A magnetically driven reciprocating probe for tokamak scrape-off layer measurements.

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Tokamak Diagnostics

Background:

• Understanding the scrape-off layer (SOL) is crucial for tokamak fusion energy research.
• Accurate in situ measurements of SOL plasma parameters are essential for validating and improving plasma models.
• Previous diagnostic methods for SOL measurements faced limitations in real-time data acquisition and spatial resolution.

Purpose of the Study:

• To develop and implement a new in situ reciprocating probe system for enhanced scrape-off layer (SOL) measurements.
• To optimize the probe system's dynamics and control mechanisms for reliable operation within the Tore Supra tokamak.
• To provide automatic, real-time SOL measurements during experimental campaigns.

Main Methods:

• Development of an in situ reciprocating probe system driven by a rotating energized coil in the tokamak magnetic field.
• Utilizing analytic approximations of a numerical model to optimize coil geometry, electrical circuit, and spring stiffness.
• Implementing real-time feedback control for probe motion based on induced current and coil position.

Main Results:

• Successful development and implementation of a novel reciprocating probe system.
• The probe's linear speed is directly proportional to the induced current, enabling precise motion control.
• Automatic SOL measurements were successfully obtained during the 2011 experimental campaign at Tore Supra.

Conclusions:

• The new in situ reciprocating probe system offers a reliable method for scrape-off layer measurements in tokamaks.
• The system's design allows for precise control and automatic data acquisition, enhancing diagnostic capabilities.
• This advancement contributes to a better understanding of plasma edge physics in fusion devices.