Ali Abdou | Zewail City of Science and Tech. (original) (raw)

Papers by Ali Abdou

The ARIES-AT study was initiated to assess the potential of high-performance tokamak plasmas toge... more The ARIES-AT study was initiated to assess the potential of high-performance tokamak plasmas together with advanced technology in a fusion power plant and to identifying physics and technology areas with the highest leverage for achieving attractive and competitive fusion power in order to guide fusion R&D. The 1000-MWe ARIES-AT design has a major radius of 5.2 m, a minor radius of 1.3 m, a toroidal β of 9.2% (β N = 5.4) and an on-axis field of 5.6 T. The plasma current is 13 MA and the current-drive power is 35 MW. The ARIES-AT design uses the same physics basis as ARIES-RS, a reversed-shear plasma. A distinct difference between ARIES-RS and ARIES-AT plasmas is the higher plasma elongation of ARIES-AT (κ x = 2.2) which is the result of a "thinner" blanket leading to a large increase in plasma β to 9.2% (compared to 5% for ARIES-RS) with only a slightly higher β N . ARIES-AT blanket is a simple, low-pressure design consisting of SiC composite boxes with a SiC insert for flow distribution that does not carry any structural load. The breeding coolant (Pb-17Li) enters the fusion core from the bottom, and cools the first wall while traveling in the poloidal direction to the top of the blanket module. The coolant then * Corresponding author.

ARIES-AT is a 1000MWe conceptual fusion power plant design with a very low projected cost of elec... more ARIES-AT is a 1000MWe conceptual fusion power plant design with a very low projected cost of electricity. The design contains many innovative features to improve both the physics and engineering performance of the system. From the safety and environmental perspective, there is greater depth to the overall analysis than in past ARIES studies. For ARIES-AT, the overall spectrum of off-normal

IEEE Transactions on Plasma Science, 2011

The six-phase Lee model code is used to fit the computed current waveform to the measured current... more The six-phase Lee model code is used to fit the computed current waveform to the measured current waveform of INTI plasma focus (PF; 2.2 kJ at 12 kV), a T2 PF device, operated as a source of neon soft X-ray (SXR) with optimum yield around 2 torr of neon. The characteristic He-like and H-like neon line SXR pulse is measured using a pair of SXR detectors with selected filters that, by subtraction, has a photon energy window of 900 to 1550 eV covering the region of the characteristic neon SXR lines. From the analysis of the fitted current and the measured SXR pulses, the characteristic neon SXR pulses are correlated to the pinch dynamics, and the subsequent slightly harder SXR pulses are correlated to the anomalous resistance phase. The characteristic neon SXR yield is measured; the pulse has a duration of 25 ns. The characteristic neon SXR typically starts 10 ns before the pinch phase and continues through the end of the 10-ns pinch phase, tailing into the anomalous resistance phase. Harder SXR pulses, probably Bremsstrahlung, are correlated to the anomalous resistance phase, with the main pulse occurring nearly 200 ns after the characteristic neon SXR pulse.

Kansas State University (KSU) dense plasma focus (DPF) is a 2.5-kJ DPF machine newly commissioned... more Kansas State University (KSU) dense plasma focus (DPF) is a 2.5-kJ DPF machine newly commissioned at the Plasma Radiation Physics Laboratory at KSU. The machine was designed to be used as a multiradiation source for applications in nuclear science and engineering. Neutrons are emitted from deuterium-deuterium (D-D) fusion reactions during high-power electric discharges at 17 kV, 140 kA, and 5 mbar. The machine circuit parameters were calculated using the short-circuit test. The emitted neutrons were measured using several radiation detection techniques. The 2.45-MeV characteristic D-D neutron energy was confirmed using the time-of-flight technique using a BC-418 plastic scintillator. The maximum neutron yield was roughly measured to be 2.8 × 10 8 neutrons per shot using a set of BTI BD-PND bubble detectors. Moreover, the neutron yield variation with pressure was measured and compared with the computed neutron yield using Lee model. Finally, the measured current showed good agreement with Lee six-phase model.

Journal of Fusion Energy, 2012

The fast pulsed electric discharge current drives all physical processes in the plasma focus devi... more The fast pulsed electric discharge current drives all physical processes in the plasma focus device; in turn all physical processes in the focus affect the current waveform. Thus the discharge current waveform is the most important indicator of plasma focus performance. This underlies the importance of properly measuring, processing and interpreting the discharge current waveform. This paper reports the measurement of fast pulsed discharge current by the Rogowski coil, in two different modes: the current transformer, "I" mode, and current derivative, "Idot" mode. The processing and interpretation of recorded current waveform to obtain useful information about the physical processes in the plasma focus device are discussed. The current transformer with a large number of turns and a sub-1 Ohm terminator has good high frequency response, necessary for the sharp current dip region when dI/dt exceeds 2×10 11 A/s. However the signal is "noisy" in the current dip region. Several methods to extract the current dip from the noise are discussed and examples of how low pass filters affect the signals are shown. The dI/dt coil, the Rogowski coil in "Idot" mode, with a few turns terminated by 50-Ohm is also described.

