Quick Turn Pulsed Plasma Thruster (QT-PPT) for Deorbiting Applications

CU Aerospace (CUA) proposes the further development of the Quick Turn Pulsed Plasma Thruster (QT-PPT) in configurations up to 3200s specific impulse that will provide CubeSat deorbit capability at end-of-life for LEO missions. While classic PPT technology is mature, it has historically been limited by its size and propellant load. CUA developed the Fiber-fed PPT (FPPT) and developed miniaturized electronics subsystems including life-tested high-density energy storage via MLCC capacitors, low-erosion discharge geometry, negligible-erosion regenerative carbon igniters, compact power electronics, electromagnetic thrust vectoring, and high-performance filament feed ofnon-toxic solid Teflon propellant. QT-PPT Phase I sought to further the miniaturization and simplification of the subsystems specifically energy storage and fuel feed.In this Phase II, CUA will leverage the prior work to build a QT-PPT system with lower size, weight, power, and cost (SWaP-C). The entire system including the PPU is tightly integrated onto a stack of PCBs approximately 0.5U in size, which offloads most of the manufacturing and quality control to the specialized PCB manufacturer, and enables the Quick Turn PPT system integrated by CUA. Recent FCC deorbit rule changes require more total impulse than was anticipated at the onset of Phase I, but QT-PPT with a fiber feed system can achieve a full 2000 km deorbit for a 12 kg spacecraft from a 0.7U thruster. The total impulse can be varied via fuel loading and capacitor energy selection, and thrust vectoring is also an option.For comparison, the baseline 0.5U configuration is estimated to have a specific impulse of 1400s and a total impulse of 1700N-s, enough to lower a 5.5 kg CubeSat from 1000 km to 400 km. CUAs long-term goal will be to establish the QT-PPT as a mature integrated system solution with standard lead times under 6 weeks. One flight-like QT-PPT will be delivered to NASA at the end of the Phase II program. CU Aerospace (CUA) proposes the further development of the Quick Turn Pulsed Plasma Thruster (QT-PPT) in configurations up to 3200s specific impulse that will provide CubeSat deorbit capability at end-of-life for LEO missions. In this Phase II, CUA will leverage the miniaturized electronics improvements from its Fiber-fed PPT (FPPT) onto a tightly integrated stack of PCBs approximately 0.5U in size to build a more accessible QT-PPT system with lower size, weight, power, and cost (SWaP-C). This offloads most of the manufacturing, quality control, and inspections onto the PCB manufacturer, who is specialized at these tasks with expedience. The baseline 0.5U QT-PPT with 124g of Teflon fiber is estimated to have a total impulse of 1700N-s, enough to deorbit a 5.5kg CubeSat from an altitude of 1000km. The system can be scaled to 0.7U with higher Isp and energy, and a total impulse of 9600N-s for a 12kg CubeSat at 2000km, and may include thrust vectoring. CUA’s long-term goal is to establish the QT-PPT as a mature integrated system solution with standard lead times under 6 weeks. The primary technical objectives of Phase II are the development, testing, and delivery of an integrated flight-like QT-PPT system. Vibration, TVAC, and EMI qualification testing will be performed. The QT-PPT uses non-toxic solid Teflon propellant, has no corrosive or propellant plugging issues, and provides on-demand thrust with no warmup time.Individual technical objectives & risk reduction conducted during Phase II will include: Requirements development for the flight-like system for deorbit applications Electronics design and testing including capacitor choice and charging circuitry Geometry optimization (cathode and anode) for a QT-PPT thruster head Determine volume impact of integrated thrust vectoring system. Identify viability of PTFE discs (high thrust) vs. PTFE fiber feed (high Isp) based on performance & requirements determination (especially following FCC rule) Integrated QT-PPT hardware package design Prototype QT-PPT unit fabrication and testing Flight-like QT-PPT unit fabrication and testing Environmental testing of a flight-like QT-PPT (vibe, TVAC, EMI) Deliver a flight-like QT-PPT to NASA
Benefits: The practice of Responsible Space and deorbit capability of LEO satellites is critical for the prevention of an escalation of space debris. Deorbit from up to 2000 km is possible at end-of-life with only power and attitude determination available from a CubeSat to guide the thrust-vectored propulsion system (no reaction wheels or magnetorquers required). Unlike drag-based deorbit systems, QT-PPT also provides an “as needed” collision avoidance option for the entire mission. Commercial interest in nano-/small-satellites continues to grow, and it is more important than ever that these satellites have access to a technology for end-of-life deorbiting. The QT-PPT provides a compact, light-weight, non-hazardous, high total impulse propulsion technology solution available in a family of sizes to meet the differing mission needs of users in DOD/industry/academia.