Generation of hydrogen isotopes with an electricpulse hydride injector

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Abstract

An Electric Pulse Hydride Injector (EPHI) designed for safe interim tritium storagehas been developed for the dosed supply of hydrogen isotopes in a time interval ranging fromseveral milliseconds up to hundreds of seconds. The release of gas occurs via current pulsesthrough the active elements of the EPHI, each of which is made of a thin molybdenum foil coatedon both sides with a thin titanium powder layer. The pulses are generated by a twenty sectorcurrent source. With this source the foils can be heated individually or in groups. In this way it ispossible to release a wide spectrum of hydrogen quantities. The shape, height and length of thecurrent pulses can be varied as required to release a predetermined amount of hydrogen.

An extensive parametric study on the performance of the injector has been carried out inthe laboratory. The data obtained have been used for the development of a model thatsatisfactorily describes the injector operation. © 1999 International Association for HydrogenEnergy. Published by Elsevier Science Ltd. All rights reserved.

Introduction

The idea of developing an electrical pulse hydride injector occurred in connection with theneed for a controlled supply of gaseous hydrogen isotopes, i.e., tritium, into large experimental fusioninstallations of the TOKAMAK type. The presently employed gas supply systems for this type ofreactor were originally developed for use with hydrogen and deuterium and use piezo valves asdosage elements. The piezo valve is installed in the gas pipeline and separates a gas at high pressurefrom the fusion chamber at vacuum. To achieve the required gas flow rate into the chamber, gasunder a pressure of a few bar and in an amount, which allows to maintain this pressure over the entiresupply time, is used. Thus, during operation with a deuterium/tritium mixture a substantial inventoryof gaseous tritium needs to be dealt with.

The EPHI is based on different principles. It keeps the hydrogen isotopes in a chemicallybound state on special absorbers. The dosed generation of gas occurs by heating selected absorberswith short, high current pulses. Detailed information on the EPHI is given in [1]. In this work,new data obtained with a new generation EPHI are reported.

Section snippets

Brief description of the EPHI-1C and the experimentalinstallation

EPHI-1C is a new-generation injector of hydrogen isotopes that can generate gas pulses inup to hundreds of s yielding more than 5.1021 molecules per shot. For the operation ofthe injector, the absorbers must first be saturated with hydrogen isotopes. The injector vessel is madeof stainless steel, at the ends of which flanges are welded (Fig. 1) . At equal distances from the flanges, a nozzle is installed on the cylindrical surface of the tube,through which evacuation of the injector, the gas

The main objectives of the experiment and experimentalresults

The main objectives of the present experiments are:

•definition of the conditions under which the titanium coated foils mounted in the injector aresaturated up to a condition, which is defined by the chemical formula TiD;

•investigation of deuterium liberation from the foils;

•quantification of the deuterium absorbed by the foils;

•definition of quasi-equilibrium pressures of deuterium as a function of the current passingthrough the foil and of the titanium saturation with deuterium.In preliminary

Discussion

As apparent from Fig. 4, the principle course of the pressure curves as a functionof time does not vary when the deuterium generation conditions are changed. The rise of pressureis decelerated with time (or number of current pulses) . By increasing the current, the requiredamount of deuterium can be released from the foil within a shorter period of time. For example,whereas at a current of 12 A the first 1 mbar is obtained in about 2200 s and the second 1 mbar inabout 3500 s, at 17 A the time

Conclusion

It is shown that the EPHI concept is suitable for the repeated dosage of hydrogen isotopeswithin a broad range of gas inventories. Prior to technological implementation further work on thelaws of gas saturation and generation is still needed. In addition, the techniques for manufacturingthe foils should be further improved.

References (3)

  • Azizov EA, Kareev YuA, Savotkin AN, Frunze VV, Penzhorn RD, Glugla M. An Electrical PulseHydride Injector (EPHI) for...
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