High Frequency Corona Discharge 157 
A CHEMICAL STUDY OF THE HIGH FREQUENCY CORONA 
DISCHARGE. 
F. O. ANDEREGG. 
All commercial methods of making ozone take advantage of the 
chemical properties of a corona or silent discharge. In order to pre- 
vent the undesirable spark discharge from forming it is necessary to 
use some device such as a dielectric. Glass, micanite or similar insulat- 
ing material interposed between two electrodes is a great aid in the 
formation of a discharge suitable for ozone production. Dielectrics 
have several disadvantages; they cannot be used at high temperatures; 
they are apt to be easily broken mechanically and finally they are sub- 
ject to annoyingly frequent punctures. Moreover, a dielectric under- 
goes progressive changes which are apt to have considerable effect on 
the yield of ozone. 
The high frequency discharge has certain advantages which have 
made desirable some investigations of its availability for ozone pro- 
duction. Because of the time necessary to build up a spark discharge 
from small electrodes it is possible in a suitably designed tube to have 
brilliant corona discharges without the use of dielectrics. 
In 1896 Nikola Tesla,’ observing the production of ozone in air 
subjected to the discharge from certain forms of his high-tension high- 
frequency coils, applied for a patent. The electrodes were parallel 
plates; these do not produce a form of discharge very suitable for 
ozone production, so that this apparatus has not achieved any com- 
mercial success. The use of a high-frequency corona discharge in re- 
ducing the molecular weight of hydrocarbons so as to render them suit- 
able for use as gasolene has been described by Cherry.” By this means, 
he has eliminated the dielectric, which, at the temperatures used (up 
to 480°), would give considerable trouble. Other investigators’ work- 
ing with frequencies as high as 1,200 cycles apparently have found 
optimum frequencies for certain conditions. 
IN. Tesla. U. S. Patent 568, 177 Sept. 22, 1896. 
2L. B. Cherry Trans. Am. Electrochem. Soc. 32. 345 (1917). U. S. Patent 1229, 
886 July 12, 1917. Doubtless a certain amount of cracking occurs under the given 
conditions. Indeed the use of a corona discharge primarily for cracking has been more 
recently patented. Schmidt and Wolcott. U. S. Patent. 1307, 931, June 21, 1919. The 
use of high frequency for polymerization of acetylene has been described by Kaufman, 
Ann. 417, 34 (1918). 
3 Shenstone and Priest, J. Chem. Soc. 63, 938 (1898) concluded that the maximum 
efficiency is to be obtained with a 16 cycle discharge. Further discussion of the effect 
of frequency has been given by Rideal, Ozone, Van Nostrand, 1920, pp. 105-107, but 
it must be remembered that uncertainties as to meter readings and as to the effect of 
other uncontrolled variables render the conclusions drawn there of doubtful value. A 
comparison of a number of ammeters placed in the primary circuit of an induction 
coil operated on direct current showed that none of them registered the same value 
or even the true value as obtained from oscillographs. The maximum deviation was 
about 25 per cent. However, the tendency to use 500 eyeles whenever available for 
commercial production of ozone must have some significance. 
