Time dependence of X-ray yield for two crystal X-ray generators

X-ray crystal generators have been developed as practical devices at Bingha mton. Here we report on X-ray intensity decay-time studies of two different units. The first is a sealed, flashlight-battery powered, portable device. The second more versatile generator consists of a 6.5 x 3.1 x 2 mm LiTaO3 crystal, whose temperature can be cycled between 120 degrees C and 3 degree s C. A thin target of Fe evaporated on to an Al foil is located directly in front of an Si(Li) detector in the chamber vacuum. The detector and target can be moved toward or away from the crystal The chamber can be pumped on so that effects of gas pressure and composition as well as geometry can be studied. The X-ray intensity increases as the crystal is heated and becomes almost zero when the crystal temperature is no longer increasing. As the c rystal is cooled the X-ray intensity increases rapidly and then decreases s lowly. (C) 1999 Elsevier Science B.V. All rights reserved.