Three separate scenarios of an electrodynamic tether mission at Jupiter following capture of a sp... more Three separate scenarios of an electrodynamic tether mission at Jupiter following capture of a spacecraft (SC) into an equatorial, highly elliptical orbit around the planet, with perijove at about 1.5 times the Jovian radius, are discussed. Repeated application of Lorentz drag on the spinning tether, at the perijove vicinity, can progressively lower the apojove. One mission involves the tethered-SC rapidly and frequently visiting Galilean moons; elliptical orbits with apojove down at the Ganymede, Europa, and Io orbits are in 2:5, 4:9, and 1:2 resonances with the respective moons. About 20 slow flybys of Io would take place before the accumulated radiation dose exceeds 3 Mrad (Si) at 10 mm Al shield thickness, with a total duration of 5 months after capture (4 months for lowering the apojove to Io and one month for the flybys). The respective number of flybys for Ganymede would be 10 with a total duration of about 9 months. An alternative mission would have the SC acquire a low circ...
A new and innovative type of gridded ion thruster, the "Dual-Stage 4-Grid" or DS4G concept, has b... more A new and innovative type of gridded ion thruster, the "Dual-Stage 4-Grid" or DS4G concept, has been proposed and its predicted high performance validated under an ESA research, development and test programme. The DS4G concept is able to operate at very high specific impulse and thrust density values well in excess of conventional 3-grid ion thrusters at the expense of a higher power-to-thrust ratio. This makes it a possible candidate for ambitious missions requiring very high delta-V capability and high power. Such missions include 100 kilowatt-level multi-ton probes based on nuclear and solar electric propulsion to distant Kuiper Belt Object and inner Oort cloud objects, and to the Local Interstellar medium. In this paper, the DS4G concept is introduced and its application to this mission class is investigated. Benefits of using the DS4G over conventional thrusters include reduced transfer time and increased payload mass, if suitably advanced lightweight power system technologies are developed. A mission-level optimisation is performed (launch, spacecraft system design and low-thrust trajectory combined) in order to find design solutions with minimum transfer time, maximum scientific payload mass, and to explore the influence of power system specific mass. It is found that the DS4G enables an 8ton spacecraft with a payload mass of 400 kg, equipped with a 65 kW nuclear reactor with specific mass 25 kg/kW (eg. Topaz-type with Brayton cycle conversion) to reach 200 AU in 23 years after an Earth escape launch by Ariane 5. In this scenario, the optimum specific impulse for the mission is over 10,000 seconds, which is well within the capabilities of a single 65 kW DS4G thruster. It is also found that
A new and innovative type of gridded ion thruster, the "Dual-Stage 4-Grid" or DS4G conc... more A new and innovative type of gridded ion thruster, the "Dual-Stage 4-Grid" or DS4G concept, has been proposed and its predicted high performance validated under an ESA research, development and test programme. The DS4G concept is able to operate at very high specific impulse and thrust density values well in excess of conventional 3-grid ion thrusters at the expense of
Helicon thrusters have recently been considered as possible new electric propulsion (EP) systems ... more Helicon thrusters have recently been considered as possible new electric propulsion (EP) systems thanks to the acceleration mechanism called the "current free double layer" which allows specific impulses up to 1300 s with argon and 4000 s with hydrogen. Although the primary interest of this technology was always regarding primary propulsion, this paper explores the possibility of using the helicon thruster as secondary propulsion system, e.g. station keeping or attitude control onboard satellites from mini to telecommunication class. Such a thruster provides several advantages with respect to EP systems currently in use: (i) consists of very few components, which increases reliability, (ii) thrust and power can be modulated, thus it is versatile, (iii) plasma interacts marginally with the thruster structure, thus erosion is not an issue, and (IV) is light and compact. Numerical analysis has been conducted through a combination of 1-D and 2-D numerical codes. A specific 1-D...
