Accession Number : ADA289552

Title :   A Finite Element Based Technique For Simulation Helix TWT Interaction Circuit Thermal Behavior.

Descriptive Note : Rept. for Jan 93-Apr 94,

Corporate Author : ROME LAB GRIFFISS AFB NY

Personal Author(s) : Rocci, Peter J.

PDF Url : ADA289552

Report Date : OCT 1994

Pagination or Media Count : 30

Abstract : A technique was developed to assess the thermal performance of a helix Traveling Wave Tube (TWT) interaction circuit accounting for the thermal contact resistance between the circuit's components. This method employed iterative finite element analyses techniques and an analytical expression that related contact pressure to thermal contact resistance. Temperature gradients across the interfaces between the helix and support rods and between the support rods and barrel increase operating temperatures, which can lead to a decline in the tube's performance. Since the circuit analyzed contained no brazes or epoxy at the component interfaces, these thermal drops become more significant. parametric runs were made using this methodology for different assembly loads as well as for both beryllia and boron nitride (APBN) support rods. Results showed that the thermal contact resistance effect was more pronounced at lower assembly loads and higher thermal loads. That is, as the thermal loading to the circuit increases, the percent increase of the maximum helix temperature over the helix temperature when the resistance is not accounted for, increases. This effect was also more pronounced when APBN support rods were modeled. The helix temperature increased a greater amount when accounting for the thermal contact resistance for APBN support rods than for BeO support rods.

Descriptors :   *HEAT TRANSFER, *FINITE ELEMENT ANALYSIS, *TRAVELING WAVE TUBES, *THERMAL RESISTANCE, THERMAL PROPERTIES, SIMULATION, IONS, PARAMETRIC ANALYSIS, INTERACTIONS, PERFORMANCE(ENGINEERING), INTERFACES, LOADS(FORCES), TEMPERATURE GRADIENTS, DROPS, PRESSURE, SUPPORTS, CIRCUITS, RODS, MICROWAVE TUBES, HELIXES, BERYLLIUM OXIDES, BORON NITRIDES.

Subject Categories : Electrical and Electronic Equipment
      Numerical Mathematics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE