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Juno: Waveguide Load Analysis
07.07.2009 1:05 PM
Ruwan Somawardhana

By Ruwan Somawardhana
Spacecraft Thermal Engineering

One of the issues that came up recently for the Juno task is the installation of a Waveguide Load (WGL). The primary purpose of this component is to dissipate energy in the event of a fault. The excess power is transferred to the WGL which is converted into thermal energy and this thermal energy has to be dissipated. The concern is that the WGL may heat up beyond its AFT due to a limited thermal path to the telecom panel, which is serving as the heat sink.

A simple hand calculation was conducted which showed that in the worst case fault condition, the WGL would surpass the operational temperature. Building a detailed model with radiation included, confirmed this. However, there are many options to solve this problem. The first issue is to determine whether the specified limit is in fact a true limit, or if there is margin. More likely than not, in this case, there is a lot of margin, and this is being investigated currently by talking to the manufacturer. In addition to this, there are many thermal design options that can be implemented based on how much more energy needs to be dissipated. Once I find out the actual margins we have to work with, I will base any design proposals off of this information.

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