In dense plasma focus (DPF) machines, the highpressure (HP) regime of operation can be used as al... more In dense plasma focus (DPF) machines, the highpressure (HP) regime of operation can be used as alternative technique to short-circuit (SC) test as the current sheet motion is minimal. The SC test was performed to get the right values for the static parameters of the machine. HP shots of more than 30 mbar were performed on the 2.5-kJ Kansas State University DPF machine to determine the deviation of HP values from SC values in computed static inductance and resistance. The test was performed using various gases over a wide range of molecular/atomic mass, starting from hydrogen as the lightest gas up to argon. It was found that the deviation in static inductance and resistance computed from HP method is inversely proportional to gas molecular mass at a certain pressure. The heavy gases like neon and argon were found to give the most accurate results. At 60 mbar of argon, the inductance deviation was 6.5%, and the resistance deviation was 14%. It was found also that increasing gas pressure over 30 mbar using heavy gases like Ar or Ne gives no effective improvement on the computed static impedance. Snowplow model was used to predict the axial position and the axial speed of the current sheet during the HP regime. The model showed that the average axial speed in heavy gases like argon was 0.8 cm/μs, whereas in hydrogen, it was 1.6 cm/μs. Index Terms-Axial speed, high-pressure (HP) discharge, plasma focus, plasma resistance, snowplow model, static inductance.

The six-phase Lee model code was developed to compute the anomalous resistance phase (RAN) follow... more The six-phase Lee model code was developed to compute the anomalous resistance phase (RAN) following the pinch phase in a plasma focus (PF) discharge. One important method to check such modeling is to look at the soft X-ray (SXR) emission time profile and to correlate this to the PF dynamics. A two-channel filtered SXR spectrometer coupled with an Excel-based analytical template was recently developed to speed up the correlation process. Using this system, we have determined that the neon PF typically operates in a normal (N) mode in which it emits characteristic He-like H-like neon line SXR (in a photon energy window of 900-1550 eV) reproducibly and efficiently. The characteristic neon line SXR pulse straddles the pinch duration starting strongly 10 ns before the start of the pinch, then diminishes through the 10-ns pinch and tails off into the subsequent RAN1 phase. We present the correlated time profiles of shots operating in the efficient N mode as well as, for comparison, poor shots, which are distinctly different in SXR time profiles. The profiles indicate the difference in dynamics of normal and poor shots. Statistics are presented as well as comparison of the yields from the numerical experiments and measurements. In the series that were studied the proportion of N-mode operation ranges from 70% in one series to 80% in another series over pressure range 1-4 torr. At 2 torr, it was found that 90% recorded the normal N profile. The results reinforce the view that while the Lee Model code incorporates the correct physics in its sequence of phases, refinement is needed to extend the radiative phase to the period before the pinch.

2013 Abstracts IEEE International Conference on Plasma Science (ICOPS), 2013

Dense plasma focus machines have been recently divided according to the value of static inductanc... more Dense plasma focus machines have been recently divided according to the value of static inductance into high and low inductance types. The Kansas State University dense plasma focus machine (KSU-DPF) is a 2.5kJ device with 90nH static inductance. The KSU-DPF is characterized by a relatively long compression phase that reaches more than 500ns in some cases. The time of flight technique has been used to determine the energy of the axially emitted deuterons at various deuterium gas pressures. The spatial distribution of the beam has been studied by means of faraday cups (FCs). Four FCs were distributed at 0, 10, 20, 30 degrees from the axial direction at 14cm distance from the top of the anode. The intensity of the deuteron beam was found to be maximum around 4mbar and then decreases gradually with the pressure. The average energy of the deuteron beam increases with the pressure in the range of a fraction of a mbar up to 1.5mbar, where the energy reaches an optimum value of more than 100keV. The energy then decreases with gas pressure. The spatial variation of the deuteron beam intensity was plotted at different gas pressures between 0.5mbar up to 8mbar.

Solid-State Electronics, 1986

ABSTRACT

Plasma focus devices with low static inductance L 0 (type T1) are found to be well modeled by the... more Plasma focus devices with low static inductance L 0 (type T1) are found to be well modeled by the 5-phase Lee code; whereas those with high L 0 (type T2) are found to have an extended dip ED beyond the regular dip RD modeled by the code. Differentiating factors based on inductance and inductive energy ratios are found and the physics explained. To model type T2's, anomalous resistance terms are proposed extending the model to 6 phases. These anomalous resistance terms represent the plasma instabilities that occur during and after the pinch phase. The fitted terms are experimental results derived from the measured current waveform. An example is tested to validate the method.

