Bipolar pulse power

A further effect of bipolar pulsed power plasma excitation addresses the disappearing anode effect and thus the long-term stability of reactive sputtering. In conventional reactive DC magnetron operation, the anode gets coated with oxide films. These insulating films give rise to plasma fluctuations... 

Bipolar pulse power (plasma technology) Applying electrical power with a periodic waveform with either an off-portion of the waveform on each cycle or a portion of the waveform having an opposite polarity on each cycle. See also Mid-frequency. 

N. Papadakis et al., Performance of Rechargeable Lithium-Alloy/Metal Disulfide Pulse Power Bipolar Batteries, Proc. IEEE 35th Int. Power Sources Symp., Cherry Hill, N.J., June 22-25, 1992, p. 285. 

I will refer to such waveforms as bipolar power. The discussion may be confused even further by the fact that if you suddenly turn off a negative dc voltage (e.g. Figure 5.8), the inductance in the circuit will cause a positive pulse before the voltage goes to zero. Again, I think this has to be called a bipolar pulse since the electron flow reverses direction. So, to have a pure pulsed negative dc you would have to block the positive reverse current. 

Pulse power Processing power that is only applied for a portion of the total process cycle time. Examples Pulsed bipolar power pulsed dc. 

Fig. 4. Modified X/Y IMPEACH-MBC pulse sequence used for 19F/15N shift correlation according to Ref. 27. The notation of 90° and 180° pulses is as before. The (d/2 — 180°(Y) — d/2) element represents a variable delay that is incremented concurrently with the decrementation of the accordion delay vd. Pulse phases are x, unless specified x = — x 2 = x, — x 3 = x, x, — x, — x = , — x, — x, x. The bipolar gradients Gs flanking the 180°(Y) pulse can be set to arbitrary power levels, and the relative strengths of the coherence selection gradients G and G2 are determined by G2/G1 =2 Yy/Tx-...

Typical power levels in unipolar electrosurgery is about 80 W (500 Q, 200 V, 400 mA rms), in bipolar work 15 W (100 Q, 40 V, 400 mA rms). The frequency content of the sine wave is of course just the repetition frequency, usually around 500 kHz. In pulsed mode, the frequency content is very broad, but most of the energy will be in the frequency band 0.5—5 MHz. In pulsed mode, the peak voltage can reach 5000 V, so insulation in very humid surroundings is a problem. 

Figure 20.11 is an illustration of a reserve Uthium/thionyl chloride battery using a bipolar plate construction. This battery weighs approximately 5.4 kg and has a volume of 2000 cm. Activation of the reserve battery is accomplished by supplying an electric pulse to the battery by firing an electric squib or actuator or by some mechanical means. This type of reserve battery has been used chiefly in artillery shells for electronic fuze power supplies and in missiles for the electronic power supply. Therefore the electric pulse can be supplied prior to firing or at the time of launch. However, for artillery fiize power supplies, the battery is usually activated by the launch acceleration (set back) and/or the spin forces. The accel-... 

Fig. 1 A dual-chamber pulse generator and two leads. The pulse generator is a hermetically sealed titanium can containing an Lil power source, circuitry (including microprocessor), niobium or tantalum/sapphire feed throughs, and a connector to receive two leads. The lead with the straight distal tip is inserted in the right ventricle while that with the J shape is placed in the right atrial appendage. Both leads are bipolar (two electrodes within the heart). The tiny projections (tines) at the tip help provide fixation for the distal stimulating electrode...

Bipolar batteries have been under development, using boiler plate pressure vessels. Design feasibility has been demonstrated, and the program is now being directed to design and demonstrate bipolar flight batteries for high power pulse applications. 

The most common definition of direct current (dc) is that the electrons flow only in one direction in a circuit, while in alternating current (ac) the direction of flow of electrons (current) in the circuit periodically reverses direction. This gets somewhat confused in some power supplies where there are negative pulses and positive pulses generated by separate circuits (Figure 5.8). This is sometimes called bipolar dc, which, I think, is an oxymoron. 

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