A new configuration for high-temperature heat shielding has been developed and tested; the shields are several times as efficient as those in common use. The configuration consists of a multiturn, close-spaced spiral, wound out of thin tantalum sheet. Conduction losses around the spiral are negligible. Turn-to-turn spacings down to about 100 μm are maintained using low loss spacers; the conduction loss of the spacers sets the limit on the design. A theory is presented for the design of vacuum heat shielding; fundamental limits are considered. Two applications are a mass spectrometer Knudsen cell generating a neutral carbon atomic beam at 2400 K using a total input power of only 165 W, and a high-temperature direct-vaporization ion source generating a 10−6-A gallium beam with a total input power of only 110 W. An attractive future application might be large high-temperature ovens, where large amounts of power have previously been required.