Thomson constructed a Crookes tube with a near-perfect vacuum.
It was a cold-cathode diode, a modification of the Crookes tube with a phosphor-coated screen.
He was a pioneer of vacuum tubes, inventing the Crookes tube.
He developed the Crookes tubes, investigating cathode rays.
His early experiments were with Crookes tubes, a cold cathode electrical discharge tube.
Crookes tubes are now used only for demonstrating cathode rays.
Later experimenters painted the back wall of Crookes tubes with fluorescent paint, to make the beams more visible.
The electronic vacuum tubes invented later around 1906 superseded the Crookes tube.
Crookes tubes were used in dozens of historic experiments to try to find out what cathode rays were.
The Crookes tube was improved by William Coolidge in 1913.