Tokamak Physics Experiment

TPX
Tokamak Physics Experiment
Device type	Tokamak
Location	United States
Affiliation	Princeton Plasma Physics Laboratory and others
Technical specifications
Major radius	2.25 m (7 ft 5 in)
Minor radius	0.5 m (1 ft 8 in)
Magnetic field	4.0 T (40,000 G)
Heating power	17.5 MW
Plasma current	2.0 MA
History
Date(s) of construction	Not built
Year(s) of operation	Not built–Not built
Succeeded by	KSTAR

Last updated November 24, 2023

The Tokamak Physics Experiment (TPX) was a plasma physics experiment that was designed but not built. It was designed by an inter-organizational team in the USA led by Princeton Plasma Physics Laboratory. The experiment was designed to test theories about how Tokamaks would behave in a high-performance, steady-state regime.^[1]

Goals

TPX was to be the successor to the Tokamak Fusion Test Reactor (TFTR). While TFTR was designed to achieve Q>1 (more fusion power produced by the plasma than injected into the plasma), TFTR only operated for short pulses, and did not provide data from and experience with plasmas behave like those of an economic Fusion power reactor. Specifically, TPX was designed to fill this need.

TPX was designed to test theories which suggested ways of making a future fusion power reactor compact, economic, and reliable. Specifically, TPX was designed to be near steady state, with pulse lengths of 1,000 seconds (more than 15 minutes). It was designed to operate at high Bootstrap current, meaning that less power would have to be expended driving toroidal current. It was designed to operate at high values of Beta, meaning that it would be able to store more plasma pressure for a given magnetic field. It was designed to operate with a high level of confinement, meaning that less auxiliary heating would be required.^[1]

History

After the cancellation of the Compact Ignition Tokamak in 1991, the United States Department of Energy directed the US fusion program to find ways to improve the tokamak. In 1993, a conceptual design review was held for TPX in 1993, finalizing the conceptual design. The design team was managed by Princeton Plasma Physics Laboratory and included members from other US institutions. The program was canceled in 1995, as the proposed cost was too high. The proposed cost was $539 Million in 1993 dollars.^[1]

Legacy

The KSTAR tokamak built South Korea is based on the TPX design.^[2] KSTAR uses Hydrogen, not Deuterium as TPX was designed to, so neutron activation of components is not as large a problem. Because of this, the titanium vacuum vessel of the TPX design was replaced with a stainless steel vessel in KSTAR, and the remote maintenance system was removed from the design.

Description

Because TPX was designed to be steady-state (or at least long-pulse, with 1,000 seconds duration), the electromagnetic coils which provide the magnetic field were to be superconducting. They were to be made of Niobium–tin superconducting cables.^[1] The toroidal magnetic field strength at the center of the plasma was to be 4.0 Tesla.

TPX was designed to have its toroidal electric current be 100% non-inductively driven. Because of this, it was to have three current drive systems: An 8 MW neutral beam injector system, an 8 MW ion cyclotron resonance system, and a 1.5 MW lower hybrid wave system.^[3] The toroidal current carried by the plasma was to be up to 2.0 MA.

Because TPX was designed to test at least six different high-performance scenarios, its poloidal field coils and current drive systems were designed for flexibility. Some examples of possible scenarios are: one inspired by the ARIES-I reactor design which had an aggressive Beta, one inspired by the Tokamak Fusion Test Reactor Supershot regime, and one with a profile which produced an internal transport barrier for enhanced confinement.^[1]

Related Research Articles

A tokamak is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being developed to produce controlled thermonuclear fusion power. As of 2016, it was the leading candidate for a practical fusion reactor. The word "tokamak" is derived from a Russian acronym meaning "toroidal chamber with magnetic coils".

