176 unifying physics of accelerators, lasers and plasma
be used. Overall, synchrotrons are a viable choice and they
are being used in many proton therapy facilities around the
world.
9.4 Plasma acceleration of protons and ions —
motivation
The motivation for developing laser plasma acceleration
techniques for beam therapy can be defined by the following
factors. On the one hand, there are advantages to using protons instead of X-rays for certain tumors, particularly in pediatric cases, where use of protons significantly reduces the
probability of tumor recurrence or side effects due to lower
dose for non-target tissues. On the other hand, widespread
use of proton therapy facilities is limited by their overall cost.
Proton therapy systems require 250 MeV beams (or above
330–350 MeV when protons are also used for diagnostic imaging). Such systems, especially the beam delivery
gantries, are large and expensive (see Fig. 9.4). The cost and
size arguments are even more pronounced for heavy ion therapy systems based on the use of carbon ions, which create
certain therapeutic advantages.
Meanwhile, laser plasma acceleration has demonstrated
rapid progress, delivering several GeV in energy of quasi monoenergetic electron beams and more than 100 MeV proton
beams. The progress is due to advances in lasers, where a
CPA laser beam of a few hundred TW or around a PW (corresponding, e.g., to 400 J energy in 400 ns or 30 J in 30 fs), when
focused to a 5 μm spot, can create an intensity on the order of
10 25 W/m 2 — which is suitable for proton plasma acceleration. Such lasers, while still bulky and expensive, are rapidly
improving and will become more efficient and compact in the
future.
Ultimately, the desire to create compact laser plasma acceleration proton therapy systems is one of the main motivations for developing plasma acceleration of protons.
9.5 Regimes of proton laser plasma acceleration
In this section, we will very briefly describe several different
regimes (mechanisms) of laser-driven proton acceleration.
We will start with a discussion of an already classical
mechanism called sheath acceleration, or TNSA — target normal sheath acceleration. As we will see, this classical method
provides protons with too large an energy spread and poor
scaling with laser power.
We will then follow up on more recent and promising
mechanisms that rely on radiation pressure acceleration, specif
be used. Overall, synchrotrons are a viable choice and they
are being used in many proton therapy facilities around the
world.
9.4 Plasma acceleration of protons and ions —
motivation
The motivation for developing laser plasma acceleration
techniques for beam therapy can be defined by the following
factors. On the one hand, there are advantages to using protons instead of X-rays for certain tumors, particularly in pediatric cases, where use of protons significantly reduces the
probability of tumor recurrence or side effects due to lower
dose for non-target tissues. On the other hand, widespread
use of proton therapy facilities is limited by their overall cost.
Proton therapy systems require 250 MeV beams (or above
330–350 MeV when protons are also used for diagnostic imaging). Such systems, especially the beam delivery
gantries, are large and expensive (see Fig. 9.4). The cost and
size arguments are even more pronounced for heavy ion therapy systems based on the use of carbon ions, which create
certain therapeutic advantages.
Meanwhile, laser plasma acceleration has demonstrated
rapid progress, delivering several GeV in energy of quasi monoenergetic electron beams and more than 100 MeV proton
beams. The progress is due to advances in lasers, where a
CPA laser beam of a few hundred TW or around a PW (corresponding, e.g., to 400 J energy in 400 ns or 30 J in 30 fs), when
focused to a 5 μm spot, can create an intensity on the order of
10 25 W/m 2 — which is suitable for proton plasma acceleration. Such lasers, while still bulky and expensive, are rapidly
improving and will become more efficient and compact in the
future.
Ultimately, the desire to create compact laser plasma acceleration proton therapy systems is one of the main motivations for developing plasma acceleration of protons.
9.5 Regimes of proton laser plasma acceleration
In this section, we will very briefly describe several different
regimes (mechanisms) of laser-driven proton acceleration.
We will start with a discussion of an already classical
mechanism called sheath acceleration, or TNSA — target normal sheath acceleration. As we will see, this classical method
provides protons with too large an energy spread and poor
scaling with laser power.
We will then follow up on more recent and promising
mechanisms that rely on radiation pressure acceleration, specif