Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Design and mechanical analysis of the PRAGYA tokamak vacuum vessel

Ravi Gupta, Rahul Babu Koneru, Saptarshi Rajan Sarkar, Santosh Ansumali, Animesh Kuley, Roshan George, Shaurya Kaushal

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.

Design and mechanical analysis of the PRAGYA tokamak vacuum vessel

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.
Paper Structure (32 sections, 13 equations, 18 figures, 3 tables)

This paper contains 32 sections, 13 equations, 18 figures, 3 tables.

Table of Contents

  1. Mechanical design of the vacuum vessel
  2. Description of the vacuum vessel
  3. Design of the vacuum vessel
  4. Ports
  5. Viewing port
  6. Trapezoidal-shaped port
  7. Diameter Nominal (DN) $200$ ConFlat (CF) ports
  8. Gas injection port
  9. Equatorial rectangular port
  10. Turbomolecular pump (TMP) port
  11. Roughing pump port
  12. Vacuum vent port
  13. Electrical break
  14. Stiffeners
  15. Vacuum vessel support structure
  16. ...and 17 more sections

Figures (18)

  • Figure 1: 3D CAD model of the Pragya vacuum vessel (VV) assembly.
  • Figure 2: A cut-section view of the 3D CAD model of tangential viewing port in the Pragya vacuum vessel assembly.
  • Figure 3: (a) A cut-section view of the 3D CAD model of the vacuum vessel assembly; zoomed-in descriptive view of (b) stiffener, (c) gas inlet system (dotted red arrows represent the direction of incoming gas flow), (d) double O-ring vacuum sealant assembly (dotted magenta arrows represent the direction of flow due to vacuum produced between the two O-ring arrangement).
  • Figure 4: (a) 3D CAD model and (b) mesh used for the simulations.
  • Figure 5: Semilogx plots of relative error in (a) von Mises stress averaged along a curve near the top trapezoidal port on the inboard side and (b) surface averaged von Mises stress averaged along top plate, bottom plate and vacuum vessel outer cylindrical surface.
  • ...and 13 more figures