Abstract: A test device (1) serves for impinging a sample (2) with a high-energy gas jet (3). A plasma torch (4, 5) provides the gas jet (3) heated by a plasma and directed towards the sample (2). A massive metal plate (6) is positioned in front of the sample (2). The metal plate (6) forms the opposing electrode for the plasma torch (4-6). A drive system (7) is provided for rotating the metal plate (6) about an rotational axis (9). The metal plate (6) is provided with a gap (11) exposing the sample (2) to the gas jet (3) when the metal plate (6) is in a certain rotational position about the rotational axis (9).