Small Scale Multi-Purpose High Vacuum Chamber
Posted: Tue Nov 28, 2017 10:12 pm
Several months ago I shared a post regarding some very large pieces of vacuum equipment I have had the opportunity to obtain. In addition to that very long-term project, I have been working on the design of a separate small system that I will be using to test a wide variety of systems, which I would like to integrate eventually into my larger chamber. These include beam on target systems, ion guns, plasma sources, electron guns, and a variety of thrusters. All of these parts will be integrated into 2.75" conflat blanks. Unlike my large chamber, this small chamber will be eventually used for neutron production, primarily beam on target, but could certainly run a traditional fusor, with ion-gun injection as well. Since the auxiliary systems would be the same for both the large chamber and the small chamber, including water cooling for the diffusion pump, rough pumping, pneumatics for the valves, low and high voltage power supplies, instrumentation, and controls, this small test stand will also serve as a way to set up and test these systems before I integrate them into a larger chamber.
This system is based off of 2.75" conflat equipment, with the main chamber made from a 5-way 2.75" conflat cross. Since I wanted this system to accommodate much more than just a fusor, I have designed it in a way to maximize inputs while keeping the design streamlined and expandable with plenty of capabilities to host the variety of systems I would like to test. Below are the various components I have collected for the design so far:
These parts include: a 5-way 2.75" conflat cross, a 4-way 2.75" conflat cross, a 2.75" manual isolation butterfly valve, an inline 2.75" conflat pneumatic gate valve, a manual KF25 90 degree valve, and a KF25 to conflat 2.75" pneumatic 90 degree valve. These serve as the main components of the system. Other than the 5-way cross (which was still obtained for a fraction of the cost that it normally goes for), all of the parts where obtained from eBay for reasonably less than $100 each, and all of them appear to be in either new or exceptional condition.
Below is a CAD model of the completed high vacuum system including the diffusion pump and the adapter plate I will machine out of 1" aluminum plate stock. After going over various design iterations, I settled on this topology to maximize vacuum throughout to the main chamber, while allowing for isolation between the various vacuum stages, and allowing for numerous instrumentation and system inputs. The system will include ports for a thermocouple gauge, a pirani or ion gauge, a purge gas inlet, isolated roughing pump inlet, and an inlet for the diffusion pump with both inline gate valve isolation as well as throttling via isolation butterfly valve (if I where to run the system with deuterium for neutron production) and roughing side isolation. In the main 5 way cross chamber, I have the front facing port dedicated for a viewport, which leaves me three inputs for my systems. Various combinations can include: fusor with up to two ion gun injectors, beam on target system with target/faraday cup and additional port for movable target or inline beam instrumentation such as beam profiling instrumentation, small magnetron sputter source with target, electron gun with faraday cup and beam profile diagnostics, ion thruster with thrust plate, and other combinations of devices and diagnostics.
I still need to obtain the rest of the KF25 hardware, but all of the big ticket items are at least out of the way at the moment, and I am not in a rush to get this running. I will be constructing a mobile stand from 8020 that will house all of the auxiliary systems such as cooling, power, control, and the roughing pump. I am also interested in exploring the possibility of creating an automated control system for either semi- or full- automated pump down control, which would monitor vacuum as well as auxiliary systems, provide automated pump-down control, as well as emergency shutdown, in addition to normal automated shutdown of the system. Since I know what the inputs and outputs of the system needs to be, this should be relatively straightforward to set up utilizing an Arduino as a controller, which could be easily built and run under simulated testing before high vacuum is established. Though I would like to get the big chamber running for large scale experiments, this test stand will serve as my main high vacuum system for all of my future high vacuum projects.
This system is based off of 2.75" conflat equipment, with the main chamber made from a 5-way 2.75" conflat cross. Since I wanted this system to accommodate much more than just a fusor, I have designed it in a way to maximize inputs while keeping the design streamlined and expandable with plenty of capabilities to host the variety of systems I would like to test. Below are the various components I have collected for the design so far:
These parts include: a 5-way 2.75" conflat cross, a 4-way 2.75" conflat cross, a 2.75" manual isolation butterfly valve, an inline 2.75" conflat pneumatic gate valve, a manual KF25 90 degree valve, and a KF25 to conflat 2.75" pneumatic 90 degree valve. These serve as the main components of the system. Other than the 5-way cross (which was still obtained for a fraction of the cost that it normally goes for), all of the parts where obtained from eBay for reasonably less than $100 each, and all of them appear to be in either new or exceptional condition.
Below is a CAD model of the completed high vacuum system including the diffusion pump and the adapter plate I will machine out of 1" aluminum plate stock. After going over various design iterations, I settled on this topology to maximize vacuum throughout to the main chamber, while allowing for isolation between the various vacuum stages, and allowing for numerous instrumentation and system inputs. The system will include ports for a thermocouple gauge, a pirani or ion gauge, a purge gas inlet, isolated roughing pump inlet, and an inlet for the diffusion pump with both inline gate valve isolation as well as throttling via isolation butterfly valve (if I where to run the system with deuterium for neutron production) and roughing side isolation. In the main 5 way cross chamber, I have the front facing port dedicated for a viewport, which leaves me three inputs for my systems. Various combinations can include: fusor with up to two ion gun injectors, beam on target system with target/faraday cup and additional port for movable target or inline beam instrumentation such as beam profiling instrumentation, small magnetron sputter source with target, electron gun with faraday cup and beam profile diagnostics, ion thruster with thrust plate, and other combinations of devices and diagnostics.
I still need to obtain the rest of the KF25 hardware, but all of the big ticket items are at least out of the way at the moment, and I am not in a rush to get this running. I will be constructing a mobile stand from 8020 that will house all of the auxiliary systems such as cooling, power, control, and the roughing pump. I am also interested in exploring the possibility of creating an automated control system for either semi- or full- automated pump down control, which would monitor vacuum as well as auxiliary systems, provide automated pump-down control, as well as emergency shutdown, in addition to normal automated shutdown of the system. Since I know what the inputs and outputs of the system needs to be, this should be relatively straightforward to set up utilizing an Arduino as a controller, which could be easily built and run under simulated testing before high vacuum is established. Though I would like to get the big chamber running for large scale experiments, this test stand will serve as my main high vacuum system for all of my future high vacuum projects.