Physik und Technik von Radiofrequenz‐Ionentriebwerken

Volkmar, Chris; Holste, K.; Simon, Jens

doi:10.1002/vipr.201600624

Cited by 4 publications

(5 citation statements)

References 8 publications

(2 reference statements)

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“…Thus, the electron temperature can be expected to rise due to the larger mean free path between collisions. This claim is confirmed by the results of Volkmar [38], whose simulation results for a smaller ion source driven with xenon showed a rise of the electron temperature at constant flow with increasing beam current. Both electron temperature and electron density influence the ratio of double-charged ions I 2+ to singly-charged ions I + .…”

Section: Iodinesupporting

confidence: 60%

“…The fraction of power which is actually coupled into the plasma remains however unknown. A global model from Volkmar [38] for a smaller ion source of the same type using xenon as propellant yielded a coupling efficiency between 35% and 45% from coil to plasma. Assuming a comparable coupling factor for the thruster used yields that approximately 25%-40% of the applied DC-power may be coupled into the plasma.…”

Section: Iodinementioning

confidence: 99%

“…However, the fluctuations are typically considered small in this type of thruster. At least, in most global models describing such thrusters successfully a constant electron temperature and a constant plasma density are assumed inside the plasma vessel [24,38]. The total uncertainty of the abundance measurement, without considering this possible inhomogeneity, is assessed to be a few percent only.…”

Section: Iodinementioning

confidence: 99%

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Molecular propellants for ion thrusters

Dietz

Gärtner

Koch

et al. 2019

Plasma Sources Sci. Technol.

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There is no ideal atomic propellant for ion thrusters. Xenon commonly used as propellant becomes resource-critical in light of electric propulsion commercialization. Combining these considerations leads to seeking alternatives to xenon as propellant. In this review, we summarize the current literature on molecular propellants. We define two classes of molecules, group I and II, comprising diatomic molecules and more complex molecules, respectively. We identify basic properties which a candidate molecule belonging to either group, I or II, should possess in order to be suitable as molecular propellant. We discuss the pits and traps in testing such candidate molecules inside a thruster on the basis of our experiences with iodine (a member of group I) and adamantane (a member of group II). The thruster system needs to be individually adopted for each propellant candidate in order to enable a thorough testing inside the thruster. The same holds for optimizing the thruster’s performance when fed with a new propellant because the microscopic processes occurring inside the plasma will differ from molecule to molecule. These circumstances make such testing time-consuming and costly. To accelerate systematic screening of the vast number of molecular species in terms of suitability as propellant, we propose a screening and evolution procedure based on combining chemical engineering and fundamental physical measurements.

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Section: Iodinesupporting

confidence: 60%

Section: Iodinementioning

confidence: 99%

Section: Iodinementioning

confidence: 99%

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Molecular propellants for ion thrusters

Dietz

Gärtner

Koch

et al. 2019

Plasma Sources Sci. Technol.

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“…(Xenon is the preferred inert gas because of its high atomic weight and thus high momentum.) [3,4] `demanding large forces, e.g. to accelerate a rocket out of the Earth's gravitational field, where chemical propulsion engines are used to burn liquid or solid propellants and accelerate the exhaust gases up to supersonic speed [5].…”

Section: I Pmentioning

confidence: 99%

“…The required suction speed, the volume flow at the inlet of the vacuum system, can be calculated from the mass flow using the equation of state for ideal gases: x the mass flow rate of component x given in kg 3 /h, M .…”

Section: I Pmentioning

confidence: 99%

How vacuum technology enables progress in spaceflight

Heitz

2022

Vak Forsch Prax

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SummaryThe use of spacecraft in space research is based on completely different environmental conditions than here on Earth. In addition to the decreasing gravity and the enormous temperature differences, the vacuum in space must also be taken into account. Since the function, e.g. of the thrusters, under these environmental conditions cannot be simulated with mathematical calculations alone, real tests have to be carried out. Vacuum technology plays an important role here. To maintain the pressure level at the desired value, the vacuum system must extract the exhaust gases from the rocket engine and compress them against atmospheric pressure. In this article, a real project and how Pfeiffer Vacuum experts worked with the customer to develop a solution based on a three‐stage Roots pumping system is described. Both the challenges and the solutions during the development process are highlighted.

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