Paschen Curve - Revision history

Ist165721: Text replacement - "\]" to ""

2015-05-24T19:40:57Z

Text replacement - "\]" to "</math>"

Ist165721: Text replacement - "\[" to " $"$

2015-05-24T18:41:49Z

Text replacement - "\[" to "<math>"

Ist165696: /* Data Analysis */

2013-12-30T16:40:17Z

Data Analysis

Ist165696: /* Protocol */

2013-12-30T16:39:47Z

Protocol

Ist165696: /* Data Analysis */

2013-12-30T16:39:30Z

Data Analysis

Ist165696: /* Protocol */

2013-12-30T16:31:31Z

Protocol

Ist165696: /* Protocol */

2013-12-30T16:30:04Z

Protocol

Ist165696 at 15:22, 30 December 2013

2013-12-30T15:22:09Z

Ist165696: /* Data Analysis */

2013-12-30T15:00:33Z

Data Analysis

Ist165696: /* Experimental Apparatus */

2013-12-30T15:00:15Z

Experimental Apparatus

@@ Line 32: / Line 32: @@
 Using the model for a chain reaction, it can be shown that the breakdown voltage under certain conditions is described by the equation:
-<math> V = \dfrac{a.pd}{\ln(pd) + b} \]
+<math> V = \dfrac{a.pd}{\ln(pd) + b} </math>
 Where (i) \(V\) is the breakdown voltage, (ii) \(p\) is the pressure, and (iii) \(d\) is the gap distance. The constants (iv) \(a\) and (v) \(b\) depend upon the composition of the gas.
@@ Line 50: / Line 50: @@
 As it is, the data is still in raw form. The values in pressure must be multiplied by the gap distance and only after this the experimental data is ready to be adjusted to the equation 1, as seen in figure 5. In order to adjust to a systematic error in the measurements, you should add an extra fitting parameter:
-<math> V = \dfrac{a.(pd + c)}{\ln(pd + c) + b} \]
+<math> V = \dfrac{a.(pd + c)}{\ln(pd + c) + b} </math>
 From the fit \(a\) and \(b\) can be extracted, which can allow the determination of the gas inside the chamber. On the contrary, taking the information regarding the gas inside the chamber, in this case Argon, the data points can be used to determine the distance between the plates by fitting the data to the equation 2.

@@ Line 32: / Line 32: @@
 Using the model for a chain reaction, it can be shown that the breakdown voltage under certain conditions is described by the equation:
-\[ V = \dfrac{a.pd}{\ln(pd) + b} \]
+<math> V = \dfrac{a.pd}{\ln(pd) + b} \]
 Where (i) \(V\) is the breakdown voltage, (ii) \(p\) is the pressure, and (iii) \(d\) is the gap distance. The constants (iv) \(a\) and (v) \(b\) depend upon the composition of the gas.
@@ Line 50: / Line 50: @@
 As it is, the data is still in raw form. The values in pressure must be multiplied by the gap distance and only after this the experimental data is ready to be adjusted to the equation 1, as seen in figure 5. In order to adjust to a systematic error in the measurements, you should add an extra fitting parameter:
-\[ V = \dfrac{a.(pd + c)}{\ln(pd + c) + b} \]
+<math> V = \dfrac{a.(pd + c)}{\ln(pd + c) + b} \]
 From the fit \(a\) and \(b\) can be extracted, which can allow the determination of the gas inside the chamber. On the contrary, taking the information regarding the gas inside the chamber, in this case Argon, the data points can be used to determine the distance between the plates by fitting the data to the equation 2.

