Direct Energy, 2018a

4 1.2 Preview of Topics
Math through Calculus I is used in the rst part of the book, and math
through Calculus III (including partial derivatives) is used in the second
part. Many topics in this text are discussed qualitatively. No attempt
is made to be mathematically rigorous, and proofs are not given. The
physics of devices is emphasized over excessive mathematics. Additionally,
all physical systems will be discussed semiclassically, which means that
explanations will involve electrons and electromagnetic elds, but the waveparticle
duality of these quantities will not be discussed. While quantum
mechanical, quantum eld theoretical, and other more precise theories exist
to describe many physical situations, semiclassical discussions will be used
to make this book more easily accessible to readers without a background
in quantummechanics.
Chapters 2-10comprisetherst part of this book. As mentioned
above, they survey various direct energy conversion processes which convert
to or fromelectricity and which do not involve magnets and coils. Table
1.1 lists many of the processes studied along with where in the text they
are discussed, and Table 1.2 lists some of the devices detailed. This text
is not intended to be encyclopedic or complete. Instead, it is intended
to highlight the physics behind some of the most widely available and
accessible energy conversion devices which convert to or fromelectrical
energy. One way to understand energy conversion devices used to convert
to or from electricity is to classify them as most similar to capacitors,
inductors, resistors, or diodes. While not all devices t neatly in these
categories, many do. The second column of Table 1.2 lists the category for
various devices. Similarly, energy conversion processes may be capacitive,
inductive, resistive, or diode-like.
Capacitive energy conversion processes are discussed in Chapters 2 and
3. Capacitors, piezoelectric devices, pyroelectric devices, and electro-optic
devices are discussed. A piezoelectric device is a device which converts
mechanical energy directly to electricity or converts electricity directly to
mechanical energy [6] [3]. A material polarization and voltage develop
when the piezoelectric device is compressed. A pyroelectric device converts
a temperature dierential into electricity [6]. The change in temperature
induces a material polarization and a voltage in the material. Electro-optic
devices convert an optical electromagnetic eld to energy of a material polarization.
In these devices, an external optical eld typically froma laser
induces a material polarization and a voltage across the material. Chapters
4 and 5 discuss inductive energy conversion devices including antennas,
Hall eect devices, and magnetohydrodynamic devices. An antenna converts
electrical energy to an electromagnetic eld or vice versa. A Hall
eect device converts a magnetic eld to or from electricity. A magnetohy-