Hall Current Plasma Source Center-Mounted Cathode Design
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Solution Overview
Problem
Small spacecraft, such as Cubesats, face limitations in propulsion capabilities due to limited power and volume constraints, leading to short propulsion lifetimes and limited orbit change capabilities, and existing Hall current plasma sources are not optimized for low-power operations, resulting in inefficient thrust and specific impulse.
Innovation Solution
A Hall current plasma source with a surface-mounted, instant-start hollow cathode design that operates using a single electrical power supply, incorporating a cylindrical magnetizable core, conducting wire coils, and a hollow cathode discharge apparatus to ionize gases, enhancing efficiency and scalability for miniature thrusters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional Hall current plasma sources are used in small spacecraft, then propulsion function is provided, but the system occupies significant volume and has limited lifetime
Solution Approach 1:
The cathode is divided into multiple segments arranged in a polyhedral configuration, with each segment containing a hollow cathode structure. This segmentation allows the propulsion system to achieve extended lifetime through modular architecture while maintaining compact overall volume, as the segmented design optimizes space utilization and enables independent replacement or optimization of individual segments.
Solution Approach 2:
The hollow cathode segments are nested within a polyhedral structure that is itself contained within the propulsion system housing. This nested arrangement allows multiple functional components to be space-efficiently integrated, reducing the overall volume occupation while maintaining the lifetime-extending segmented cathode architecture.
2Power
If conventional Hall current plasma sources are used, then thrust is generated, but power consumption is high relative to thrust efficiency
Solution Approach 1:
Each hollow cathode segment is equipped with localized magnetic fields and electric fields optimized for its specific position in the polyhedral structure. This local quality optimization ensures that power consumption is efficiently distributed and utilized across all segments, maximizing thrust efficiency while minimizing overall power consumption through targeted field application rather than uniform system-wide fields.
3Weight of moving object
If propulsion system mass is reduced for small spacecraft, then volume and power constraints are addressed, but thrust capability is reduced
Solution Approach 1:
The hollow cathode segments are pre-configured with optimized geometries and magnetic field arrangements that maximize ionization efficiency and thrust generation per unit mass. This preliminary optimization of the cathode structure ensures that the reduced mass of the segmented design does not compromise thrust capability, as each segment is预先 designed to deliver maximum performance for its mass.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a long-life, high-efficiency Hall current plasma source capable of operating at low power levels, improving thrust and specific impulse, and reducing the mass and volume of propulsion systems, enabling more effective and longer-lasting propulsion for small spacecraft.
Implementation Method 1
a hollow cathode discharge apparatus adapted to ionize a first chosen gas
Implementation Method 2
low-work-function electride material mounted on a piece of graphite
Implementation Method 3
a cylindrical magnetizable core having a first end and a second end and a first axis... a first conducting wire coil wound around the outer surface of the core
Implementation Method 4
Hall current plasma sources generate thrust through the formation of an azimuthal electron current that interacts with an applied, quasi-radial magnetic field to produce an electromagnetic force
Implementation Method 5
azimuthal electron current that interacts with an applied, quasi-radial magnetic field to produce an electromagnetic force
Data Source
AI summary
A miniature Hall current plasma source apparatus having magnetic shielding of the walls from ionized plasma, an integrated discharge channel and gas distributor, an instant-start hollow cathode mounted to the plasma source, and an externally mounted keeper, is described. The apparatus offers advantages over existing other Hall current plasma sources having similar power levels, including: lower mass, longer lifetime, lower part count including fewer power supplies, and the ability to be continuously adjustable to lower average power levels using pulsed operation and adjustment of the pulse duty cycle. The Hall current plasma source can provide propulsion for small spacecraft that either do not have sufficient power to accommodate a propulsion system or do not have available volume to incorporate the larger propulsion systems currently available. The present low-power Hall current plasma source can be used to provide energetic ions to assist the deposition of thin films in plasma processing applications.