A compact flexible pellet injector for the TJ-II stellarator

Area of Science:

• Fusion Energy Research
• Plasma Physics
• Accelerator Technology

Background:

• The TJ-II stellarator requires advanced fueling and diagnostic capabilities.
• Existing pellet injector technology has limitations in flexibility and cost-effectiveness.

Purpose of the Study:

• To design and build a compact, cost-effective, and upgradeable pellet injector for the TJ-II stellarator.
• To enable flexible fabrication and acceleration of hydrogen pellets for plasma fueling and active diagnostics.

Main Methods:

• Development of a four-barrel pellet injection system.
• Integration of a cryogenic refrigerator for in situ hydrogen pellet formation.
• Implementation of a combined mechanical punch/propellant valve system for pellet acceleration.
• Inclusion of pellet diagnostics and a dedicated injection line.

Main Results:

• The injector is designed for maximum flexibility at minimal cost.
• It allows for fabrication of pellets with diameters from 0.4 to 1 mm.
• Pellet acceleration velocities will range from 150 to approximately 1000 m/s.

Conclusions:

• The new pellet injector will enhance the TJ-II stellarator's capabilities for plasma fueling and diagnostics.
• The flexible design ensures adaptability for future upgrades and diverse experimental needs.
• This system represents a significant advancement in compact pellet injection technology for fusion research.