<span class="mw-page-title-main">Princeton Plasma Physics Laboratory</span> National laboratory for plasma physics and nuclear fusion science at Princeton, New Jersey

Princeton Plasma Physics Laboratory (PPPL) is a United States Department of Energy national laboratory for plasma physics and nuclear fusion science. Its primary mission is research into and development of fusion as an energy source. It is known for the development of the stellarator and tokamak designs, along with numerous fundamental advances in plasma physics and the exploration of many other plasma confinement concepts.

Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices designed to harness this energy are known as fusion reactors. Research into fusion reactors began in the 1940s, but as of 2023, no device has reached net power.

This timeline of nuclear fusion is an incomplete chronological summary of significant events in the study and use of nuclear fusion.

A reversed-field pinch (RFP) is a device used to produce and contain near-thermonuclear plasmas. It is a toroidal pinch which uses a unique magnetic field configuration as a scheme to magnetically confine a plasma, primarily to study magnetic confinement fusion. Its magnetic geometry is somewhat different from that of the more common tokamak. As one moves out radially, the portion of the magnetic field pointing toroidally reverses its direction, giving rise to the term reversed field. This configuration can be sustained with comparatively lower fields than that of a tokamak of similar power density. One of the disadvantages of this configuration is that it tends to be more susceptible to non-linear effects and turbulence. This makes it a useful system for studying non-ideal (resistive) magnetohydrodynamics. RFPs are also used in studying astrophysical plasmas, which share many common features.

JT-60 is a large research tokamak, the flagship of Japan's magnetic fusion program, previously run by the Japan Atomic Energy Research Institute (JAERI) and later by the Japan Atomic Energy Agency's (JAEA) Naka Fusion Institute in Ibaraki Prefecture. As of 2023 the device is known as JT-60SA and it is the largest operational superconducting tokamak in the world to date, and is build and operated jointly by Europe and Japan. SA stands for super advanced tokamak, including a D-shaped plasma cross-section, superconducting coils, and active feedback control.

The Tokamak Fusion Test Reactor (TFTR) was an experimental tokamak built at Princeton Plasma Physics Laboratory (PPPL) circa 1980 and entering service in 1982. TFTR was designed with the explicit goal of reaching scientific breakeven, the point where the heat being released from the fusion reactions in the plasma is equal or greater than the heating being supplied to the plasma by external devices to warm it up.

<span class="mw-page-title-main">Magnetic confinement fusion</span> Approach to controlled thermonuclear fusion using magnetic fields

Magnetic confinement fusion (MCF) is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of controlled fusion research, along with inertial confinement fusion.

DIII-D is a tokamak that has been operated since the late 1980s by General Atomics (GA) in San Diego, USA, for the U.S. Department of Energy. The DIII-D National Fusion Facility is part of the ongoing effort to achieve magnetically confined fusion. The mission of the DIII-D Research Program is to establish the scientific basis for the optimization of the tokamak approach to fusion energy production.

Alcator C-Mod was a tokamak that operated between 1991 and 2016 at the Massachusetts Institute of Technology (MIT) Plasma Science and Fusion Center (PSFC). Notable for its high toroidal magnetic field, Alcator C-Mod holds the world record for volume averaged plasma pressure in a magnetically confined fusion device. Until its shutdown in 2016, it was one of the major fusion research facilities in the United States.

The Experimental Advanced Superconducting Tokamak (EAST), internal designation HT-7U, is an experimental superconducting tokamak magnetic fusion energy reactor in Hefei, China. The Hefei Institutes of Physical Science is conducting the experiment for the Chinese Academy of Sciences. It has operated since 2006.

<span class="mw-page-title-main">National Spherical Torus Experiment</span>

The National Spherical Torus Experiment (NSTX) is a magnetic fusion device based on the spherical tokamak concept. It was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, Columbia University, and the University of Washington at Seattle. It entered service in 1999. In 2012 it was shut down as part of an upgrade program and became NSTX-U, for Upgrade.

