The Exploration and Space Technology (EaST) Lab

Dr. Andrew KetsdeverDepartment of Mechanical and Aerospace Engineering

Charge Exchange Containment CellTrey Quiller, Michael Johnson, Doug Claes, & Ryan Bosworth

Abstract: The charge exchange process between ionized and neutral particles is of significant importance in the propulsion industry. Propulsion concepts use charge exchange to create very high energy neutral particles to be propelled out of the system. In order to study this occurrence, we have designed and built a charge exchange containment cell. This cell has the ability to hold a neutral gas, such as Argon or Neon, in a vacuum environment with the gas keeping a constant number density and having the ability to vary the gas pressure. This containment cell was built to contain the neutral gas within the cell with minimal leakage of the contained gas into the rest of the vacuum chamber.

Introduction: A new electronic propulsion device is being developed to reduce the mass of electronic propulsion, while still giving the same thrust and impulse as similar devices. The device being built is an Electrodeless Lorentz Force (ELF) thruster, which creates a plasmoid called a Field Reversed Configuration or FRC by the use of rotating magnetic fields imposed upon an ionized gas. The primary loss mechanism in a device of this type is the formation of the plasma. In order to alleviate this issue, neutral gas is entrained in the thruster after the plasma is created and then is accelerated out of the system through the charge exchange process.

Goals:1. Contain a neutral gas in a vacuum environment2. Vary neutral gas pressure3. Constant gas number density4. Easy to machine device

Neutral Charge Exchange Gas

Ion Beam

Fast Neutrals

Remaining Ions

Vacuum

Design Selection: The final design was created from taking features from a number of different ideas and compiling them into a single design. The figure to the right is an artist rendition of our final design. It has the following features:

• A perforated mesh allows for uniform pumping of the cloud area by removing any differential pressure in the device.• Four total skimmers are positioned within the device

which provide containment for the gas cloud.• Four different jets are strategically placed within the

chamber to interially tether the gas inside which helps contain the gas.•The distance between the jets and the skimmers was

experimentally found by Dr. Ketsdever in a previous experiment. We maintained the same distance for optimum containment.

•We added a differential pumping system to assure that any additional gas does not escape and interfere with the high vacuum environment.

Testing:A series of tests were devised to fully characterize the charge exchange containment cell. These tests are listed below:Test 1: The gas jets with a flow perpendicular to the ion source will be used with only the outer skimmers in use.Test 2: The gas jets with a flow perpendicular to the ion source will be used with both the inner and outer skimmers in place.Test 3: The gas jets parallel to the ion source will be used with only the outside skimmer plates attached to the device.Test 4: The gas jets parallel to the ion source will be used with both the outside skimmer plates attached and the inside skimmer plates attached.Test 5: The gas jets that are both parallel and perpendicular to the ion source will be used. Only the outside skimmer jets will be attached.Test 6: The gas jets that are both parallel and perpendicular to the ion source will be used. Both the outside and inside skimmer plates will be attached.

The flow rates will be 1, 5, 10, 15, 20, 25, 40, and 50 standard cubic centimeters per second.

Perforated Mesh in Device

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Differential Pressure for Argon

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