@@ Line 48: / Line 48: @@
 The data from a single experiment gives only one point, so the experiment should be repeated several times for different pressures. As with the other e-lab experiment, when the user activates the experiment and the pressure is set, a voltage ramp starts sweeping the electrodes, and the ADC is used to get both current and voltage applied to the electrodes. The software client prints the values in the interface of the voltage, current and pressure during the whole experiment. After that, the user will be able to see a clear transition from 0 to saturation in the current graph. The corresponding point in the voltage is that pressure breakdown similar to the contents of figure 3. After gathering the points of many different pressures, the user will have a data set similar to the one displayed in figure 4. Although there is a very high precision in the determination of the voltage values in the chamber, multiple runs of the experiment under the same conditions will show that there is often a window of about 50V under which the disruption can occur. Therefore this value was used for errors in the fit instead of the error with the ADC.
-As it is, the data is still in raw form. The values in pressure must be multiplied by the gap distance and only after this the experimental data is ready to be adjusted to the equation <!--\ref{paschen_protocol:paschen}-->, as seen in figure 5. In order to adjust to a systematic error in the measurements, you should add an extra fitting parameter:
+As it is, the data is still in raw form. The values in pressure must be multiplied by the gap distance and only after this the experimental data is ready to be adjusted to the equation 1, as seen in figure 5. In order to adjust to a systematic error in the measurements, you should add an extra fitting parameter:
 \[ V = \dfrac{a.(pd + c)}{\ln(pd + c) + b} \]
-From the fit \(a\) and \(b\) can be extracted, which can allow the determination of the gas inside the chamber. On the contrary, taking the information regarding the gas inside the chamber, in this case Argon, the data points can be used to determine the distance between the plates by fitting the data to the equation <!--\ref{paschen_protocol:paschen}-->.
+From the fit \(a\) and \(b\) can be extracted, which can allow the determination of the gas inside the chamber. On the contrary, taking the information regarding the gas inside the chamber, in this case Argon, the data points can be used to determine the distance between the plates by fitting the data to the equation 2.
 =Links=
 *Principles of Plasma Diagnostics, Hutchinson, Cambridge
 *[[Curva de Paschen | Portuguese version (Versão em Português)]]

← Older revision		Revision as of 16:39, 30 December 2013
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	[[File:Paschen_Config.png\|200\|thumb\|Figure 2: Diagram illustrating the variables from the voltage ramp]]		[[File:Paschen_Config.png\|200\|thumb\|Figure 2: Diagram illustrating the variables from the voltage ramp]]
		+	[[File:Paschen_Data_Out.png\|200\|thumb\|Figure 3: Paschen GUI in data output window]]
		+	[[File:Paschen_data_unmodified.png\|200\|thumb\|Figure 4: Fit to probe characteristic equation]]
		+	[[File:Paschen_data_modified_fitted.png\|200\|thumb\|Figure 5: Fit to probe characteristic equation]]

	The breakdown phenomenon can be interpreted as a chain reaction, where one charged particle collides with a neutral one and generates an extra charged particle. If this collision process has a net gain, then there will be a discharge across the electrodes, otherwise the process will decay and the ionization will stop. It is therefore required that energy of the impacting particle exceeds the ionization energy of the neutral particle, so that there is no recombination and this is a function of both the gas pressure and the plates distance.		The breakdown phenomenon can be interpreted as a chain reaction, where one charged particle collides with a neutral one and generates an extra charged particle. If this collision process has a net gain, then there will be a discharge across the electrodes, otherwise the process will decay and the ionization will stop. It is therefore required that energy of the impacting particle exceeds the ionization energy of the neutral particle, so that there is no recombination and this is a function of both the gas pressure and the plates distance.

@@ Line 43: / Line 43: @@
 ==Data Analysis==
-[[File:Paschen_Data_Out.png|200|thumb|Figure 3: Paschen GUI in data output window]]
+The data from a single experiment gives only one point, so the experiment should be repeated several times for different pressures. As with the other e-lab experiment, when the user activates the experiment and the pressure is set, a voltage ramp starts sweeping the electrodes, and the ADC is used to get both current and voltage applied to the electrodes. The software client prints the values in the interface of the voltage, current and pressure during the whole experiment. After that, the user will be able to see a clear transition from 0 to saturation in the current graph. The corresponding point in the voltage is that pressure breakdown similar to the contents of figure 3. After gathering the points of many different pressures, the user will have a data set similar to the one displayed in figure 4. Although there is a very high precision in the determination of the voltage values in the chamber, multiple runs of the experiment under the same conditions will show that there is often a window of about 50V under which the disruption can occur. Therefore this value was used for errors in the fit instead of the error with the ADC.
-The data from a single experiment gives only one point, so the experiment should be repeated several times for different pressures. As with the other e-lab experiment, when the user activates the experiment and the pressure is set, a voltage ramp starts sweeping the electrodes, and the ADC is used to get both current and voltage applied to the electrodes. The software client prints the values in the interface of the voltage, current and pressure during the whole experiment. After that, the user will be able to see a clear transition from 0 to saturation in the current graph. The corresponding point in the voltage is that pressure breakdown similar to the contents of figure 3. After gathering the points of many different pressures, the user will have a data set similar to the one displayed in figure <!--\ref{paschen_protocol:fit1}-->. Although there is a very high precision in the determination of the voltage values in the chamber, multiple runs of the experiment under the same conditions will show that there is often a window of about 50V under which the disruption can occur. Therefore this value was used for errors in the fit instead of the error with the ADC.
+As it is, the data is still in raw form. The values in pressure must be multiplied by the gap distance and only after this the experimental data is ready to be adjusted to the equation <!--\ref{paschen_protocol:paschen}-->, as seen in figure 5. In order to adjust to a systematic error in the measurements, you should add an extra fitting parameter:
 \[ V = \dfrac{a.(pd + c)}{\ln(pd + c) + b} \]

