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Why can vacuum-type centrifuges reach very high rotational speeds with less energy?

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tubular centrifuge — centrifuge Figure 1: Tubular centrifuge

Vacuum-type centrifuges can reach very high rotational speeds with less energy because they operate within an evacuated chamber, which eliminates air resistance.1

In standard centrifuges, a rotor spins in air or gas at atmospheric pressure. This creates gaseous friction that increases rapidly with speed, requiring significantly more power to drive the rotor. This friction also generates heat, which can lead to temperature gradients and convection currents that disturb sedimentation. By removing this air resistance, vacuum-type centrifuges minimize the energy expenditure needed to overcome drag, allowing for the attainment of high rotational speeds—often exceeding 20,000 revolutions per minute in ultracentrifuges—while avoiding the heat buildup and convection problems associated with air friction.1