Procyon is a two-stage explosive pulsed-power system, consisting of a MK-IX helical generator and an explosively formed fuse (EFF) opening switch. A complete assembly including load and diagnostics is shown. The system was originally developed for the purpose of powering plasma z-pinch experiments and, in its original concept, was coupled to the plasma z-pinch load through a third pulsed power stage, a plasma flow switch (PFS). The authors have performed plasma z-pinch experiments both with and without a PFS, and they have now conducted the first heavy liner experiment. In this paper, they will summarize the results obtained to date with the system, and briefly discuss future applications.
The Procyon high explosive pulsed power (HEPP) system was designed to drive plasma z-pinch experiments that produce Megajoule soft x-ray pulses when the plasma stagnates on axis. In the proceedings of the Ninth IEEE Pulsed Power Conference, we published results from system development tests. At this time, we have fielded seven tests in which the focus was on either vacuum switching or load physics. Four of the tests concentrated on the performance of a Plasma Flow Switch (PFS) which employed a 1/r mass distribution in the PFS barrel. Of the four tests, two had dummy loads and one had an implosion load. In addition, one of the tests broke down near the vacuum dielectric interface, and the result demonstrated what Procyon could deliver to an 18 nH load. We will summarize PFS results and the 18 nH test which is pertinent to upcoming solid/liquid liner experiments. On our other three tests, we eliminated the PFS switching and powered the z-pinch directly with the HEPP system. From the best of these direct drive tests we obtained 1.5 MJ of radiation in a 250 ns pulse, our best radiation pulse to date. We will also summarize direct drive test results. More details are given in other papers in this conference for both the PFS and direct drive experiments, and an updated analysis of our opening switch performed is also included. The remainder of this paper describes the parameters and capabilities of our system, and we will use the data from several experiments to provide more precise information than previously available.
An optically powered fireset has been developed for the Procyon high explosive pulsed-power generator at Los Alamos National Laboratory. The fireset was located inside this flux compression experiment where large magnetic fields are generated. No energy sources were allowed inside the experiment and no wire connections can penetrate through the wall, of the experiment because of the high magnetic fields. The flux compression was achieved with high explosives in the experiment. The fireset was used to remotely charge a 1.2?f capacitor to 6,500V and to provide a readout of the voltage on the capacitor at the control room. The capacitor was charged by using two 7W fiber coupled GaAlAs laser diodes to illuminate two fiber coupled 12V solar cells. The solar cell outputs were connected in parallel to the input of a DC-DC converter which step up a 12V to 6,500V. A voltmeter, powered by illuminating a third 12V solar cell with 1W laser diode, was used to monitor the charge on the capacitor. The voltage was measured with a divider circuit, then converted to frequency in a V-F converter and transmitted to the control room over a fiber optic link. A fiducial circuit measured the capacitor firing current and provided an optical output timing pulse.
The aim of the Trailmaster series of experiments is to generate an intense source of soft x-rays by imploding a thin (2000 Å) aluminum cylinder. The present scheme incorporates a plasma flow switch for the final pulse shaping and requires careful diagnostic analysis. The emphasis of this work is to transfer the energy to the load area and to understand the dynamics of the plasma flow switch. The experiments are carried out at LANL in two facilities. Laboratory experiments that answer questions about the details of the plasma flow switch are done on the 1.5-MJ Pegasus capacitor bank. The higher energy experiments (Procyon series) utilize explosive pulsed power systems and are conducted at the Ancho Canyon firing site. It is the latter set of experiments that will eventually supply an x-ray radiation source at the megajoule level. At the present time, the emphasis of the Procyon experiments is to deliver energy from the generator to the plasma flow switch and the load area. The details of these experiments are given in other papers at this conference. In order to characterize these experiments one needs to diagnose the driver performance and the dynamics of the plasma and power flow in the plasma flow switch region. The difficulty of experiments in which high current high voltage, and high explosive are combined, leads to severe problems. Many of the diagnostics are unique and untested. Since only a limited number of experiments are done during a year, the effort is to maximize the information per shot. The aim in this report is to present some of the diagnostic techniques used in the adverse Trailmaster environment. 8 refs., 10 figs.
