Comment on "On the spatial and temporal resolution of ion temperature measurements based on neutral beam scattering"

The discrepancies found by Donné and Barbian [A. J. H. Donné and E. P. Barbian, Rev. Sci. Instrum. 58 (1987)] can be attributed principally to the choice of experimental and technical limits, basic assumptions, and definitions

Breakdown voltage estimation of a supercritical nitrogen plasma switch

Supercritical fluids (SCFs), characterized by a high pressure and high density, combine the advantages of gasses and liquids: high ability of mass transfer and high heat transfer. SCFs have a high potential as an electrical switching medium owing to their high breakdown strength, quick self healing, no bubble formation, high heat capacity, high heat conductivity, low viscosity, and low impact to the environment. In this work the thermodynamic characteristics of supercritical fluids are introduced. An experimental analysis of electrical breakdown phenomena of a supercritical plasma switch with pressure up to 180 bar is presented, focusing on the breakdown voltage variation as a function of the fluid pressure, gap width of the electrodes and fluid flow rate through the gap. A new design of a supercritical switch, with flexible gap width, flushing velocity, and repetitive voltage source is introduced

Breakdown voltage estimation of a supercritical nitrogen plasma switch

Supercritical fluids (SCFs), characterized by a high pressure and high density, combine the advantages of gasses and liquids: high ability of mass transfer and high heat transfer. SCFs have a high potential as an electrical switching medium owing to their high breakdown strength, quick self healing, no bubble formation, high heat capacity, high heat conductivity, low viscosity, and low impact to the environment. In this work the thermodynamic characteristics of supercritical fluids are introduced. An experimental analysis of electrical breakdown phenomena of a supercritical plasma switch with pressure up to 180 bar is presented, focusing on the breakdown voltage variation as a function of the fluid pressure, gap width of the electrodes and fluid flow rate through the gap. A new design of a supercritical switch, with flexible gap width, flushing velocity, and repetitive voltage source is introduced

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

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 1010 shots (~106 C) 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, respectively). For up to 450 pulses/s (pps), pre-firing can be prevented by increasing the gap pressure (up to 2.5 and 7 bars, respectively), no gas flush is required. Above 450 pps, up to 820 pps, a forced gas flow of maximal 35 Nm3/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 µs, respectively. For 20 kV average switching voltage these values are: 30–160 and 4–50 µs. During a test run of 2.5 h (at 100 Hz, 0.75 J/pulse) the feasibility of the switch was proved, and the switching voltage jitter was less than 0.7%. ©2005 American Institute of Physic

Hot biogas conditioning using pulsed corona

A new technology area for pulsed corona is hot biogas cleaning, important in view of the growing interest in biomass gasification. Our work concentrates on the development and optimization of pulsed electrical methods for treatment of thermally generated biogas. Corona energized by narrow voltage pulses (100 kV) makes a well ordered and concentrated deposition possible of electrical energy from a circuit into a hot polluted gas. The created plasmas can break down various contaminants. Successful introduction of pulsed corona for industrial processes very much depends on the reliability of high-voltage and pulsed power technology and on the efficiency of energy transfer. In addition, we must achieve adequate electromagnetic compatibility (EMC)

Efficiency and reliability of a repetitive pulse source for continuous pulsed corona processes

Successful introduction of pulsed corona for industrial applications depends very much on the reliability of the high-voltage and pulsed power technology, as well as on the efficiency of energy transfer from the AC-mains to the corona discharge.Furthermore adequate electromagnetic compatibility (EMC) should be achieved between high-voltage pulse source and surrounding equipment. A prototype of an industrial high-voltage pulse source which closely meets these demands has been developed

Decomposition of VOCs in a continuous high-voltage pulsed corona process

To decompose VOCs (volatile organic compounds) in an air stream several new technologies arc emerging. We are using a corona reactor for decomposing these VOCs. The advantage of our pulsed corona process is the energy efficiency with which the VOCs decompose. To examine the reactor, a model is developed which can describe the conversion of the VOCs in our industrial proto type high-voltage pulsed corona reactor