Superpower Semiconductor Switch
Superpower Semiconductor Switch Based on Reversed Switched Dinistor
Tech Area / Field
- NNE-OTH/Other/Non-Nuclear Energy
3 Approved without Funding
VNIIEF, Russia, N. Novgorod reg., Sarov
- Russian Academy of Sciences / Physical Technical Institute, Russia, St Petersburg
- Lawrence Livermore National Laboratory, USA, CA, Livermore
Project summaryAs is known, pulsed power technologies for civil applications have been widely em-ployed for the past decade. Many industries and national laboratories, and universities are involved in the research in order to find civil applications for pulsed power technologies, which were earlier used for defense purposes.
The most promising trends in peaceful use of pulsed power technologies providing a high-energy storage are the following:
- Transmutation of Nuclear Waste
- Organic Destruction in Mixed Waste
- Flue Gas Cleanup
- Water Treatment
- Material Processing (including polymers)
- Food Processing
- Workpieces Shaping by Magnetic Compression or Expanding
- Paint Stripping and Surface Modification By High Intensity Light
- Surface and Materials Modifications by Electron and Ion Beams
- Pollution, Biological and Toxic Waste Reduction
- Electrically Assisted Chemical Reactions
- Powder Fabrication for Powder Metallurgy
- Rock Fragmentation
- and others .
The switch is one of the crucial units of any pulsed power facility. Therefore, rather strict, and sometimes contradictory, requirements are imposed on it. The switch should be reliable, with a long lifetime and cost-effective, i.e. it should not be very expensive. On the other hand, the switch is to be operational at high pulsed power (or energy), for which high operational voltages and currents are necessary.
Basically, switches of two types, i.e. gas-discharge and semiconductor, are used in or-der to provide switching of pulsed power.
The possibility to increase the energy transferred through gas-discharge switches un-der high pressure is limited by the erosion of electrodes occurring as a result of the arc stage of the discharge. Gas-discharge devices under low pressure (with the pressure in the working volume less than 1 atm.), e.g. pulsed hydrogen thyratrons, pseudo-spark gaps, ig-nitrons, triggered vacuum switches, have limited capabilities of increasing the transferred energy. Thyratrons are not suitable for transferring high energies because of a considerable internal release of energy, while the up-to-date pseudo-spark gaps exist only in the form of laboratory prototypes. As to high-power ignitrons, their main drawback is a short lifetime, as well as the use of the cathode made of mercury, which is rather hazardous for the envi-ronment. In addition, in case of increasing the current transferred trough a triggered vac-uum switch, the bulk discharge converts into the arc discharge causing erosion of elec-trodes.
Recently, semiconductor switches compete with gas-discharge devices more and more successfully because they have a longer lifetime and a more stable operation. Semiconduc-tor switches are operational, when connected to the circuit both in parallel or in series. Therefore, their working currents and voltages vary widely, so facilitating attaining of many goals of pulsed power systems.
The highest transferred energy (or power) is defined by effectiveness of using of work-ing area of a semiconductor switch. As is known, a high-power silicon thyristor is the most suitable and widely employed switch for microsecond times. Though, these switches have disadvantage feature of localizing the initiation process in the area, which is near to the controlled electrode and is 0.1 - 0.2 mm wide, as well as they provide a comparatively slow propagation of initiation (0.05 - 0.l mm/us) at the area of thyristor. Thus, this is quite a strong restriction on the permissible magnitude and increase velocity of the transferred current.
For the past 10 years a new class of semiconductors was developed, i.e. reversed switched dinistors (RSD) providing a uniform and simultaneous initiation of the whole area of the semiconductor. This operational mode allows switching greater current as compared to thyristors.
In 50-60s, electron vacuum tubes were replaced by semiconductors in electronics. The use of RSD may be a comparable breakthrough in pulsed power engineering.
Prototypes of RSD are produced in Russia, but their permissible operational modes and complicated triggering circuitry are not very well researched. Besides, some aspects of manufacturing technology need to be optimized.
The scientific and technical approach and methodology of the RSD research are based on publications of the Project inpidual participants [2,3], and their presentations at the international conferences . The Project participants have designed an RSD switch with the peak current up to 200 RA.
The project of development of a high-power RSD switch will contribute to the solu-tion one of the most significant fundamental problems of civil pulsed power technology, i.e. designing of a reliable switch, which would be superior to other similar devices as to committed energy (power), and lifetime.
The project technological challenge is to develop a solid state semiconductor switch with the peak operational current up to 500RA (with the duration up to 1ms), switch-on time 2.0±0.2 us, charge transferred up to 130 C per shot, lifetime not less than 20,000 shots.
Scope of Work
The Project is planned to be fulfilled in three stages. At the first stage, the develop-ment of RSD switch manufacturing technology, research of parallel operation of RSD stacks, and designing of a reliable initiation unit will be stressed. The result of the first Project stage is expected to be the development of a prototype of a high power RSD switch.
At the second stage, the aforementioned prototypes will be tested. There are several methods of integrating the switch and the pumping circuit into the main discharge contour. Therefore, it is necessary to select optimal configuration for different operational modes of the switch. It is required to define the highest performance of the switch, i.e. maximum working and permissible voltages, maximum peak current, maximum transferred energy, and charge per one shot. The possibility of the technology improvement is to be studied in order to increase the thermal power dissipation in the semiconductor. The result of the second Project stage is expected to be the determination of the permissible operational modes of the switch.
At the third Project stage, the work will be focused on the one of the above men-tioned modes in order to define the service life of the switch. The issue of RSD switch cost is to be regarded as well. Potential customers, i.e. RSD switch producers, are to be searched. The possibility of the RSD manufactory technology transfer is to be considered, as well as that of the technology improvement. The RSD production is to be estimated from economical and marketing viewpoints. The result of the third Project stage is the commercialization of the product.
Possible Role of Foreign Collaborators
The Project participants are successfully collaborating with Lawrence Livermore Na-tional Laboratory, California, USA, in the aforementioned area.
VNIIEF is greatly interested in the Project fulfillment jointly with this laboratory, as well as other U.S. laboratories and industries companies.
1. M.Kristiansen "Pulsed Power Applications"/9-th IEEE International Pulsed Power Conf., Albuquerque, New Mexico, June 1993, p.p.6-10.
2. Tuchkevich V.M., Grekhov I.V. "New technique of high power switching by semicon-ductor devices" L., "Nauka", 1988.
3. Grekhov I.V., Korotkov S.V., Yakovchuk N.S. "Study of RSD in high current pulse modes" Elektrotechnika, n.3, 1986, pp.44-46.
4. Galakhov I.V., Gudov S.N., Kirillov G.A., Murugov V.M., Osin V.A., Zolotovski V.I. Chumakov G.N., Kovtun V.I., Martynenko V.A., D.Larson. Switching of high-power current pulses up to 250ka and submillisecond duration using new silicon devices-reverse switched dinistors//10th IEEE Inter.Pulsed Power Conf. - Albuquerque, July 1995, p.p.
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