3.3 km/s solid D/sub 2/ single pellet injector for the Frascati Tokamak Upgrade

Frattolillo, E.; Migliori, S.; Angelone, G.; Baldarelli, M.; Domma, C.; Scaramuzzi, F.; Cardoni, P.; Ronci, G.

doi:10.1109/fusion.1991.218746

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…The preliminary tests performed so far also indicate that, for the same value of the pressure peak, the IPI has the potential of achieving higher speeds, as compared with the performance of previous two-stage gun injectors, such as the Single Pellet Injector (SPIN) installed on the FTU in the early 90's [6], which was capable of a maximum speed of 3.3 kmls. This is shown in Fig.…”

Section: A Summary Of Experimental Results Of Previous Campaignsmentioning

confidence: 86%

Advances on the high speed ignitor Pellet Injector (IPI)

Frattolillo

Bombarda

Migliori

et al. 2011

2011 IEEE/NPSS 24th Symposium on Fusion Engineering

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The control of the density profile during the initial plasma current rise is a critical issue to optimize ohmic and fusion heating rates of Ignitor plasmas. Simulations performed with the NGS ablation model, for the reference ignition plasma parameters (neO == niO == 10 21 m-3 , Teo == TiO == 11 keY), indicate that deuterium pellets of a few mm (S; 4 mm) in size injected at 3-4 km/s from the low field side should ensure adequate deep fuelling. ENEA and ORNL are collaborating on the development of a four barrel, two-stage pneumatic injector for the Ignitor experiment, featuring two innovative concepts: (i) the proper shaping of the propellant pressure pulse to improve pellet acceleration, and (ii) the use of fast closing (-9 ms) valves to eliminate the need of large expansion volumes for propellant gas removal. Two independent sub-systems have been built. The ENEA equipment, including four independent two-stage guns (TSG) and pulse shaping valves, the gas removal system, and the associated controls and diagnostics, has been built and thoroughly tested at CRIOTEC, prior to being shipped to ORNL. The ORNL apparatus consists of the cryostat and pellet diagnostics, with related control and data acquisition system. Integration of the two subsystems (except for the gas removal system) has been readily achieved. The present arrangement accommodates both a TSG and a standard propellant valve on each barrel, allowing seamless switching between standard and high-speed operation on any or all gun barrels. Previous joint experiments at ORNL, demonstrated that the two systems match properly, while their respective control systems interface correctly. The injector performed outstandingly, showing excellent repeatability. These preliminary results indicate that, for the same peak pressure, the IPI has the potential of achieving higher speed performance, as compared with those attained by previous high speed injectors, such as the Single Pellet Injector (SPIN) installed on the FTU in the early 90's. Launching sequences at moderate propellant pressure and speeds up to -2.6 kmls were performed with all four barrels; however, it was not possible to observe intact pellets at speeds above 2 km/s. The analysis of experimental data indicate that, at high speeds, the 978-1-4577-0668-41111$26.00

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Section: A Summary Of Experimental Results Of Previous Campaignsmentioning

confidence: 86%

Advances on the high speed ignitor Pellet Injector (IPI)

Frattolillo

Bombarda

Migliori

et al. 2011

2011 IEEE/NPSS 24th Symposium on Fusion Engineering

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“…A more detailed investigation is still ongoing, aimed at optimizing the injection location, and will be published elsewhere as soon as the results will become available. Two-stage pneumatic launchers have already demonstrated their ability to reliably propel solid D 2 pellets in the 3 to 4 km/s range [13][14], if combined with suitable "pipe gun" cryogenic pellet sources (equipped with either one or more launching barrels) [15], as well as to accelerate sequences of extruded D 2 pellets, 2.7 mm in size, at speeds up to 2.5 km/s and frequency of 1 Hz [16,17]. Large D 2 pellets (6 mm) have also been launched at speed up to 2.5 km/s using a pipe-gun injector equipped with a two-stage driver [18].…”

Section: Hfs Injection Of High-speed Pellets Along "Direct-line-of-si...mentioning

confidence: 99%

“…In a pneumatic injector, once the pellets get out of the launching barrel, their free-flight trajectories spread within a given scatter cone. Experiments performed many years ago with the high-speed pellet injectors for the Frascati Tokamak Upgrade (FTU), have shown that the free-flight trajectories of 1.6 mm solid deuterium pellets, travelling at velocities up to  3 km/s, are enclosed within a cone having a vertex angle of about 0.01 rad ( 0.57°) [13]. Actually, the angular distribution width of free-flight high-speed pellets trajectories is an important information to derive a functional design for DEMO.…”

Section: Angular Dispersion Of Free-flight High-speed Pelletsmentioning

confidence: 99%

Injection of high-speed solid D2 pellets using a “Direct-Line-of-Sight” (DLS) guide tube

Frattolillo

Baylor

Day

et al. 2021

Fusion Engineering and Design

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“…In particular, the "in-situ" pellet formation process was optimized to provide accurate control of deuterium freezing parameters; temperatures need to be carefully controlled during pellet formation under a constant D2 gas pressure, and then smoothly lowered to ~7 K and kept stable to ensure good resistance of cryogenic projectiles. This was shown to be a key issue for the attainment of launching speeds in excess of 3 km/s [11], [12].…”

Section: The Enea-ornl High-speed Pellet Injectormentioning

confidence: 99%

Core Fueling of DEMO by Direct Line Injection of High-Speed Pellets From the HFS

Frattolillo

Baylor

Bombarda

et al. 2018

IEEE Trans. Plasma Sci.

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Pellet injection represents to date the most realistic candidate technology for core fueling of a DEMO tokamak fusion reactor. Modelling of both pellet penetration and fuel deposition profiles, for different injection locations, indicates that effective core fuelling can be achieved launching pellets from the inboard high field side at speeds not less than 1 km/s. Inboard pellet fueling is commonly achieved in present tokamaks, using curved guide tubes; however, this technology might be hampered at velocities  1 km/s. An innovative approach, aimed at identifying suitable inboard "direct line" paths, to inject high-speed pellets (in the 3 to 4 km/s range), has been recently proposed as a potential complementary solution. The fuel deposition profiles achievable by this approach have been explored using the HPI2 simulation code. The results presented here show that there are possible geometrical schemes providing good fueling performance. The problem of neutron flux in a direct line of sight injection path is being investigated, though preliminary analyses indicate that, perhaps, this is not a serious problem. The identification and integration of straight injection paths suitably tilted may be a rather difficult task, due to the many constraints and to interference with existing structures. The suitability of straight guide tubes to reduce the scatter cone of high-speed pellets, is therefore of main interest. A preliminary investigation,, aimed at addressing these technological issues, has been recently started. A possible implementation plan, using an existing ENEA-ORNL facility is shortly outlined. Index Terms-DEMO tokamak fusion reactor, HFS highspeed pellet injection, straight guide tubes Manuscript received June 2017. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

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3.3 km/s solid D/sub 2/ single pellet injector for the Frascati Tokamak Upgrade

Cited by 4 publications

References 5 publications

Advances on the high speed ignitor Pellet Injector (IPI)

Advances on the high speed ignitor Pellet Injector (IPI)

Injection of high-speed solid D2 pellets using a “Direct-Line-of-Sight” (DLS) guide tube

Core Fueling of DEMO by Direct Line Injection of High-Speed Pellets From the HFS

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