Patent ID: 7806115

Claim:
A tubular radiation absorbing device ( 1 ) for solar thermal applications, with a collector in a solar power plant, said tubular radiation absorbing device ( 1 ) comprising a central tube ( 2 ); a tubular jacket ( 3 ) comprising glass and surrounding the central tube so as to form a ring-shaped space ( 4 ) between the tubular jacket and the central tube; at least one gas-tight, closed container ( 10 ) filled with at least one inert gas ( 7 ) and arranged in said ring-shaped space ( 4 ), said at least one gas-tight, closed container ( 10 ) being provided with at least one outlet ( 20 ) and a sealing material closing said at least one outlet ( 20 ) and said at least one inert gas being selected from the group consisting of helium, neon, argon, krypton, xenon and radon; and means for heating the at least one gas-tight, closed container ( 10 ) and melting the sealing material closing said at least one outlet ( 20 ) so as to open said at least one outlet and thus release said at least one inert gas into said ring-shaped space ( 4 ).