I have been simulating the positive thermal feedback operation of ECAT types of devices and written several posts in an attempt to explain their behavior. My simulations have been constructed using spice programs and Excel like models. The particular model I am attaching to this post is a very simple static one that does not involve time domain behavior, but instead demonstrates how the negative resistance region is constructed and where it should be located with a real life type of stable product.
I consider operation of one of these devices as being conducted according to 3 basic overall plans. My recent post describes the three in more detail and I can direct anyone who wishes more information to it. The present attached model shows a device that operates at the dividing line between the second mode and third mode of operation. In this particular case the negative resistance region exactly matches a temperature level at which the output will latch when adequate drive is removed. That temperature is at 60 degrees above ambient according to the toy model. Keep in mind that this is a toy that does not match any actual real world values. The temperature scale runs from 0 to 100 just for convenience and is representative of the process. The power levels are also made up for simplicity. Note that it is possible to adjust both the core power generation function as well as the function that defines the output power escape routes by radiation and convection. I encourage anyone with an interest in math to play with the model and visualize for themselves how the positive feedback comes into play and the variables interact. It is quite interesting to observe how the negative resistance region is modified by the coefficients for the heat generation and escape processes. You will notice how sensitive the functions are which is an indication of how carefully Rossi and others need to calibrate their fuel charges and geometries in order to end up with a system that is controllable. This particular model uses simple polynomial functions to describe the variable interactions, but a piecewise construction would work with a bit of modification. Of, if one day we are given the actual functional relationships among the variables, it can be modified to include that information. Perhaps others will find it worthwhile to take this simple model and expand it in other interesting ways. I encourage that but expect proper credit to be given to me for my initial input. I will attempt to attach the model to this email and it might not transfer to vortex-l. If that happens interested parties can contact me for an individual copy. (P.S. It apparently did happen and the posting did not appear on the site. Anyone who wishes a copy just send your email address and I will forward a copy to you.) One last point: I used LibreOffice Calc for this particular model. Good luck modifying the model and I encourage anyone interested in the simulation to discuss the subject further on vortex. Dave