The ARIES-AT study was initiated to assess the potential of high-performance tokamak plasmas toge... more The ARIES-AT study was initiated to assess the potential of high-performance tokamak plasmas together with advanced technology in a fusion power plant and to identifying physics and technology areas with the highest leverage for achieving attractive and competitive fusion power in order to guide fusion R&D. The 1000-MWe ARIES-AT design has a major radius of 5.2 m, a minor radius of 1.3 m, a toroidal β of 9.2% (β N = 5.4) and an on-axis field of 5.6 T. The plasma current is 13 MA and the current-drive power is 35 MW. The ARIES-AT design uses the same physics basis as ARIES-RS, a reversed-shear plasma. A distinct difference between ARIES-RS and ARIES-AT plasmas is the higher plasma elongation of ARIES-AT (κ x = 2.2) which is the result of a "thinner" blanket leading to a large increase in plasma β to 9.2% (compared to 5% for ARIES-RS) with only a slightly higher β N . ARIES-AT blanket is a simple, low-pressure design consisting of SiC composite boxes with a SiC insert for flow distribution that does not carry any structural load. The breeding coolant (Pb-17Li) enters the fusion core from the bottom, and cools the first wall while traveling in the poloidal direction to the top of the blanket module. The coolant then * Corresponding author.

ARIES-AT is a 1000MWe conceptual fusion power plant design with a very low projected cost of elec... more ARIES-AT is a 1000MWe conceptual fusion power plant design with a very low projected cost of electricity. The design contains many innovative features to improve both the physics and engineering performance of the system. From the safety and environmental perspective, there is greater depth to the overall analysis than in past ARIES studies. For ARIES-AT, the overall spectrum of off-normal

IEEE Transactions on Plasma Science, 2011

The six-phase Lee model code is used to fit the computed current waveform to the measured current... more The six-phase Lee model code is used to fit the computed current waveform to the measured current waveform of INTI plasma focus (PF; 2.2 kJ at 12 kV), a T2 PF device, operated as a source of neon soft X-ray (SXR) with optimum yield around 2 torr of neon. The characteristic He-like and H-like neon line SXR pulse is measured using a pair of SXR detectors with selected filters that, by subtraction, has a photon energy window of 900 to 1550 eV covering the region of the characteristic neon SXR lines. From the analysis of the fitted current and the measured SXR pulses, the characteristic neon SXR pulses are correlated to the pinch dynamics, and the subsequent slightly harder SXR pulses are correlated to the anomalous resistance phase. The characteristic neon SXR yield is measured; the pulse has a duration of 25 ns. The characteristic neon SXR typically starts 10 ns before the pinch phase and continues through the end of the 10-ns pinch phase, tailing into the anomalous resistance phase. Harder SXR pulses, probably Bremsstrahlung, are correlated to the anomalous resistance phase, with the main pulse occurring nearly 200 ns after the characteristic neon SXR pulse.

Kansas State University (KSU) dense plasma focus (DPF) is a 2.5-kJ DPF machine newly commissioned... more Kansas State University (KSU) dense plasma focus (DPF) is a 2.5-kJ DPF machine newly commissioned at the Plasma Radiation Physics Laboratory at KSU. The machine was designed to be used as a multiradiation source for applications in nuclear science and engineering. Neutrons are emitted from deuterium-deuterium (D-D) fusion reactions during high-power electric discharges at 17 kV, 140 kA, and 5 mbar. The machine circuit parameters were calculated using the short-circuit test. The emitted neutrons were measured using several radiation detection techniques. The 2.45-MeV characteristic D-D neutron energy was confirmed using the time-of-flight technique using a BC-418 plastic scintillator. The maximum neutron yield was roughly measured to be 2.8 × 10 8 neutrons per shot using a set of BTI BD-PND bubble detectors. Moreover, the neutron yield variation with pressure was measured and compared with the computed neutron yield using Lee model. Finally, the measured current showed good agreement with Lee six-phase model.

Journal of Fusion Energy, 2012

The fast pulsed electric discharge current drives all physical processes in the plasma focus devi... more The fast pulsed electric discharge current drives all physical processes in the plasma focus device; in turn all physical processes in the focus affect the current waveform. Thus the discharge current waveform is the most important indicator of plasma focus performance. This underlies the importance of properly measuring, processing and interpreting the discharge current waveform. This paper reports the measurement of fast pulsed discharge current by the Rogowski coil, in two different modes: the current transformer, "I" mode, and current derivative, "Idot" mode. The processing and interpretation of recorded current waveform to obtain useful information about the physical processes in the plasma focus device are discussed. The current transformer with a large number of turns and a sub-1 Ohm terminator has good high frequency response, necessary for the sharp current dip region when dI/dt exceeds 2×10 11 A/s. However the signal is "noisy" in the current dip region. Several methods to extract the current dip from the noise are discussed and examples of how low pass filters affect the signals are shown. The dI/dt coil, the Rogowski coil in "Idot" mode, with a few turns terminated by 50-Ohm is also described.

