Experimental "Magnetic Arc-Spreading" compact fluorescent lamp

The energy crises of the 1970s inspired inventors to try novel ideas for new light bulbs. One of the more unusual designs emerged from the drawing board of Manhattan Project veteran Leo Gross. Supported by Merrill Skeist at Spellman High Voltage Electronics Corporation, Gross designed a compact fluorescent lamp that he called a "magnetic arc spreader" (MAS).
The design took advantage of a fundamental aspect of electro-magnetism known since the early 1800s. When a current flows through a coil of wire, it produces a magnetic field. The arc discharge that travels between the electrodes of a fluorescent lamp can be affected by the presence of such a field. In the center of the MAS lamp seen here there is a copper coil. Current moving through the coil creates a magnetic field that spreads out the electrical arc within the lamp. The expanded arc energizes phosphor throughout the lamp's entire length.
The concept was tested at Lawrence Berkeley Laboratory, and General Electric became interested. In 1978 GE purchased a one-year license from Spellman in order to conduct further tests but determined that the necessary glasswork would make the lamp too expensive for commercial production. GE donated one of their test lamps to the Smithsonian in 1998—the only known surviving example of this experimental design.
Lamp characteristics: No base. Two stranded lead-wires extend about 2" from either end, and each end has one lead wire encased in a glass insulating tube. Two coiled tungsten electrodes are mounted in a hollow cylindrical envelope. The exhaust tip is near one set of leads, and the envelope has an internal phosphor coating. A coil of bare copper wire held together with black string is inserted into the center of the envelope. A current passing thru this coil spreads the arc between electrodes so that more of the phosphor is activated.
Object Name
discharge lamp
Date made
ca 1978
date made
ca. 1978
General Electric Corporate Research & Development Laboratory
Spellman High Voltage Electronics Corp.
Physical Description
glass (overall material)
copper (overall material)
tungsten (overall material)
overall: 8 3/4 in x 3 in; 22.225 cm x 7.62 cm
Place Made
United States: New York, Hicksville
ID Number
accession number
catalog number
See more items in
Work and Industry: Electricity
Energy & Power
Data Source
National Museum of American History, Kenneth E. Behring Center


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