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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. It creates thrust by accelerating ions using electricity.
An ion thruster ionizes a neutral gas by extracting some electrons out of ...
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 with the 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 ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ra ...
and
magnetic
Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particl ...
fields. The ionization 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 m ...
(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 ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ra ...
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 (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...
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 mN of thrust at a power level of 39.3 kW using 7.0 mg/s of fuel giving a specific impulse of 9620 s.
Page 8 of the September 2004 HiPEP report NASA/TM—2004-213194 Downrated to 24.4 kW, the HiPEP used 5.6 mg/s of fuel giving a specific impulse of 8270 s and 460 mN of thrust.
Project and development history
Phase 1 was early 2003.[''HiPEP Project'' Jan 2004]
/ref>
Current status
See also
*List of spacecraft with electric propulsion
In chronological order, spacecraft are listed equipped with electric space propulsion. This includes both cruise engines and/or thrusters for attitude and orbit control. It is not specified whether the given engine is the sole means of propulsion ...
*Solar electric propulsion
Solar electric propulsion (SEP) refers to 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 by the European Space Agency (ESA), th ...
*Exploration of Jupiter
The exploration of Jupiter has been conducted via close observations by automated spacecraft. It began with the arrival of ''Pioneer 10'' into the Jovian system in 1973, and, , has continued with eight further spacecraft missions. All of thes ...
References
External links
NASA GRC Media Packet on HiPEP
*
{{spacecraft propulsion
Ion engines