JET plans for 2009
2 Mar 2009

An intensive series of experimental campaigns was conducted on JET during 2008, following the installation of the first set of major JET enhancements implemented under EFDA (known as EP1). 2009 will see more crucial work being carried out at JET as preparations for ITER gather pace.

Operations are continuing in the first three months of 2009. During this time a number of the enhancements will complete their transition from a commissioning phase into full exploitation. In particular:

• The ‘ITER-like Antenna’, the largest of the EP1 enhancements, is an advanced system for launching radio-frequency waves for plasma heating, designed to prove features which are essential for ITER. These requirements include the ability to launch large amounts of power per unit antenna area, while ensuring the RF generators remain insensitive to rapid fluctuations at the plasma edge. These fluctuations are caused by Edge Localised Modes (or ELMs), which occur in ITER-like plasma operating scenarios.
• Another new system coming into full operation this year is the High Frequency Pellet Injector. This is designed to inject tiny repetitive pellets of frozen hydrogen or deuterium ice into the plasma edge to provoke high frequency ELMs which are more benign, thus avoiding large heat pulses on plasma-facing components – another key ITER requirement.

Starting in April will be a short intervention to implement important elements of the second phase of major JET enhancements in support of ITER (EP2). In particular, an all-new Enhanced Radial Field Amplifier (ERFA) and plasma control system will be installed and commissioned. The ERFA is a special power supply that will allow JET’s unique capability of operating at very high plasma current to be fully exploited, necessary to get even closer to ITER-like combinations of plasma parameters.

After the Spring intervention, there will be a short experimental campaign to bring the ERFA into operation and to carry out experiments under a number of ITER-related themes and exploiting the new JET capabilities.

Following this campaign, the next major shutdown for the installation of the rest of the EP2 enhancements will start later in the year. The ITER-like Wall (ILW) and Neutral Beam Enhancement (NBE) are the largest elements of the EP2 programme. The ILW will provide an all-metal set of plasma-facing components (to replace the existing graphite elements) utilising beryllium and tungsten, as in ITER. The NBE will increase the neutral beam plasma heating power by 50% (to >34MW) and double the pulse length to 20 seconds at full power.

The EP2 enhancements will permit JET to carry out a programme able to support even more closely the needs of ITER in future. The implementation of ILW and NBE will be one of the largest and most complex installation activities ever undertaken on JET, and the start of the EP2 shutdown in 2009 is a major milestone in JET’s development.

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