43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2007
The present paper describes an analytical model for the preliminary prediction of the noncavitati... more The present paper describes an analytical model for the preliminary prediction of the noncavitating flow field and performance of helical inducers. The proposed model is based on the traditional troughflow theory approximations with empirical corrections for outlet flow deviation and hydraulic losses due to inlet incidence effects and friction in the blade channels. Unlike most classical models, it allows-even if under still rather restrictive assumptions-for the prediction of the radial and circumferential flow velocity fields at the inducer exit section and for the approximate evaluation of the head coefficient as a function of the flow coefficient in terms of the static pressure rise generated by the inducer. The results are presented of the model validation by comparison with the experimental data obtained for several inducers tested in different facilities worldwide.
Helicon thrusters have recently been considered as possible new electric propulsion (EP) systems ... more Helicon thrusters have recently been considered as possible new electric propulsion (EP) systems thanks to the acceleration mechanism called the "current free double layer" which allows specific impulses up to 1300 s with argon and 4000 s with hydrogen. Although the primary interest of this technology was always regarding primary propulsion, this paper explores the possibility of using the helicon
42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2006
Alta S.p.A. (Italy) and DELTACAT Ltd. (United Kingdom) are conducting a study, funded by the Euro... more Alta S.p.A. (Italy) and DELTACAT Ltd. (United Kingdom) are conducting a study, funded by the European Space Agency, into the development of hydrogen peroxide monopropellant thrusters using advanced catalytic beds. The present paper focuses on the design of two different demonstration thrusters with nominal ratings of 5 N and 25 N. Design requirements and specifications are presented, followed by the main results of a concept study, which was conducted to define the approximate dimensions needed. Some details about the specific design of the two prototypes and the choice of the main components are provided, with particular regard to the sensors and transducers to be used during the experimentation. Different catalytic bed configurations, including pure silver gauzes and pellets coated with manganese oxide or platinum, are going to be tested in the prototype thrusters, in order to find the optimum one for further industrial development. A dedicated test bench, designed and realized by Alta S.p.A. for tests on the thruster prototypes, is also illustrated.
The present paper describes an analytical model for the preliminary prediction of the noncavitati... more The present paper describes an analytical model for the preliminary prediction of the noncavitating flow field and performance of helical inducers. The proposed model is based on the traditional troughflow theory approximations with empirical corrections for outlet flow deviation and hydraulic losses due to inlet incidence effects and friction in the blade channels. Unlike most classical models, it allows-even if under still rather restrictive assumptions-for the prediction of the radial and circumferential flow velocity fields at the inducer exit section and for the approximate evaluation of the head coefficient as a function of the flow coefficient in terms of the static pressure rise generated by the inducer. The results are presented of the model validation by comparison with the experimental data obtained for several inducers tested in different facilities worldwide.
... Angelo Cervone ∗ Alta SpA, 56121 Pisa, Italy Renzo Testa University of Pisa, 56100 Pisa, Ita... more ... Angelo Cervone ∗ Alta SpA, 56121 Pisa, Italy Renzo Testa University of Pisa, 56100 Pisa, Italy Cristina Bramanti and Emilio Rapposelli§ Alta ... performance liquid-propellant rocket fuel feed systems, including the US space shut-tle main engine, the European Ariane 5 engine ...
The present paper illustrates the setup and the preliminary results of an experimental investigat... more The present paper illustrates the setup and the preliminary results of an experimental investigation of cavitation flow instabilities carried out by means of a high-speed camera on a three-bladed inducer in the cavitating pump rotordynamic test facility (CPRTF) at Alta S.p.A. The brightness thresholding technique adopted for cavitation recognition is described and implemented in a semi-automatic algorithm. In order to test the capabilities of the algorithm, the mean frontal cavitating area has been computed under different operating conditions. The tip cavity length has also been evaluated as a function of time. Inlet pressure signal and video acquisitions have been synchronized in order to analyze possible cavitation fluid-dynamic instabilities both optically and by means of pressure fluctuation analysis. Fourier analysis showed the occurrence of a cavity length oscillation at a frequency of 14.7Hz, which corresponds to the frequency of the rotating stall instability detected by me...
