page_title: Woodward effect
section_title: Mach-Lorentz Thruster
hierarchical_section_title: Woodward effect / Experiments / Test devices / Mach-Lorentz Thruster
caption_attribution_description: English: Photograph of the 2006 Woodward effect test article.
context_page_description: The Woodward effect, also referred to as a Mach effect, is part of a hypothesis proposed by James F. Woodward in 1990. The hypothesis states that transient mass fluctuations arise in any object that absorbs internal energy while undergoing a proper acceleration. Harnessing this effect could generate a reactionless thrust, which Woodward and others claim to measure in various experiments.
  Hypothetically, the Woodward effect would allow for field propulsion spacecraft engines that would not have to expel matter. Such a proposed engine is sometimes called a Mach effect thruster or a Mach Effect Gravitational Assist drive. So far, experimental results have not strongly supported this hypothesis, but experimental research on this effect, and its potential applications, continues.
  The Space Studies Institute was selected as part of NASA's Innovative Advanced Concepts program as a Phase I proposal in April 2017 for Mach Effect research. The year after, NASA awarded a NIAC Phase II grant to the SSI to further develop these propellantless thrusters.
context_section_description: A former type of Mach effect thruster was the Mach-Lorentz thruster (MLT). It used a charging capacitor embedded in a magnetic field created by a magnetic coil. A Lorentz force, the cross product between the electric field and the magnetic field, appears and acts upon the ions inside the capacitor dielectric. In such electromagnetic experiments, the power can be applied at frequencies of several megahertz, unlike PZT stack actuators where frequency is limited to tens of kilohertz. The photograph shows the components of a Woodward effect test article used in a 2006 experiment.
  However, a problem with some of these devices was discovered in 2007 by physicist Nembo Buldrini, who called it the Bulk Acceleration Conjecture:
  What [Nembo Buldrini] pointed out was that given the way the transient terms of the Mach effect equation are written – in terms of the time-derivatives of the proper energy density – it is easy to lose sight of the requirement in the derivation that the object in which the mass fluctuations occur must be accelerating at the same time. In some of the experimental cases, no provision for such "bulk" acceleration was made.¹⁵ As an example, the capacitors affixed to the tines of the tuning fork in the Cramer and the students' experiments made no provision for such an acceleration. Had the tuning fork been separately excited and an electric field applied to the capacitor(s) been properly phased, an effect might have been seen. But to simply apply a voltage to the capacitors and then look for a response in the tuning fork should not have been expected to produce a compelling result.
  Other examples could be cited and discussed. Suffice it to say, though, that after Nembo focused attention in the issue of bulk accelerations in the production of Mach effects, the design and execution of experiments changed. The transition to that work, and recent results of experiments presently in progress, are addressed in the next chapter.
  ¹⁵ By "bulk" acceleration we are referring to the fact that the conditions of the derivation include that the object be both accelerated and experience internal energy changes. The acceleration of ions in the material of a capacitor, for example, does not meet this condition. The capacitor as a whole must be accelerated in bulk while it is being polarized.
  
   
  — James F. Woodward, in Making Starships and Stargates, Springer 2013, page 132.
caption: Photograph of the 2006 Woodward effect MLT test article.
exif: {}