Abstract
The plasmas of the negative glow region of a cold-cathode discharge in helium and neon are examined for their ability to supply free electrons for operation of a ``vacuum'' amplifier tube. The plasma replaces the conventional oxide-coated hot cathode in a tube with closely-spaced fine-mesh grids. At gas pressures ∼1-mm Hg the volt-ampere characteristics of the amplifier portion of the total discharge tube are essentially the same as found in the high-vacuum, hot-cathode counterpart. The noise content of the plate current of the ``glow-cathode'' tube, defined by equivalent noise-diode current, was examined from 50 kc to 50 Mc. At the lower frequency this equivalent current is ∼10 times the actual plate current flowing. At frequencies approaching 50 Mc the equivalent current drops to a factor ∼0.5 and may be considerably lower for unexamined frequencies above 50 Mc.
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