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High Power Electric Propulsion (HiPEP) is a variation of
ion thruster
An ion thruster, ion drive, or ion engine is a form of electric propulsion used for spacecraft propulsion. An ion thruster creates a cloud of positive ions from a neutral gas by ionizing it to extract some electrons from its atoms. The i ...
for use in nuclear electric propulsion applications.
, which was canceled in 2005.
Theory
The HiPEP thruster differs from earlier ion thrusters because the
xenon
Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
ions are produced using a combination of
microwave
Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...
and
magnetic
Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, m ...
fields. The
ionization
Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged at ...
is achieved through a process called
Electron Cyclotron Resonance
Electron cyclotron resonance (ECR) is a phenomenon observed in plasma physics, condensed matter physics, and accelerator physics. It happens when the frequency of incident radiation coincides with the natural frequency of rotation of electrons in ...
(ECR). In ECR, the small number of free electrons present in the neutral gas gyrate around the static magnetic field lines. The injected microwaves' frequency is set to match this gyrofrequency and a resonance is established. Energy is transferred from the right-hand
polarized portion of the
microwave
Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...
to the electrons. This energy is then transferred to the bulk gas/
plasma via the rare - yet important - collisions between electrons and neutrals. During these collisions, electrons can be knocked free from the neutrals, forming ion-electron pairs. The process is a highly efficient means of creating a plasma in low density gases. Previously the electrons required were provided by a
hollow cathode.
Specifications
The thruster itself is in the 20-50 kW class, with a
specific impulse
Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine, such as a rocket engine, rocket using propellant or a jet engine using fuel, generates thrust. In general, this is a ratio of the ''Impulse (physics), ...
of 6,000-9,000 seconds, and a propellant throughput capability exceeding 100 kg/kW.
The goal of the project, as of June 2003, was to achieve a
technology readiness level
Technology readiness levels (TRLs) are a method for estimating the maturity of technologies during the acquisition phase of a program. TRLs enable consistent and uniform discussions of technical maturity across different types of technology. TR ...
of 4-5 within 2 years.
The pre-prototype HiPEP produced 670
milli
''Milli'' (symbol m) is a unit prefix in the metric system denoting a factor of one thousandth (10−3). Proposed in 1793, and adopted in 1795, the prefix comes from the Latin , meaning ''one thousand'' (the Latin plural is ). Since 1960, the pre ...
newton
Newton most commonly refers to:
* Isaac Newton (1642–1726/1727), English scientist
* Newton (unit), SI unit of force named after Isaac Newton
Newton may also refer to:
People
* Newton (surname), including a list of people with the surname
* ...
(mN) of thrust at a power level of 39.3 kW using 7.0 mg/s of reaction mass giving a specific impulse of 9620 s.
Downrated to 24.4 kW, the HiPEP used 5.6 mg/s of reaction mass giving a specific impulse of 8270 s and 460 mN of thrust.
Project and development history
Phase 1 of HiPEP development concluded in early 2003.
[''HiPEP Project'' Jan 2004]
/ref> Conceptual Design of the thruster was completed, and individual component testing concluded. A full-scale laboratory thruster was constructed for Phase 2 of the HiPEP's development. However, with cancellation of the Jupiter Icy Moon Orbiter mission in 2005, HiPEP's development also came to a halt. Before cancellation, HiPEP completed a 2000 hour wear test.
See also
* Exploration of Jupiter
The exploration of Jupiter has been conducted via close observations by robotic spacecraft, automated spacecraft. It began with the arrival of ''Pioneer 10'' into the Moons of Jupiter, Jovian system in 1973, and, , has continued with eight furth ...
* List of spacecraft with electric propulsion
* Solar electric propulsion
Solar electric propulsion (SEP) is the combination of solar cells and electric thrusters to propel a spacecraft through outer space. This technology has been exploited in a variety of spacecraft designs by the European Space Agency (ESA), ...
References
External links
NASA GRC Media Packet on HiPEP
*
{{spacecraft propulsion
Ion engines