State-of-the-art insulator and electrode materials for use in high current high energy switching

Donaldson, A. L.; Engel, T.G.; Kristiansen, M.

doi:10.1109/20.22522

Cited by 20 publications

(8 citation statements)

References 2 publications

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“…If that were the case and if the depth of the erosion Seen in these tests were averaged over the brush portion of the electrode, then the erosion rate would be about 4-6 mg per coulomb. Low erosion of non-thoriated tungsten electrodes has been noted by other authors [5,6,7]. We found thoriated tungsten to be a low erosion material for electrodes and expect it is better than non-thoriated tungsten.…”

Section: B Plasma Brush Formationmentioning

confidence: 51%

Materials evaluation for use as plasma brush electrodes with hybrid armatures

1995

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AWucf-There is a strong motivation to develop a railgun armature which will function as a non-arc, solid contact armature throughout the complete projectile acceleration to launch process. Solid contact armatures are more ef'ficient in converting electrical to kinetic energy and generally cause less erosion of the rail. Considerable effort is being directed towards designing armatures capable of reaching 3+km/s while avoiding transition from a solid to an arcing contact. While nearly 2 W s has been achieved in a non-arcing contact, it may be inevitable that an arcing contact will be unavoidable during the finial acceleration to full desired velocities. At present most solid armatures are fabricated from aluminum or copper. While aluminum or copper might be good choices for solid contacts, this paper introduces the possibility that a different material will better serve as an electrode in an arcing contact. For example upon transition, the'conduction of current through a plasma brush results in rapid erosion of aluminum armatures. When transition to an arcing contact occurs, we have found that magnetic pressure can be used to minimize the length of the plasma brush, which helps minimize the mass of the armature and improves the overall effiiency of energy transfer to the projectile payload. However, Short length brushes result in high current density, and high erosion rates. We have measured the erosion of aluminum surfaces when used as a cathode and as an anode while magnetically containing the brushes. We have also measured the erosion of a thoriated tungsten (W-Th) cathode when used in the same manner. The erosion of the W-Th was more about a factor of 100 less than the A.! This paper presents these results and a discussion of electron emission for AI, Cu, W and W-Th.

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Section: B Plasma Brush Formationmentioning

confidence: 51%

Materials evaluation for use as plasma brush electrodes with hybrid armatures

1995

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“…Also the electrode erosion rate is low according to the result found in literatures [21,22]. If necessary, brass can be easily replaced by other materials.…”

Section: Spark Gap Switchesmentioning

confidence: 85%

“…Donaldson et al conducted comprehensive investigations on the electrode erosion [22,[24][25]. They developed a law using a thermal model to scale the electrode erosion rate (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…According to their observations, the electrode erosion rate exhibits a similar trend as function of pulse parameters [24], as predicted by their scaling law. There exist three different regions [22,24]: (1) when the typical parameter is below a certain threshold, the erosion is dominated by the vaporization and increases linearly (in the logarithmic coordinates) with the parameter; (2) when the parameter is above a certain value, the erosion is dominated by the ablation and has the same dependence on the parameter as in region (1), but with one order higher magnitude; (3) there is a narrow transient area between (1) and (2); in this region the erosion increases fast from the first regime to the second regime. From their findings, one can see that the erosion rate will decrease when the parameter decreases, no matter which regime is considered.…”

Section: Discussionmentioning

confidence: 99%

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An Efficient, Repetitive Nanosecond Pulsed Power Generator with Ten Synchronized Spark Gap Switches

Liu

Pemen

Hoppe

et al. 2009

IEEE Trans. Dielect. Electr. Insul.

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“…This can be accomplished by a good material choice or by minimizing energy transfer per shot, for example, by using several switches in parallel. 4 As a result of data found in literature, 12,14,15 brass was chosen as electrode material since the erosion rate is low compared to other materials and the material is cheap. The "moving arc" principle 15 can also ensure reduced evaporation per shot since for moving arcs the hot-spot temperature and thus the evaporation rate decreases.…”

Section: Spark-gap Switch Designmentioning

confidence: 99%

Long lifetime, triggered, spark-gap switch for repetitive pulsed power applications

Winands

Liu

Pemen

et al. 2005

Review of Scientific Instruments

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In this article a critical component for pulsed power applications is described: the heavy-duty switch. The design of a coaxial, high repetition rate, large average power, and long lifetime spark-gap switch is discussed. The switch is used with a fail-free LCR trigger circuit. Critical issues for switch design are presented together with experimental results. It is observed that the switch has a good stability, and its lifetime is estimated to be in the order of 10 10 shots ͑ϳ10 6 C͒ at 10 J / pulse, 60 kV and 100 ns pulses. Measurements were performed with 20 and 34 kV average switching voltage ͑100 ns pulses, energy per pulse 0.4 and 0.75 J, respectively͒. For up to 450 pulses/ s ͑pps͒, pre-firing can be prevented by increasing the gap pressure ͑up to 2.5 and 7 bars, respectively͒, no gas flush is required. Above 450 pps, up to 820 pps, a forced gas flow of maximal 35 Nm 3 /h, is required for stable operation. Measurements on the time delay and jitter of the switch demonstrate that these values are influenced by pressure, flow, and pulse repetition rate. For 34 kV average switching voltage the time delay and time jitter vary between 35 and 250 and 10 and 80 s, respectively. For 20 kV average switching voltage these values are: 30-160 and 4 -50 s. During a test run of 2.5 h ͑at 100 Hz, 0.75 J / pulse͒ the feasibility of the switch was proved, and the switching voltage jitter was less than 0.7%.

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State-of-the-art insulator and electrode materials for use in high current high energy switching

Cited by 20 publications

References 2 publications

Materials evaluation for use as plasma brush electrodes with hybrid armatures

Materials evaluation for use as plasma brush electrodes with hybrid armatures

An Efficient, Repetitive Nanosecond Pulsed Power Generator with Ten Synchronized Spark Gap Switches

Long lifetime, triggered, spark-gap switch for repetitive pulsed power applications

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