Geissler tube
Concise Oxford English Dictionary © 2008 Oxford University Press:
Geissler tube /ˈgʌɪslə/
▶noun a sealed tube of glass or quartz with a central constriction, filled with vapour for the production of a luminous electrical discharge.
– origin C19: named after its German inventor Heinrich Geissler.
'Geissler tube' also found in these Oxford entries:

