Helion is a fusion energy startup focused on developing a commercial fusion power plant. They have achieved significant milestones, including reaching 150 million degrees Celsius in their Polaris prototype reactor and operating with deuterium-tritium fuel. Helion's unique approach involves a field-reversed configuration reactor that directly generates electricity from fusion reactions, aiming for higher efficiency than traditional methods. They plan to use deuterium-helium-3 fuel in their future commercial reactors, with a goal of delivering electricity to Microsoft by 2028 from their larger Orion reactor.