Use of a new type of propellant for electric propulsion

Abstract

This invention relates to the use of natural uranium hexafluoride (UF6) as a propellant in electric propulsion systems.

Description

Technical Field

[0001] The present invention relates to the use of a new type of propellant for electric propulsion, particularly space electric propulsion.

[0002] Generally, propulsion depends on the momentum exchange between the ejected substance and the propulsion body, and the ejected substance can be composed of:

[0003] High-temperature gases resulting from the exothermic combustion reaction of a propellant containing fuel and an oxidizer, and these gases are ejected by high-temperature expansion through a nozzle, which corresponds to chemical propulsion in this case; or Charged particles derived from a plasma generated from a propellant, and the energy for generating the plasma and accelerating the ions of this plasma for ejection is energy of electrical origin, which corresponds to electric propulsion in this case.

[0004] Electric propulsion, also called plasma propulsion or ion propulsion, can achieve a high ejection speed by separating the energy source and the ejected substance, and thereby, different from chemical propulsion, can achieve a very low propellant consumption. When electric propulsion is used in the space field, more specifically in artificial satellite propulsion, it is possible to reduce the mass of the propelled artificial satellite and thus its launch cost, or further extend the mission period and increase its impact. In this way, despite having a lower thrust level than chemical propulsion, electric propulsion enables maneuvers and tasks that would otherwise be difficult to achieve by enabling savings in capabilities and costs.

[0005] Currently, electric propulsion is mainly and operationally provided by two relatively similar technologies, namely the gridded electric thruster and the Hall effect thruster. These two technologies differ in the way they generate the electric field that gives rise to ion ejection. The electric field is generated by a grid with two polarities in the gridded electric thruster, and in the Hall effect electric thruster, it is generated by a combination of a magnetic field and the electrostatic potential difference between the anode and the cathode.

[0006] These electric propulsion systems can use different types of propellants, including:

[0007] Noble gases, such as xenon (the most commonly used), or krypton or argon; Solid propellants, such as iodine, magnesium, or zinc.

[0008] Electric propulsion can also be provided by so-called "electronegative thrusters," although they are still in the prototype stage at present. These thrusters use both positive and negative ions for thrust, which traditionally requires the management of two propellants: one propellant capable of generating positive ions (e.g., argon) and another capable of generating negative ions (e.g., sulfur hexafluoride) under similar pressures. However, the use of two types of propellants results in excess weight that is detrimental to propulsion performance. [Overview of the project] [Problems that the invention aims to solve]

[0009] Taking existing technologies into consideration, the inventors of the present invention aimed to provide a novel propellant that can be used efficiently in the field of electric propulsion, more specifically in space electric propulsion. This propellant can be used as a substitute for propellants already used in this field, and more precisely, can be used in all types of electric propulsion systems, particularly in electro-negative electric propulsion systems, without requiring two separate propellants. [Means for solving the problem]

[0010] Thus, the present invention relates to the use of natural uranium hexafluoride (UF6) as a propellant in electric propulsion systems, and more specifically, in space electric propulsion systems.

[0011] The term "propellant" can also be called "propellant gas."

[0012] Traditionally, natural uranium hexafluoride corresponds to uranium hexafluoride having an isotopic composition that includes low abundances of lighter isotopes of uranium, more specifically, 0.6% to 0.8% 235 Includes U

[0013] Natural uranium hexafluoride, as a propellant in electric propulsion, has the following advantages: - Vapor pressure at which sublimation limits are reached at approximately ambient temperature and pressure. - Significantly superior thrust at the set power level. This is because UF6 gas is significantly heavier (352 g / mol) than xenon (131 g / mol). - Control of the density of the uranium hexafluoride being transported is solely by temperature. This is because the highly stable uranium hexafluoride sublimes at room temperature, and therefore can be transported in a crystalline form, eliminating the need for control of liquefied or cryogenic gases. - A simplified ground test in which the vacuum in the test chamber is achieved by cryogenics rather than by a pump. The handling of uranium hexafluoride is well known to those skilled in the nuclear fuel cycle. - It is usable in all types of electric propulsion systems, especially in electronegative electric propulsion systems. This is because uranium hexafluoride undergoes an ionization process that produces a positive ion (here, UF5). + ) and anions (here, F - This is because it can produce both of the above. - It must be usable for all types of spaceflight except those involving high gravity. In particular, it must be usable for spaceflight aimed at orbital changes, satellite reorientation, interplanetary travel, and object avoidance. [Modes for carrying out the invention]

[0014] The present invention will be described with respect to the following examples.

[0015] A successful test was conducted using natural uranium hexafluoride in a Hall effect electric propulsion system with a power output of approximately 1 kilowatt.

[0016] Furthermore, the particularly high ionization cross-section can accommodate the wide range of available power levels for Hall effect thrusters available on the market.

Claims

1. Natural uranium hexafluoride (UF) as a propellant in electric propulsion systems 6 Use.

2. The use according to claim 1, wherein the electric propulsion device is a space electric propulsion device.

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