The KSTAR is a magnetic fusion device at the Korea Institute of Fusion Energy in Daejeon, South Korea. It is intended to study aspects of magnetic fusion energy that will be pertinent to the ITER fusion project as part of that country's contribution to the ITER effort. The project was approved in 1995, but construction was delayed by the East Asian financial crisis, which weakened the South Korean economy considerably; however, the project's construction phase was completed on September 14, 2007. The first plasma was achieved in June 2008.

The Helically Symmetric Experiment, is an experimental plasma confinement device at the University of Wisconsin–Madison, with design principles that are intended to be incorporated into a fusion reactor. The HSX is a modular coil stellarator which is a toroid-shaped pressure vessel with external electromagnets which generate a magnetic field for the purpose of containing a plasma. It began operation in 1999.

Robert James Goldston is a professor of astrophysics at Princeton University and a former director of the Princeton Plasma Physics Laboratory.

The Princeton Large Torus, was an early tokamak built at the Princeton Plasma Physics Laboratory (PPPL). It was one of the first large scale tokamak machines, and among the most powerful in terms of current and magnetic fields. Originally built to demonstrate that larger devices would have better confinement times, it was later modified to perform heating of the plasma fuel, a requirement of any practical fusion power device.

The history of nuclear fusion began early in the 20th century as an inquiry into how stars powered themselves and expanded to incorporate a broad inquiry into the nature of matter and energy, as potential applications expanded to include warfare, energy production and rocket propulsion.

The Compact Ignition Tokamak (CIT) was a plasma physics experiment that was designed but not built. It was designed by an inter-organizational team in the USA led by Princeton Plasma Physics Laboratory. The experiment was designed to achieve a self-sustaining Thermonuclear fusion reaction (ignition) in a Tokamak with the minimum possible budget.

References

1 2 3 4 5 Schmidt, J. A.; Thomassen, K. I.; Goldston, R. J.; Neilson, G. H.; Nevins, W. M.; Sinnis, J. C.; Andersen, P.; Bair, W.; Barr, W. L.; Batchelor, D. B.; Baxi, C. (1993-09-01). "The design of the Tokamak Physics Experiment (TPX)". Journal of Fusion Energy. 12 (3): 221–258. Bibcode:1993JFuE...12..221S. doi:10.1007/BF01079667. ISSN 1572-9591. S2CID 1993786.
↑ "PPPL physicist Hutch Neilson receives award for decades of leadership on national and international fusion experiments". Princeton Plasma Physics Laboratory. Retrieved 2021-12-03.
↑ Davidson, Ronald C.; Goldston, Robert J.; Neilson, George H.; Thomassen, Keith I. (1995-06-01). "The Tokamak Physics Experiment". Physics of Plasmas. 2 (6): 2417–2426. Bibcode:1995PhPl....2.2417D. doi:10.1063/1.871265. ISSN 1070-664X.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[:0-1] 1 2 3 4 5 Schmidt, J. A.; Thomassen, K. I.; Goldston, R. J.; Neilson, G. H.; Nevins, W. M.; Sinnis, J. C.; Andersen, P.; Bair, W.; Barr, W. L.; Batchelor, D. B.; Baxi, C. (1993-09-01). "The design of the Tokamak Physics Experiment (TPX)". Journal of Fusion Energy. 12 (3): 221–258. Bibcode:1993JFuE...12..221S. doi:10.1007/BF01079667. ISSN 1572-9591. S2CID 1993786.

[2] "PPPL physicist Hutch Neilson receives award for decades of leadership on national and international fusion experiments". Princeton Plasma Physics Laboratory. Retrieved 2021-12-03.

[3] Davidson, Ronald C.; Goldston, Robert J.; Neilson, George H.; Thomassen, Keith I. (1995-06-01). "The Tokamak Physics Experiment". Physics of Plasmas. 2 (6): 2417–2426. Bibcode:1995PhPl....2.2417D. doi:10.1063/1.871265. ISSN 1070-664X.

[1]

[2]

[3]