High-speed repetitive pellet injector for plasma fueling of magnetic confinement fusion devices

Combs, S. K.; Baylor, L. R.; Foust, C. R.; Gouge, M.J.; Milora, S.L.; Frattolillo, A.; Gasparotto, M.; Migliori, S.; Scaramuzzi, F.; Angelone, G.; Baldarelli, M.; Capobianchi, M.; Domma, C.; Ronci, G.

doi:10.1109/fusion.1993.518279

Cited by 4 publications

(4 citation statements)

References 22 publications

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“…A facility was assembled at ORNL, combining an existing ORNL piston extruder and an ENEA repeating TSG [13], [14]. Sequences of up to 20 solid D2 pellets (limited by the capacity of the extruder reservoir) were launched with a repetition rate of up to  1 Hz and speeds up to  2.5 km/s [15], [16], [17], [18]. A component was discovered to be crucial for these achievements; it was a special "spring-loaded" relief valve [19], developed by the ENEA team, placed at the gun breech and capable of suitably tailoring the rising edge of the pressure pulse to prevent pellets from starting to move prematurely (thus producing almost the same effect of increasing the breakaway pressure, which is very low in the case of extruded pellets).…”

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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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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“…The injector presently has the capability to inject 100 pellets into a single plasma discharge but is being upgraded to produce up to 400 pellets with better repeatability of pellet size [4]. The injected pellet speeds are nominally 600 m/s with sizes ranging from 4 to 12 mbar-1 per pellet (2 -7 x 1G20 atoms per pellet).…”

Section: Tritium Pellet Injector For Tftrmentioning

confidence: 99%

“…A program to upgrade the present ORNL centrihge injector technology to longer pulse operation (up to 400 pellets per discharge) is described by Foster et al [3]. A collaboration between ORNL and ENEA-Frascati in the development of a repeating two-stage light gas gun based on an extrusion type pellet feed system is described by Combs et al [4].…”

Section: Introductionmentioning

confidence: 98%

“…The recent emphasis has been in the areas of (1) tritium pellet injector development in support of TFTR deuterium-tritium (DT) operation, (2) long pulse centrifuge pellet injector development for Tore Supra and ITER high throughput applications, (3) modification of the JET repeating pneumatic pellet injector for installation on DIII-D, (4) repeating two-stage light gas gun development (for anticipated higher speed ITER application at 2.5-5 k d s ) , and (5) e-beam rocket accelerator concept for future ultrahigh-speed applications. In this paper we describe recent developments and experimental applications with emphasis on items 1-3.…”

Section: Introductionmentioning

confidence: 99%

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Pellet injector development and experiments at ORNL

Baylor

Argo

Barber

et al.

15th IEEE/NPSS Symposium. Fusion Engineering

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The development of pellet injectors for plasma fueling of magnetic confinement fusion experiments has been under way at Oak k d g e National Laboratoty (ORNL) for the past 15 years. Recently, ORNL provided a tritium-compatible four-shot pneumatic injector for the Tokamak Fusion Test Reactor (TFTR) based on the in situ condensation technique that features three single-stage gas guns and an advanced two-stage light gas gun driver. In another application, ORNL supplied the Tore Supra tokamak with a centrifuge pellet injector in 1989 for pellet fueling experiments that has achieved record numbers of injected pellets into a discharge. Work is progressing on an upgrade to that injector to extend the number of pellets to 400 and improve pellet repeatability. In a new application, the ORNL three barrel repeating pneumatic injector has been returned from JET and is being readied for installation on the DIII-D device for fueling and enhanced plasma performance experiments.In addition to these experimental applications, ORNL is developing advanced injector technologies, including high-velocity pellet injectors, tritium pellet injectors, and long-pulse feed systems. The two-stage light gas gun and electron-beam-driven rocket are the acceleration techniques under investigation for achieving high velocity. A tritium proof-of-principle (TPOP) experiment has demonstrated the feasibility of tritium pellet production and acceleration. A new tritium-compatible, extruder-based, repeating pneumatic injector is being fabricated to replace the pipe gun in the TPOP experiment and will explore issues related to the extrudability of tritium and acceleration of large tritium pellets. The tritium pellet formation experiments and development of long-pulse pellet feed systems are especially relevant to the International Tokamak Engineering Reactor (ITER).

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