@@ Line 22: / Line 22: @@
 =Protocol=
 The breakdown phenomenon can be interpreted as a chain reaction, where one charged particle collides with a neutral one and generates an extra charged particle. If this collision process has a net gain, then there will be a discharge across the electrodes, otherwise the process will decay and the ionization will stop. It is therefore required that energy of the impacting particle exceeds the ionization energy of the neutral particle, so that there is no recombination and this is a function of both the gas pressure and the plates distance.
@@ Line 32: / Line 34: @@
 Taking into account the fact that there is no remote control over the distance between electrodes, the first step for the user should be to devise the pressure range through which the experiment will be performed. This will determine the number of times you will have to do the experiment. To configure this parameter, you must use the "Gas Pressure" slider. While the experiment is not in use, the vacuum pump will be connected to the main reaction chamber since the last time the experiment was performed until the moment it was activated. Considering that by the end of the experiment the pump down is monitored as it goes down until it reaches a limit of \(0.05 mBar\), the pressure inside the vessel before the experiment starts will always be at least that one. After the experiment begins, the chamber will be filled with Argon gas until the "Gas Pressure" is reached.
 After that, the user can choose the voltage sweeping characteristics by selecting its "Maximum", "Minimum" and "Increase Step", which affect the signal as shown in figure 2. Choosing a bigger step might hide the details but will allow a faster determination of the region at which the breakdown occurs, while a smaller step will provide a higher detail on the determination of the data. It is recommended that the step value remains constant, since the quickly varying signal of the steps makes the breakdown easier and if it changes throughout the experiment the data will not be usable.

← Older revision		Revision as of 15:00, 30 December 2013
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	The state of matter transition from gas into plasma is investigated in this experiment, allowing the study of Paschen's law. This is accomplished through an apparatus similar to the one used by Paschen, in which a voltage is applied to two parallel electrodes surrounded by low pressure gas. The breakdown voltage is determined as a function of pressure and distance separating the two plates.		The state of matter transition from gas into plasma is investigated in this experiment, allowing the study of Paschen's law. This is accomplished through an apparatus similar to the one used by Paschen, in which a voltage is applied to two parallel electrodes surrounded by low pressure gas. The breakdown voltage is determined as a function of pressure and distance separating the two plates.
		+
		+	=Protocol=

	The breakdown phenomenon can be interpreted as a chain reaction, where one charged particle collides with a neutral one and generates an extra charged particle. If this collision process has a net gain, then there will be a discharge across the electrodes, otherwise the process will decay and the ionization will stop. It is therefore required that energy of the impacting particle exceeds the ionization energy of the neutral particle, so that there is no recombination and this is a function of both the gas pressure and the plates distance.		The breakdown phenomenon can be interpreted as a chain reaction, where one charged particle collides with a neutral one and generates an extra charged particle. If this collision process has a net gain, then there will be a discharge across the electrodes, otherwise the process will decay and the ionization will stop. It is therefore required that energy of the impacting particle exceeds the ionization energy of the neutral particle, so that there is no recombination and this is a function of both the gas pressure and the plates distance.

Paschen Curve - Revision history

Ist165721: Text replacement - "\]" to ""

Ist165721: Text replacement - "\[" to ""

Ist165696: /* Data Analysis */

Ist165696: /* Protocol */

Ist165696: /* Data Analysis */

Ist165696: /* Protocol */

Ist165696: /* Protocol */

Ist165696 at 15:22, 30 December 2013

Ist165696: /* Data Analysis */

Ist165696: /* Experimental Apparatus */

Ist165721: Text replacement - "\[" to " $"$