Design and mechanical analysis of the PRAGYA tokamak vacuum vessel

TL;DR

This paper details the design and structural analysis of India's first privately developed low aspect ratio tokamak vacuum vessel, ensuring safety and performance under various operational loads.

Contribution

It presents the final design and a comprehensive 3D FEM assessment of the PRAGYA vacuum vessel, highlighting its robustness and suitability for plasma operations.

Findings

Design meets safety margins under combined loads

Structural performance confirmed through 3D FEM analysis

Vacuum vessel features reduce eddy currents and leakage

Abstract

PRAGYA is India's first privately developed low aspect ratio tokamak designed by Pranos Fusion Energy. The device is designed for a plasma major radius (R0) of about 0.4 m, a plasma minor radius (a) greater than 0.18 m, a plasma current (Ip) of up to 25 kA, and a toroidal magnetic field (B_T) of 0.1 T. The PRAGYA vacuum vessel incorporates several distinctive features, including a toroidal electrical break to minimize induced eddy currents and a double O-ring arrangement to reduce vacuum leakage. This paper presents the final design of the PRAGYA vacuum vessel and a comprehensive three-dimensional (3D) finite element model (FEM) assessment of its structural performance. The analysis evaluates the effects of self-weight, atmospheric pressure loading, and thermal stress arising from in-situ baking. The results confirm that the design satisfies the required safety margins under these combined loading conditions, providing a robust foundation for subsequent plasma operations in this compact tokamak.