High explosive pulsed power (HEPP) techniques can address a wide range of pulsed power needs. The basis for HEPP techniques is the use of high explosives to reduce the inductance of a current-carrying circuit, thus multiplying the current due to magnetic flux conservation. For the past twenty years at Los Alamos, our high energy density physics (HEDP) program has followed a path leading to more sophisticated and higher current (and often power) systems. Twenty years ago, we had the capability of conducting tests at 10, or even 30 MA, with no power conditioning and low inductance loads. The time scale of the experiment was the time it took to compress the flux explosively, and our fastest generator with high current capability was a plate generator. The operating time of the generator is less than 15 [mu]s, and flux loading requires either an additional ≈60 [mu]s or a reduced-efficiency inductive coupling scheme. We could also deliver shortened pulses to select loads by completing our generator circuit, initially, with a relatively high inductance circuit element, then switching in a lower inductance with 2-3 [mu]s left of the generator pulse. Figure 1 shows the results of such a test. The test was conducted in 1974 to investigate our capability to drive plasma z-pinch experiments for the production of soft x-rays, and was a pulsed power success. However, our understanding of vacuum power flow issues was not mature enough at that time to design a functioning plasma z-pinch load. There was a renewed need for such a system in 1980, and at that time we began assembling a complete set of techniques required for success. We first fielded a baseline test using a simplified version of the HEPP system that generated the Figure 1 data. Subsequent tests followed a 'bite size' philosophy. That is, we first designed a complete system for a level of complexity at which we believed success could be achieved. We conducted tests of that system, and once it was working in all respects, we designed the next generation system. The ultimate goal of this process was to develop a source of ≈1 MJ of soft x-rays. The process culminated, after the development of two intermediate level systems, with the development of the Procyon system. This system produced x-ray pulses of up to 1.7 MJ at temperatures up to 97 eV. Following those experiments, our attention turned to powering solid-density z-pinch liners, requiring even higher current systems. At Los Alamos, we developed the Ranchero system for that purpose, and we have collaborated with HEPP experts in Russia to power similar liner loads using disk generator systems. Our Ranchero system includes a module tested at ≈50 MA, that should operate easily at 70-90 MA. We designed Ranchero to allow modules arrayed in parallel to generate currents over 200 MA, and we are confident that we can do experiments now at 50-200 MA in the same way that we could do tests at 10-30 MA with plate generators 20 years ago. We have recently stepped back from our quest for higher energy and power systems to consider what applications we can address using relatively low cost plate generators coupled with advances achieved in our HEDP system development. We will describe relevant HEPP components, and discuss two promising applications.
High explosive pulsed power (HEPP) systems are capable of accessing very high energy densities and can reach conditions that are not possible with capacitor bank systems. The Procyon system was developed and used for experiments over a period of six years, and is exemplary of the capabilities of HEPP systems for state-of-the-art research. In this paper we will summarize some of the more interesting aspects of the work done in the past but will suggest ideas toward applications for future research. One of the main, unique features of HEPP systems is that they integrate easily to a particular physics experiment and the power flow can be optimized for a specific test. Magnetic flux compression generators have been an ideal power source for both high current plasma physics and hydrodynamic experimental loads. These experiments have contributed greatly to the understanding of high temperature and density plasmas and more recently to the understanding of instability growth in thick ((almost equal to)1 mm) imploding metal cylinders. Common to all these experiments is the application of a large current pulse to a cylindrically symmetric load. The resulting Lorenz force compresses the load to produce hydrodynamic motion and/or high temperature, high density plasma. In the plasma physics experiments, plasma thermalizes on axis and a black body distribution of x-rays is produced. To get better access to the radiation pulse, the load electrode geometry was modified. For example, by shaping the plasma implosion glide planes, a mass depletion region was formed along one electrode at pinch time which generated a very large voltage drop across a 1-2 mm segment of the pinch, and also produced a high energy ion beam on axis. These results were predicted by magneto-hydro-dynamic (MHD) codes and verified with framing camera and x-ray, pinhole, camera pictures. We have not previously published these features but will take another look and propose possible scenarios for studying and generating high intensity ion beams. The conditions generated in the implosion load region may be ideal for generating K and L-shell radiation via ion-atom collisions. In recent years, and in a previous conference, the simulation community has shown interest for Ar K-shell radiation and other soft x-ray sources. We will speculate on ways to use this system to generate a high fluence pulse of Ar K-shell radiation, and also to use the high intensity ion beam to study the mechanisms involved in the ion-atom collisions process. These processes can be used to enhance x-ray radiation from a variety of elements.
Procyon is a high explosive driven pulsed power system designed to drive plasma z-pinch experiments to the 1-MJ level. Details of this system are provided elsewhere in these proceedings. The final switching stage of the Procyon system is a plasma flow switch (PFS). Our most recent experiment (April 29, 1993) included a full power test of the PFS designed for the Procyon system. In this test the Mark IX explosively driven generator delivered 22 MA of current to the storage inductor. The slight flux compression that occurs in the explosively formed fuse (EFF) opening switch increased this current to 24.5 MA. The EFF then opened and switched 16.5 MA to the PFS. The PFS switched 15.5 MA to the load region (the slot that will contain an imploding foil liner in future experiments) with a 10-90 rise time of 500 ns. In this present paper we discuss the computer modeling we have done on this Procyon plasma flow switch. In the next section we discuss the design of the Procyon switch and preshot calculations. Although the April 1993 experiment was quite successful there were significant surprizes in the performance of the PFS. In the last sections of this paper we discuss the work we have done in understanding the results of this experiment and the conclusions that we have reached to date.
