The response of a transverse biased photoconductive detector (PCD) may be modeled as a continuously variable parallel resistor through the depth of the detector. Since the bias is perpendicular to the dose gradient the electric field is constant and the mean conductivity is proportional to the mean dose rate. The response of a parallel biased PCD can be modeled as a continuously variable series resistor through the depth of the detector with the bias electric field dependent on the resistivity at the given depth in the detector. Hence, even though the front region the PCD becomes highly conductive, the PCD will not respond unless free carriers are generated through the entire depth of the PCD between the bias
electrodes. Experimental measurements on parallel biased gallium arsenide, GaAs, PCDs using the MBS (Modular Bremsstrahlung Source) pulse x-ray source at AEDC (Arnold Engineering Development Center) are given that substantiate the response model. Agreement in the response between PCDs of varying x-ray filtration were observed
with the effective dose model given in the paper as opposed to a 40% discrepancy when the mean dose is used.
Recent advances in the Dense Plasma Focus (DPR) under investigation by Cymer as an EUV light source have increased both the total energy storage capacity and the peak drive current. Previous generation DPF tools built by Cymer produced no measurable EUV radiation while employing Xenon as a source gas, but instead employed Lithium vapor due to its higher emission efficiency at low plasma temperatures. With Xenon as a source gas, this generation DPF exhibits efficiency similar to other sources employing direct electrical drive of the Xenon plasma. An emission efficiency of greater than 0.20% has been measured into 2(pi) str and 2% bandwidth centered at 13.5 nm. Other characteristics of this DPF have been measured such as energy stability, spectrum, source size, position stability, and operation at high repetition rates. In addition, the out-of-band radiation in the UV/Vis region (130nm-1300nm) has been measured and found to be only 0.38% of all radiation emitted by this source. Such low out-of-band radiation opens up the possibility of eliminating the Spectral Purity Filter and the problems associated with its use. This source concept does not use a multi-layer dielectric mirror as the first collector, but instead employs a grazing incidence collector that is more tolerant to debris. Progress has been made in the fabrication quality of this optic. Recent measurements of prototypes show that this optic will not degrade the source brightness. Also, a more efficient design has been created that consist of two shells coated with Ruthenium. This design collects and re-images 18.6% of the EUV radiation emitted into 2(pi) str.