<aside> <img src="/icons/flash_orange.svg" alt="/icons/flash_orange.svg" width="40px" /> Commonwealth Fusion Systems (CFS) is a spinoff company from the MIT Plasma Science and Fusion Center with the audacious mission to commercialize clean, limitless fusion energy to meet humanity’s growing energy demands and combat climate change.
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<aside> <img src="/icons/light-bulb_blue.svg" alt="/icons/light-bulb_blue.svg" width="40px" /> I was a mechanical R&D intern at CFS over summer 2023 and am continuing part-time in the fall semester.
I worked on a lot at CFS, but my main project was designing cooling systems for a high vacuum test stand to test high-power RF antennas in their operating conditions including high magnetic fields, high vacuum, asymmetric plasma loading, etc. Read on to learn more
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All content on this page - including CAD, technical drawings, photos, and calculations - has been reviewed and explicitly approved for publishing by the IP review team at CFS.
<aside> 💪 Main skills I used and developed include:
The radio frequency (RF) antennas will be used in SPARC to heat the plasma to fusion-relevant temperatures. VATS is a test chamber designed to place the antennas in the rigorous operating environment they will see in the tokamak to de-risk the antenna design.
Because my project was designing around the non IP-sensitive test stand I can share CAD, technical drawings, photos, and calculations, but will obscure any details of the proprietary antenna design or manufacturing.
<aside> <img src="/icons/shower_red.svg" alt="/icons/shower_red.svg" width="40px" /> To determine the specifications of the pumps, heat exchanger, sensors, and fittings I conducted comprehensive thermal fluids calculations considering the energy absorbed by the coolant, flow rate necessary, and pressure drop induced due to major and minor head losses
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Absorbs the energy from the RF antennas to measure their performance as well as test features like resilience to asymmetric loading
System requirements
Calculated pumping requirements
Cools a Helmholtz coil that creates a ~uniform 0.5 Tesla magnetic field through the center of the vacuum chamber
System requirements
Calculated pumping requirements
Flow rate = $4.3LPM$
Max operating pressure $P = 155 psi$
↖️ very different pumping requirements ↗️
<aside> 🚿 For simplicity, I combined parts of the cooling systems, namely the water tank, but because of the vastly different pumping requirements, we still needed separate pumps for each.
I selected a constant flow rate and high-pressure rotary vane pump for the magnet cooling loop and a high flow rate, low-pressure centrifugal circulating pump for the RF absorption cooling loop
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There are 10, 2 inch diameter quartz tubes (because quartz is transparent to RF) going through the center of the chamber and between the RF antennas. Room temperature water flows through these tubes absorbs the energy from the RF antennas and is fed by the cooling system I designed below.
Designed to support the asymmetric flow of coolant to test the asymmetric loading on the RF antennas
Assembled in NX with off-the-shelf McMaster components as well as custom-designed 3D printed pieces and 80/20 fixtures
Needs pressure, temperature, and flow rate measurements for fully defined flow and antenna energy output
Uses flexible tubing and barbed fittings
I created several technical drawings using GD&T for machinists to manufacture parts for the test stand. I also assembled a Bill of Materials for the procurement of purchased parts
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Vacuum flange for quartz tubes drawing
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Vacuum tube seal cylinder drawing
This part (final machined part shown here below) has 4 O-rings glands and is the interface between the vacuum, the coolant system, and the outer room. It thus requires tight tolerancing in many (but not all) parts.