For instruments that are designed to acquire the entire spectrum with good sensitivity on light as well as heavy elements, a different approach is taken. A tube anode material is chosen to give a high bremsstrahlung or continuum output, which is used to excite a secondary fluorescer, or target, which gives off its own characteristic lines without the continuum. The sample is then excited by the emission from the target, which is chosen to efficiently excite elements in a certain Z range. A system may be set up to change targets automatically during the analysis so that the low, middle, and high end of the sample spectrum may be sequentially boosted. When an EDXRF instrument uses such a system, tube powers must be increased dramatically since most of the original X-ray intensity is lost.