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Marx generator
About: Marx generator is a research topic. Over the lifetime, 1276 publications have been published within this topic receiving 8970 citations.
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21 Oct 1986
TL;DR: In this article, a 2 cm aperture X-ray preionized TEA CO laser was successfully operated, achieving an output energy of 12.6 % with an average dose of typically 50 mr/shot.
Abstract: A 2 cm aperture X -ray preionized TEA CO laserReinder J. ZuidemaTwente University, Department of Applied Physics,P.O. Box 217, 7500 AE Enschede, The NetherlandsAbstractA cryogenically cooled 2 cm aperture sealed -off UV or X -ray preionized TEA CO laser wassuccesfully operated. It was found that X -ray preionization performed better than UVpreionization. 17.5 J /R, output energy was extracted from a 2x2x40 cm3 discharge volume. Themaximum efficiency was 12.6 %.IntroductionThe CO laser is subject of a growing interest especially as a tool for materialprocessing and for medical applications. It has several advantages with respect to the CO2laser: a potential for higher efficiency, variable pulselength from several hundreds of psecto over 10 msec, and the wavelength between 5 -6 pm allows beam handling by means of fibers.Besides for medical applications this wavelength offers also more favourable absorbtionproperties.On the other side a self -sustained discharge CO laser is more difficult to operate,especially for large apertures. The reason is that for efficient operation the laser has tobe used at low temperatures. At these temperatures impurities are frozen out of the laser gasmixture so that sufficient preionization is difficult to achieve with an UV source. This isthe main reason for us to investigate X -rays as an alternative way of preionization. Thistechnique proved to be very succesful for RGH- lasersl and high -pressure CO2 lasers2'3. Wefound this technique to perform better in the case of a CO laser too.A cryogenically cooled 2 cm aperture sealed -off TEA CO laser was succesfully operated,using an X -ray preionization source. For reasons of comparison the laser was also operatedwith an UV preionization source. Using X -ray instead of UV preionization yielded an increasein output energy in the order of 20 %.The present work is an extension of our previous work on UV preionized TEA CO lasers4,where we obtained a maximum output energy of 625 mJ per pulse from a 1x1x18 cm3 dischargevolume with an efficiency of 11.4 %.System descriptionA schematic cross -section of the system is given in figure 1. The X -ray photons areformed in a 10 pm thick Ta -foil serving as the anode of a cold -cathode e -beam machine. A 50pm thick Ti -foil is serving as the exit window for these photons. The voltage is producedby a two -stage Marx generator equipped with two 40nF /50kV capacitors operating at a chargingvoltage of 35kV. The pulse length is in the order of 2 psec.The laser chamber essentially consists of two concentric stainless steel tubes withrespectively diameters of 20 and 24.5 cm, surrounded by 3.5 cm of insulating foam. The spacein between the tubes can be filled with liquid nitrogen. The inner tube contains the lasergas and the laser electrodes. The laser actually operates at 100K. The X -ray photons areentering the laser gas through a 50 um thick Ti -foil of the same dimensions as the exit foilof the X -ray source. Using a dosimeter located just behind this foil inside the laser chamberwe found an average dose of typically 50 mr /shot.The laser electrodes are profiled according to a publication of Chang5, with k = 0.02 andv = arccos( -k). The discharge dimension are 2x2x40 cm3. Mounted to this electrodes is asimple construction for UV production based on the corona discharge technique. A descriptionof this method can be found in a paper by Ernst6. Two 5 mm thick pyrex glass plates areused. When operating the laser with X -ray preionization, this construction is removed sothat the X -ray photons can freely enter the discharge volume. The electrodes are connectedto a two -stage Marx generator equipped with two 40nF /50kV capacitors by means of two low -impedance high -voltage feed -throughs separated by 22 cm. The total circuit inductance isabout 250 nH, resulting in a current pulse length of 0.20 psec FWHM.The optical cavity is formed by a flat 80% R /AR coated Ge outcoupling mirror and acurved Au- coated Al reflector with a radius of curvature of 5 m. These mirrors are sealingboth ends of the laser chamber. The outcoupling is nearly optimized. The total cavity length
Patent•
25 Jun 2014
TL;DR: In this article, a method for determining the parameters of equivalent parallel resistors of a Marx generator was proposed, based on the structure, series-parallel connection and nest relations of a complex local discharging loop.