Three separate scenarios of an electrodynamic tether mission at Jupiter following capture of a sp... more Three separate scenarios of an electrodynamic tether mission at Jupiter following capture of a spacecraft (SC) into an equatorial, highly elliptical orbit around the planet, with perijove at about 1.5 times the Jovian radius, are discussed. Repeated application of Lorentz drag on the spinning tether, at the perijove vicinity, can progressively lower the apojove. One mission involves the tethered-SC rapidly and frequently visiting Galilean moons; elliptical orbits with apojove down at the Ganymede, Europa, and Io orbits are in 2:5, 4:9, and 1:2 resonances with the respective moons. About 20 slow flybys of Io would take place before the accumulated radiation dose exceeds 3 Mrad (Si) at 10 mm Al shield thickness, with a total duration of 5 months after capture (4 months for lowering the apojove to Io and one month for the flybys). The respective number of flybys for Ganymede would be 10 with a total duration of about 9 months. An alternative mission would have the SC acquire a low circ...
A new and innovative type of gridded ion thruster, the "Dual-Stage 4-Grid" or DS4G concept, has b... more A new and innovative type of gridded ion thruster, the "Dual-Stage 4-Grid" or DS4G concept, has been proposed and its predicted high performance validated under an ESA research, development and test programme. The DS4G concept is able to operate at very high specific impulse and thrust density values well in excess of conventional 3-grid ion thrusters at the expense of a higher power-to-thrust ratio. This makes it a possible candidate for ambitious missions requiring very high delta-V capability and high power. Such missions include 100 kilowatt-level multi-ton probes based on nuclear and solar electric propulsion to distant Kuiper Belt Object and inner Oort cloud objects, and to the Local Interstellar medium. In this paper, the DS4G concept is introduced and its application to this mission class is investigated. Benefits of using the DS4G over conventional thrusters include reduced transfer time and increased payload mass, if suitably advanced lightweight power system technologies are developed. A mission-level optimisation is performed (launch, spacecraft system design and low-thrust trajectory combined) in order to find design solutions with minimum transfer time, maximum scientific payload mass, and to explore the influence of power system specific mass. It is found that the DS4G enables an 8ton spacecraft with a payload mass of 400 kg, equipped with a 65 kW nuclear reactor with specific mass 25 kg/kW (eg. Topaz-type with Brayton cycle conversion) to reach 200 AU in 23 years after an Earth escape launch by Ariane 5. In this scenario, the optimum specific impulse for the mission is over 10,000 seconds, which is well within the capabilities of a single 65 kW DS4G thruster. It is also found that
A new and innovative type of gridded ion thruster, the "Dual-Stage 4-Grid" or DS4G conc... more A new and innovative type of gridded ion thruster, the "Dual-Stage 4-Grid" or DS4G concept, has been proposed and its predicted high performance validated under an ESA research, development and test programme. The DS4G concept is able to operate at very high specific impulse and thrust density values well in excess of conventional 3-grid ion thrusters at the expense of
Helicon thrusters have recently been considered as possible new electric propulsion (EP) systems ... more Helicon thrusters have recently been considered as possible new electric propulsion (EP) systems thanks to the acceleration mechanism called the "current free double layer" which allows specific impulses up to 1300 s with argon and 4000 s with hydrogen. Although the primary interest of this technology was always regarding primary propulsion, this paper explores the possibility of using the helicon thruster as secondary propulsion system, e.g. station keeping or attitude control onboard satellites from mini to telecommunication class. Such a thruster provides several advantages with respect to EP systems currently in use: (i) consists of very few components, which increases reliability, (ii) thrust and power can be modulated, thus it is versatile, (iii) plasma interacts marginally with the thruster structure, thus erosion is not an issue, and (IV) is light and compact. Numerical analysis has been conducted through a combination of 1-D and 2-D numerical codes. A specific 1-D...
