSWR, attenuation, gain, or phase angle for passive quantities. Data output is in watts, volts, or fractional (decimal) parts thereof for active quantities. The connector types for connection to the automatic network analyzer may be in coaxial type such as APC-7, GR-900, type "N" male or female, and in all the waveguide sizes used in the above frequency range.

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These capabilities can be adjusted for either normal laboratory precision or for high accuracy standards and calibration type measurements. The NBS add-on system for high accuracy measurements and calibrations is presently undergoing evaluation.

Applications: The automatic network analyzer is intended for design, measurement, and calibration of rf and microwave components such as terminations, attenuators, thermistor mounts, crystal detectors, FIM receivers, antennas, filters, amplifiers, transistors, etc. As described previously these may be of coaxial or waveguide type usage devices.

Availability: To any qualified NBS research worker, after an initial training period with supervisor. In appropriate instances individual research workers from other Federal organizations can gain access to the facility.

Contact: D. H. Russell, Program Chief, Microwave Measurement Services, Radio Building, Room 4633, NBS Boulder, Colo. 80302, Phone 303-499-1000, ext. 3811.

ELECTRO-OPTICAL

HIGH VOLTAGE

FIELD MAPPING SYSTEMS

State-of-the-art electrical and electro-optical measurement techniques are employed for measurement of high voltages, and for observation and probeless fringe-pattern mapping of high-intensity electric fields in insulating dielectrics. Apparatus allows operation under microsecond pulsed, and either steadystate direct or alternating voltages. Unique advantages afforded by the recently developed NBS electrooptical systems include their freedom from electromagnetic interference errors and their provision for direct visual observations (analogous to those used conventionally in photoelastic studies of mechanical. stress) of electrical stress distributions. Capability, Operating Ranges, and Accuracy:

[1] Pulsed Operation: peak voltages from 20 to 300 kV, risetimes of 0.5 to 2.0μs, with durations up to 10μs, repetition to 4 pulses per minute, measurement accuracy within ±1%. [2] DC Operation: from 0 to 100 kV.

[3] AC Operation: from 0 to 50 kV rms, from 40 to 200 Hz.

Programs are available for automatic reduction and analysis of data, using NBS computer facility. Applications: For calibration of HV pulse-measuring devices; for design studies with visualization of both steady-state and dynamic electrical stress distributions in selected insulating dielectrics; for visualization of the effects of space charge, suspended particles, dissolved ionic impurities and electrode composition, polish and geometry on electrical conduction in selected insulating liquids; for mapping of electric field distribution around immersed solid insulator models; for measurement of Kerr electro-optical coefficients of liquids; for dynamic and steady-state electrical breakdown studies in selected dielectrics;

etc.

Availability: To qualified U.S. research workers from industry, government, and academic communities in cooperation with NBS supervisor. Scheduling is required to avoid conflict with in-house NBS research, calibration and testing programs.

Literature:

[1] NBS Tech. News Bull., Sept. 1972, Vol. 56, pp. 207-209.

[2] Rev. Sci. Instr., June 1972, Vol. 43, pp. 886893.

[3] J. Res. NBS, Vol. 73C, pp. 5-13, Jan.-June

1969.

Contact: Dr. Oskars Petersons, Chief, High Voltage Measurements Section, Metrology Building, Room B344, Phone 301-921-3121.

NON-MAGNETIC FACILITY

The non-magnetic building is located on an isolated area of the Bureau grounds, in the center of a 600-ft square buffer zone. The building is a three-story structure (ground level plus two stories) constructed of non-magnetic materials and contains a minimum amount of electrically conducting materials. The building contains four isolation piers, one serving the ground floor and three serving the second floor level. A service building 300 ft from the non-magnetic building provides the general laboratory equipment and support. Experiments in the non-magnetic building can be controlled and monitored from the service building.

Capability: Typical earth's magnetic field gradients are 10 nT⚫m1 in the vertical direction and 3 nT⚫m-1 in the horizontal direction. Three-dimensional Helmholtz coils are available for cancelling the earth's magnetic field. Variations in the earth's field can be reduced by servo-ing to a magnetometer system in the magnetometer station located nearby. A precision solenoid is available to provide a magnetic field of 1.2 X 10-3 T which is uniform within a 4-cm diameter sphere and accurate to about 0.5 ppm in terms of the NBS electrical standards. Equipment for automation and data acquisition is available.

Applications: The facilities of the non-magnetic building provide an environment where accurately known uniform magnetic fields can be applied to an experiment or where the earth's magnetic field strength and variations can be reduced a known amount. Currently the gyromagnetic ratio of the proton and the absolute ampere experiments are housed there. Availability: The facility is available, when neither of the above two experiments are in active operation, for a compatible experiment which will not compromise the non-magnetic environment.

Literature:

[1] R. L. Driscoll and P. T. Olsen, The Review of Scientific Instruments, Vol. 42, No. 10, 1427.

[2] R. L. Driscoll and P. T. Olsen, Proc. of the International Conf. on Precision Measurement and Fundamental Constants, NBS Special Publ. 343, 117 (1970).

[3] B. N. Taylor, D. N. Langenberg, and W. H. Parker, Scientific American, Vol. 223, No. 4, 62 (1970).

Contact: Dr. E. R. Williams, Absolute Electrical Measurements Section, Metrology Building, Room A247, Phone 301-921-3806.

The use of the instrument is also available to outside groups in the form of calibration and test services. Literature: NBS Tech. News Bull., April 1973, Vol. 57, No. 4, page 91.

Contact: Dr. Oskars Petersons, Chief of High Voltage Measurements Section, Metrology Building, Room B344, Phone: 301-921-3121.

REACTANCE BRIDGE FOR POWER LOSS MEASUREMENT

A typical high voltage inductor or shunt reactor on a power transmission lines has a reactive power rating of 100 megavolt-amperes and a power loss of about 200 kilowatts. Thus the power losses are of economic significance, but it is difficult if not impossible to measure them by conventional wattmeter methods because of the low power factor, i.e. the presence of very large reactive or circulating power. The shunt reactors are used to "tune out" the capacitances of transmission lines. A reactance bridge has been developed and constructed which in conjunction with readily available high-voltage standard capacitors can measure accurately such losses. Inductance and capacitance can also be measured. The instrument is designed for measurement of devices rated at moderate to extra high voltages-several hundred volts to one megavolt.

Capability: The instrument can be used at either the NBS or a commercially available high voltage laboratory. The voltage and power ranges depend principally on the capability of the power supply in the laboratory-for the NBS laboratory these are 220 kV, 200 kVA. Some commercial laboratories have capabilities of the order of 1 MV and 100 MVA. When used in conjunction with a typical high voltage standard capacitor having a capacitance value of 100 pF, the inductance range of the specimen is from 0.12 H to 600 H; the range for capacitors is from 100 pF to 50μF. The power losses can be measured to about one-percent accuracy; the inductance and capacitance to about 0.01 percent to 0.1 percent accuracy. Applications: Primarily power loss measurements of large capacitors and inductors such as energy storage and power factor correction capacitors, high voltage shunt reactors (inductors); also impedance measurements of the same.

Availability: To any qualified NBS research worker or group. The High Voltage Measurements Section will provide an operator of the instrument and high voltage power supplies.

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