Abstract: The invention provides a method for determining parameters of equivalent parallel resistors of a Marx generator. The process for determining the parameters of the resistors and a calculation method are quite simple, the structure, series-parallel connection and nest relations of a complex local discharging loop do not need to be analyzed, total energy consumed on all the resistors can be learnt conveniently only by learning the resistance values of each resistor and the potential difference of the two ends of each resistor and finding out the number of capacitors bridged by each resistor, and the equivalent parallel resistors of the Marx generator can be determined according to energy conservation.
07 Oct 2014
TL;DR: In this paper, the authors present the results of a study on the balance of charge in accelerator TEMP-4M operating in double-pulse mode with resistance load and ion diode.
Abstract: The paper presents the results of a study on the balance of charge in accelerator TEMP–4M operating in double-pulse mode with resistance load and ion diode. Crucially, it was found, that during the switching there is no losses of accumulated charge. It means, that all accumulated charge transferred to the load. However when the charge is transferred from the Marx generator to Blumlein line the half of accumulated charge is lost. Calibration of diagnostic equipment showed a good agreement between the calculated and experimental values of voltage and current. It means, that our diagnostic system is correct for registration parameters of the ion accelerator. A distinctive feature of the ion accelerators with self-magnetically insulated diode is that there is no need to use additional energy source for the creation of an external magnetic field. That's why the efficiency of ion diodes with an external magnetic field is not more than 10–15%. The efficiency of energy conversion in self-magnetically insulated diodes will be determined by not only the efficiency of the diode, but the energy losses in the units of the accelerator. The aim of the researches is the analysis of the balance of charge in units of the ion beams pulsed generator and definition of the most significant channels of energy loss.
TL;DR: In this article, the reproducibility of a steep and short-tailed lightning impulse voltage waveform was verified by the detailed equivalent circuit. But the authors did not discuss the occurrence of sparkover on a medium-voltage line.
Abstract: The overvoltage waveforms on a medium-voltage (MV) line generated by lightning have a steep front and a short tail due to behavior of protection devices. To discuss the occurrence of sparkover on a MV line, it is necessary to estimate the insulation characteristics of the distribution instruments by using such waveforms. Therefore, it is of practical importance to develop an equivalent circuit of an impulse generator, applicable to the case of generation of such waveforms. In this letter, the authors verify the reproducibility of a steep and short-tailed lightning impulse voltage waveform by the detailed equivalent circuit.
01 Jun 2017
TL;DR: In this paper, an L band axial extraction relativistic magnetron (RM) working at 1.57 GHz is presented, where microwave from two adjacent cavities is coupled into an axially oriented coaxial sector waveguide through radial slots on the cavities.
Abstract: Experimental results of an L band all cavity axial extraction relativistic magnetron (RM) working at 1.57 GHz is presented. In this 6-cavity RM configuration, microwave from two adjacent cavities is coupled into an axially oriented coaxial sector waveguide through radial slots on the cavities. This configuration is more compact because only three sector waveguides are added outside the magnetron cavity without increasing the radial dimension significantly. Simulation results reveal that this tube could generate a microwave power of 700 MW at the frequency of 1.57 GHz, corresponding to a power conversion efficiency of 50% when employing an electron beam of 350 kV and 4.0 kA. This tube is tested on a compact Marx generator in our lab. In experiment, this tube could generate a microwave power of over 500 MW at 1.57 GHz when employing guiding magnetic field of 0.22 T and input beam voltage of 345 kV and current of 4.8 kA, with a corresponding efficiency of about 30%. Experimental results reveal that this tube is a preferred configuration for a compact relativistic magnetron with relatively high power conversion efficiency.