**INTRODUCTION**

**PART I - OVERVIEW**

For the past several months, I have been working heavily on the design of my high vacuum system. A good deal of my initial research has been going through and reading as many posts as possible from this forum, which has provided an extraordinary amount of knowledge from many years of cumulative experience of many members, slowly transitioning into a more intensive academic study of the subject. I have noticed that there does not appear to be a post yet diving into more rigorous and intensive engineering design, simulation, and calculation for high vacuum systems. This is certainly not needed for the average fusor builder, however I have found this field to be very fascinating and on the rather obscure and lesser practiced areas of engineering in general, and could prove helpful and useful for those looking to take a more rigorous approach to the design process of their system. Since this hobby largely involves long periods of time for waiting on finding the right components, sourcing parts from eBay and other various resources, as well as being a rather expensive hobby, I have decided to spend my free time while waiting for parts to complete all of the major design calculations and simulations that would apply to my system. This has proven to be a tedious and challenging endeavor, but incredibly rewarding in understanding the deeper principles of high vacuum systems and engineering. I have decided to focus purely on the high vacuum system itself for this next year while I await for more funds for my projects. This includes all of the required calculations, simulations, and designs related to the system, as well as building, conditioning, and working with the high vacuum system itself. The main goal for this year will be to establish a well prepared system capable of achieving the desired ultimate vacuum needed, as well as getting all peripheral support systems (power, control, instrumentation, data acquisition) properly running, and generating data on the vacuum system itself, including pump down curves, rate of rise curves, and other data to compare with how close the system actually behaves to my initial calculations. I have decided to share this long term design work here, which I will continue to update and post continuously throughout the year as progress is made. Because there is such a massive amount of information to be presented, I will break each informational post in this walk-through/walk-along in titled sections in the following order:

*1.) INITIAL HIGH VACUUM SYSTEM CONCEPT DESIGN, REQUIREMENTS, AND MODELLING*

*2.) CALCULATION AND COMPARISON OF SYSTEM CONDUCTANCES AND EFFECTIVE SPEEDS FOR MOLECULAR FLOW FOR VARIOUS PROCESS GASES*

*3.) CALCULATION AND COMPARISON OF SYSTEM CONDUCTANCES AND EFFECTIVE SPEEDS FOR TRANSITIONAL FLOW FOR VARIOUS PROCESS GASES*

*4.) TOTAL GAS LOAD DUE TO OUTGASSING AND DETERMINATION OF ULTIMATE PRESSURE DURING PUMPDOWN*

*5.) PUMPDOWN TIMES FOR ROUGH AND HIGH VACUUM*

*6.) MAXIMUM GAS LOADS FOR PROCESS GASES FOR VARIOUS EXPERIMENTS*

*7.) THERMAL MODELLING OF THE HIGH VACUUM SYSTEM*

*8.) THERMAL MODELLING OF SYSTEM RUNNING A STANDARD FUSOR GRID*

*9.) ELECTRONICS, CONTROL, AND INSTRUMENTATION*

*10.) SYSTEM BUILD*

*11.) SYSTEM CONDITIONING, PUMPDOWN, AND BAKEOUT*

*12.) PUMPDOWN AND RATE OF RISE CURVES*To supplement the information I will also be providing PDFs of the calculations I have done for the various sections in the process. Due to the fact that the calculations are very long and tedious, I will not post the math here but refer to it from the PDFs. Since I have many calculations repeating the same thing for different gases, I may just only post a single example for each section to reduce document clutter. Pictures, models, and other data will be provided as I go along. While this is not meant to be a substitute in any way for proper research and reading of high vacuum engineering from academic literature, it is my hope that I may be able to provide useful information and help in these areas and add a contribution to this group that has already been such a major help to myself and others. A few additional notes to consider:

- This series of posts is meant as both documentation of my own efforts, as well as a walk-along for more intensive engineering design. I am by no means an expert in this field, and do not claim complete accuracy to data and math present. Inevitably, I will make mistakes along the way, as I am still also in the process of learning, so constructive criticism and correction is always welcome.

- The initial calculations presented are not meant to be hard set actual numbers. Since there are so many variables present in high vacuum systems, these calculations can only provide a very rough guide to what may be expected, and provide a point of initial design comparison and order of magnitude expectations. They are meant as rough estimates and a guide, not exact figures.

- Many material properties and constants used, such as outgassing rates, will vary between sources. Data I have presented here are general values acquired from a variety of sources, and will differ depending on a wide number of factors due to the complex nature of vacuum systems in general.

- This intensive of an approach to high vacuum system design is by no means necessary for any fusioneer to accomplish fusion. The math and modelling can be quite long and tedious, but it certainly do-able - the complexity comes from accounting for such a large amount of variables present in such designs. Most members here are looking to build simple fusors with whatever available resources, and a good, solid working fusor does not require any of these calculations. However, some calculations may be very useful to look at if you want to have a more fundamental grasp of what exactly is happening in the system and understanding how high vacuum systems work. Modelling, whether CAD, thermal, electrostatic, or other, can also provide a very powerful way of understanding your system, and there are so many free resources available now for various types of modelling it is much more accessible now to the determined hobbyist. Since I am not focusing on building a fusor, but various types of experimental setups, these calculations and approach has provided very useful for my own endeavors, as well as any general high vacuum system one may be working on.