Universal probe, which contains a unique frequency discriminator, measures the static and dynamic levels of cryogenic liquids in a hydrogen bubble chamber. The probe allows boiling conditions or other turbulence to be observed throughout all the transition stages

Dinkel, J. A.

Wegner, C. R.

English

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August 1968	 Brief 68-10291 
•	 AEC-NASA TECH BRIEF 
RES
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
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the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Cryogenic Liquid Level Measuring Probe 
Outer Probe Element
Inner Probe Element 
to 
The problem: 
To design a probe to measure the static and dy-
namic levels of cryogenic liquids in a hydrogen bubble 
chamber. The sensitive volume, pressure, and density 
of the liquid are dependent on the liquid height. The 
probe must be able to perform at —246°C with a 
short response time. 
The solution: 
A universal liquid level measuring probe, with a 
unique frequency discriminator, which provides con-
tinuous readings on the levels of nitrogen, hydrogen, 
or helium to an accuracy of ±l°. The probe has a
dynamic response time of less than ISO zsec. allow-
ing boiling conditions or other turbulence to be ob-
served throughout all the transition stages. 
How it's done: 
The coaxial probe, immersed in the liquid, measures 
the difference in the dielectric constants between the 
liquid and gas phases of the media. The probe capacity 
is therefore a function of the height of the liquid 
within the probe elements. The probe and its associ-
ated cable constitute the capacity in the tuned circuit 
of an oscillator and a change in the liquid level is 
reflected as an oscillator frequency change.
(continued overical) 
this document was prepared under the sponsorship of the Atomic 	 liability resulting from the use of the information contained in this 
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A unique feature of the probe is its frequency dis-
criminator. A voltage controlled oscillator is phase-
locked to the probe oscillator frequency. The error 
voltage required to tune the voltage controlled oscil-
lator to the probe oscillator is then a function of the 
liquid level. 
A percentage readout is used with the probe to 
provide a more efficient use of the instrument's dy-
namic range and to reduce operator error. In addition, 
the system may be used in a data logger to record 
liquid levels in a number of containers through a 
scanning operation. 
Notes: 
1. Results are available for a number of test meas-
urements made with N 2
 and He4. 
2. Additional details may be found in The Review of 
Scient. Insir,ns., vol. 37, no. II, 1966, p. 1549-1554.
3. Inquiries concerning this innovation may be di-
rected to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B68-10291
Source: J. A. Dinkel, 
Particle Accelerator Division 
and C. R. Wegner, 
High Energy Physics 
(ARG-l0l38) 
Patent status: 
Inquiries about obtaining rights for commercial 
use of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439
. 
Brief 68-10291	 S	 Category 01


Cryogenic liquid level measuring probe

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