End Calorimeter Warm Tube Heater

Technical Report · Tue Aug 06 00:00:00 EDT 1991

DOI:https://doi.org/10.2172/1031762· OSTI ID:1031762

Primdahl, K.

The Tevatron accelerator beam tube must pass through the End Calorimeter cryostats of the D-Zero Collider Detector. Furthermore, the End Calorimeter cryostats must be allowed to roll back forty inches without interruption of the vacuum system; hence, the Tev tube must slide through the End Calorimeter cryostat as it is rolled back. The Tev pass through the End Calorimeter can actually be thought of as a cluster of concentric tubes: Tev tube, warm (vacuum vessel) tube, IS layers of superinsulation, cold tube (argon vessel), and Inner Hadronic center support tube. M. Foley generated an ANSYS model to study the heat load. to the cryostat. during collider physics studies; that is, without operation of the heater. A sketch of the model is included in the appendix. The vacuum space and superinsulation was modeled as a thermal solid, with conductivity derived from tests performed at Fermilab. An additional estimate was done. by this author, using data supplied by NR-2. a superinsulation manufacturer. The ANSYS result and hand calculation are in close agreement. The ANSYS model was modified. by this author. to incorporate the effect of the heater. Whereas the earlier model studied steady state operation only. the revised model considers the heater-off steady state mode as the initial condition. then performs a transient analysis with a final load step for time tending towards infinity. Results show the thermal gradient as a function of time and applied voltage. It should be noted that M. Foley's model was generated for one half the warm tube. implying the tube to be symmetric. In reality. the downstream connection (relative to the collision point) attachment to the vacuum shell is via several convolutions of a 0.020-inch wall bellows; hence. a nearly adiabatic boundary condition. Accordingly. the results reported in the table reflect extrapolation of the curves to the downstream end of the tube. Using results from the ANSYS analysis, that is, tube temperature and corresponding heat flux, temperature of the nichrome wire can be estimated. The possibility of frost is of genuine concern, as evidenced by the 250 K minimum temperature for the warm tube while heaters are not operating. Noting that steady state operation at 1 Amp (40 volts) allows the nichrome wire to stay below the critical temperature for Kapton, a conservative plan is to allow several days of heater operation, at 1 Amp (40 volts), before roll-back. Warm-up can be accelerated by operating the heaters in excess of 1 Amp, as evidenced by the test where a maximum of 3.2 Amp was supplied. Operating the heaters in excess of 1 Amp must be done with care since a rapid rise in temperature will likely occur once any ice present has been melted.

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 1031762
• Report Number(s): FERMILAB-D0-EN-318; TRN: US201201%%952
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
36 MATERIALS SCIENCE
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCELERATORS
ARGON
BOUNDARY CONDITIONS
CALORIMETERS
CRITICAL TEMPERATURE
CRYOSTATS
EXTRAPOLATION
FERMILAB
FERMILAB TEVATRON
FROST
HEAT FLUX
HEATERS
NICHROME
PHYSICS
TEMPERATURE GRADIENTS
TRANSIENTS
VACUUM SYSTEMS
Experiment-HEP