Abstract: A plasma generator according to the invention comprises a chamber (2) at a first potential (V1) filled with a gas at a low pressure and a transparent electrode surface comprised of wires, grid or perforated plate (3) at a second potential (V2) higher than (V1). Thus, an electron (4) present in the chamber will be oscillating on both sides of the transparent electrode surface (3) for providing secondary electrons (11 and 12) which create in turn other secondary electrons (13-14, 15-16). At each occurence of an electron pair, one ion (i1, i2, i3, . . . ) is created.

Abstract: An X-ray gas detector for analyzing a material by studying X-ray diffraction. In order to minimize the parallax error without resorting to auxiliary electrodes, difficult to manufacture, a radial field in the whole gas space (40) is generated only by means of input electrodes (36) set to appropriate voltages and by means of lateral electrodes (44) also individually set to appropriate voltages. By modifying the voltages, it is also possible to move the center of the spheric equipotentials for permitting the analysis without parallax error of samples (20) placed at variable distances (D) from mthe input window (32) of the detector.

Abstract: Gas-filled detector for locating the presence in space of particles or radiations. The detector according to the invention comprises a curved body containing a gaseous fluid under pressure, and being provided with a window, and on the inside, an elongated element forming means of picking-up an avalanche of elements, said means being constituted by a structure of the type with at least one curved conducting strip held in such a way by the body that it projects into the enclosure and that one of its longitudinal edges is parallel to the axis of the window. The invention finds an application in X-ray crystallography.