Fusion Reactor First Wall Conditioning via Plasma Sputtering
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Solution Overview
Problem
Current methods for first wall conditioning in fusion reactors, such as boronization and lithiumization, face challenges due to the use of toxic and flammable substances like decaborane and deuterated trimethyl boron, and high-cost ECR systems for plasma generation, which pose safety and economic concerns.
Innovation Solution
The use of plasma sputtering techniques with RF electrodes and filaments to deposit boron or lithium on interior surfaces of fusion reactor vessels, replacing hazardous substances with safer materials like crystalline boron and lithium, and employing low-power RF sources for efficient plasma generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If chemical vapour deposition (CVD) of elemental boron using decaborane is used for first wall conditioning, then plasma performance is improved due to reduced radiation losses, but safety risks increase due to decaborane being highly flammable, toxic, and explosive
Solution Approach 1:
The patent replaces hazardous decaborane with solid boron carbide targets that can be disposed of after use. The solid target material is contained within a replaceable cartridge system, eliminating the need to handle toxic gaseous decaborane while maintaining effective boron deposition for plasma conditioning
Solution Approach 2:
The patent substitutes the chemical CVD process with a physical sputtering process. Instead of using chemical reactions from gaseous decaborane, the system uses ion bombardment of solid boron carbide targets to deposit boron onto the first wall, replacing chemical mechanisms with physical ones to eliminate toxicity and flammability risks
2Power
If electron cyclotron resonance (ECR) systems are used for plasma generation, then plasma production is achieved, but device cost and complexity increase due to high-cost equipment requirements
Solution Approach 1:
The patent extracts the plasma generation function from the complex ECR microwave system and relocates it to simple filament-based thermionic emission sources. The filaments emit electrons that are accelerated by electric fields to create plasma, separating the essential plasma generation function from the expensive ECR infrastructure
Solution Approach 2:
The patent changes the operating parameters from high-power microwave resonance (ECR) to low-power filament emission with electric field acceleration. This parameter change transforms the plasma generation mechanism from requiring complex high-frequency electromagnetic resonance to using simple thermal emission and electrostatic acceleration, dramatically reducing system complexity
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
This approach allows for safer, cost-effective, and efficient first wall conditioning and plasma generation, reducing radiation losses and improving energy confinement while avoiding the hazards associated with toxic chemicals and high-cost equipment.
Implementation Method 1
an RF electrode for insertion into the reactor vessel and operably coupled to an RF power supply. The RF electrode is configured to generate a plasma within the reactor vessel
Implementation Method 2
one or more filaments operably coupled to one or more power supplies. The one or more filaments are configured to provide electrons into the reactor vessel
Implementation Method 3
The first apparatus is configured such that power supplied to the RF electrode within the vessel causes a plasma located in proximity to the solid material to sputter the solid material in order to deposit a protective material on said interior surface
Data Source
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AI summary
An apparatus for protecting an interior surface of a fusion reactor vessel. The apparatus comprises a power supply operably connected to an electrode for insertion into the vessel. The apparatus supports a solid material within the vessel, and is configured such that power supplied to the electrode within the vessel causes a plasma located in proximity to the solid material to sputter the solid material in order to deposit a protective material on said interior surface.