![]() Actually, the current Is is not constant with U, taking values higher than those predicted by the previous expression. In this expression A is the cross section area of the diode and A* is the Richardson constant=120A/cm2/K2. It is given by the expression I S= AA* T 2exp(- qF B/KT). This current is known as the saturation current, which in spite of being based on different physical mechanisms than those related to the p-n diodes, has a similar meaning (it is greater in Schottky diodes). The reversed current is mainly determined by those electrons in the metal that may overcome the barrier given by qF B, which are nearly independent on the value of the applied voltage U. The voltage U is taken as positive when applied from the metal to the semiconductor. When the diode is reversed polarized (U<0), the electric field (directed from the semiconductor towards the metal) increases, meaning that the barrier for the electrons coming from the semiconductor, q(V c0-U), increases. Therefore, the device corresponds to a non-ohmic or rectifier type contact. Near the contact, there is a depletion charge zone formed by the ionized donor atoms in the semiconductor. On the other hand, the potential barrier seen by the electrons within the metal is given by qF B=W sm-W af, where W sm is the metal work function and W af is the semiconductor electro-affinity. The barrier seen by the electrons in the semiconductor is the contact potential metal-semiconductor, qV co. Considering a metal-n semiconductor heterojunction, the work function is generally greater for the metal than for the semiconductor. The Schottky diode is a rectifier contact. ![]() Using AC circuit theory, the no load readings will give you the magnetization branch components, and the locked rotor test will give you the stator and rotor resistance and reactance. the readings are voltage, current and power at no load and at locked rotor cases. But, be very careful as the motor will burn if you went more. You will reach that amount of current at a very low value of the voltage, may be 6% of the rated voltage. Having your meters already connected start increasing the voltage very carefully form zero up to reaching the maximum allowed current given in the name-plate. After you lock the rotor, you need to set the voltage of the variable AC source to zero before you supply the motor. Whereas, in the rotor locking test, you need to lock the rotor mechanically, and can not apply the full voltage. In the no load test you apply the full voltage to the motor and leave it run freely while you take the readings. But these tests require a variable AC voltage source, and besides the Voltmeter and Ammeter, you need to use a Watt-meter. ![]() Hi, You need to do open circuit (No load) and short circuit (Rotor mechanical locking) tests. Ideal are short wires to some opto coupler and having an optical transmission wherever possible. Our experience was to connect the shield of BNC wires to the plasma device ground is favorable. Any electromagnetic stray radiation is always an issue. I guess the laser and CCD camera can be operated completely separated from the plasma device ground - but ensure a sufficient isolation there might occur rather high potential (which might be an argument to run at the same reference potential). For the diagnostics you have to decide connected to some different ground in the lab or attach to the plasma device. At this stage you can test if your computer are properly running when the plasma is triggered. I guess they have to run on the same ground like you plasma chamber - so they have to be isolated from the power grid via a transformer. Then add your 'plasma chamber hardware' like the pulse generator. So first you have to take your plasma device and make one well defined groung connection.
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