43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2007
The present paper describes an analytical model for the preliminary prediction of the noncavitati... more The present paper describes an analytical model for the preliminary prediction of the noncavitating flow field and performance of helical inducers. The proposed model is based on the traditional troughflow theory approximations with empirical corrections for outlet flow deviation and hydraulic losses due to inlet incidence effects and friction in the blade channels. Unlike most classical models, it allows-even if under still rather restrictive assumptions-for the prediction of the radial and circumferential flow velocity fields at the inducer exit section and for the approximate evaluation of the head coefficient as a function of the flow coefficient in terms of the static pressure rise generated by the inducer. The results are presented of the model validation by comparison with the experimental data obtained for several inducers tested in different facilities worldwide.
Helicon thrusters have recently been considered as possible new electric propulsion (EP) systems ... more Helicon thrusters have recently been considered as possible new electric propulsion (EP) systems thanks to the acceleration mechanism called the "current free double layer" which allows specific impulses up to 1300 s with argon and 4000 s with hydrogen. Although the primary interest of this technology was always regarding primary propulsion, this paper explores the possibility of using the helicon
42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2006
Alta S.p.A. (Italy) and DELTACAT Ltd. (United Kingdom) are conducting a study, funded by the Euro... more Alta S.p.A. (Italy) and DELTACAT Ltd. (United Kingdom) are conducting a study, funded by the European Space Agency, into the development of hydrogen peroxide monopropellant thrusters using advanced catalytic beds. The present paper focuses on the design of two different demonstration thrusters with nominal ratings of 5 N and 25 N. Design requirements and specifications are presented, followed by the main results of a concept study, which was conducted to define the approximate dimensions needed. Some details about the specific design of the two prototypes and the choice of the main components are provided, with particular regard to the sensors and transducers to be used during the experimentation. Different catalytic bed configurations, including pure silver gauzes and pellets coated with manganese oxide or platinum, are going to be tested in the prototype thrusters, in order to find the optimum one for further industrial development. A dedicated test bench, designed and realized by Alta S.p.A. for tests on the thruster prototypes, is also illustrated.
The present paper describes an analytical model for the preliminary prediction of the noncavitati... more The present paper describes an analytical model for the preliminary prediction of the noncavitating flow field and performance of helical inducers. The proposed model is based on the traditional troughflow theory approximations with empirical corrections for outlet flow deviation and hydraulic losses due to inlet incidence effects and friction in the blade channels. Unlike most classical models, it allows-even if under still rather restrictive assumptions-for the prediction of the radial and circumferential flow velocity fields at the inducer exit section and for the approximate evaluation of the head coefficient as a function of the flow coefficient in terms of the static pressure rise generated by the inducer. The results are presented of the model validation by comparison with the experimental data obtained for several inducers tested in different facilities worldwide.
... Angelo Cervone ∗ Alta SpA, 56121 Pisa, Italy Renzo Testa University of Pisa, 56100 Pisa, Ita... more ... Angelo Cervone ∗ Alta SpA, 56121 Pisa, Italy Renzo Testa University of Pisa, 56100 Pisa, Italy Cristina Bramanti and Emilio Rapposelli§ Alta ... performance liquid-propellant rocket fuel feed systems, including the US space shut-tle main engine, the European Ariane 5 engine ...
The present paper illustrates the setup and the preliminary results of an experimental investigat... more The present paper illustrates the setup and the preliminary results of an experimental investigation of cavitation flow instabilities carried out by means of a high-speed camera on a three-bladed inducer in the cavitating pump rotordynamic test facility (CPRTF) at Alta S.p.A. The brightness thresholding technique adopted for cavitation recognition is described and implemented in a semi-automatic algorithm. In order to test the capabilities of the algorithm, the mean frontal cavitating area has been computed under different operating conditions. The tip cavity length has also been evaluated as a function of time. Inlet pressure signal and video acquisitions have been synchronized in order to analyze possible cavitation fluid-dynamic instabilities both optically and by means of pressure fluctuation analysis. Fourier analysis showed the occurrence of a cavity length oscillation at a frequency of 14.7Hz, which corresponds to the frequency of the rotating stall instability detected by me...
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Papers by C. Bramanti