Welcome to the Aerospace Plasma Lab!
The APLab comprises 1200 total square feet of high-bay space in Toomey Hall. Because many plasma and space propulsion systems operate at pressure lower than atmospheric pressure, many of the facilities in the APLab are vacuum systems with associated hardware and diagnostics.

Panoramic View from North-West Corner of the APLab

Panoramic View from South-East Corner of the APLab

The centerpiece of the APLab is a 1.8-m-dia. x 3-m-long vacuum chamber. The vessel is evacuated by four 35-inch diameter high-vacuum oil diffusion pumps backed by a 2-stage backing pump assembly consisting of an Edwards EH 4200 roots-blower and a Tokuda rotary-vane pump. The facility provides 200,000 liters-per-second of pumping speed at an ultimate pressure of 10-6 Torr.

Motion of probes and hardware inside the vacuum facility is possible with a dual-axis, X-Y motion control system. Axial and radial translation stages are capable of traversing up to 100 and 40 cm, respectively. Both stages are driven with stepper motors controlled via LabView v8.6 through a National Instruments PCI-7334 motion controller connected to a National Instruments 4SX-411 nuDrive multi-axis power amplifier.

Belljar Vacuum Facility
The horizontal belljar vacuum facility in the APLab has an inner diameter of 23.75 in. and an inner length of 27.5 in. A Leybold-Heraeus rotary vane pump evacuates the belljar to its base pressure of 25 mTorr, then a Leybold-Heraeus turbo pump further reduces the pressure to the base pressure of 10-7 Torr. This facility uses a KJL275800 thermocouple pressure gauge to measure pressures from 1000 Torr to 10-4 Torr at an accuracy of +/-10%. Additionally, a KJL2200 ion gauge is used to measure pressure within a range of 9.9x10-4 to 2.0x10-9 Torr. This facility has been used for low-pressure plasma actuator flow control studies, cold-gas spacecraft propulsion system testing, and hollow cathode electron source testing.

Belljar Vacuum Facility being used for Low-pressure Plasma Actuator Testing. 1. Belljar Chamber; 2. BNC-BNC Passthrough; 3. Lesker Pressure Gauge; 4. Tektronix DPO 2024 ; 5. Op-Amp Integrator Circuit; 6. Rigol Function Generator; 7. Faraday Cage; 8 High Voltage Probe

The micro-reactor test setup in the APLab consists of a stainless steel tube with stainless steel plates for the bottom and top plates of the reactor. The total internal volume of the reactor is 440 mL. The bottom plate has a 1” by 1” square machined to a depth of 1/4” to accommodate the thermal and catalyst bed. The catalyst bed consists of a small stainless steel plate on top of a Kapton heating element capable of reaching preheat temperatures up to 232oC. A catalyst can be placed on the bed or left empty to evaluate thermal ignition. A type-K thermocouple is used to monitor the bed preheat temperature, as well as the catalyst bed temperature during the ignition process. A process controller is used to set preheat temperatures. The top plate is removable and contains the majority of the instrumentation. An o-ring groove accommodates a proper static seal when the top plate is bolted to the reactor. A stainless steel, fast response (2 ms typical) pressure transducer capable of 0-2.5 bar pressure measurements is located on the top plate. This is used to evaluate pressure rise and ignition delays for each propellant-catalyst combination. Additionally, a type-K thermocouple is secured to the top plate to monitor the internal atmosphere temperature. A photodiode of 400-1100 nm measurement range is also located on the top of the plate. It is used as redundancy in the ignition verification and delay measurement and may provide a measure of ignition delay more accurate than solely the pressure transducer. An oscilloscope is used to monitor all of the aforementioned instrumentation and record the data. Finally, a mechanical pump is used to create a vacuum in the reactor to a pressure of roughly 10-2 Torr.

Photograph of the micro-reactor experimental setup in the APLab

Pulsed Inductive Test Article
The APLab has a pulsed inductive test article for fundamental pulsed inductive plasma studies. It is a theta-pinch test article with evacuated cylindrical dimensions of 91.5 cm length by 15.5 cm inner diameter for a volume of 1,418 cm3 and a length-to-diameter (L/D) ratio of 5.90. The theta-pinch coil itself is constructed from 11 aluminum segments that span approximately 83% of the evacuated length at 76.2 cm and have an inner diameter of 17.8 cm. In its current configuration the discharge circuit consists of a single Maxwell Technologies 0.7 ?F, 40 kV rated high-energy capacitor and a Perkin-Elmer GP-14B spark-gap trigger. This existing setup results in an approximately 450 kHz waveform with peak current of 30 kA, peak magnetic field of 0.09 T, and peak electric field of 4 kV/m.

Pulsed Inductive Test Article

Data Acquisition and Other Misc. Capabilities
The APLab is also equipped with a high-resolution, fast sampling data acquisition system for acquiring the multiple probe signals necessary for multiple plasma and propulsion system diagnostics. The data acquisition system is a PXI 1000B chassis. The chassis uses a PXI-PCI8336 control card to interface with the PCI slot of a computer. The computer communicates with chassis through fiber optics and can sustain data communication at a rate of 78 MB/s and provides electrical isolation for added protection. A LabVIEW program is used to manage communication and data retrieval between the computer and chassis. Two PXI-5105 modules provide eight channels of simultaneous 12-bit resolution data at 60 MS/s per module. Each channel possesses 16 MB of dedicated memory.

Additional data acquisition capabilities include a 4-channel Agilent 54815A 500 MHz 1 GS/s oscilloscope, three 4-channel Tektronix DPO 2024 200 MHz 1 GS/s oscillscopes, and a 4-channel Tektronix TDS 2014B 100 MHz 1 GS/s oscilloscope. All oscilloscopes interface (via USB or GPIB) with a dedicated 64-bit workstation.

The APLab is also equipped with a dedicated gaseous mass flow control system, laboratory DC power supplies for capacitor charging, multiple high-voltage probes for discharge circuit voltage measurements including a PVM-5 80 MHz 100-kV-pulsed North Star high-voltage probe, and multiple Rogowski “Pearson” coils for pulsed discharge current measurements.