The feasibility of pellet re-fuelling of a fusion reactor

Chang, C. T.; Jørgensen, L. W.; Nielsen, P.; Lengyel, L.L.

doi:10.1088/0029-5515/20/7/008

Cited by 70 publications

(47 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Injection of high-speed hydrogenic pellets is being considered as a means for fuelling future fusion power reactors of the tokamak type [1,2]. This technique differs from cold-gas inlet at the plasma boundary (i.e.…”

Section: Introductionmentioning

confidence: 99%

Multiple Eigenvalues of the Laplace Operator

Nadirashvili¹

1988

Math. USSR Sb.

View full text Add to dashboard Cite

Initial hydrogen pellet injection experiments have been performed in plasmas characterized by a low particle re-cycle fraction resulting from the action of a poloidal magnetic divertor. As in past experiments, the interaction of the fuel with the plasma is observed to be adiabatic. Moreover, the pellet mass is accounted for in the core plasma density increase, indicating only a small loss of fuel while the pellet transits the divertor scrape-off plasma. The effect of edge re-cycling on the density was studied by comparing divertor (low-re-cycle) and limiter (high-re-cycle) plasmas; the distinction between the two cases is clearest in the edge plasma region where the density decay rates differ most. Particle transport subsequent to pellet injection is less ambiguous for divertor cases, and, by comparing the density profile relaxation and the electron temperature recovery with an empirical transport model that closely approximates the pre-injection plasma conditions, it is concluded that the plasma confinement properties do not deteriorate as a result of pellet injection. The principal difference between central and edge fuelling is demonstrated by a peaking of the density profile and an extended decay time for the density perturbation.

show abstract

Section: Introductionmentioning

confidence: 99%

Multiple Eigenvalues of the Laplace Operator

Nadirashvili¹

1988

Math. USSR Sb.

View full text Add to dashboard Cite

show abstract

“…Effective fueling of diverted discharges requires that the fuel be injected directly into the plasma, at least beyond the scrape off layer. This was first proposed by Lyman Spitzer as early as 1954 and later by Rore [1]. Such methods might include injection of solids, liquid hydrogen, or neutral beam injection.…”

Section: Tokamak Fuelingmentioning

confidence: 99%

“…As an example, a typical reactor might require beam energies of around 100 keV coupled with 10's of kilo amps of current. [1]. This leads to beam powers in the gigawatt range.…”

Section: Tokamak Fuelingmentioning

confidence: 99%

“…The flux term is one quarter of the gas density ,n, times the mean molecular speed V . The average molecular speed is dependent on the temperature and mass of the gas molecule,m, and is given by is given by: 1 The total heat flow to the plate, H, has been calculated for both hydrogen and air and the results are plotted as a function of pressure in figure 3.2.1. The results show that at lxl0-7torr the heat flow is below one milliwatt for both hydrogen and air.…”

Section: Convectionmentioning

confidence: 99%

See 1 more Smart Citation

The design and performance of a twenty barrel hydrogen pellet injector for Alcator C-Mod

Urbahn¹

1994

View full text Add to dashboard Cite

A twenty barrel hydrogen pellet injector has been designed, built and tested both in the laboratory and on the Alcator C-Mod Tokamak at MIT. The injector functions by firing pellets of frozen hydrogen or deuterium deep into the plasma discharge for the purpose of fueling the plasma, modifying the density profile and increasing the global energy confinement time.The design goals of the injector are: 1) Operational flexibility, 2) High reliability, 3) Remote operation with minimal maintenance. These requirements have lead to a single stage, pipe gun design with twenty barrels. Pellets are formed by in-situ condensation of the fuel gas, thus avoiding moving parts at cryogenic temperatures. The injector is the first to dispense with the need for cryogenic fluids and instead uses a closed cycle refrigerator to cool the thermal system components. The twenty barrels of the injector produce pellets of four different size groups and allow for a high degree of flexibility in fueling experiments. Operation of the injector is under PLC control allowing for remote operation, interlocked safety features and automated pellet manufacturing. The injector has been extensively tested and shown to produce pellets reliably with velocities up to 1400 m/sec. During the period from September to November of 1993, the injector was successfully used to fire pellets into over fifty plasma discharges. Experimental results include data on the pellet penetration into the plasma using an advanced pellet tracking diagnostic with improved time and spatial response. Data from the tracker indicates pellet penetrations were between 30 and 86 percent of the plasma minor radius. Line averaged density increases of up to 300 percent were recorded with peak densities of just under 1 × 1021/ m 3, the highest achieved on C-Mod to date. A comparison is made " between the ablation source function derived from tracker data with that predicted by four different variations of the neutral shield model. Results suggest rapid heat flow from the interior of the plasma maintains temperatures on the ablation flux surface. Localized " density perturb_ttions with a specific m=l,n=l structure and location on the q=l flux surface were observed following injection.

show abstract

“…Some mechanism for refueling the burning plasma is needed. Most magnetic fusion reactor concepts have incorporated pellet injection refueling schemes into their designs [10][11][12][13][14][15][16][17][18][19][20][21][22]. Therefore, modeling the pellet-plasma interaction is very important to both alpha particle diagnostics and refueling techniques.…”

Section: Background and Motivation For This Studymentioning

confidence: 99%

The Modeling Of The Interactions Of Pellets With Magnetic Fusion Plasmas For Alpha Particle Diagnostics

Cashlan

Gerdin

Vahala

et al. 1991

IEEE Conference Record - Abstracts. 1991 IEEE International Conference on Plasma Science

View full text Add to dashboard Cite

A model for the interactions of hydrogen and carbon pellets with thermonuclear fusion plasmas has been developed and solved to determine the charge-state spatial distributions in the ablation cloud surrounding the pellet. The ionization is treated in a self-consistent manner in the energy balance and the collisional radiative (CR) model is used to calculate the ionization levels. External plasma electron effects on ionization are included. The electron heat flux is modeled as a multigroup distribution. The channelling of the flow along the field line is treated phenomenologically by restricting the cross-sectional area of the flow. The predictions of the model are compared with the results from the General Atomics experiments on the TEXT tokamak for C+2 and C+3 clouds of definite size. A reasonable agreement for the C+2 cloud is found. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

show abstract

The feasibility of pellet re-fuelling of a fusion reactor

Cited by 70 publications

References 59 publications

Multiple Eigenvalues of the Laplace Operator

Multiple Eigenvalues of the Laplace Operator

The design and performance of a twenty barrel hydrogen pellet injector for Alcator C-Mod

The Modeling Of The Interactions Of Pellets With Magnetic Fusion Plasmas For Alpha Particle Diagnostics

Contact Info

Product

Resources

About