In dense plasma focus (DPF) machines, the highpressure (HP) regime of operation can be used as al... more In dense plasma focus (DPF) machines, the highpressure (HP) regime of operation can be used as alternative technique to short-circuit (SC) test as the current sheet motion is minimal. The SC test was performed to get the right values for the static parameters of the machine. HP shots of more than 30 mbar were performed on the 2.5-kJ Kansas State University DPF machine to determine the deviation of HP values from SC values in computed static inductance and resistance. The test was performed using various gases over a wide range of molecular/atomic mass, starting from hydrogen as the lightest gas up to argon. It was found that the deviation in static inductance and resistance computed from HP method is inversely proportional to gas molecular mass at a certain pressure. The heavy gases like neon and argon were found to give the most accurate results. At 60 mbar of argon, the inductance deviation was 6.5%, and the resistance deviation was 14%. It was found also that increasing gas pressure over 30 mbar using heavy gases like Ar or Ne gives no effective improvement on the computed static impedance. Snowplow model was used to predict the axial position and the axial speed of the current sheet during the HP regime. The model showed that the average axial speed in heavy gases like argon was 0.8 cm/μs, whereas in hydrogen, it was 1.6 cm/μs. Index Terms-Axial speed, high-pressure (HP) discharge, plasma focus, plasma resistance, snowplow model, static inductance.

The six-phase Lee model code was developed to compute the anomalous resistance phase (RAN) follow... more The six-phase Lee model code was developed to compute the anomalous resistance phase (RAN) following the pinch phase in a plasma focus (PF) discharge. One important method to check such modeling is to look at the soft X-ray (SXR) emission time profile and to correlate this to the PF dynamics. A two-channel filtered SXR spectrometer coupled with an Excel-based analytical template was recently developed to speed up the correlation process. Using this system, we have determined that the neon PF typically operates in a normal (N) mode in which it emits characteristic He-like H-like neon line SXR (in a photon energy window of 900-1550 eV) reproducibly and efficiently. The characteristic neon line SXR pulse straddles the pinch duration starting strongly 10 ns before the start of the pinch, then diminishes through the 10-ns pinch and tails off into the subsequent RAN1 phase. We present the correlated time profiles of shots operating in the efficient N mode as well as, for comparison, poor shots, which are distinctly different in SXR time profiles. The profiles indicate the difference in dynamics of normal and poor shots. Statistics are presented as well as comparison of the yields from the numerical experiments and measurements. In the series that were studied the proportion of N-mode operation ranges from 70% in one series to 80% in another series over pressure range 1-4 torr. At 2 torr, it was found that 90% recorded the normal N profile. The results reinforce the view that while the Lee Model code incorporates the correct physics in its sequence of phases, refinement is needed to extend the radiative phase to the period before the pinch.

2013 Abstracts IEEE International Conference on Plasma Science (ICOPS), 2013

Dense plasma focus machines have been recently divided according to the value of static inductanc... more Dense plasma focus machines have been recently divided according to the value of static inductance into high and low inductance types. The Kansas State University dense plasma focus machine (KSU-DPF) is a 2.5kJ device with 90nH static inductance. The KSU-DPF is characterized by a relatively long compression phase that reaches more than 500ns in some cases. The time of flight technique has been used to determine the energy of the axially emitted deuterons at various deuterium gas pressures. The spatial distribution of the beam has been studied by means of faraday cups (FCs). Four FCs were distributed at 0, 10, 20, 30 degrees from the axial direction at 14cm distance from the top of the anode. The intensity of the deuteron beam was found to be maximum around 4mbar and then decreases gradually with the pressure. The average energy of the deuteron beam increases with the pressure in the range of a fraction of a mbar up to 1.5mbar, where the energy reaches an optimum value of more than 100keV. The energy then decreases with gas pressure. The spatial variation of the deuteron beam intensity was plotted at different gas pressures between 0.5mbar up to 8mbar.

Solid-State Electronics, 1986

ABSTRACT

Plasma focus devices with low static inductance L 0 (type T1) are found to be well modeled by the... more Plasma focus devices with low static inductance L 0 (type T1) are found to be well modeled by the 5-phase Lee code; whereas those with high L 0 (type T2) are found to have an extended dip ED beyond the regular dip RD modeled by the code. Differentiating factors based on inductance and inductive energy ratios are found and the physics explained. To model type T2's, anomalous resistance terms are proposed extending the model to 6 phases. These anomalous resistance terms represent the plasma instabilities that occur during and after the pinch phase. The fitted terms are experimental results derived from the measured current waveform. An example is tested to validate the method.