[On_site_list] Cryogenics Colloquia Today: JLab Cryogenics Advancements Used by NASA

[deborah magaldi]

***JLab Liquid Nitrogen Thermo-siphon Design
for NASA's Space Environment Simulation Lab*

Immediately followed by:
*20 K Helium Refrigerator for NASA's
Space Environment Simulation Lab*

*Tuesday, Sept. 18, 2012
1:30 p.m. (Please note special time)
CEBAF Center auditorium*

*Combined Abstract*
In 2006, NASA's Johnson Space Center requested technical assistance from 
the JLab Cryogenics Group for the process design, development of 
specifications and construction of a new 20 K helium refrigerator 
necessary for ground testing the James Webb Space Telescope (JWST) in 
Chamber A of NASA's Space Environment Simulation Lab (SESL). SESL 
simulates a deep-space environment necessary for ground testing critical 
spacecraft including the JWST.

*Venkatarao "Rao" Ganni, Principal Staff Engineer, JLab Cryogenics 
Group*, will present the first colloquium, which will cover JLab's work 
on SESL's Chamber A 80 K liquid nitrogen (LN) system needed to shield 
the 20 K helium cryopanels that provide a simulated deep-space 
environment necessary to perform ground testing of the JWST. The 
original system was a forced flow LN system that was not reliable due to 
heavy use of pumps and components. After determining that refurbishment 
was cost prohibitive, NASA asked JLab for options. JLab proposed a 
thermo-siphon, or natural flow, system that eliminated the need for 
pumps and used a factor of 10 fewer valves. Recent commissioning results 
indicate that the new thermo-siphon system exceeded the (predicted) 
design goals and far surpassed the performance of the original force 
flow system. This talk will outline the thermodynamic-process comparison 
between the two designs, as well as the commissioning results of the 
thermo-siphon system.

*In the second colloquium, Pete Knudsen, Cryo Process Engineer, JLab 
Cryogenics Group*, will outline the JLab process design work and 
commissioning results of SESL's 20 K Helium Refrigerator.  JWST testing 
requirements demanded that the refrigerator be capable of 12.5 kW at 20 
K, 100 kW at 100 K and a temperature stability of ±0.25 K during steady 
state operating conditions. Recent commissioning results indicate an 
unprecedented load temperature range, load turn-down capability and 
temperature stability.  All of these exceed the design goals, including 
the cool-down and transition time between load temperatures and will 
contribute to important and significant project cost savings for NASA. 
These colloquia will present critical Jefferson Lab cyrogenics 
advancements that are being integrated with industry to help support 
U.S. scientific needs.
---
Complete abstracts are posted on the Jefferson Lab At A Glance calendar at:
https://misportal.jlab.org/ul/calendar/calendar_date.cfm?date=18&month=9&year=2012
---
Regards,
Deb Magaldi
Jefferson Lab
12000 Jefferson Ave.
Newport News, VA 23606
757-269-5102

-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/on_site_list/attachments/20120918/aeaa8b93/attachment.html