I
Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

NAT90NAL BUREAU OF STANDARDS REPORT

MBS PROJECT NBS REPORT

1002-12-10121 January 29, 1-962 ?

Tenth Progress

Report

on the

Mechanisms of lire Ignition and Extinguishment

by

E. Co Creitz

Covering the period 1 February 1961 to 31 January 1962

for

Bureau of Ships

Department of the xavy

Code 636

IMPORTANT NOTICE

NATIONAL BUREAU OF STANDARDS REPORTS are usually preliminary or progres*s accounting documents

intended for use within the Government. Before material in the reports is formally published it is subjected

to additional evaluation and review. For this reason, the publication, reprinting, reproduction, or open-literature

listing of this Report, either in whole or in part, is not authorized unless permission is obtained in writing from

the Office of the Director, National Bureau of Standards. Washington 25, D. C. Such permission is not needed,

however, by the Government agency for which the Report has been specifically prepared if that agency wishes

to reproduce additional copies for its own use.

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U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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I I i I I I I I I I I I I I I I I I
1 . Summary

It was planned to submit, in August 1961, a final report

on the Langmuir probe work and such a report was written.

Editorial revision has been more extensive than expected and

the report is still not quite ready. After 1 July 1961, the

project was inactive because of lack of funds. Financial

support was received in October and the project reactivated

as of December 1, 1961. It is Fanned to use these funds to

finance the continued development of a new type of mass spectrometer which is considered important in the study of the

mechanism of inhibition, work was started on the instrument

in 1959 under Order Fo. BuSlii; s 17003570, Index Mo. F1 3—183—001

,

but has mere recently been supported by the National Bureau

of Standards' fund s . Development of the instrument has progressed to the point of its showing acceptable resolution.

Fresent efforts are toward an increase in sensitivity and

stability.

Previous work on inhibition has indicated a possible

connection between dissociative resonance capture of electrons

and the efficiencies of extinguishing agents. Some work was

done, partly supported by this project and partly by the MBS,

in the study of methods of measuring attachment coefficients

and in the collection and assembly cf ap aratus.

2. The Fass 3 ect remoter

The mass spectrometer being developed operates on the

principle of acceleration of the ions by a sawtooth voltage

between the ends of field-free drift tubes. Inside the drift

tube the velocities of the different ions produces a spread

in both space and time of emergence from the exit end. Upon

emergence, the ions are either accelerated or decelerated

depending upon their phase with respect to the sawtooth

voltage. Since phasing is involved, harmonies of the original

time-of -flight are important, and it has been shown by the use

of higher harmonies, that a resolution of one mass number at

mass 5-0 is readily attained.

It is expected that the present design will have higher

sensitivity than conventional mass spectrometers because of

the presence of the smaller number of grids, each of which

produces a loss of ions. The present sensitivity is such as

to show the isotope of potassium, which is resent in a concentration of 6% of the normal ions. This was accomplished

with the use of a heated filament, on which otassium salts

had been deposited. This source was unsatisfactory because

of the potential difference between the ends of the filament,

which produced an energy spread in the ions leaving the filament.

T T T
[ I I I I I I I I [ FTT I I
During December a unipotential, indirectly-heated source was

designed, constructed and tested. Improvements have been

made and it is hoped that a more satisfactory source is now

available. It has been necessary to use a stable source of

known ions in order to determine the other instrumental

parameters which affect the sensitivity and stability, before

using the instrument on flames.

3 . A 1 1 a element of f; le c tr ons

.

There is only a limited amount of information in the

literature on the attachment of electrons by gases, and even

less information on gases known to be inhibitors. A study

was made of methods of measurement of the phenomena and

apparatus was assembled. Since July this phase of the work

has been continued with '138 funds. There is evidence that the

method selected will permit the classification of compounds

into attaching and non-attaching gases and also give information with regard to the energies of the electrons attached.

It is not expected to give information on the mechanism of

the attachment process but should serve to provide a first

classification prior to the more concentrated mass spectrometric study.

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